Diesel Particulate Matter Exposure of Underground Metal and Nonmetal Miners, 28924-29012 [06-4494]
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Federal Register / Vol. 71, No. 96 / Thursday, May 18, 2006 / Rules and Regulations
Mine Safety and Health Administration
30 CFR Part 57
RIN 1219–AB29
Diesel Particulate Matter Exposure of
Underground Metal and Nonmetal
Miners
Mine Safety and Health
Administration (MSHA), Labor.
ACTION: Final rule.
AGENCY:
SUMMARY: This final rule revises the
May 20, 2006 effective date of the diesel
particulate matter (DPM) final
concentration limit of 160 micrograms
of total carbon (TC) per cubic meter of
air (160TC µg/m3) promulgated in the
2001 final rule ‘‘Diesel Particulate
Matter Exposure of Underground Metal
and Nonmetal Miners,’’ and published
in the Federal Register on January 19,
2001 (66 FR 5706) and amended on
September 19, 2005 (70 FR 55019).
This final rule increases flexibility of
compliance for mine operators by
allowing staggered effective dates for
implementation of the final DPM limit,
phased-in over a two-year period,
primarily based on feasibility issues
which have surfaced since promulgation
of the 2001 final rule.
Furthermore this final rule establishes
requirements for medical evaluation of
miners required to wear respiratory
protection and transfer of miners who
are medically unable to wear a
respirator; deletes the existing provision
that restricts newer mines from applying
for an extension of time in which to
meet the final concentration limit;
addresses technological and economic
feasibility issues, and the costs and
benefits of this rule.
31 Mine Study ...................................................
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Commission .......................................................
CV ......................................................................
DPF ....................................................................
DPM ...................................................................
EC .......................................................................
ETS ....................................................................
Filter Selection Guide .......................................
First Partial Settlement Agreement ..................
MARG ................................................................
M/NM .................................................................
MSHA ................................................................
NIOSH ...............................................................
NTP ....................................................................
OC ......................................................................
PAPR ..................................................................
PEL .....................................................................
PPM ....................................................................
QRA ...................................................................
REA ....................................................................
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This final rule is
effective on May 18, 2006 except for
amendments to § 57.5060(d), which is
effective August 16, 2006.
FOR FURTHER INFORMATION CONTACT:
Patricia W. Silvey, Acting Director,
Office of Standards, Regulations, and
Variances, MSHA, 1100 Wilson Blvd.,
Room 2350, Arlington, Virginia 22209–
3939; 202–693–9440 (telephone); or
202–693–9441 (facsimile).
You may obtain copies of this final
rule and the Regulatory Economic
Analysis (REA) in alternative formats by
calling 202–693–9440. The alternative
formats are either a large print version
of these documents or electronic files
that can be sent to you either on a
computer disk or as an attachment to an
e-mail. The documents also are
available on the Internet at https://
www.msha.gov/REGSINFO.HTM.
SUPPLEMENTARY INFORMATION:
EFFECTIVE DATE:
DEPARTMENT OF LABOR
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Outline of Preamble
This outline will assist the mining
community in finding information in
this preamble.
I. List of Common Terms
II. Background
A. First Partial Settlement Agreement
B. Second Partial Settlement Agreement
III. Rulemaking History
A. Advance Notice of Proposed
Rulemaking (ANPRM) on the Interim
and Final Concentration Limits
B. Notice of Proposed Rulemaking (NPRM)
on the Interim Limit
C. Final Rule Revising the Interim
Concentration Limit
D. September 2005 Notice of Proposed
Rulemaking
IV. Risk Assessment
V. Feasibility
A. Technological Feasibility
B. Economic Feasibility
VI. Summary of Benefits
VII. Section 101(a)(9) of the Mine Act
VIII. Section-by-Section Analysis
A. PEL § 57.5060(b)
B. Special Extensions § 57.5060(c)(3)(i)
C. Medical Evaluation and Transfer
§ 57.5060(d)
D. Diesel Particulate Records § 57.5075(a)
IX. Regulatory Costs
A. Costs of Medical Evaluation and
Transfer
B. Costs of Implementing the 160TC µg/m3
Limit
X. Regulatory Flexibility Act Certification
(RFA) and Small Business Regulatory
Enforcement Fairness Act (SBREFA)
A. Definition of a Small Mine
B. Factual Basis for Certification
XI. Paperwork Reduction Act
XII. Other Regulatory Considerations
A. The Unfunded Mandates Reform Act of
1995
B. National Environmental Policy Act
C. The Treasury and General Government
Appropriations Act of 1999: Assessment
of Federal Regulations and Policies on
Families
D. Executive Order 12630: Government
Actions and Interference With
Constitutionally Protected Property
Rights
E. Executive Order 12988: Civil Justice
Reform
F. Executive Order 13045: Protection of
Children From Environmental Health
Risks and Safety Risks
G. Executive Order 13132: Federalism
H. Executive Order 13175: Consultation
and Coordination With Indian Tribal
Governments
I. Executive Order 13211: Actions
Concerning Regulations That
Significantly Affect Energy Supply,
Distribution, or Use
J. Executive Order 13272: Proper
Consideration of Small Entities in
Agency Rulemaking
XIII. Information Quality
XIV. References Cited
XV. Regulatory Text
I. List of Common Terms
Listed below are the common terms
used in the preamble.
Joint MSHA/Industry Study: Determinations of DPM levels in Underground Metal and
Nonmetal Mines.
Federal Mine Safety and Health Review Commission.
Coefficient of Variation.
diesel particulate filter.
diesel particulate matter.
elemental carbon.
environmental tobacco smoke.
Diesel Particulate Filter Selection Guide for Diesel-powered Equipment in Metal and
Nonmetal Mines.
66 FR 35518 (2001) & 66 FR 35521 (2001): basis for July 5, 2001 NPRM.
Methane Awareness Resource Group.
metal/non-metal.
Mine Safety and Health Administration.
National Institute for Occupational Safety and Health.
National Toxicology Program.
organic carbon.
powered air-purifying respirator.
permissible exposure limit.
parts per million.
quantitative risk assessment.
Regulatory Economic Analysis.
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Federal Register / Vol. 71, No. 96 / Thursday, May 18, 2006 / Rules and Regulations
67 FR 47296 (2002): basis for August 14, 2003 NPRM.
standard deviation.
SKC, Inc.
total carbon (the sum of elemental and organic carbon).
United Steelworkers of America.
United Steelworkers.
micrograms per square centimeter.
micrograms per cubic meter.
January 19, 2001 DPM final rule.
2001 final rule amended on February 27, 2002.
February 27, 2002 final rule.
Advance Notice of Proposed Rulemaking published on September 25, 2002.
Notice of Proposed Rulemaking published on August 14, 2003.
June 6, 2005 final rule.
Notice of Proposed Rulemaking published on September 7, 2005.
II. Background
On January 19, 2001, MSHA
published a final rule addressing the
health hazards to underground metal
and nonmetal miners from exposure to
diesel particulate matter (DPM) (66 FR
5706). The rule established new health
standards for these miners by requiring,
among other things, mine operators to
use engineering and work practice
controls to reduce DPM to prescribed
limits. It set an interim and final DPM
concentration limit in the underground
metal and nonmetal mining
environment with staggered effective
dates for implementation of the
concentration limits. The interim
concentration limit of 400TC µg/m3 was
to become effective on July 20, 2002.
The final concentration limit of 160TC
µg/m3 was scheduled to become
effective January 20, 2006. In the 2001
final rule, MSHA projected that the
mining industry would meet the final
concentration limit in their mines
through the use of diesel particulate
filtration devices, ventilation changes,
and the turnover of equipment and
engines to less polluting models (66 FR
5713, 5888).
Several mining trade associations and
individual mine operators challenged
the final rule and the United
Steelworkers of America (USWA)
intervened in the case, which is now
pending in the United States Court of
Appeals for the District of Columbia
Circuit. The parties agreed to resolve
their differences through settlement
negotiations with MSHA and we
delayed the effective date of certain
provisions of the standard.
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Second Partial Settlement Agreement .............
SD ......................................................................
SKC ....................................................................
TC ......................................................................
USWA ................................................................
USW ...................................................................
µg/cm2 ...............................................................
µg/m3 .................................................................
2001 final rule ...................................................
Amended 2001 final rule .................................
2002 final rule ...................................................
2002 ANPRM .....................................................
2003 NPRM .......................................................
2005 final rule ...................................................
2005 proposed rule ...........................................
make limited revisions to § 57.5066(b)
and added a new paragraph to
§ 57.5067(b) ‘‘Engines’’ regarding the
definition of the term ‘‘introduced.’’
MSHA published the final rule on
February 27, 2002 (67 FR 9180).
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A. First Partial Settlement Agreement
On July 5, 2001, as a result of an
agreement reached in settlement
negotiations, MSHA published two
notices in the Federal Register. One
notice (66 FR 35518) delayed the
effective date of § 57.5066(b) related to
tagging requirements in the
maintenance standard. The second
notice (66 FR 35521) proposed a rule to
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B. Second Partial Settlement Agreement
Settlement negotiations continued on
the remaining unresolved issues in the
litigation, and on July 15, 2002, the
parties finalized a written agreement (67
FR 47296, 47297). Under the agreement,
the interim concentration limit of 400TC
µg/m3 became effective on July 20, 2002,
without further legal challenge. MSHA
afforded mine operators one year to
develop and implement good-faith
compliance strategies to meet the
interim concentration limit, and MSHA
agreed to provide compliance assistance
during this one-year period. MSHA also
agreed to propose rulemaking on several
other disputed provisions of the 2001
final rule. The legal challenge to the rule
was stayed pending completion of the
additional rulemakings.
On July 20, 2003, MSHA began full
enforcement of the interim
concentration limit of 400TC µg/m3.
MSHA’s enforcement policy was also
based on the terms of the second partial
settlement agreement and includes the
use of elemental carbon (EC) as an
analyte to ensure that a citation based
on the 400 TC concentration limit is
valid and not the result of interferences
(67 FR 47298). The policy was
discussed with the DPM litigants and
stakeholders on July 17, 2003.
III. Rulemaking History
A. Advance Notice of Proposed
Rulemaking (ANPRM) on the Interim
and Final Concentration Limits
On September 25, 2002, MSHA
published an Advance Notice of
Proposed Rulemaking (ANPRM) (67 FR
60199). MSHA noted in the ANPRM
that the scope of the rulemaking was
limited to the terms of the Second
Partial Settlement Agreement and posed
a series of questions to the mining
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community related to the 2001 final
rule. MSHA also stated its intent to
propose a rule to revise the surrogate for
the interim and final concentration
limits and to propose a DPM control
scheme similar to that included in our
longstanding hierarchy of controls
scheme used in MSHA’s air quality
standards (30 CFR 56.5001 through
56.5005 and 57.5001 through 57.5005)
for M/NM mines. In addition, MSHA
stated that it would consider
technological and economic feasibility
for the underground M/NM mining
industry to comply with revised interim
and final DPM limits. MSHA
determined at that time that some mine
operators had begun to implement
control technology on their
underground diesel-powered
equipment. Therefore, MSHA requested
relevant information on current
experiences with availability of control
technology, installation of control
technology, effectiveness of control
technology to reduce DPM levels, and
cost implications of compliance with
the 2001 final rule.
B. Notice of Proposed Rulemaking
(NPRM) on the Interim Limit
In response to our publication of the
ANPRM, some commenters
recommended that MSHA propose
separate rulemakings for revising the
interim and final concentration limits to
give MSHA an opportunity to gather
further information to establish a final
DPM limit, particularly regarding
feasibility. In the subsequent notice of
proposed rulemaking (NPRM) published
on August 14, 2003 (68 FR 48668),
MSHA concurred with these
commenters and notified the public in
the NPRM that we would propose a
separate rulemaking to amend the
existing final concentration limit of
160TC µg/m3. MSHA also requested
comments on an appropriate final DPM
limit and solicited additional
information on feasibility. The proposed
rule also addressed the interim
concentration limit by proposing a
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comparable PEL of 308 µg/m3 based on
the EC surrogate and included a number
of other provisions.
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C. Final Rule Revising the Interim
Concentration Limit
MSHA published the final rule
revising the interim concentration limit
on June 6, 2005 (70 FR 32868). This rule
changed the interim concentration limit
of 400 µg/m3 measured by TC to a
comparable PEL of 308 µg/m3 measured
by EC. The rule requires MSHA’s
longstanding hierarchy of controls that
is used for other MSHA exposure-based
health standards at M/NM mines, but
retains the prohibition on rotation of
miners for compliance. Furthermore, the
rule, among other things, requires
MSHA to consider economic as well as
technological feasibility in determining
if operators qualify for an extension of
time in which to meet the final DPM
limit, and deletes the requirement for a
control plan.
Currently, the following provisions of
the DPM standard are effective:
§ 57.5060(a), establishing the interim
PEL of 308 micrograms of EC per cubic
meter of air which is comparable in
effect to 400 micrograms of TC per cubic
meter of air; § 57.5060(d), Addressing
control requirements; § 57.5060(e),
Prohibiting rotation of miners for
compliance with the DPM standard;
§ 57.5061, Compliance determinations;
§ 57.5065, Fueling practices; § 57.5066,
Maintenance standards; § 57.5067,
Engines; § 57.5070, Miner training;
§ 57.5071, Exposure monitoring; and,
§ 57.5075, Diesel particulate records.
D. September 2005 Notice of Proposed
Rulemaking
On September 7, 2005, (70 FR 53280)
MSHA proposed a rule to phase in the
final DPM limit because MSHA was
concerned that there may be feasibility
issues for some mines to meet that limit
by January 20, 2006.
Accordingly, the proposed rule
considered staggering the effective date
for implementation of the final DPM
limit, phased in over a five-year period,
primarily based on feasibility issues
which had surfaced since promulgation
of the 2001 final rule. MSHA also
proposed to delete existing
§ 57.5060(c)(3)(i) that restricts new
mines from applying for an extension of
time for meeting the final concentration
limit. MSHA sought comment and data
on an appropriate conversion factor for
the final DPM limit, technological
implementation issues, and the costs
and benefits of the final rule. In
addition, MSHA requested comments
on the appropriateness of including in
a final rule a provision for medical
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evaluation of miners required to wear
respiratory protection and transfer of
miners who have been determined by a
medical professional to be unable to
wear a respirator.
MSHA set hearing dates and a
deadline for receiving comments on the
September 7, 2005 proposed rule with
the expectation that MSHA would
complete the rulemaking to phase in the
final DPM limit before January 20, 2006.
After publication of the September 7,
2005 proposed rule, MSHA received a
request from the United Steel, Paper and
Forestry, Rubber, Manufacturing,
Energy, Allied Industrial and Service
Workers International Union (USW) for
more time to comment on the proposed
rule. The USW explained that Hurricane
Katrina had placed demands on their
resources that would prevent them from
participating effectively in the
rulemaking under the current schedule
for hearings and comments. MSHA
recognized the USW’s need to devote
resources to respond to the aftermath of
Hurricane Katrina and the impact that
would have on their participation under
the current timetable. MSHA also
received a request from the National
Stone, Sand and Gravel Association
(NSSGA) for additional time to
comment on the proposed rule and for
an additional public hearing in
Arlington, Virginia.
Accordingly, due to requests from the
USW and NSSGA, MSHA published a
notice on September 19, 2005 (70 FR
55018) that changed the public hearing
dates from September 2005 to January
2006. MSHA also extended the public
comment period from October 14, 2005
to January 27, 2006. Also on September
19, 2005, MSHA issued a second notice
delaying the applicability of the final
concentration limit of 160TC µg/m3
until May 20, 2006.
Public hearings were held on the
proposed rule in Arlington, Virginia on
January 5, 2006; Salt Lake City, Utah on
January 9, 2006; Kansas City, Missouri
on January 11, 2006; and Louisville,
Kentucky on January 13, 2006. The
comment period was scheduled to close
on January 27, 2006. However, the
National Mining Association and the
Methane Awareness Resource Group
(MARG) Diesel Coalition requested that
the comment period be extended an
additional 30 days beyond January 27,
2006 to allow for more time to prepare
their comments. Additionally, the
Agency received a request from the
National Institute for Occupational
Safety and Health (NIOSH) for a three
week extension. On January 26, 2006,
MSHA determined that a three week
extension of the comment period was
sufficient to allow additional public
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comment on the proposed rule and
extended the comment period until
February 17, 2006.
What follows is a discussion of the
specific revisions to the 2001 DPM
standard. The final rule addresses:
• Section 57.5060(b) addressing the
final dpm concentration limit;
• Section 57.5060(c)(3)(i) addressing
special extensions;
• Section 57.5060(d)addressing
medical evaluation and transfer; and
• Section 57.5075 addressing
recordkeeping requirements.
IV. Risk Assessment
A. Introduction
We rely on our comprehensive
January 2001 risk assessment published
at 66 FR 5752–5855 (as corrected at 66
FR 35518–35520) to support this final
rule. This risk assessment was updated
in the 2005 final rule (70 FR 32868)
establishing the 308EC µg/m3 interim
permissible exposure limit (PEL). In the
following discussion, we will refer to
the risk assessment published in the
2001 final rule as the ‘‘2001 risk
assessment’’ and the updates published
in the 2005 final rule as the ‘‘updated
2001 risk assessment.’’
The discussion of the 2001 risk
assessment in our 2005 final rule
presented our evaluation of health risks
associated with DPM exposure levels
encountered in the mining industry and
is based on a review of the scientific
literature available through March 31,
2000, along with consideration of all
material submitted during the public
comment periods for the 2001 and 2005
rulemakings.
The 2001 risk assessment was divided
into three main sections. Section 1 (66
FR 5753–5764) contained a discussion
of U.S. miner exposures based on field
data collected through mid-1998.
Section 2 of the 2001 risk assessment
(66 FR 5764–5822) reviewed the
extensive scientific literature on health
effects associated with exposures to
DPM. In section 3 of the 2001 risk
assessment (66 FR 5822–5855), we
evaluated the best available evidence to
ascertain whether exposure levels
currently existing in mines warranted
regulatory action pursuant to the Mine
Act. After careful consideration of all
the submitted public comments, the
2001 risk assessment established three
main conclusions:
1. Exposure to DPM can materially impair
miner health or functional capacity. These
material impairments include acute sensory
irritations and respiratory symptoms
(including allergenic responses); premature
death from cardiovascular, cardiopulmonary,
or respiratory causes; and lung cancer.
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2. At DPM levels currently observed in
underground mines, many miners are
presently at significant risk of incurring these
material impairments due to their
occupational exposures to DPM over a
working lifetime.
3. By reducing DPM concentrations in
underground mines, the rule will
substantially reduce the risks of material
impairment faced by underground miners
exposed to DPM at current levels (66 FR
5854–5855).
Exposure to DPM can materially
impair miner health or functional
capacity. These material impairments
include acute sensory irritations and
respiratory symptoms (including
allergenic responses); premature death
from cardiovascular, cardiopulmonary,
or respiratory causes; and lung cancer.
Scientific evidence gathered after the
peer-review of the 2001 risk assessment
generally supports our conclusions, and
nothing in our reviews suggests that
they should be altered.
Some commenters presented critiques
challenging the 2001 risk assessment
and disputing scientific support for any
DPM exposure limit, especially by
means of an EC surrogate. Other
commenters endorsed the risk
assessment and stated that recent
scientific publications support our
conclusions.
Some commenters continue to
question the scientific basis for linking
DPM exposures with an increased risk
of adverse health effects. Many of these
comments are the same as those
addressed in the 2005 final rule. We
refer the reader to section VI, DPM
Exposures and Risk Assessment, in the
2005 final rule (70 FR at 32888) for
discussions addressing earlier
commenters’ positions on the
underlying basis of the risk assessment.
After considering the additional peerreviewed scientific literature submitted
in response to the proposed rule, and all
of the comments, we did not identify
any reason to reduce our concern with
regard to adverse health risks associated
with DPM exposure as identified in the
2001 risk assessment.
Section IV.B, summarizes the DPM
exposure data that became available
after publication of the 2001 final rule.
Section IV.C, Health Effects,
summarizes additional scientific
literature pertaining to adverse health
effects of DPM and fine particulates
submitted to the record since our 2005
final rule. The reader is encouraged to
refer to the 2001 quantitative risk
assessment (66 FR 5752–5855) that
reviewed the health effects associated
with exposure to DPM. This discussion
evaluates the extent to which literature
added to the record changes the
conclusions of the 2001 risk assessment.
Section IV.D, Significance of Risk,
supplements Section 2 of the 2001 risk
assessment (66 FR 5764–5822) by
addressing comments related to the risk
assessment.
We reviewed comments on the
potential health effects of substituting
EC for TC as a surrogate measure of
DPM. We believe that the issue of an
appropriate surrogate for a measure of
DPM is separate from the issue of
determining whether adverse health
effects are caused by whole DPM or a
specific component of DPM. The 2001
risk assessment is definitive in
explaining relevant adverse health
effects caused by exposure to DPM. The
risk assessment accurately portrays
adverse health effects ranging from
sensory irritation to lung cancer caused
by exposure to DPM. The method by
which exposures are measured does not
affect the conclusion that exposure to
DPM produces serious adverse health
effects. Comments concerning the
analytical method are addressed in part
VIII.A. Section 57.5060(b), addressing
the final limits.
B. Exposures to DPM in Underground
Metal and Nonmetal Mines
The 2001 risk assessment and the
update presented in 2005 used the best
available data on exposure to DPM at
underground M/NM mines to quantify
excess lung cancer risk. ‘‘Excess risk’’
refers to the lifetime probability of dying
from lung cancer during or after a 45year occupational DPM exposure. All of
the exposure-response models for lung
cancer are monotonic (i.e., increased
exposure yields increased excess risk).
We evaluated exposures based on 355
samples collected at 27 underground
U.S. M/NM mines prior to promulgating
the 2001 rule. Mean DPM
concentrations found in the production
areas and haulageways at those mines
ranged from about 285 µg/m3 to about
2000 µg/m3, with some individual
measurements exceeding 3500 µg/m3.
The overall mean DPM concentration
was 808 µg/m3. All of the samples
considered in the 2001 risk assessment
were collected prior to 1999.
Two sets of DPM exposure data,
collected after promulgation of the 2001
final rule, were compiled for
underground M/NM mines: (1) data
collected in 2001 and 2002 from 31
mines for purposes of the 31-Mine
Study (Table IV–1) and (2) data
collected between 10/30/2002 and 10/
29/2003 from 183 mines to establish a
baseline for future sample comparisons
(Table IV–2). The mean whole DPM
concentration across all 358 valid
samples in the 31-Mine Study was
432DPM µg/m3. The mean
concentration across all valid 1,194
baseline samples was 318DPM µg/m3.1
TABLE IV–1.—DPM CONCENTRATIONS (µg/m3) BY MINE CATEGORY FOR SAMPLES COLLECTED FOR THE 31-MINE STUDY
(2001–2002)
[DPM is estimated by TC ÷ 0.8]
Estimated 8-hour Full Shift Equivalent
DPM Concentration (µg/m3)
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Metal
Stone
116
46
2,581
491
610
45
699
522
1 The relationship DPM ≈ TC/0.8 is the same as
that assumed in the 2001 risk assessment. The
the Second Partial Settlement Agreement, based on
TC:EC ratios observed in the joint 31-Mine Study.
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54
20
331
82
94
9
113
75
Other
No. of samples .........................................................................................................................
Minimum ..................................................................................................................................
Maximum .................................................................................................................................
Median .....................................................................................................................................
Mean ........................................................................................................................................
Std. Error ..........................................................................................................................
95% UCL ..........................................................................................................................
95% LCL ...........................................................................................................................
relationship TC ≈ 1.3 × EC was formulated under
105
16
1,845
331
465
36
537
394
Trona
83
27
1,210
341
359
27
412
306
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TABLE IV–2.—DPM CONCENTRATIONS BY MINE CATEGORY FOR SAMPLES COLLECTED DURING THE BASELINE SAMPLING
PERIOD (10/30/2002–10/29/2003)
[DPM is estimated by (1.3 × EC) ÷ 0.8.]
Estimated 8-hour Full Shift Equivalent DPM Concentration ( µg/m3)
Metal
No. of Samples ............................................................................
Maximum ......................................................................................
Median .........................................................................................
Mean ............................................................................................
Std. Error ..............................................................................
95% UCL ..............................................................................
95% LCL ...............................................................................
Thus, despite substantial
improvements attained since the 1989–
1999 sampling period addressed by the
2001 risk assessment, underground M/
NM miners are still faced with an
unacceptable risk of lung cancer due to
their occupational exposure to DPM.
The reader is referred to part D of this
section, Significance of Risk, for further
discussion of excess risk.
Personal exposure samples taken after
October 2003 are collected according to
our enforcement sampling policy. These
enforcement samples collected after the
end of the Baseline Sampling period are
not representative of the average M/NM
miner’s exposure to DPM because we
collect samples to target the highest risk
miner, not the average miner. Therefore,
this exposure information is not used to
characterize the average miner’s
exposure to DPM. See section V.B,
Economic Feasibility, for a summary of
enforcement sampling results. However,
our enforcement activities from
November 1, 2003 through January 31,
2006 continue to show some miners
have experienced exposures
substantially greater than 308EC µg/m3.
During the time period from November
1, 2003 to January 31, 2006, 1,798 valid
personal compliance samples from all
mines covered by the regulation were
collected. From these samples collected,
18% (324) of samples exceeded 308EC
µg/m3, 22% (396) exceeded 350TC µg/
m3, and 64% (1,151) exceeded 160TC µg/
m3. These percentages show that miners
are still being exposed to high levels of
DPM.
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C. Health Effects
A key conclusion of the 2001 risk
assessment was:
Exposure to DPM can materially impair
miner health or functional capacity. These
material impairments include acute sensory
irritations and respiratory symptoms
(including allergenic responses); premature
death from cardiovascular, cardiopulmonary,
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Stone
284
2,532
339
444
23
490
399
Other N/M
689
3,724
186
295
13
320
270
or respiratory causes; and lung cancer. [66 FR
5854–5855]
We have reviewed scientific literature
pertaining to health effects of fine
particulates in general and DPM in
particular published later than what was
considered in the 2001 risk assessment.
This scientific evidence supports the
2001 risk assessment, and nothing in
our review suggests that it should be
altered.
A number of commenters endorsed
the 2001 risk assessment, and suggested
that the latest evidence strengthens its
conclusions. Some other commenters
responding to our 2003 NPRM jointly
stated that ‘‘[t]he scientific evidence for
the [adverse] health effects of DPM is
overwhelming’’ and that ‘‘evidence for
the carcinogenicity and non-cancer
health effects of DPM has grown since
1998.’’
A number of commenters contended
that all of the evidence to date is
insufficient to support limitation of
occupational exposure to DPM. We
believe that these commenters did not
appreciate evidence presented in the
2001 risk assessment and/or
mischaracterized its conclusions. For
example, a few commenters erroneously
stated that promulgation of the 2001
rule was based on only ‘‘two principal
health concerns: (1) The transitory,
reversible health effects of exposure to
DPM; and, (2) the long-term impacts
that may result in an excess risk of lung
cancer for exposed workers.’’ Actually,
as shown in the conclusion cited above,
the 2001 risk assessment identified
three different kinds of material health
impairment associated with DPM
exposure: (1) Acute sensory irritations
and respiratory symptoms (including
allergenic responses); (2) premature
death from cardiovascular,
cardiopulmonary, or respiratory causes;
and (3) lung cancer. Although the
cardiovascular, cardiopulmonary, and
respiratory effects were associated with
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Trona
196
1,200
185
243
15
272
214
25
509
102
132
20
173
91
Total
1,194
3,724
218
318
10
338
299
Total
excluding
Trona
1,169
3,724
223
322
10
342
303
acute exposure to DPM, commenters
presented no evidence that any such
effects were ‘‘transitory’’ or ‘‘reversible.’’
Nor did commenters present evidence
that immunological responses
associated with either short-term or
long-term DPM exposure were
‘‘transitory’’ or ‘‘reversible.’’
In addition, some commenters
erroneously stated that ‘‘no
[quantitative] dose/response
relationship related to the PELs could be
demonstrated by MSHA.’’ These
commenters apparently did not
appreciate the discussion of exposureresponse relationships in the 2001 risk
assessment (66 FR 5847–54) and failed,
specifically, to note the quantitative
exposure-response relationships shown
for lung cancer in the two tables
provided (66 FR 5852–53). Relevant
exposure-response relationships were
also demonstrated in articles by Pope et
al. cited in the 2003 NPRM, which will
be discussed further below.
Some commenters objected that the
exposure-response relationships
presented in the 2001 risk assessment
did not justify adoption of the specific
DPM exposure limits promulgated.
These commenters mistakenly assume
the limits set forth in the 2001 final rule
were derived from an exposure-response
relationship. As explained in 66 FR at
5710–14, the choice of exposure limits,
while justified by quantifiable adverse
health effects, was actually driven by
feasibility concerns. The exposureresponse relationships provided clear
evidence of significant adverse human
health effects (both cancer and noncancer) at exposure levels far below
those determined to be feasible for
mining.
The additional scientific literature
cited in the 2003 NPRM, the 2005 final
rule and this 2006 final rule is meant
only to update and supplement the
evidence of health effects cited in the
2001 risk assessment. Although the
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Federal Register / Vol. 71, No. 96 / Thursday, May 18, 2006 / Rules and Regulations
2001 risk assessment presented ample
evidence to justify its conclusions,
additional supplemental DPM health
effects literature is reviewed in this
document that became available after
the 2001 risk assessment was published.
The following section summarizes
additional studies submitted to the
record. Our review focuses on the
implications of these study results for
the characterization of risk presented in
MSHA’s 2001 assessment. These study
summaries are presented in three tables
that correspond to the material health
impairments identified in the 2001 risk
assessment: (1) Respiratory and
immunological effects, including
asthma, (2) cardiovascular and
cardiopulmonary effects, and (3) cancer.
A fourth table focuses on a recent study
about potential mechanisms of action
for DPM. These tables describe the
studies that some commenters and the
agency felt were representative of the
type of new information available since
the completion of the 2001 assessment
and the updated 2001 risk assessment,
however, these tables are not to
represent a comprehensive review of all
information published about particulate
matter.
(1) Respiratory and Immunological
Effects, Including Allergenic Responses
In the 2001 risk assessment, acute
sensory irritations with respiratory
symptoms, including immunological or
allergenic effects such as asthmatic
responses, were grouped together.
Similar material health impairments
likely to be caused or exacerbated by
excessive exposures to DPM were
identified. This finding was based on
human experimental and
epidemiological studies and was
supported by experimental toxicology.
28929
(For an explanation of what type of
health effects are considered by us to be
material impairments of health, the
reader is referred to the 2001 risk
assessment (See 66 FR 5766.)
Table IV–3 summarizes five studies
dealing with respiratory and
immunological effects of DPM and/or
fine particulates in general that have
been submitted to the record since the
2005 literature update to the 2001 risk
assessment. The epidemiological studies
by Hoppin (2004) and Pourazar (2004)
provide additional support for the
association between diesel exhaust
exposure and development of asthma.
Three of the studies, Gluck (2003),
Stenfors (2004), and Behndig (2006),
have also shown that exposures of
human volunteers to diesel exhaust at
levels below 160TC µg/m3 cause
inflammation of the human respiratory
tract.
TABLE IV–3.—STUDIES OF HUMAN RESPIRATORY AND IMMUNOLOGICAL EFFECTS
Authors, year
Description
Key results
Behndig et al., 2006 .............
15 healthy volunteers exposed to diesel exhaust or air
(2 hours, diesel concentration measured as PM10:
100 µg/m3) Eighteen hours after exposure, the volunteers were assessed using bronchoscopy with
bronchoalveolar lavage and endobronchial mucosal
biopsy.
Comparison of nasal cytological examinations of 136
customs officers involved solely in clearance of
heavy-goods vehicles using diesel engines with examinations of 58 officers working only in offices. Examinations were performed twice a year over a period of 5 years. Measured diesel engine emission
concentrations for the exposed group varied between
31 and 60 µg/m3.
An association between diesel exhaust exposure and
development of asthma is explored. The study evaluated the odds of wheeze associated with nonpesticide occupational exposures in a cohort of approximately 21,000 farmers in Iowa and North Carolina.
Logistic regression models controlling for age, state,
smoking, and history of asthma or atopy were applied to evaluate odds of wheeze in the past year.
15 healthy volunteers were exposed to diesel exhaust
or air for 1 hour. Diesel concentration was measured
as PM10 at 300 µg/m3).
Exposure to diesel exhaust at this concentration is sufficient to cause airway inflammation.
Gluck et al., 2003 .................
Hoppin et al., 2004 ..............
Pourazar et al., 2004 ...........
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Stenfors et al., 2004 ............
25 healthy volunteers and 15 mild asthmatics were exposed to diesel exhaust or air alone for two hours
(diesel concentration measured as PM10 at 108 µg/
m3). At six hours after exposure, subjects underwent
bronchoscopy with bronchoalveolar lavage and
mucosal biopsies.
Review Article on Respiratory and
Immunological Effects Considered after
the 2005 Final Rule
There is a progressive accumulation
of evidence showing the inflammatory
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The exposed group was found to have chronic inflammatory changes of the nasal mucosa, including goblet cell hyperplasia, increased metaplastic and
dysplastic epithelia, and increased leukocytes while
the unexposed group did not.
Driving diesel tractors was significantly associated with
elevated odds of wheeze (odds ratio = 1.31; 95%
confidence interval = 1.13, 1.52). The odds ratio for
driving gasoline tractors was lower but significant at
1.11 (95% confidence interval = 1.02, 1.21). A duration-response relationship was observed for driving
diesel tractors but not for driving gasoline tractors.
This level of diesel exposure caused a significant increase in expression of the cytokine interleukin-13 in
the airways of these volunteers. Interleukin-13 is
known to play a key role in the pathogenesis of asthma.
Diesel exhaust exposure was documented to cause airways inflammation in healthy volunteers. Diesel exhaust exposure did not significantly worsen existing
airways inflammation in the asthmatics, but did significantly increase airways expression of the important allergy-associated cytokine, interleukin-10.
and immunologic effects of diesel
exhaust particulate exposure plays a
role in the development of allergies and
asthma. The 2001 risk assessment and
the update to the risk assessment
describe in detail review articles
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addressing these effects. The most
recent review by Riedl and DiazSanchez (2005), summarized in Table
IV–4, provides an overview of
observational and experimental studies
that link DPM and asthma.
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Federal Register / Vol. 71, No. 96 / Thursday, May 18, 2006 / Rules and Regulations
TABLE IV–4.—REVIEW ARTICLES ON RESPIRATORY AND IMMUNOLOGICAL EFFECTS
Authors, year
Riedl and Diaz-Sanchez,
2005.
Description
Key results
Review of evidence-based studies of the health effects
of air pollutants on asthma, focusing on diesel exhaust particles (DEP).
Intact DEP and extracts of DEP induce reactive oxygen
species production. DEP and particulate matter induce release of Granulocyte Macrophage-Colony
Stimulating Factor and increase intracellular peroxide
production.
The ultrafine particle fraction of diesel exhaust might
also exert biologic effects independent of chemical
composition through penetration of cellular components, such as mitochondria.
In its 2002 ‘‘Health Assessment
Document for Diesel Engine Exhaust,’’
the Environmental Protection Agency
(EPA) reached the following conclusion
with respect to immunological effects of
diesel exhaust:
Recent human and animal studies show
that acute DE [diesel exhaust] exposure
episodes can exacerbate immunological
reactions to other allergens or initiate a DEspecific allergenic reaction. The effects seem
to be associated with both the organic and
carbon core fraction of DPM. In human
subjects, intranasal administration of DPM
has resulted in measurable increases of IgE
antibody production and increased nasal
mRNA for some proinflammatory cytokines.
These types of responses also are markers
typical of asthma, though for DE, evidence
has not been produced in humans that DE
exposure results in asthma. The ability of
DPM to act as an adjuvant to other allergens
also has been demonstrated in human
subjects. (EPA, 2002)
Submissions to the rulemaking record
since the 2005 final rule support our
previous position that exposure to DPM
is associated with the development of
adverse respiratory and immunological
effects.
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(2) Cardiovascular and
Cardiopulmonary Effects
In the 2001 risk assessment, the
evidence presented for DPM’s adverse
cardiovascular and cardiopulmonary
effects relied on data from air pollution
studies in the ambient air. This
evidence identifies premature death
from cardiovascular, cardiopulmonary,
or respiratory causes as an endpoint
significantly associated with exposures
to fine particulates. The 2001 risk
assessment found that ‘‘[t]he mortality
effects of acute exposures appear to be
primarily attributable to combustionrelated particles in PM2.5 [i.e., fine
Particulate Matter] (such as DPM)
* * *.’’
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There are difficulties involved in
utilizing the evidence from such studies
in assessing risks to miners from
occupational exposure to DPM. As
noted in the 2001 risk assessment,
First, although DPM is a fine particulate,
ambient air also contains fine particulates
other than DPM. Therefore, health effects
associated with exposures to fine particulate
matter in air pollution studies are not
associated specifically with exposures to
DPM or any other one kind of fine particulate
matter. Second, observations of adverse
health effects in segments of the general
population do not necessarily apply to the
population of miners. Since, due to age and
selection factors, the health of miners differs
from that of the public as a whole, it is
possible that fine particles might not affect
miners, as a group, to the same degree as the
general population (66 FR 5767).
However,
Since DPM is a type of respirable particle,
information about health effects associated
with exposures to respirable particles, and
especially to fine particulate matter, is
certainly relevant, even if difficult to apply
directly to DPM exposures (66 FR 5767).
One new study on cardiovascular and
cardiopulmonary effects was added to
the record. See Toxicological Effects in
this section for a summary of this
article.
The EPA concluded in its 2002 Health
Assessment Document for Diesel Engine
Exhaust that diesel exhaust (as
measured by DPM) is ‘‘likely to be a
human carcinogen.’’ Furthermore, the
assessment concluded that ‘‘[s]trong
evidence exists for a causal relationship
between risk for lung cancer and
occupational exposure to
D[iesel]E[xhaust] in certain
occupational workers’’ (Health
Assessment Document for Diesel Engine
Exhaust, EPA, 2002, Sec. 9, p. 20). The
EPA’s 2004 Air Quality Criteria
Document for particulate matter (EPA,
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2004b) describes a number of additional
studies related to the cardiopulmonary
and cardiovascular effects of PM2.5,
including work published later than that
cited in MSHA’s 2003 NPRM (68 FR
48668). One of the summary
conclusions presented in that document
is:
Overall, there is strong epidemiological
evidence linking (a) short-term (hours, days)
exposures to PM2.5 with cardiovascular and
respiratory mortality and morbidity, and (b)
long-term (years, decades) PM2.5 exposure
with cardiovascular and lung cancer
mortality and respiratory morbidity. The
associations between PM2.5 and these various
health endpoints are positive and often
statistically significant. [EPA, 2004b, Sec. 9
p. 46]
Submissions to the rulemaking record
since the 2001 final rule support our
previous position that exposure to DPM
is associated with the development of
adverse cardiovascular and
cardiopulmonary effects.
(3) Cancer Effects
The 2001 risk assessment concluded
that DPM exposure, at occupational
levels encountered in mining, was likely
to increase the risk of lung cancer. The
assessment also found that there was
insufficient evidence to establish a
causal relationship between DPM and
other forms of cancer. This update
contains a description of three human
research studies and a literature review
relating DPM and/or other fine
particulate exposures to lung cancer.
Lung Cancer
Table IV–5 presents three human
studies pertaining to the association
between lung cancer and exposures to
DPM or fine particulates submitted to
the record after the 2005 update of the
2001 risk assessment was done.
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28931
TABLE IV–5.—STUDIES ON LUNG CANCER EFFECTS
Authors, year
Description
Key results
Garshick et al., 2004 ............
An evaluation of lung cancer mortality in 54,793 railroad workers ages 40–64 with 10–20 years of service in 1959. Based on evaluation of death certificates, subsequent mortality was assessed through
1996. Diesel-exposed workers such as engineers
and conductors were compared to a referent group of
less exposed workers such as ticket agents, station
agents, signal-maintainers, and clerks.
Guo et al., 2004 ...................
Evaluation of lung cancer mortality in all working Finns
born between 1906 and 1945 and participating in the
national census of December 1970. Based on the reported occupation held for longest time and a national database of exposures for various occupations,
a variety of exposures including diesel exhaust were
estimated. Information about subsequent diagnosis of
lung cancer during the period 1971 to 1995 was obtained from the Finnish Cancer Registry.
Jarvholm et al., 2003 ...........
Mortality study of Swedish construction workers. Information about occupation and smoking was taken
from computerized health records available for the
period 1971–1992. Workers in two occupations exposed to diesel exhaust, 6,364 truck drivers and
14,364 drivers of heavy construction vehicles were
compared to a reference group of 119,984 carpenters and electricians.
Railroad workers in jobs associated with operating
trains had a relative risk of lung cancer mortality of
1.4 (95% confidence limits = 1.30–1.51). The authors
did not think this association was due to uncontrolled
confounding. No relationship was found between
years of exposure and lung cancer risk. The authors
discussed the potential for this to be due to factors
such as a healthy worker survivor effect, lack of information on historical changes in exposure, and the
potential contribution of coal combustion product before the transition to diesel locomotives.
After controlling for other exposures such as asbestos
and quartz dust, only a slight excess of lung cancer
was found in men aged 20–59 associated with diesel
exhaust exposure. A parallel, but weaker, association
was documented in women. The authors concluded
that risk associated with diesel exhaust ‘‘was not
consistently elevated’’ and speculated that this was
the result of factors such as low exposures or confounding from unmeasured non occupational exposures.
Truck drivers had significantly increased risk for cancer
of the lung, while heavy construction vehicle operators did not. In heavy construction operators, a significant trend of decreased risk for lung cancer was
associated with increasing use of vehicle cabins. The
authors explained that there was a difference between truck and heavy equipment operators, but no
conclusion could be reached without more detailed
information about the duration and concentration of
diesel exhaust exposures and smoking habits.
dsatterwhite on PROD1PC76 with RULES
A Cohort Mortality Study With a Nested
Case-Control Study of Lung Cancer and
Diesel Exhaust Among Nonmetal Miners
[NIOSH/NCI 1997]
A number of commenters expressed
opinions on the unpublished document
authored by Dr. Gerald Chase (2004)
entitled Characterizations of Lung
Cancer in Cohort Studies and a NIOSH
Study on Health Effects of Diesel
Exhaust in Miners. This document
presents an analysis of some very
preliminary data provided by NIOSH
and the National Cancer Institute at a
public stakeholder meeting held on
Nov. 5, 2003. These data were taken
from unpublished charts that NIOSH
and NCI used to inform the public of the
status and progress of their ongoing
project, A Cohort Mortality Study with
a Nested Case-Control Study of Lung
Cancer and Diesel Exhaust Among
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Nonmetal Miners (NIOSH/NCI Study
1997). We previously addressed Dr.
Chase’s analysis in our 2005 final rule
(70 FR 32906). NIOSH and NCI
researchers involved in that project have
not yet published their analyses or
conclusions based on these data. When
the study is concluded, we will assess
the results and their association to our
updated 2001 risk assessment findings.
Therefore, the Agency believes that the
opinions expressed by commenters on
Dr. Chase’s unpublished analysis of
preliminary data are inappropriate for
identifying or assessing the relationship
between occupational DPM exposure
and excess lung cancer mortality in that
data set.
Bladder Cancer and Pancreatic Cancer
would change our position that bladder
cancer is associated with exposure to
DPM. The Agency has not received
additional information that would
change our position that there is
insufficient evidence to support a link
between exposure to DPM and
pancreatic cancer.
(4) Toxicological Effects of DPM
Exposure
Table IV–6 presents one new
particulate matter toxicity study (Sun et
al., 2005) obtained since the 2005 final
rule. The table identifies the agent(s) of
toxicity investigated and indicates how
the results support the risk assessment
by categorizing the toxic effects and/or
markers of toxicity found in each study.
No additional information was
submitted to the rulemaking record that
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TABLE IV–6.—STUDY ON TOXICOLOGICAL EFFECTS OF DPM EXPOSURE
Authors, year
Description
Key results
Sun et al., 2005 .........
Assessment of effects
of subchronic exposure to environmentally relevant
particulate matter
on atherosclerosis
and vasomotor tone
in a mouse disease
model.
Long-term exposure
to low concentration of PM2.5 altered vasomotor
tone, induced vascular inflammation,
and potentiated
atherosclerosis.
Concentrated PM2.5
from northeastern
regional background particulate.
No new review articles on various
aspects of the scientific literature related
to mechanisms of DPM toxicity were
submitted to the record since the 2005
final rule. In summary, the peerreviewed publications submitted to the
rulemaking record addressing the health
effects of exposure to diesel exhaust
support our 2001 risk assessment (66 FR
5526; 30 CFR Part 2005) and nothing in
our review suggests that it should be
altered.
D. Significance of Risk
Adverse Health Effects
The first principal conclusion of the
2001 risk assessment was:
Exposure to DPM can materially impair
miner health or functional capacity. These
material impairments include acute sensory
irritations and respiratory symptoms
(including allergenic responses); premature
death from cardiovascular, cardiopulmonary,
or respiratory causes; and lung cancer (66 FR
5854).
We agree with commenters who
characterized the weight of evidence
from the most recent scientific literature
and the comprehensive scientific
literature reviews carried out by other
institutions and government agencies as
supporting and potentially
strengthening this conclusion.
In 2002, for example, the U.S. EPA,
with the concurrence of its Clean Air
Scientific Advisory Committee
(CASAC), published its Health
Assessment Document for Diesel Engine
Exhaust (EPA, 2002). With respect to
sensory irritations, respiratory
symptoms, and immunological effects,
this document concluded that:
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Toxic
effect(s)*
Agent(s) of toxicity
At relatively high acute exposures, DE
[diesel exhaust] can cause acute irritation to
the eye and upper respiratory airways and
symptoms of respiratory irritation which may
be temporarily debilitating. Evidence also
shows that DE has immunological toxicity
that can induce allergic responses (some of
which are also typical of asthma) and/or
exacerbate existing respiratory allergies.
[EPA, 2002]
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In 2003, the World Health
Organization (WHO) issued a review
report on particulate matter air
pollution and health. WHO concluded
that ‘‘fine particles (commonly
measured as PM2.5) are strongly
associated with mortality and other
endpoints such as hospitalization for
cardiopulmonary disease, so that it is
recommended that air quality guidelines
for PM2.5 be further developed.’’ (WHO,
2003)
In the 10th edition of its Report on
Carcinogens, the National Toxicology
Program (NTP) of the National Institutes
of Health formally retained its
designation of diesel exhaust
particulates as ‘‘reasonably anticipated
to be a human carcinogen.’’ (U.S. Dept.
of Health and Human Services, 2002)
The report noted that:
Diesel exhaust contains identified
mutagens and carcinogens both in the vapor
phase and associated with respirable
particles. Diesel exhaust particles are
considered likely to account for the human
lung cancer findings because they are almost
all of a size small enough to penetrate to the
alveolar region.
* * * Because of their high surface area,
diesel exhaust particulates are capable of
adsorbing relatively large amounts of organic
material * * * A variety of mutagens and
carcinogens such as PAH and nitro-PAH
* * * are adsorbed by the particulates. There
is sufficient evidence for the carcinogenicity
for 15 PAHs (a number of these PAHs are
found in diesel exhaust particulate
emissions) in experimental animals. The
nitroarenes (five listed) meet the established
criteria for listing as ‘‘reasonably anticipated
to be a human carcinogen’’ based on
carcinogenicity experiments with laboratory
animals. [U.S. Dept. of Health and Human
Services, 2002]
Although many commenters agreed
that the adverse health effects associated
with miners’ exposure to DPM
warranted an exposure limit,
commenters from trade associations and
industry continued to challenge the
conclusions of the 2001 risk assessment.
Discussions addressing this issue were
summarized in the 2001 risk assessment
and the 2005 update. As referenced in
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Inflammation, Adverse cardiovascular effects.
Limitations
Exposure not specific
to DPM.
this section, the U.S. Environmental
Protection Agency, World Health
Organization, and the National
Toxicology Program regard DPM
exposure as adversely affecting human
health.
Statement of Excess Lung Cancer Risk
In our 2001 risk assessment, we
explained why we focused our
quantification of health effects on lung
cancer only. We estimated lower bounds
on the significance of risks faced by
miners occupationally exposed to DPM
with respect to (1) acute sensory
irritations and respiratory symptoms or
(2) premature death from
cardiovascular, cardiopulmonary, or
respiratory causes. We expect the final
rule to significantly and substantially
reduce these two kinds of risk as well
as (3) lung cancer. However, we were
unable, based on available data, to
quantify with confidence the reductions
expected for the first two kinds and are
still unable to do so. Therefore, MSHA’s
quantitative assessment of the rule’s
impact on risk is restricted to its
expected impact on the third kind of
risk—the risk of lung cancer (66 FR
5854).
In the 2001 risk assessment, MSHA
assumed that, in the absence of this
rule, underground M/NM miners would
be occupationally exposed to DPM for
45 years at a mean level of 808 µg/m3,
and estimated reductions in lifetime risk
expected to result from full
implementation of the rule, based on the
various exposure-response relationships
¨
obtained from Saverin et al. (1999),
Steenland et al. (1998), and Johnston et
al. (1997).
Miner’s exposures to DPM levels have
declined since 1989–1999. We expect
that further improvements will continue
to significantly reduce the health risks
identified for miners. There is clear
evidence of adverse health effects due to
exposure to DPM in the rulemaking
record, not only at pre-2001 exposure
levels but also at the generally lower
levels currently observed at many
underground mines. The adverse health
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effects associated with exposure to DPM
are material health impairments as
specified under section 101(a)(6)(A) of
the Mine Act.
Because the exposure-response
relationships used in the risk
assessment are monotonic, we expect
that industry-wide implementation of
each final limit will significantly reduce
the risk of lung cancer and other adverse
health effects among miners. The 2001
risk assessment used the best available
data on DPM exposures at underground
M/NM mines to quantify excess lung
cancer risk. ‘‘Excess risk’’ refers to the
lifetime probability of dying from lung
cancer during or after a 45 year
occupational DPM exposure. This
probability is expressed as the expected
excess number of lung cancer deaths per
thousand miners occupationally
exposed to DPM at a specified mean
DPM concentration. The excess is
calculated relative to baseline, agespecific lung cancer mortality rates
taken from standard mortality tables. In
order to properly estimate this excess, it
is necessary to calculate, at each year of
life after occupational exposure begins,
the expected number of persons
surviving to that age with and without
DPM exposure at the specified level. At
each age, standard actuarial adjustments
must be made in the number of
survivors to account for the risk of dying
from causes other than lung cancer.
Occupational exposure is assumed to
begin at age 20 and to continue, for
surviving miners, until retirement at age
65. The accumulation of lifetime excess
28933
risk continues after retirement through
the age of 85 years.
Table IV–7, taken from the 2001 risk
assessment, shows excess lung cancer
estimates at mean exposures equal to
the final limit equivalent to 200
micrograms of DPM per cubic meter of
air for eight hour shift weighted average.
The eight exposure-response models for
lung cancer used in the 2001 risk
assessment were based on studies by
¨
Saverin et al. (1999), Johnston et al.
(1997), and Steenland et al. (1998).
Assuming that TC is 80 percent of
whole DPM, and that the mean ratio of
TC to EC is 1.3, the DPM limit of 200
µg/m3 shown in Table IV–7 corresponds
to the 160 µg/m3 TC limit adopted under
the present rulemaking.
TABLE IV–7.—EXCESS LUNG CANCER RISK EXPECTED AT SPECIFIED DPM EXPOSURE LEVELS OVER AN OCCUPATIONAL
LIFETIME
[Extracted from Table III–7 of the 2001 risk assessment]
Excess lung
cancer deaths
per 1,000
occupationally
exposed
workers†
Final DPM Limit
200 µg/m3
(160 µg/m3 TC)
Study and statistical model
¨
Saverin et al. (1999):
Poisson, full cohort .................................................................................................................................................................
Cox, full cohort .......................................................................................................................................................................
Poisson, subcohort .................................................................................................................................................................
Cox, subcohort .......................................................................................................................................................................
Steenland et al. (1998):
5-year lag, log of cumulative exposure ..................................................................................................................................
5-year lag, simple cumulative exposure .................................................................................................................................
Johnston et al. (1997):
15-year lag, mine-adjusted .....................................................................................................................................................
15-year lag, mine-unadjusted .................................................................................................................................................
15
70
93
182
67
159
313
513
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† Assumes 45-year occupational exposure at 1,920 hours per year from age 20 to retirement at age 65. Lifetime risk of lung cancer adjusted
for competing risk of death from other causes and calculated through age 85. Baseline lung cancer and overall mortality rates from NCHS
(1996).
As explained in the 2005 final rule,
the exposure-response models shown
are monotonic (i.e., increased exposure
yields increased excess risk, though not
proportionately so). Therefore, using our
estimates of mean exposure levels, they
all predict excess lung cancer risks
somewhere above the final whole DPM
limit of 200 µg/m3, or equivalently,
160TC µg/m3. Thus, despite substantial
improvements apparently attained since
the 1989–1999 sampling period
addressed by the 2001 risk assessment,
underground M/NM miners are still
faced with an unacceptable risk of lung
cancer due to their occupational
exposure to DPM.
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V. Feasibility
Section 101(a)(6)(A) of the Mine Act
requires the Secretary of Labor, in
establishing health standards, to most
adequately assure, on the basis of the
best available evidence, that no miner
will suffer material impairment of
health or functional capacity over his or
her working life. Standards promulgated
under this section must be based upon
research, demonstrations, experiments,
and such other information as may be
appropriate. MSHA, in setting health
standards, is required to achieve the
highest degree of health and safety
protection for the miner, and as stated
in the legislative history of the Mine
Act, MSHA must consider the latest
available scientific data in the field, the
feasibility of the standards, and
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experience gained under this or other
health and safety laws.
Though the Mine Act and its
legislative history are not specific in
defining feasibility, the Supreme Court
has clarified the meaning of feasibility
in the context of OSHA health standards
in American Textile Manufacturers’
Institute v. Donovan (OSHA Cotton
Dust), 452 U.S. 490, 508–09 (1981), as
‘‘capable of being done, executed, or
effected,’’ both technologically and
economically.
The legislative history to the Mine Act
indicates Congress’ intent for MSHA
when considering feasibility and states:
While feasibility of the standard may be
taken into consideration with respect to
engineering controls, this factor should have
a substantially less significant role. Thus, the
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Secretary may appropriately consider the
state of the engineering art in industry at the
time the standard is promulgated. However,
as the circuit courts of appeals have
recognized, occupational safety and health
statutes should be viewed as ‘‘technology
forcing’’ legislation, and a proposed health
standard should not be rejected as infeasible
‘‘when the necessary technology looms on
today’s horizon’’. AFL–CIO v. Brennan, 530
F.2d 109 (3d Cir. 1975); Society of Plastics
Industry v. OSHA, 509 F.2d 1301 (2d Cir.
1975), cert. denied 427 U.S. 992 (1975).
Similarly, information on the economic
impact of a health standard, which is
provided to the Secretary of Labor at a
[public] hearing or during the public
comment period, may be given weight by the
Secretary. In adopting the language of [this
section], the Committee wishes to emphasize
that it rejects the view that cost benefit ratios
alone may be the basis for depriving miners
of the health protection which the law was
intended to insure. The Committee concurs
with the judicial constitution that standards
may be economically feasible even though
from the standpoint of employers, they are
‘‘financially burdensome and affect profit
margins adversely’’ (I.U.D. v. Hodgson, 499
F.2d 6a47 (D.C. Cir. 1974)). Where substantial
financial outlays are needed in order to allow
industry to reach the permissible limits
necessary to protect miners, other regulatory
strategies are available to accommodate
economic feasibility and health
considerations. These strategies could
include delaying implementation of certain
provisions or requirements of standards in
order to allow sufficient time for engineering
controls to be put in place or a delay in the
effective date of the standard. S. Rep. No. 95–
181, 95th Cong. 1st Sess. 21 (1977).
The ‘‘arbitrary and capricious test’’ is
usually applied to judicial review of
rules issued in accordance with the
Administrative Procedure Act. The
legislative history of the Mine Act
further indicates that Congress
explicitly intended the ‘‘arbitrary and
capricious test’’ be applied to judicial
review of mandatory MSHA standards.
‘‘This test would require the reviewing
court to scrutinize the Secretary’s action
to determine whether it was rational in
light of the evidence before him and
reasonably related to the law’s
purposes.’’ S. Rep. No. 95–181, 95th
Cong., 1st Sess. 21 (1977). In achieving
the Congressional intent of feasibility
under the Mine Act, MSHA may also
consider reasonable time periods of
implementation. Ibid. at 21.
In order to establish the economic and
technological feasibility of a new rule,
an agency is required to produce a
reasonable assessment of the likely
range of costs that a new standard will
have on an industry, and an agency
must show that a reasonable probability
exists that the typical firm in an
industry will be able to develop and
install controls that will meet the
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standard. United Steelworkers of
America, AFL–CIO–CLC v. Marshall,
(OSHA Lead) 647 F.2d 1189, 1273 (D.C.
Cir. 1980).
Like, the Mine Act, the OSH Act
contains the term ‘‘technology-forcing’’
with respect to standards setting. The
D.C. Circuit Court also determined with
respect to technological feasibility
under the OSH Act that:
* * * ‘‘technology-forcing’’ under the OSH
Act, means, at the very least, that OSHA can
impose a standard which only the most
technologically advanced plants in an
industry have been able to achieve-even if
only in some of their operations some of the
time. American Iron & Steel Institute v.
OSHA, supra, 577 F.2d at 832–835.
Since ‘‘technology-forcing’’ assumes that
‘‘an agency will make highly speculative
projections about future technology, a
standard is obviously not infeasible solely
because OSHA has no hard evidence to show
that the standard has been met. More to the
point here, we cannot require OSHA to prove
with any certainty that industry will be able
to develop the necessary technology, or even
to identify the single technological means by
which it expects industry to meet the PEL.
OSHA can force employers to invest all
reasonable faith in their own capacity for
technological innovation. Society of Plastics
Industries, Inc. v. OSHA, supra 509 F.2d at
1309, and can thereby shift to industry some
of the burden of choosing the best strategy for
compliance. United Steelworkers of America,
647 F.2d at 1266.
This same court found that proving
economic feasibility presented different
issues from that of technological
feasibility, where it stated:
But when the agency has proved
technological feasibility by making
reasonable predictions about experimental
means of compliance, the court probably
cannot expect hard and precise estimates of
costs. Nevertheless, the agency must of
course provide a reasonable assessment of
the likely range of costs of its standard, and
the likely effects of those costs on the
industry. Ibid. at 1266.
A. Technological Feasibility
Courts have ruled that in order for a
standard to be technologically feasible
an agency must show that modern
technology has at least conceived some
industrial strategies or devices that are
likely to be capable of meeting the
standard, and which industry is
generally capable of adopting. Ibid.
(citing American Iron and Steel Institute
v. OSHA, (AISI–I) 577 F.2d 825 (3d Cir.
1978) at 832–35; and, Industrial Union
Dep’t., AFL–CIO v. Hodgson, 499 F.2d
467 (DC Cir.1974)); American Iron and
Steel Institute v. OSHA, (AISI–II) 939
F.2d 975, 980 (DC Cir. 1991). A control
may be technologically feasible when
‘‘if through reasonable application of
existing products, devices or work
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methods with human skills and
abilities, a workable engineering control
can be applied’’ to the source of the
hazard. It need not be an ‘‘off-the-shelf’’
product, but ‘‘it must have a realistic
basis in present technical capabilities.’’
(Secretary of Labor v. Callanan
Industries, Inc. (Noise), 5 FMSHRC
1900, 1908 (1983)). The Secretary may
also impose a standard that requires
protective equipment, such as
respirators, if technology does not exist
to lower exposures to safe levels. See
United Steelworkers of America, 647
F.2d at 1269.
We have established that it is
technologically feasible for the
underground M/NM mining industry to
reduce miners’ exposures to the DPM
final limits as prescribed in the final
rule. Unlike the 2005 NPRM, we are
phasing in the final limit of 160 Total
Carbon micrograms per cubic meter of
air (160TC µg/m3) over a two-year
period, due to the updated feasibility
information in the rulemaking record.
This updated feasibility information
relates primarily to the wider
availability of alternative fuels, and in
particular biodiesel, improved filter
technology, and the impending
availability of EPA compliant 2007 onroad diesel engines. Consequently, on
May 20, 2006, the initial final limit will
be 308 micrograms of EC per cubic
meter of air (308EC µg/m3), which is the
same as the existing interim limit; on
January 20, 2007, the final limit will be
reduced by 50 micrograms and will be
a TC limit of 350TC µg/m3; and on May
20, 2008, the final limit of 160TC µg/m3
will become effective. Note that the
350TC µg/m3 final limit and the 160TC
µg/m3 final limit are established as TCbased limits in this final rule. It is our
intention to convert these TC limits to
comparable EC limits; however,
developing appropriate conversion
factors for these limits was beyond the
scope of the current rulemaking. These
TC limits will be converted to
comparable EC limits through a separate
rulemaking.
To meet the final DPM limits, mine
operators will be able to continue to use
existing available engineering control
technology and various administrative
control methods used in meeting the
interim DPM limit. However, we are
affording the mining industry the
additional time from that provided
under the 2001 final rule to work
through their remaining implementation
issues with DPM control technology and
to gain access to alternative fuels and
DPFs. The additional time will also
allow mine operators, especially small
mine operators, time to find effective
approaches to utilizing available DPM
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control technology so that they will be
capable of meeting the standard.
Altogether, the mining industry will
have been afforded over seven years to
institute control technology to reduce
miners’ exposures to the final DPM limit
of 160TC µg/m3. Our decisions in the
final rule are based on our enforcement
experience, along with information and
data in the updated DPM rulemaking
record, which includes the 2001 and
2005 DPM rulemaking records. The final
rulemaking record lacks feasibility
documentation to justify lowering the
final DPM limit to 160TC µg/m3 at this
time.
The existing requirement for methods
of compliance will continue to be
applicable to the final limits. To attain
the final limits, mine operators are
required to install, use, and maintain
engineering and administrative controls
to the extent feasible. When engineering
and administrative controls do not
reduce a miner’s exposure to the DPM
limit, the controls are infeasible, or
controls do not produce significant
reductions (defined in the 2005 rule (70
FR 32868, 32916) as at least 25%
reduction in the affected miners’ DPM
exposures), operators must continue to
use all feasible engineering and
administrative controls and supplement
them with respiratory protection.
Though mine operators may choose to
use an engineering control or an
administrative control to reduce a
miner’s exposure, or a combination
thereof, existing § 57.5060(d) prohibits a
mine operator from using respiratory
protection in lieu of feasible controls.
When respiratory protection is required
under the final standard, mine operators
must establish a respiratory protection
program that meets the specified
requirements under existing
§ 57.5060(d) of the DPM standard.
MSHA emphasizes that DPM
engineering and administrative controls
may be feasible, and therefore be
required by MSHA, even if controls do
not reduce a miner’s exposure to the
DPM limit.
Under this rule, MSHA intends that
feasible DPM controls must be capable
of achieving a significant reduction in
DPM. We also note that most of the
practical and effective controls that are
currently available, such as DPM filters,
enclosed cabs with filtered breathing
air, and low-emission engines will
achieve at least a 25% reduction. Other
controls such as ventilation upgrades or
alternative fuel blends may achieve a
25% reduction, depending on exposure
circumstances and the specific nature of
the subject control. It should also be
noted that reductions of less than 25%
could be due to normal day-to-day
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variations in mining operations as
opposed to reductions due to
implementing a control technology.
Thus, for mines that are out of
compliance with the DPM final limits,
controls would be required that attain
compliance, or that achieve at least a
25% reduction in DPM exposure if it is
not possible to attain compliance by
implementing feasible controls. If
engineering and administrative controls
are not capable of reducing exposure to
the limits in this final rule, and cannot
reduce DPM exposures by at least 25%,
we would not require the
implementation of those controls. In
such cases, we will require miners to be
protected using appropriate respiratory
protective equipment.
If a particular DPM control were
capable of achieving at least a 25%
reduction all by itself, we would
continue to evaluate the costs of that
individual control to determine its
economic feasibility. If a number of
controls could together achieve at least
a 25% reduction, but no individual
control, if implemented by itself, could
achieve a 25% reduction, we will
evaluate the total costs of all controls
added together to determine their
economic feasibility as a group. In
determining whether a combination of
controls is economically feasible, we
will consider whether the total cost of
the combination of controls is wholly
out of proportion to the expected
results. We will not cost the controls
individually, but will combine their
expected results to determine if the 25%
significant reduction criterion can be
satisfied. The concept of significant
reduction is not new to the M/NM
mining industry. MSHA’s 2005
Compliance Guide includes the 25%
significant reduction for determining
feasibility.
At this time, we believe that this
compliance approach coupled with the
phased-in final limits provides mine
operators with flexibility necessary to
assure feasible compliance. This current
enforcement approach results in
feasibility of compliance for the
industry as a whole with each of the
phased-in limits contained in this final
rule while protecting miners’ health.
However, we continue to acknowledge
that compliance difficulties may be
encountered at some individual mines,
but on a much smaller scale than what
we project if the final limit of 160TC µg/
m3 became effective in May 2006. This
primarily will be due to implementation
issues and the cost of purchasing and
installing certain types of controls at
these mines.
Moreover, pursuant to existing
§ 57.5060(c), mine operators can apply
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28935
to the District Manager for a special
extension for additional time in which
to meet the final limits, including the
initial final limit of 308EC µg/m3.
Although we anticipate that special
extensions and our traditional hierarchy
of controls in enforcement will address
some compliance issues, we envision
that some miners will have to wear
respiratory protection under the final
limit of 160TC µg/m3.
Based upon a review of enforcement
data, we believe that a large portion of
the mining industry will initially
encounter implementation issues as
they attempt to attain compliance with
the final limits using engineering and
administrative controls. However, we
believe that most mine operators will be
able to overcome these issues within the
two-year period during which the final
limits will be phased-in. For example,
the wider use of high biodiesel content
fuel blends, which can reduce DPM
emissions by up to 80% or more, will
be greatly facilitated by the significant
increases in biodiesel fuel production
that will occur in the United States over
the next two years. The National
Biodiesel Board reports that annual
biodiesel production rose from 25
million gallons in 2004 to 75 million
gallons in 2005. They also report that
biodiesel plants that are either under
construction at the present time or in
the pre-construction phase will add
another 847 million gallons of annual
production capacity. A large portion of
this added capacity will be on-line by
2008.
Another example of a recent
development that will help enable mine
operators attain our final DPM limit of
160TC µg/m3 by May 2008 is the
impending availability of U.S. EPA 2007
on-road diesel engines. U.S. EPA 2007
on-road diesel engine standards have
DPM emission limits that are about 90%
lower than the current EPA limits allow.
The DPM reduction will be attained
through the use of DPFs. The DPFs will
be part of the engine and vehicle when
sold. For example, a new 2007 on-road
pickup truck will have a DPF installed
on the vehicle at the time of purchase.
The 2007 on-road engines will be
commercially available starting in early
2007.
In addition to the EPA 2007 on-road
DPM standards, EPA also has new Tier
4 off-road standards that will reduce
DPM about 90%. Tier 4 will be phasedin beginning in 2008. Similar to the
2007 on-road engines, a DPF will be
installed on the engine and vehicle
when purchased. Even though the EPA
implementation dates of Tier 4 is after
the date of the final limit, the DPF
technology is being developed at this
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time by the engine and filter
manufacturers in order to be ready for
the tier 4 standards. This current work
will enhance the developments and
availability of DPF systems that can be
retrofitted to mining vehicles.
Although the emission limits for 2007
on-road engines were established some
time ago, we had very little insight as to
the strategies and technologies that the
engine manufacturers would use to meet
these limits. For competitive reasons,
the engine manufacturers did not
publicize their strategies or designs for
complying with these EPA regulations.
We were therefore uncertain as to
whether any 2007 on-road compliant
engines would be compatible with
typical underground M/NM mine
operational and production
requirements, duty cycles, and
maintenance practices, and thus,
whether they could be readily used or
adapted for use in underground M/NM
mines.
With the first 2007 on-road engines
scheduled for release in early 2007,
however, we now have a much clearer
picture of the technologies that will be
incorporated into these engines. The
predominant technology will be DPM
filters which incorporate some form of
active regeneration to accommodate any
duty cycle, ranging from constant highspeed over-the-road trucks to light duty
delivery vehicles and pickup trucks and
SUVs in stop-and-go traffic conditions.
As noted later in this section of the
preamble, we are confident that such
filter technology is suitable for
application in underground M/NM
mines. Therefore, we expect appropriate
2007 on-road engines to be readily
usable or adaptable for use in
underground M/NM mining equipment.
These engines will begin to become
available in early 2007, with more and
varied models becoming available in
subsequent months and years.
In the future, we project that the
number of miners who will need to
wear respiratory protection will
decrease as mine operators learn more
about effectively selecting, retrofitting,
and maintaining DPFs, as they begin to
use EPA compliant 2007 on-road
engines with integral DPFs, and as mine
operators in remote locations are able to
gain easier access to alternative fuels,
primarily biodiesel.
1. MSHA’s 2001 Assumptions Regarding
Compliance With the Final
Concentration Limit
We stated in the proposed rule that
the assumptions that we used in 2001 in
support of our cost estimates included:
(a) Fifty percent of the fleet will have
new engines (these new engines do not
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impact cost of the rule) * * * Moreover,
due to EPA [Environmental Protection
Agency] regulations, which will limit
DPM emissions from engines used in
surface construction, surface mining,
and over-the-road trucks (the major
markets for heavy duty diesel engines),
the market for low tech ‘‘dirtier’’
engines will dry up * * *; (b) one
hundred percent of the production
equipment and about fifty percent of the
support equipment will be equipped
with filters; (c) about thirty percent of
all equipment will need to be equipped
with environmentally controlled cabs;
(d) twenty three percent of the mines
would need new ventilation systems
(fans and motors); (e) forty percent of
the mines will need new motors on
these fans; and (f) thirty two percent of
the mines will need major ventilation
upgrades (66 FR 5889–90).
Furthermore, we concluded that it
would not be feasible to require the
metal and nonmetal sector, as a whole,
to lower DPM concentrations further, or
to implement the required controls more
swiftly (66 FR 5888).
2. Reasons Why the 2001 Assumptions
Were Questioned
Over the five years since the 2001
final rule was promulgated, both MSHA
and the mining industry have gained
considerable experience with the
implementation, use, and cost of DPM
control technology. We have reviewed
this experience, and our own
enforcement data, and other relevant
information, and conclude that effective
DPM controls sufficient to attain
compliance with the DPM limits
specified in this final rule will be
feasible and commercially available to
mine operators by May 2008. For
example, in addition to currently
available DPM controls such as
environmental cabs with filtered
breathing air, a variety of DPF systems,
low-emission engines, upgraded
ventilation, and alternative fuels, by
May 2008, we believe mine operators
will benefit from wider availability of
alternative fuels, particularly biodiesel,
improved filter technology, and the
availability of EPA compliant 2007 onroad diesel engines and diesel powered
equipment. As implementation issues
are resolved, the most successful
implementation strategies will be
adopted by other mine operators,
thereby speeding up compliance by the
industry as a whole. For example, in
2004, we were aware of only one mine
operator that was using a high biodiesel
content fuel blend as a DPM compliance
method. DPM levels measured in this
mine were consistently greater than
200EC µg/m3 prior to the change to
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biodiesel fuel, compared to levels less
than 100EC µg/m3 after the change-over.
In the most recent enforcement
sampling at this mine, all samples were
less than 50EC µg/m3. By late 2005, we
were aware of at least four other mine
operators that had learned from this
experience and adopted this compliance
strategy. Another example is the
recently developed Diesel Particulate
ReactorTM (described later in this
section of the preamble). This new
technology has been successfully
implemented by a large nonmetal mine
operator. Reactors are currently
installed on about 80% of the mine’s
fleet of roughly 50 pieces of diesel
equipment with no installation,
operation, or maintenance problems
reported. These experiences
demonstrate that even the more
complex DPM control technologies can
be successfully implemented by mine
operators. As these successful
experiences are shared throughout the
mining industry, compliance by the
underground M/NM mining industry as
a whole by May 2008 will be greatly
facilitated. The extended time specified
in this final rule is necessary to address
the implementation issues that the
industry as a whole must overcome.
However, as noted above, we believe
these issues can be resolved within the
extended compliance timeframes
established in the final rule.
Several commenters quoted previous
MSHA statements from the rulemaking
record they believe support their
position that the final DPM limit is
technologically infeasible. A few quoted
a passage from the 2005 final rule:
‘‘MSHA acknowledges that the current
DPM rulemaking record lacks sufficient
feasibility documentation to justify
lowering the DPM limit below 308EC µg/
m3 at this time’’ (70 FR 32916).
However, these commenters did not
include the statements that followed,
which explained that we believed it was
feasible for the industry as a whole to
fully comply with the interim limit, but
that at that time—June of 2005—
attaining levels lower than 308EC µg/m3
was not feasible for the entire industry.
In our 2005 NPRM, we indicated that a
DPM limit lower than 308EC µg/m3
should not become effective before
January 2007, at the earliest, due to
concerns about implementation
difficulties. It was our intention that
mine operators would use the period of
nearly 20 months from June 2005
through January 2007 and the
subsequent phased-in timeframes
proposed in the NPRM to overcome
implementation challenges and attain
compliance with the reduced limit.
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Some commenters stated that any
delay in the effective date for the final
DPM limit was unjustified on either
technological or economic grounds. A
number of commenters said that our
2005 NPRM makes it clear that several
technologies are available which, alone
or in combination, would permit mines
to meet the final limit. Doubts about
whether all mines can do so in all
operations, or doubts about whether
current distribution networks for
alternative fuels are as complete as may
be necessary under the final rule, do not
in these commenters’ views detract from
the conclusion that the final limit is
feasible. According to these
commenters, MSHA’s search for
certainty that all mines can comply at
all times in all circumstances is a
violation of its technology-forcing
mandate. In response, the Mine Act
does not mandate that MSHA standards
must be technology-forcing.
Another commenter stated that no
technological reason exists for granting
industry an additional five years, on top
of the five years they have already had,
to install existing technology to protect
workers.
Although technology currently exists
for compliance with both the interim
and final DPM limits, we conclude that
implementation challenges and
difficulties with this technology and the
costs of implementing it in the M/NM
mining industry affect feasibility. We
have observed the difficult applications
engineering challenges faced by a
substantial number of mine operators in
implementing these technologies.
Consequently, these challenges have led
us to determine that additional time is
needed by the industry as a whole to
feasibly meet the final limit.
Another passage that several
commenters in opposition to the 2005
NPRM quoted, stated that:
When we established the 2001 final limit,
we were expecting some mine operators to
encounter difficulties implementing control
technology because the rule was technology
forcing. We projected that by this time,
practical and effective filter technology
would be available that could be retrofitted
onto most underground diesel powered
equipment. However, as a result of our
compliance assistance efforts and through
our enforcement of the interim limit, we have
become aware that this assumption may not
be valid. The applications engineering and
related technological implementation issues
that we believed would have been easily
solved by now are more complex and
extensive than previously thought (70 FR
53283).
Although we have evidence of
successful applications of DPM controls
in the rulemaking record and the proven
effectiveness of various products,
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systems, and strategies for controlling
DPM emissions and exposures, we
believe that the implementation
challenges presented by the industry
warrant granting some additional time
to attain full compliance with the final
limit. We intend, however, for the
mining industry to utilize this extra
time to diligently move forward in
achieving compliance with the final
limits.
Some commenters quoted the
decision of Secretary of Labor v.
Callanan Industries, Inc. (Noise), 5
FMSHRC 1900, 1908 (1983)), which
addresses feasibility of an individual
mine operator to comply with an MSHA
exposure-based health standard. These
commenters concluded that based on
the current existence of alternative fuels
and DPFs, that no delay in the final
limit was justified. However, as noted
above, based on present implementation
issues, we have determined that
additional time is needed by the mining
industry, as a whole, to meet the final
limits.
Some other commenters stated that
they do not believe there is a ‘‘realistic
basis in present technical capabilities,’’
[quoting Callanan]. These commenters
believe that there is not an adequate
array of mine worthy, technically
feasible solutions that are readily
available for implementation in
underground metal and nonmetal
mines. They believe that their
conclusion is confirmed by MSHA’s
statement in the 2005 NPRM that,
‘‘effective control technology that will
reduce exposures to the final limit is
speculative at this time’’ (70 FR 53285).
We find these arguments made by
some commenters not persuasive,
because in the 2005 NPRM, we
acknowledged that full compliance with
the final DPM limit by the industry as
a whole by the original effective date of
January 2006 was unlikely to be
feasible. Over the past five years, we
have been working with all members of
the M/NM mining community affected
by this final rule. We believe that the
industry has made tremendous progress
and will continue to work through these
feasibility challenges and that it will be
feasible for the industry to comply by
the dates established in this final rule.
We continue to conclude, based on
experience gained under the existing
DPM rule, that the applications
engineering required to adapt advanced
DPM control devices and systems to
new and existing mining equipment, to
introduce alternative fuels, to train
miners on their proper installation,
operation, inspection, maintenance, and
repair, and to integrate new methods
and work practices into complex mining
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28937
processes will take more time than we
originally anticipated. However, we find
one commenter’s position that suitable
DPM controls are not readily available
to not be persuasive. The rulemaking
record contains evidence that mine
worthy control technology is available,
and includes a number of examples of
the successful implementation of such
controls in all types of M/NM
underground mines. The preamble to
this final rule expands on those
available technologies, indicating as we
have suggested previously, that as
demand for these technologies grows,
manufacturers will respond by
increasing the availability of feasible
control systems for use at underground
M/NM mines.
We know that, when properly
implemented, DPFs, environmental
cabs, alternative diesel fuels,
ventilation, and modern low emission
engines are effective engineering
controls for reducing DPM exposures in
underground M/NM mines. They have
all been successfully implemented at
numerous mining operations to comply
with the current interim limit. We know
that when properly implemented,
various administrative and work
practice controls can also effectively
reduce DPM exposures. Effective control
technology, however, cannot be
successful if mine operators are not
diligent in resolving their unique
implementation issues. Implementation
issues vary from mine to mine, and
what accounts for some mine operators
being successful while others have had
only limited success attaining DPM
compliance primarily depends on the
particular choices of controls selected,
and the corresponding implementation
strategies employed. Clearly, it is easier
and cheaper to obtain compliance at
some mines than at other mines, due to
factors such as mine size, mining
conditions, the amount, type, and age of
diesel equipment in use, height and
width of roadways, grades that must be
traversed, elevation of the workings,
remoteness of the mine, and so on.
A commenter expressed the need for
DPM controls that are, ‘‘readily
available for implementation in
underground metal and nonmetal
mines.’’ Although we believe the
rulemaking record supports the
conclusion that the required DPM
controls are commercially available, as
noted above, the additional time offered
by this final rule to meet the final limit
is necessary for the mining community
as a whole to implement these DPM
controls.
A commenter observed that ‘‘The ‘put
a filter on it’ solution, suggested in prior
MSHA analysis as the primary mode of
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compliance, is now acknowledged to be
a very goal that is not often achievable.’’
This commenter goes on to say
‘‘Therefore, by implication, the
compliance model used to estimate
compliance feasibility, and costs in the
PREA and FREA is suspect.’’
Several other commenters also
claimed that our technological
feasibility determinations were based on
predictions that retrofitting diesel
equipment with exhaust filters would be
the primary means of compliance, but
that no such filters were commercially
available at the time. We believe these
commenters may not fully appreciate
our position on technological feasibility
in at least two key respects. First, we
have never advised the industry that full
compliance with either DPM limit
would be a simple process of ‘‘[putting]
a filter on it.’’ Rather, our feasibility
determinations were based on the
assumption that mine operators would
choose the control or combination of
controls that best suited the unique
circumstances and conditions at their
mine. In the preamble to the 2001 final
rule (66 FR 5713), we said, ‘‘the best
actions for an individual operator to
take to come into compliance with the
interim and final concentration limits
will depend upon an analysis of the
unique conditions of the mine.’’ In the
same preamble (66 FR at 5859), we
indicated that,
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The final rule contemplates that an
operator of an underground metal or
nonmetal mine have considerable discretion
over the controls utilized to bring down dpm
concentrations to the interim and final
concentration limits. For example, an
operator could filter the emissions from
diesel-powered equipment, install cleanerburning engines, increase ventilation,
improve fleet management, use traffic
controls, or use a variety of other readily
available controls. A combination of several
control measures, including both engineering
controls and work practices, may be
necessary, depending on site specific
conditions.
We expected mine operators would
have had less difficulty in appropriately
selecting and experimenting with
technology applications than we had
observed at many mines. Also, we
expected mine operators to be able to
more effectively address their
maintenance and regeneration issues
with DPFs, and would have had better
access to alternative fuels. Our
experience revealed that many mine
operators did not fully resolve all the
complex implementation issues that
were encountered. Some operators
simply removed the controls instead of
working through these implementation
issues.
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The other aspect of our position on
technological feasibility that these
commenters may not fully appreciate is
our position on current technological
feasibility versus feasibility at a future
date. They have assumed that because
we acknowledged that it was infeasible
to meet the final limit by May 20, 2006,
that it is also infeasible to meet the final
limit at a future date as required in the
final rule. Again, our position is that we
believe that additional time will be
required for certain key technologies to
become sufficiently diffused and
available, and that the industry as a
whole will require additional time
under this final rule to successfully
implement the necessary controls to
attain compliance with the final phasedin limits.
We believe it will be feasible for the
industry as a whole to implement the
required controls and attain compliance
with the phased-in DPM limits within
the timeframes established in the final
rule. For example, biodiesel production
in the U.S. will increase dramatically
over the next two years, making it
increasingly easier for mine operators to
gain access to a reliable supply of this
alternative fuel. Also, EPA compliant
2007 on-road diesel engines will begin
to become available in early 2007, and
their availability will grow in the
months and years to follow. We believe
that the industry as a whole will be
capable of attaining compliance with
the final limits using these and other
existing DPM control methods. We also
believe that industry-wide compliance
within the timeframes established in the
final rule will not require the
development of new technologies.
We believe that the three-step phasein approach for establishing the DPM
limits and the wider use of alternative
fuels, improved filter technology, and
EPA compliant 2007 on-road engines
along with other engineering and
administrative controls, will enable the
underground M/NM mining industry as
a whole to resolve lingering
implementation challenges and
difficulties relating to the 160TC µg/m3
final limit.
In our 2005 NPRM, we proposed that
the final DPM limit be phased-in in five
steps over a five-year period. The choice
of five-years for the length of the phasein period was based on our compliance
assistance and enforcement experience
that indicated that mine operators were
encountering more significant
implementation issues than originally
anticipated. These issues affected a
greater portion of the industry and
presented greater challenges to resolve
than we anticipated in the 2001 final
rule. The five-year phase-in period was
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proposed based on the rate at which we
observed these implementation issues
being successfully addressed at that
time by the industry as a whole. We
believed this five-year timetable for
phasing-in the final limit was
reasonable, providing for feasible
compliance by the industry as a whole
while insuring substantial annual
reductions in DPM exposure of miners.
However, we asked for comments on
whether this proposed five-year phasein would be the appropriate timeframe
for mine operators to attain the final
DPM limit of 160TC µg/m3. Some
commenters provided information
opposing the five-year phase-in, saying
any delay was unjustified. Other
commenters supported the five-year
phase-in as an improvement from the
original January 2006 deadline, but
suggested that due to feasibility
concerns, even more time would be
needed to attain compliance. Other
commenters have consistently
maintained that controls sufficient to
attain the final limit do not exist, so the
timeframe for compliance is irrelevant.
Other commenters provided information
supporting a shorter phase-in of the
final limit.
We now believe that the three step
phase-in of the final limit over two years
that is incorporated into this final rule
is the most appropriate approach and
phase-in time period that both provides
for maximum protection of miners and
is also technologically and economically
feasible for the industry to achieve. This
determination was based on our
enforcement experience, the comments
in the rulemaking record addressing
feasibility, and other relevant technical
information we have obtained since we
issued the 2005 NPRM.
The key information that we relied on
to reduce the timeframe from the
originally proposed five-year phase-in of
the final limit to the two-year phase-in
incorporated into the final rule included
wider availability of alternative fuels,
particularly biodiesel, improved filter
technology, and the impending
availability of EPA compliant 2007 onroad diesel engines. As previously
discussed, we were also encouraged by
the accelerating rate at which effective
DPM control technologies were being
implemented by mine operators, for
example, high temperature disposable
diesel particulate filter (HTDPF)
systems. We believed the development
of these systems would fill a critical gap
in available filter technology, as they are
particularly well suited to filter the
exhaust from small and mid-sized
equipment having low to medium duty
cycles that were not good candidates for
passive regeneration filter systems, and
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on which mine operators did not wish
to implement active filter systems.
These systems demonstrated high
filtration efficiency for EC, and did not
increase NO2 emissions. However, when
used in underground M/NM mines,
these systems were subject to filter
element damage due to occasional high
temperature exhaust exposures. We are
now confident that these systems can be
used successfully in mining
applications if a heat exchanger is
placed upstream from the filter element
in the vehicle’s exhaust system. We
have recently learned that purpose-built
heat exchangers are now commercially
available, either as separate units that
can be retrofitted to an existing HTDPF
system or as an integrated unit that
combines a heat exchanger with a filter.
Another example is the impending
availability of EPA compliant 2007 onroad diesel engines. As noted earlier in
this section, these engines must reduce
DPM emissions by about 90% compared
to current models, and also must meet
strict NOX standards. As recently as the
fall of 2005, we could not be certain
these new engines would be fully
compatible with underground M/NM
mine operational and production
requirements, duty cycles, and
maintenance practices. With the
introduction of EPA compliant 2007 onroad engines less than 8 months away,
we are now aware that the predominant
technology that will be used by the
engine manufacturers to comply with
these requirements will be DPFs with
provision for continuous or automatic
active filter regeneration regardless of
equipment duty cycle. As noted later in
this section of the preamble, we are
confident such DPFs can be
implemented by mine operators. These
DPFs typically have very high EC
filtration efficiency approaching 99% or
more, and the method of filter
regeneration eliminates implementation
issues relating to whether a particular
machine’s duty cycle is sufficiently
severe to enable passive regeneration
and the perceived logistical
complications associated with active onboard or active off-board filter
regeneration.
These recent developments and
technologies, along with increased
utilization of the other engineering and
administrative controls that we have
discussed throughout the remaking
record, such as environmental cabs with
filtered breathing air, ventilation
upgrades, and a host of administrative
control options, will enable the
underground M/NM mining industry as
a whole to resolve lingering
implementation challenges and
difficulties relating to compliance with
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17:42 May 17, 2006
Jkt 208001
the 160TC µg/m3 final limit by May
2008. We are confident compliance
under the final rule can be attained by
most mines regardless of size or the
commodity produced, because none of
these technologies are mine size or
commodity dependent.
Regarding biodiesel, the National
Biodiesel Board noted in their
comments that the domestic annual
production capacity of biodiesel fuel
would increase by at least 100 million
gallons between May 2005 and May
2006. Based on production statistics
released on November 8, 2005 by the
National Biodiesel Board (https://
www.nbb.org/resources/pressreleases/
gen/20051108_ productionvolumes
05nr.pdf) we also learned that biodiesel
production and consumption in the
United States grew 300% in one year,
from 25 million gallons per year in 2004
to an estimated 75 million gallons per
year by the end of 2005. Biodiesel plants
currently under construction will add
329 million gallons of annual
production capacity (https://
www.nbb.org/buyingbiodiesel/
producers_marketers/ProducersMapConstruction.pdf), and plants in the preconstruction phase will add another 518
million gallons of annual production
capacity (https://www.nbb.org/
buyingbiodiesel/producers_marketers/
ProducersMap-Pre-Construction.pdf).
Much of this added production capacity
is expected to be on-line by 2008, and
some of these plants are being, or will
be built in areas of the country that are
currently underserved by biodiesel
production facilities, such as Wyoming,
Montana, Washington, California,
Colorado, and Texas in the west, and
Tennessee, Kentucky, Pennsylvania,
Virginia, North Carolina, and New York
in the east. This expected increased
availability of biodiesel fuel by 2008
supports our decision to phase-in the
final DPM limits in three steps from
308EC µg/m3 in May 2006 to 350TC µg/
m3 in January 2007 to 160TC µg/m3 in
May 2008.
Increased use of these fuels is
consistent with and in support of recent
U.S. initiatives towards greater energy
independence. On October 22, 2004,
President Bush approved a tax credit for
blenders of biodiesel as part of H.R.
4520, also known as the American Jobs
Creation Act of 2004 (Pub. L. 108–357).
The tax credit for biodiesel produced
from agricultural feedstocks is equal to
$0.01 per gallon per percentage
biodiesel in the blended product,
essentially erasing the price difference
between biodiesel and standard
petroleum-based diesel fuel. In the late
summer and fall of 2005 and again in
the spring of 2006, due to price swings
PO 00000
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28939
in the market, the net cost of biodiesel,
when the tax credit is applied, was less
than the cost of standard #2 diesel fuel
in many parts of the country. As noted
in more detail later in this section of the
preamble, biodiesel consumption is
expected to grow as more product is
produced, as its availability increases in
presently underserved parts of the
country, and as the price gap between
biodiesel and standard diesel closes, or
as has recently occurred, when biodiesel
becomes cheaper than standard diesel.
Retrofit options for self-cleaning DPFs
should increase as the manufacturers of
these filter systems become assured of a
reliable market both in underground
mining and on diesel-powered
equipment intended for surface
applications. In addition, two
manufacturers of synthetic high
temperature disposable filters have
updated their specification sheets
(discussed further in this section) to
advise mine operators of the exhaust gas
temperature limitations when using
these filters. In order to meet these
exhaust gas temperature limits, mine
operators can purchase commercially
available heat exchanger systems that
can lower the exhaust gas temperature
before contact with the filter. This can
allow application of this type filter to be
expanded to a wider variety of
machines, especially ones that have low
to medium duty cycle.
The more stringent EPA 2007 on-road
exhaust emission standards (https://
yosemite.epa. gov/opa/admpress.nsf/
b1ab9f485b098972852562e7004dc686/
f20d2478833ea3bd85256e
91004d8f90?OpenDocument) that begin
in 2007 for on-road diesel engines
(https://www.epa.gov/otaq/diesel.htm)
will lead to an additional 90 percent
reduction in particulate emissions when
fully implemented. In addition, the EPA
is mandating a reduction of the sulfur
content of diesel fuel to no more than
15 ppm beginning in mid year of 2006
for on highway diesel engines and 2010
for nonroad diesel engines. Use of this
fuel will enable advanced DPM control
technology that would otherwise have
been inhibited by the use of higher
sulfur content fuel. Note that biodiesel
fuel already meets this 15 ppm sulfur
content requirement. Use of newer
equipment with cleaner engines will
also increase as older equipment is
retired from service.
We anticipate that the three-step two
year phased-in approach to establishing
the final DPM limit that is incorporated
in this final rule will provide the
needed time to resolve the logistical,
operational, and market-based factors
that make implementation of the final
limit infeasible at this time for the
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Federal Register / Vol. 71, No. 96 / Thursday, May 18, 2006 / Rules and Regulations
industry as a whole. In addition, this
delay may decrease our 2001 projection
of the cost of compliance with the rule.
During this phase-in, we will continue
to work with the Diesel Partnership
(discussed below) and the mining
industry to help facilitate resolution of
DPF selection and implementation
problems for the diverse metal and
nonmetal mining environment.
dsatterwhite on PROD1PC76 with RULES
3. Diversity of Underground Mines
Affected by the 2001 Final DPM
Concentration Limit
The M/NM mining industry has
approximately 168 underground mines
that use numerous pieces of diesel
powered equipment, widely distributed
throughout each mining operation.
These mines employ an array of mining
methods to produce commodities
including metals such as lead, zinc,
platinum, gold, silver, etc. Also, there
are different types of nonmetal mines
that produce stone products such as
limestone, dolomite, sandstone, and
marble. Other underground nonmetal
mines produce clay, potash, trona, and
salt. Not only do these mines vary in the
commodities that they produce, but they
also use different mine designs and
mining techniques such as room and
pillar mining and stope mining. Some of
these mines are large, complex
multilevel mines, while others are small
adit-type mines.
Ventilation levels in these mines also
vary widely. Many limestone mines
have only natural ventilation with
variable air movement, whereas trona
mines have high ventilation rates to
dilute and remove methane gas released
during the mining process. There are
also deep metal mines with multiple
levels that have far less ventilation than
that found in underground trona mines.
Furthermore, many metal and nonmetal
mines are located in remote areas of the
country, at high altitudes, or are subject
to extremely hot or cold environments.
Considering these factors as a whole,
we have found that there is no single
control technology that would be
suitable and effective for all M/NM
mines in significantly reducing current
DPM levels to or below the 2001 final
DPM concentration limit of 160TC µg/m3
by May 2006.
4. Work of the M/NM Diesel Partnership
(The Partnership)
Since promulgation of the 2005 final
rule, the Partnership has been engaged
in on-going NIOSH diesel research. One
project involves a contract issued to
Johnson Matthey Catalyst to develop a
system to control nitrogen dioxide (NO2)
emissions from diesel-powered
underground mining vehicles equipped
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with Johnson Matthey’s Continuously
Regenerating Trap (CRT) system. This
system promotes regeneration at lower
temperatures and is widely used in
urban bus applications. If the results of
laboratory evaluations show that a
system is suitable for use in
underground mining, NIOSH would
continue studying this control
technology with a long-term field
evaluation in an underground mine. The
M/NM Diesel Partnership is continuing
to investigate this and other DPF
applications.
5. Remaining Technological Feasibility
Issues
In January 2001, we concluded that
technology existed to accurately sample
for DPM with a TC method and to
reduce DPM levels to the 160TC µg/m3
limit by January 2006 (66 FR 5889). In
June 2005, we concluded that it was
technologically feasible to reduce M/
NM underground miners’ exposures to
the interim PEL of 308EC µg/m3 by using
available engineering control technology
and various administrative control
methods. However, we acknowledged
that compliance difficulties may be
encountered at some mines due to
implementation issues and the cost of
purchasing and installing certain types
of controls. Specifically, we indicated
that implementation issues may
adversely affect the use of DPFs to
reduce exposures despite the results
reported in NIOSH’s Phase I Isozone
Study.
A number of commenters expressed
the view that our enforcement sampling
experience demonstrates that both the
interim DPM limit, and especially the
final DPM limit are technologically
infeasible. Some of these commenters
stated that our sampling data published
in our June final rule and on our web
site demonstrates that 90% or more of
the regulated industry cannot comply
with the January 19, 2006 limit of 160TC
µg/m3.
We have carefully examined these
comments, the data in the June final
rule, and our more recent enforcement
sampling data. We note first that the
commenters were not questioning the
validity of the sampling method or
whether our sampling data are complete
and representative. Our sampling and
analytical methods have been validated
by NIOSH, and our longstanding
sampling strategy that focuses on miners
we believe will experience the greatest
exposures is fully consistent with good
industrial hygiene practice. Second, in
evaluating the sampling data we
recognize that current DPM levels at
many mines exceed the final limit. In
the 2005 NPRM, we pointed out that,
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‘‘* * * in 2002 and 2003, we found that
over 75% of the underground mines
covered by the 2001 final rule have
levels that would exceed the final
concentration limit of 160TC µg/m3.’’ We
are encouraged, nevertheless, that DPM
levels across the industry have been
steadily and significantly reduced from
the levels observed prior to the
promulgation of the 2001 rule, and they
are continuing to go down. As we stated
in the 2005 NPRM (70 FR 53283), DPM
exposures in affected mines have
declined from a mean of 808 DPM µg/
m3 (646TC µg/m3 equivalent) prior to the
implementation of the standard, to a
mean of 233TC µg/m3 based on current
enforcement sampling. During the time
period from November 1, 2003 to
January 31, 2006, 1798 valid personal
compliance samples from all mines
covered by the regulation were
collected. From these samples collected,
18% of samples exceeded the 308EC µg/
m3 interim limit, and 64% exceeded the
160TC µg/m3 final limit. The fact that
64% of the enforcement samples
collected from November 1, 2003 to
January 31, 2006 are above 160TC µg/m3
does not establish infeasibility of the
standard. We expect that overexposures
will continue to decline as operators
install new equipment, address
implementation issues with DPFs, make
use of biodiesel fuel, and install cleaner
engines. Thus by May 2008, we would
expect operators to achieve full
compliance.
Our experience reveals that little
progress was made in reducing DPM
levels across the industry until the
interim DPM limit became effective.
Once the interim limit became effective,
mine operators implemented the
controls they believed were necessary to
attain compliance. Based on our
experience with other health standards,
we would not have expected the
industry as a whole to have achieved
compliance with the final limit before
the compliance deadline. Further, as
discussed throughout this section of the
preamble, we believe sufficient
technologically feasible DPM controls
exist for the industry as a whole to
comply with the final DPM limit within
the prescribed regulatory timeframe in
this final rule.
Commenters, acknowledging that
some DPM levels at some mines
currently exceed both the interim and
final DPM limits, indicated that the
existence of such overexposures was the
primary justification for the rule. These
commenters observed that the
rulemaking process is long, cumbersome
and costly and that there ‘‘would be
little point in invoking it to require the
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industry to do something it is already
doing on its own.’’
These commenters continued, ‘‘It is
settled law that MSHA ‘can impose a
standard which only the most
technologically advanced [mines] have
been able to achieve even if only in
some of their operations some of the
time.’ ’’ United Steelworkers, 647 F.2d at
1264.
We realize that some commenters will
disagree with our decision not to
presently implement the final limit.
However, we have carefully reviewed
all comments and data and believe that
a number of mines have made good faith
attempts to implement control
technology but need more time to make
such technology work. It is not our
intent to have a majority of the mining
industry apply for special extensions, or
for a significant number of miners to be
overexposed to DPM and have to wear
respirators. We stated in the 2005 NPRM
that a significant number of
overexposures may:
dsatterwhite on PROD1PC76 with RULES
* * * lead to another problem by requiring
a large number of miners to wear respirators
until feasible controls are fully implemented.
We have never had a standard that resulted
in a significant percentage of the workforce
being required to wear respiratory protection,
and we are concerned about the impact on
worker acceptance of the rule and about mine
operators’ ability to remain productive. We
are interested in public comment on how
many miners would need to wear respirators
to comply with the 2001 final limit and
proposed multi-year phase-in of the final
limit, and whether in each case they would
need to wear respirators for their entire work
shift, whether this amount of respirator usage
is practical, and any other comments or
observations concerning this issue (70 FR
53285)
The commenters that referenced the
OSHA Lead decision also presented the
results of an extensive analysis of our
DPM sampling and enforcement actions
at 11 selected mines. According to these
commenters, these data show that we
are not adequately enforcing the interim
DPM limit because there were 56
sample results that exceeded the interim
DPM limit, but we issued only 24 DPM
citations. These commenters further
assert that our failure to enforce the
interim limit provides encouragement
for mine operators who have delayed
the implementation of controls that are
necessary to attain both the interim and
final DPM limit.
These commenters did not provide
information that indicated which mines
were included in the commenter’s
analysis. However, assuming the
commenters’ numbers are accurate,
there are three plausible reasons for the
discrepancy between the number of
samples exceeding the enforceable limit
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17:42 May 17, 2006
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and the number of citations. First, the
commenters indicate that the data for
their analysis were gathered from the
MSHA Data Retrieval System, which
can be accessed from a link on the
MSHA internet home page. The DPM
sampling data contained in this
database includes DPM samples
obtained by our inspectors during the
‘‘baseline’’ sampling period prior to July
20, 2003. In accordance with provisions
of the Second Partial Settlement
Agreement, samples that exceeded the
enforceable limit during the baseline
sampling period were not subject to
citation as long as the subject mine
operator was exercising good faith
efforts toward developing a DPM
compliance strategy. Thus, the Data
Retrieval System includes numerous
overexposure sample results that were
not citable because they pre-dated our
full enforcement of the interim limit.
Second, our enforcement policy for
DPM, which is posted on our M/NM
DPM Single Source page, identifies
certain situations where a normally
citable overexposure to DPM will not
prompt a citation. In one case, a citation
will not be issued if the mine operator
can demonstrate that controls that
would normally be effective in attaining
compliance with the limit have been
ordered, and the affected miner is
wearing a suitable respirator in the
context of a compliant respiratory
protection program. This situation is
covered in question 24 in the
enforcement policy:
24. If MSHA finds a miner overexposed to
DPM and I have a valid purchase order for
controls that have not been delivered to my
mine site, will I be cited for a violation? No.
If you can demonstrate to MSHA, through
appropriate documentation such as purchase
orders, that you are making reasonable
progress toward implementing feasible
engineering and/or administrative controls
that have a reasonable likelihood of
achieving compliance with the interim DPM
limit within a reasonable timeframe, and you
have implemented a respiratory protection
program meeting the requirements of ANSI
Z88.2–1969 that covers all affected miners,
MSHA will not conduct compliance
sampling of affected miners at that time. The
inspector will return to the mine to verify
that adequate progress is being made toward
full implementation of controls and/or to
conduct DPM sampling based on the
completion timeframe established by the
mine operator.
In the other case, if the mine operator
has fully implemented all feasible
engineering and administrative controls
and the affected miner is wearing a
suitable respirator in the context of a
compliant respiratory protection
program, no citation will be issued even
if an exposure exceeding the limit is
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measured. This situation is covered in
question 29 in the enforcement policy:
29. How will MSHA determine if a citation
is warranted when evaluating whether I have
implemented all feasible controls? Once you
use and maintain all feasible engineering and
administrative controls to reduce a miner’s
exposure, implement the required respiratory
protection program and require the miner to
use a respirator, you will be in compliance
with § 57.5060(a), even though a miner’s
DPM exposure may continue to exceed the
limit and a citation will not be issued. Keep
in mind that feasibility is an MSHA
determination. If the agency finds that you
failed to install, use and maintain all feasible
controls, or you failed to establish an
appropriate respiratory protection program,
you will be out of compliance.
Third, some samples that exceed the
interim DPM limit may be resamples of
previously cited overexposures. Our
enforcement sampling practice requires
that after an overexposure is cited, the
mine operator is given the opportunity
to implement engineering and/or
administrative controls to reduce the
subject miner’s exposure to or below the
enforceable limit. Once these steps have
been taken, we resample the miner to
confirm that controls have been
successful in lowering the miner’s
exposure to or below the limit. On
occasion, the resample is still over the
limit, in which case, if the operator has
made good faith efforts to apply
normally effective controls, the citation
will be extended so that additional
controls can be implemented, followed
by another resample.
Thus, due either to controls being on
order, to issues relating to feasibility, or
to resample that continues to exceed the
DPM limit, and depending on other
factors, we may not issue a citation even
though a sample result represents a
DPM overexposure. We intend to
continue this enforcement practice
under this final rule and will issue
necessary compliance guidance.
Several commenters repeated earlier
public comments regarding their views
that previous technological and
economic feasibility determinations are
invalid because they were based
partially on analyses conducted using a
‘‘flawed’’ computer simulation program.
The economic feasibility issues are
addressed latter in this section. The
computer program in question, referred
to as the DPM Estimator, is a Microsoft
Excel spreadsheet program that
calculates the reduction in DPM
concentration that can be obtained
within an area of a mine by
implementing individual, or
combinations of engineering controls.
This program was the subject of a
Preprint published for the 1998 Society
of Mining Engineers Annual Meeting
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(Preprint 98–146, March 1998), and it
was fully described in a peer reviewed
article in a professional journal (Haney
and Saseen, Mining Engineering, April
2000). Its algorithm is accurate, and we
have not received comments that
challenged the mathematical basis for
its calculation.
Although this program was criticized
as ‘‘flawed’’ by several commenters, few
specific errors in the design or
utilization of the program were offered.
One commenter indicated that the
* * * computer model was based on
invalid assumptions of the availability of
filters that would fit the entire fleet of
equipment in use, and assumptions of perfect
ventilation conditions throughout the
industry.
This commenter continues,
* * * no such filters were available
commercially at the time of the MSHA
prediction, nor when the 2001 rule was
published, nor had any undergone testing.’’
Regarding the issue of ventilation, this
commenter stated that,
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* * * the assumption of ‘The Estimator’ of
perfect ventilation in mines did not exist in
reality and the rule could not be declared
feasible based on these incorrect
assumptions.
This same commenter goes on to say
that our technological feasibility
determinations for all of our DPM
rulemakings, from the original 2001
final rule to this rulemaking, are invalid
because they are founded on analytical
results obtained from the Estimator.
We have responded previously to
both of these comments, and to many
other criticisms of the Estimator.
Regarding the availability of DPFs, we
must emphasize that our DPM rules
have always been performance oriented,
and that mine operators have been given
wide latitude to select DPM controls
that were best suited to their unique
circumstances and conditions. Neither
the original 2001 rule nor this current
final rule requires DPFs as the exclusive
means of compliance with the DPM
limit. The Estimator contains provisions
for estimating the effect of applying
DPFs, ventilation upgrades, low DPM
engines, and other DPM controls on
DPM levels in an area of a mine. At the
time that we promulgated our 2001 final
rule, however, we acknowledged our
limited in-mine documentation on
implementation of DPM control
technology with issues such as
retrofitting and regeneration of filters.
Consequently, we committed to
continue to consult with NIOSH,
industry and labor representatives on
the availability of practical mine worthy
filter technology.
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Regarding the same commenter’s
concerns that ventilation issues were
handled inappropriately in the 31 Mine
Study, we believe the commenter used
the term ‘‘perfect ventilation,’’ when
they may have meant perfect mixing of
ventilation airflows. ‘‘Perfect
ventilation’’ is a term with which we are
unfamiliar. We have never used this
term in this or any other rulemaking,
and are unfamiliar with it in the context
of mine ventilation engineering.
‘‘Perfect mixing,’’ in the context of
ventilation systems, is a common
technical term that refers to an idealized
process in which two or more airflows
of dissimilar composition join, and in
which the composition of the composite
airflow is an instant and homogonous
mix of the input airflows. The issue of
perfect mixing was raised by one of the
same commenters in their public
comments on the August 14, 2003
proposed rule on the interim DPM limit,
and we responded in detail to these
comments in the preamble to the 2005
final rule (70 FR 32920–32921).
The commenters believe that the
Estimator’s computations of DPM
concentrations are valid only if engine
emissions are perfectly mixed with the
air flow, which they suggest does not
occur in an actual mine. As discussed
in the 2005 final rule preamble, these
commenters make an erroneous
assumption with respect to our
utilization of the Estimator. The
Estimator actually incorporates two
independent means of calculating DPM
levels: one based on DPM sampling data
for the subject mine, and one based on
the absence of such sampling data.
Where no sampling data exist, the
Estimator calculates DPM levels based
on a straightforward mathematical ratio
of DPM emitted from the tailpipe (or
DPF, in the case of filtered exhaust) per
volume of ventilation air flow over that
piece of equipment. This is referred to
in the Estimator as the ‘‘Column B’’
option for calculating DPM
concentrations. The commenters’’
observation that the Estimator fails to
account for imperfect mixing between
DPM emissions and ventilating air flows
is a valid criticism of the ‘‘Column B’’
option. For this and other reasons, the
Estimator’s instructions urge users to
utilize the ‘‘Column A’’ option
whenever sampling data are available.
In the ‘‘Column A’’ option, the
Estimator’s calculations are ‘‘calibrated’’
to actual sampling data. Whatever
complex mixing between DPM
emissions and ventilating air flows
existed when DPM samples were
obtained, are assumed to prevail after
implementation of a DPM control. This
is an entirely reasonable assumption,
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and in fact, there is no engineering basis
to assume otherwise. Indeed,
comparisons of ‘‘Column A’’ Estimator
calculations and actual DPM
measurements taken in mines before
and after implementation of DPM
controls have shown good agreement,
indicating that Estimator calculations do
adequately incorporate consideration for
complex mixing of DPM and air flows
when the ‘‘Column A’’ option is used.
The Estimator was originally
developed with both the Column A and
Column B options because at the time
it was developed (1997), the specialized
equipment required for reliable and
accurate in-mine DPM sampling, such
as the submicron impactor, was not
widely available. Consequently, few
mine operators were able to obtain the
in-mine DPM sample data required for
utilizing the Column A option. Though
mine operators may continue to use the
Estimator, we rely more on our in-mine
documentation and enforcement
experience on the feasibility of DPFs.
This background and detailed
explanation on perfect mixing was
provided in the preamble to the 2005
final rule (70 FR 32920). However, the
comments we received on this subject
for the instant rulemaking do not
acknowledge or respond to the
background and explanation we
provided in the earlier preamble. The
commenters simply restate their
previous assertion that the Estimator is
flawed because it assumes perfect
ventilation, which as noted above, we
believe was meant to refer to perfect
mixing.
As we have maintained throughout
this rulemaking, mine operators should
determine the control or combination of
controls that will be best suited to their
mine-specific circumstances and
conditions, and that controls need to be
evaluated, selected, and implemented
on a case-by-case and application-byapplication basis. Nonetheless, based on
our experience, observations, and the
comments received from mine
operators, we believe to attain the final
DPM limit, many mine operators that
are not yet using DPFs will have to start
using them, and most mine operators
that are already using DPFs to attain the
interim limit will have to continue or
increase their use to attain the final
limit. The mining industry maintains
that while some operators are using
DPFs to control miners’ exposures to the
interim PEL, it is infeasible for them to
further reduce miners’ exposures
through expanded use of DPFs.
However, we maintain that feasibility
difficulties encountered with the use of
DPFs can be resolved within the
prescribed timeframe offered in this
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final rule, and that the greatest
impediment to more widespread use of
DPFs throughout the industry is the
need to overcome implementation
challenges and difficulties relating to
specific pieces of mining equipment.
For example, as the final limits become
effective, some mines that were possibly
using one or two DPFs on large
horsepower haul trucks may have to
install more DPF systems on other types
of machines, such as loaders or support
and utility equipment, in order to attain
the final limit.
As discussed extensively throughout
the rulemaking record and as we
explained in detail in the 2005 NPRM,
mine operators continue to prefer
passive DPF regeneration systems over
active regeneration systems. Passive
regeneration is the process where the
temperature of the exhaust gas produced
by the engine is sufficiently high for a
sufficient percentage of the working
shift to burn off the collected DPM on
the DPF. In order for passive
regeneration to be a viable option, filter
regeneration has to occur frequently
enough to prevent the DPM that
accumulates in the filter from causing
backpressure on the engine that exceeds
the engine manufacturer’s backpressure
specification. Passive regeneration is
normally preferred by mine operators
because the DPF will regenerate in the
normal course of equipment operation,
with no interruption to mine production
activities and no equipment downtime
required for filter regeneration. Also,
passive regeneration occurs without the
need for intervention by the equipment
operator, and it does not require any
special external equipment or facilities.
However, many pieces of mining
equipment do not have engine duty
cycles that will presently support
consistent passive regeneration. This
problem will take more time for
individual mine operators to resolve.
If a passive DPF loads up with DPM,
but the exhaust temperature is not
sufficient to ignite and burn off the
accumulated DPM, the backpressure on
the engine will increase. Prolonged
engine operation in excess of the
manufacturer’s backpressure
specifications can cause engine and DPF
damage. Therefore, it is strongly
recommended that when passive
regeneration DPF systems are installed,
a means for the machine operator to
monitor the engine’s exhaust
backpressure should be included. Such
a provision is important even on
equipment where the normal duty cycle
easily supports passive regeneration.
For example, if a piece of equipment on
which a filter normally passively
regenerates is used temporarily for some
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other activity having a less severe duty
cycle, the filter may not passively
regenerate, and backpressure could
build up. Likewise, if the subject
equipment experiences a maintenance
related problem that causes an increase
in the level of ‘‘engine out’’ DPM
emissions, the rate of DPM buildup in
the filter could exceed the capacity of
the filter to passively regenerate. In such
cases, excessive engine backpressure
could build up in less than a working
shift. If the equipment is provided with
a means for monitoring backpressure,
and the equipment operator observes
engine backpressure rising to excessive
levels, corrective action can be taken
before engine or filter damage occurs.
Successful implementation of passive
DPF systems has been reported where
the mine operators have determined that
a machine has sufficient exhaust gas
temperature for passive regeneration
and exhaust backpressure is being
monitored.
If passive regeneration is infeasible
due to an insufficient duty cycle, active
regeneration may be a feasible
alternative. Active regeneration depends
on an external heat source for burning
off the DPM collected in a filter. Some
mine operators commented that it is not
feasible for them to utilize active
regeneration due to the physical size of
filters, machine downtime, and/or the
cost associated with building and
equipping underground regeneration
stations required for active DPF
regeneration. We disagree that these
factors render active regenerating DPF
systems infeasible. As discussed
throughout the rulemaking record, and
later in this section of the preamble,
filter size and machine downtime issues
relate to implementation challenges and
difficulties which can impact feasibility
of compliance with the final limits. We
believe these factors can usually be
effectively addressed through proper
system selection and deployment, as
described below, which take time to
effect. We also believe the deployment
of an active DPF system is economically
feasible under the prescribed time
frames for the final limit. Economic
feasibility is discussed in detail later in
this section in this preamble.
Engine emissions and exhaust flows
affect the size of the DPF that needs to
be installed. These factors are important
considerations for both passive and
active regeneration. If the DPF is
undersized for a particular application
due to high DPM emissions or high
exhaust flows, a passive or active DPF
system may become overloaded,
requiring the filter to be removed from
service for regeneration. If such an
interruption occurred mid-shift, it
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28943
would typically have a greater negative
effect on production than if it occurred
at the end of a shift. Active regeneration
DPF systems are normally sized so that
the filter has sufficient capacity for the
host vehicle to operate over its normal
duty cycle for at least a full shift or
longer. In some cases, especially when
a machine with an older, high emission
engine needs to be filtered, a filter
having sufficient capacity to allow for a
full shift of machine operation may be
too large to fit in the available space on
the machine. For this reason, most DPF
manufacturers do not recommend DPF
installation on older high emission
engines. Some mine operators who have
faced this dilemma have opted to
compromise by installing a smaller
filter. The result is DPM overloading.
DPM overloading leading to excessive
backpressure on the engine is the main
problem that mine operators experience
when the DPF installation is not correct
for the application and duty cycle.
Possible feasible corrective actions
include utilizing a larger DPF or a lower
DPM emission engine, or both. As noted
later in this section of the preamble,
installation of a new, low-emission
engine, in addition to facilitating use of
a reasonably sized DPF, can cut DPM
emissions by up to 90% or more, and
their greater operating efficiencies can
reduce maintenance costs and lower
fuel usage by 10% to 15% compared to
older technology high emission engines.
Regarding commenters’ concern about
the physical size of DPFs, if the DPF for
a particular piece of equipment is too
large to handle or too large to fit in the
space available on the equipment, the
exhaust could be divided into two
branches fitted with smaller sized filters
on each branch, or as noted above, the
engine could be replaced by one with
lower DPM emissions that can be
effectively filtered by a correspondingly
smaller DPF.
Since 2001, a number of older, high
DPM emitting engines have been
replaced with new, low DPM emitting
engines, either through direct engine
replacement into existing equipment or
through the acquisition of new
equipment, but not as many as we
predicted in 2001. From our
enforcement experience, we believe this
has occurred in mostly the larger
horsepower engines, greater than 150
hp, in production equipment. This
equipment is typically turned over more
frequently because it has more severe
duty cycles, is worked harder, and
typically has a shorter life than smaller,
lower horsepower support equipment.
High horsepower production equipment
also typically accounts for the greatest
proportion of DPM produced in the
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mine, so replacing these engines was the
highest priority at most mines. Thus, the
smaller engines normally found in
support equipment often have older
engines with higher DPM emissions per
horsepower than the newer and larger
production equipment.
We estimated in the 2001 final rule
that 50% of the support equipment
would probably need DPFs for
compliance with the final limit (66 FR
5889–90). The higher DPM emissions
from these engines, however, can
complicate the expanded use of DPFs on
this equipment. It is our belief that the
mining industry will need additional
time to further evaluate the proper
sizing of both passive and active
regeneration DPF systems on this
equipment. Consequently, we expect the
implementation issues relating to DPFs,
particularly the selection of appropriate
DPFs for a given application,
regeneration issues, filter maintenance,
etc. may extend over a larger portion of
the mining industry as operators work
toward compliance with the final limit.
Although we believe these
implementation issues are sufficient to
warrant the additional time offered in
this final rule, we are nonetheless
confident these issues can be effectively
resolved within the compliance
timeframes established in the final rule.
For example, EPA compliant 2007 onroad engines will be provided with
engine manufacturer supplied DPF
systems that will regenerate
continuously or automatically
regardless of duty cycle, thereby greatly
reducing implementation issues for the
owner. Another example is the HTDPF
with integral heat exchanger. This
recently commercialized technology
will enable filtering the exhaust from
small to mid-size equipment with low to
medium duty cycles. In addition to
these and other new developments,
competitive pressures will force the
manufacturers of existing DPF systems
to make incremental product
improvements over time.
Note that high engine exhaust
temperatures are an implementation
issue only for disposal particulate filter
element type DPFs. Ceramic and
metallic filter element type DPFs can
tolerate the normal range of exhaust
temperatures from any diesel engine. In
fact, passive regenerating DPFs depend
on high exhaust temperatures to initiate
the regeneration process. Where high
exhaust temperatures could potentially
occur, but where the user wishes to
implement a disposal particulate filter
element system, the use of a heat
exchanger upstream from the filter
element is required to lower the exhaust
gas temperature and prevent filter
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element damage. For ceramic and
metallic filter element type DPFs, heat
exchangers are neither required nor
desired.
Several commenters stated that we
admitted to implementation problems
with DPF systems in the preamble to the
proposed rule. We agree with these
commenters that we did express
concerns about implementation issues
with DPFs, and that these concerns,
along with concerns about
implementation issues with other DPM
engineering controls led to our decision
to propose delaying the effective date of
the final limit of 160TC µg/m3 until
January 2011. We continue to believe
that a delay to the effective date for the
final limit is necessary due to feasibility
considerations. However, as we
explained earlier in this section of the
preamble, based on our enforcement
experience and comments and other
data in the rulemaking record
addressing feasibility since we issued
the 2005 NPRM, we have subsequently
determined that delaying the final limit
until 2011 is not justified. Primarily due
to wider availability of alternative fuels,
particularly biodiesel, improved filter
technology, and the impending
availability of EPA compliant 2007 onroad diesel engines, we believe the
rulemaking record supports the three
step phase-in of the final limit over two
years, with the final limit of 160TC µg/
m3 becoming effective in May 2008.
This is the approach that is incorporated
into this final rule, and we believe it
provides for the maximum protection of
miners that is technologically and
economically feasible for the industry to
achieve.
As discussed earlier in this section of
the preamble, recent developments in
the three key areas of biodiesel,
improved filters, and EPA compliant
2007 engines, along with the application
of a variety of other existing DPM
controls, will enable compliance by the
industry as a whole significantly sooner
than was proposed in the September
2005 NPRM. Biodiesel, improved filters,
and EPA compliant 2007 engines can be
used by any size mine producing any
M/NM commodity, and these
technologies are not subject to many of
the difficult implementation issues that
have slowed the adoption of some DPM
controls. For example, biodiesel can be
used in any diesel engine with
elastomeric fuel system components
that are biodiesel compatible, and any
non-compatible components can be
easily replaced. No other engine or
equipment modifications of any kind
are required. Improved diesel
particulate filters are commercially
available for retrofit to any size diesel
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engine, and systems like the HTDPF and
diesel particulate ReactorTM are
particularly well suited to installation
on small and medium sized production
and support equipment that had been
problematic for some mine operators.
No implementation issues in regards to
selection of the DPF media, sizing, or
regeneration type are expected for EPA
compliant 2007 on-road engines. As
discussed previously in this section, the
engine will have a DPF installed in the
vehicle when purchased by the mine
operator.
DPF systems are a more effective
control technology for reducing EC than
TC. In order to comply with the final
limit, we expected that most mine
operators would need to add to the DPM
controls they had previously
implemented for compliance with the
interim limit. We also anticipated that
many mine operators that had
successfully attained compliance with
the interim limit without DPFs would
need to utilize DPFs to obtain
compliance with the final limit.
We acknowledged in previous
preambles that DPFs may not be the
optimal solution for all machines,
especially machines equipped with
dirtier engines. But we have also
advised that machines with older,
dirtier engines should be replaced or repowered with cleaner engines, and then
if necessary, be equipped with DPF
systems.
We continue to emphasize to the
mining industry to utilize our DPM
Single Source Page to obtain
information to assist with installation of
DPF systems. This information stresses
that DPFs require the engine to be
maintained through a good maintenance
program and to monitor the exhaust
backpressure in order to prevent the
DPF system from becoming overloaded
with DPM. Minimizing these problems
can help prevent premature DPF or
engine failure, which affect feasibility.
NIOSH commented that
Although adverse health effects occur at
the proposed concentration limits and below,
NIOSH recognizes that all factors, including
technical and economic feasibility must be
considered by MSHA in developing an
exposure standard. NIOSH is aware of the
‘implementation and operational difficulties’
currently facing the metal and nonmetal
mining industry presented in MSHA’s
preamble, Section IV. Technological
Feasibility (page 53282). A phase-in period
may provide time to resolve such issues.
Requiring control technologies before mine
operators have had sufficient time to work
through selection and implementation
problems may create hazards and adverse
health effects, such as the elevated levels of
NO2 experienced when some PT-catalyzed
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diesel particulate filters (DPFs) have been
used in poorly or marginally ventilated areas.
NIOSH also recognizes that the mines
covered by this proposed standard have
unique designs and operational differences
presenting unique challenges in controlling
and reducing diesel emissions. For some
metal and nonmetal mines, targeted
reductions in exposures of underground
miners to DPM below the 400 µg/m3 TC or
308 µg/m3 elemental carbon (EC) current
limit may be achieved only through
implementation of complex, integrated
strategies and state-of-the-art control
technologies.
The first steps to control diesel emissions
are fundamental changes to improve mine
ventilation and diesel engine maintenance
practices, along with the introduction of
cleaner engines or the use of alternative fuels,
such as biodiesel, when practical. When
these are insufficient to achieve compliance,
more advanced diesel emission control
technologies, such as DPF systems, may be
necessary to achieve compliance.
We have considered the technological
and economic feasibility of achieving
the final limits specified in this final
rule as discussed throughout this
preamble. The three step phase-in
approach allows mine operators more
time to work towards implementation of
DPM control technologies. We agree
with NIOSH that the first steps that the
mine operators took to lower DPM
levels were changes to engines,
maintenance practices, ventilation
systems, and to a lesser extent,
alternative fuels. As we have discussed
in this preamble, these efforts have
lowered miners’ exposure to DPM as our
enforcement sampling has shown.
Even though NIOSH refers to DPFs as
‘‘more advanced diesel emission control
technologies,’’ some mines have already
implemented DPFs in order to comply
with the interim standard. These same
mines will most likely continue using
DPFs, plus add additional DPFs or other
DPM controls such as biodiesel, to meet
the final limits. However, we agree that
the final limits will require a larger
segment of the mining industry to
implement DPFs and alternative fuels.
We agree that underground metal and
nonmetal mines present unique designs
and operational differences which affect
the application of DPM controls. This
three step phase-in approach provides
the time for mine operators to learn
more about advanced control
technologies with regards to
implementation issues.
NIOSH further referenced a June 25,
2003 letter to the Assistant Secretary
from Dr. John Howard, Director, NIOSH,
relating to DPFs. NIOSH stated that
although DPFs ‘‘* * * are commercially
available, the successful application of
these systems is predicated on solving
technical and operational issues
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associated with the circumstances
unique to each mine.’’ This three step
phase-in of the final limits will provide
the necessary time for mine operators to
overcome these technical and
operational issues, since we believe that
DPFs are now more readily available
and DPF implementation issues can be
resolved.
This commenter also agreed with us
that mine ventilation, maintenance,
cleaner engines or use of alternative
fuels, such as biodiesel were effective
DPM control measures. However, the
commenter stated that when these
methods are insufficient to achieve
compliance, more advanced control
technologies would be needed, such as
DPF systems. Gaining extensive
experience with implementation and
operation of DPF systems on production
vehicles would greatly assist in
resolving some of these issues. The
commenter further stated that to ensure
success of the phase-in period,
individual mine operators or a
consortium of mine operators or other
partnerships should have compliance
plans detailing their integrated
approach to reducing DPM levels in
terms of maintenance, ventilation, fuels,
control technologies, retrofitting, and
monitoring.
We agree with the commenter that the
final limit does require mine operators
to continue implementing the current
controls needed to meet the interim
concentration limit, however, in order
to meet the final limit, more controls
may need to be implemented. If DPF
systems are needed, then the mine
operator will need to continue work to
properly install and maintain DPF
systems to manufacturers’
specifications.
Some commenters referred to the
NIOSH Phase I and II studies, stating
that they were successful in showing
that the DPM controls, especially DPF
systems, work in reducing DPM.
However, these commenters believed
that NIOSH did not provide reliable
data to indicate that the selected filter
technology would provide the necessary
reductions of DPM in actual mining
applications. We responded to the
NIOSH Phase I and II studies in the
2005 final rule. We noted the successful
DPM reductions that were achieved
from the DPM controls, especially DPF,
in the Isozone study of Phase I. We
further reviewed the work done by
NIOSH in the production area of the
mine in Phase II. We maintain as we did
in the preamble to the 2005 final rule
that ‘‘the Phase II study helped to
confirm existing agency data that shows
that it is technologically feasible to
reduce miners’ exposures to DPM to 308
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µg/m3 interim PEL.’’ (70 FR 32928) The
NIOSH work confirmed that DPFs can
reduce DPM to MSHA’s DPM limits. As
stated previously, as the final limit is
reduced over the time frame specified in
this final rule, the mine operator can
implement additional DPF systems (or
other DPM control technologies) to
further reduce the DPM exposure. The
NIOSH Phase II study and MSHA’s
Greens Creek study as discussed in the
June 6 preamble (70 FR 32928—32929)
showed reductions in EC.
The same commenters stated that the
Phase II study showed that the
efficiencies of the DPF did not always
agree with laboratory studies. However,
the commenters failed to acknowledge
that the comment was directed towards
the DPF systems performing better than
laboratory data, especially for EC
reductions. We highlighted this finding
from NIOSH’s Phase II study in the
preamble to our 2005 final rule (70 FR
32928).
Several commenters continued to
state concerns with the use of catalyzed
ceramic DPF systems due to increased
NO2 levels. We discussed this issue
thoroughly in the preamble to the 2005
final rule (70 FR 32928–32929). We
concluded then, and we believe the
evidence is still persuasive, that the NO2
issues discussed in the NIOSH Phase II
studies were related to deficient
ventilation in the areas where the
testing occurred. The results of the
Greens Creek study, which also
evaluated heavily platinum catalyzed
DPFs, showed a possible rise in NO2;
however the small increase detected
made it unclear as to the cause
(preamble to the 2005 final rule, (70 FR
32884 and 32921)). Even if the NO2
increases at Greens Creek were caused
entirely by the catalyzed DPFs, the rise,
which was about 1 ppm downstream
from stopping operations involving one
loader and two or three haulage trucks
totaling over 1,000 horsepower, was
manageable due to effective auxiliary
ventilation. We continue to
acknowledge that highly catalyzed
platinum ceramic DPFs have the
potential to generate higher levels of
NO2 than the baseline emissions from
the subject diesel engine. However,
when such DPFs are used in
conjunction with proper ventilation,
NO2 has not increased to hazardous
levels. As discussed previously in this
section, NIOSH commented that
increased NO2 levels occurred in poorly
or marginally ventilated areas with the
use of some catalyzed DPFs.
Several commenters agree that
progress has been made with the
application of ceramic DPF systems that
regenerate passively on larger
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horsepower production machines. The
DPF systems have been shown to be
highly efficient in collecting DPM and
mine operators have reported that they
do passively regenerate on the larger
horsepower, production machines. The
production machines operate at a heavy
duty cycle that corresponds to high
exhaust gas temperatures for a sufficient
portion of the shift. This allows the DPF
to regenerate passively and burn off the
collected DPM, thus keeping the DPF
below the engine manufacturers’
maximum allowable exhaust
backpressure.
One mine operator provided a list of
their DPF systems that have been in
operation up to 9000 hours. The DPF
systems were supplied by two different
DPF manufacturers, but were both
designed for passive regeneration. This
commenter stated that 13 of their 17
haul trucks were equipped with passive
regeneration DPFs and they are
currently evaluating 4 more units on
their haul trucks. According to the
information submitted by this
commenter, they have plans for
installation of DPFs on 6 of their
loaders. The commenter stated that the
process of achieving DPF reliability has
been arduous, and required much
discussion and work with the DPF
manufacturer.
Another mine operator also stated that
32 passive regeneration DPF systems
have been installed with an average life
of the DPF system from 3000–4000
hours. The operator stated that the
success has been with haul trucks and
they are working on evaluating the
installation of this type DPF on LHD’s.
Yet another mine reported installing
four passive DPF systems on machines
and the exhaust backpressure quickly
exceeded the manufacturer’s
specification for exhaust backpressure.
The commenter stated that the DPF
would not passively regenerate,
requiring the mine to remove them for
cleaning.
The experiences described by these
three mine operators continue to show
that DPF system selection and
installation must be carefully evaluated.
However, overall it appears that a
number of mine operators have been
successful in installing passive
regeneration DPF systems on machines
that have high duty cycles and are
therefore acceptable for passive
regeneration, particularly haulage trucks
and some loaders. We continue to
advise mine operators that DPF systems
that utilize passive regeneration must be
carefully evaluated and well-maintained
for their successful operation. Both
MSHA and NIOSH continue to post
extensive information on DPF systems
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on our respective Web sites. The Filter
Selection Guide (detailed in the
preamble to the 2005 final rule (70 FR
32922)) that was designed by NIOSH
and MSHA continues to be an important
tool for understanding the steps that
must be taken to evaluate, select, and
install a DPF system, especially one that
depends on passive regeneration.
The same commenters also stated that
when passive DPF systems were not
feasible for some types of machines,
especially those with medium to low
duty cycles, they began evaluating
active regeneration systems. In contrast
to passive regeneration systems that
depend on the high temperature of the
engine’s exhaust for burning off the
DPM collected in the DPF, active
systems use an external heat source to
initiate the burning process for DPM.
These commenters stated they have
purchased some active systems for
evaluation. However, they question the
feasibility of utilizing active DPF
systems in their mines due to a variety
of logistical and operational concerns.
For example, they point out that the
mining production cycle at many mines
does not provide for sufficient machine
downtime to stop the machine and take
it out of service in order to ‘‘plug’’ the
machine into a regeneration station for
regeneration of the DPF to occur. These
commenters also stated that if they tried
to change out DPFs, then the number of
DPFs they would need to maintain on
hand to store and rotate would be both
cost prohibitive and storage space
consuming. These commenters
indicated that machines that return to
the surface at the end of the shift would
be candidates for active regeneration.
We agree that using active systems
that require prolonged machine
downtime for regeneration may not be
feasible at all mines. However, at mines
that only operate for a single shift or
have a gap between shifts for blasting
gases to clear, for example, regenerating
active filters between shifts would be
more feasible. For mines that operate
around the clock, shutting down a key
piece of production equipment for filter
regeneration may present a problem.
While such an implementation scheme
would undoubtedly adversely affect
mine production, the commenters did
not provide information or data
sufficient to establish the significance of
the effect to determine the feasibility of
the method.
More importantly, however, we have
continued to recommend alternatives to
this implementation scheme for active
DPFs. For example, the fuel burner
system regenerates the filter during
normal equipment operations, without
intervention by the equipment operator,
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and regardless of equipment duty cycle.
Another option is to swap out filters
instead of regenerating them on-board
the equipment. Between shifts, a used
filter can be removed from a piece of
equipment and swapped for a
regenerated filter. The used filter can
then be placed in a regenerating
appliance so it will be ready by the
beginning of the next shift, and the
equipment can be returned to duty
without further delay. Using this
implementation method, equipment
downtime to accommodate DPF
regeneration is measured in minutes
rather than hours.
The technology for a variety of active
systems continues to be commercially
available. Implementation of active
regeneration systems does require the
mine operator to look at the logistics of
time, place, and manpower to
successfully perform the task. Those
logistical decisions have been outlined
in the NIOSH Filter Selection Guide.
However, the mechanism for
installation of a DPF system with active
regeneration is less complex than
passive regeneration because the
location of the DPF on the machine,
distance of the DPF from the exhaust
manifold or turbocharger, and the
orientation of the DPF are less
important. On passive regeneration
systems, the DPF must be as close as
possible to the outlet of the exhaust
manifold or turbocharger to utilize the
maximum exhaust gas temperature. On
active regeneration systems, this is not
an installation requirement.
We continue to believe that for
installation of either type of
regeneration system, engine
maintenance is vital. The engine must
be maintained in good working
condition. The engine must be
maintained to limit excess DPM being
emitted from unburned fuels or oil.
Intake filters must be maintained and
the engine’s intake air restrictions and
exhaust backpressure must be
maintained to the manufacturer’s
specifications.
In addition, the exhaust gas
backpressure measurement provides
critical information on the amount of
DPM loading on the DPF. Engine
manufacturers and DPF manufacturers
provide maximum limits that should
not be exceeded to ensure proper engine
and DPF operation. The exhaust
backpressure ports and devices must be
maintained. This has become a special
concern in the underground coal sector,
prompting the Coal DPM Partnership to
form a Subcommittee to investigate the
proper procedures to monitor
backpressure and the proper type of
equipment to use. MSHA and NIOSH
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are working with labor and industry on
this issue. Recommendations from this
subcommittee will be shared with both
coal and M/NM industry personnel
since the information will be pertinent
to both mining sectors involved with
DPF systems. These recommendations
will cover all types of DPF systems.
We believe that in place of ceramic
DPF systems that require passive or
active regeneration, machines could be
installed with disposal DPF technology.
These systems are commercially
available and include exhaust heat
exchangers to limit the exhaust gas
temperature at the DPM media. These
systems are available for all horsepower
ranges typically found in M/NM mines.
From the comments received to the
proposed rule, mine operators have
installed synthetic high temperature
disposable particulate filters (HTDPFs)
as a means for DPM control. HTDPFs
were initially used on permissible
machines in underground coal mines to
further reduce the chance of a filter fire
that could occur more easily with paper
filter media. Since that first introduction
on permissible machines, manufacturers
have developed systems to use HTDPFs
on non-permissible machines in
underground coal mines and on
machines in underground M/NM mines.
The HTDPFs were tested by NIOSH in
the Isozone studies and shown to be
effective in DPM EC reductions.
One commenter stated that they
estimated the DPM reduction to be
about 60–65% with the use of HTDPFs.
We would consider that reduction
estimate to be low (assuming the data
the commenter was referring to was EC)
when compared to our laboratory test
that showed up to 80–83% percent
reduction of whole DPM and higher
efficiencies for EC.
However, several commenters stated
that the synthetic HTDPF systems were
removed from the machines that they
were originally installed on when the
DPF ‘‘burned out’’ and melted. The
commenters stated that the backpressure
would rise quickly when the DPF
loading exceeded the specified loading
capacity of the DPF media size. When
this occurred, there was the potential for
a DPF ignition.
One of these commenters also stated
that the use of HTDPF was discouraging
because the DPFs were only lasting 4–
10 hours, requiring filters to be
discarded and replaced every two shifts
or less. It is well known that the
operating life of a disposable DPF is
mainly due to the size of the DPF
installed, the amount of DPM that the
engine emits, and the condition of the
engine. Any one of these parameters can
affect DPF life. The size of the DPF
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should be evaluated and engineered into
the machine prior to installation. The
DPM output of the engine should also
be known prior to installation, and the
condition of the engine is an important
factor that can change and can severely
affect DPF life. However, the engine
DPM output and the condition of the
engine can be altered. If DPF life is too
short due to an older engine, then an
engine replacement with a newer,
cleaner engine can usually be done.
Engine maintenance can increase DPF
life by minimizing burning oil or
unburned fuels.
Underground coal mine operators
faced these same implementation issues
when they began using disposable DPFs
to comply with the coal DPM rule. They
resolved these issues by replacing high
DPM emitting engines and improving
engine maintenance procedures. The
same methods for extending DPF
operating life are applicable to M/NM
machines and are discussed in the DPF
Selection Guide.
The DPM overloading issue also led to
DPF ignition events. These concerns
were raised by the underground coal
mine operators. In response to this, we
performed an extensive investigation on
the causes of DPF ignitions. We
determined that when the DPF collected
the DPM, oils and unburned fuels were
also collected on the media. When the
DPF was exposed to exhaust gas
temperatures that were in excess of 650
°F, the DPM, oils, and unburned fuels
ignited, but not the DPF media.
However, when the burning occurred,
temperatures were high enough to melt
the DPF media. When paper filter media
was involved, the paper filter media
also caught fire.
To help resolve this issue and to
provide the mine operators with more
awareness of the potential for an
ignition of a DPF, we worked with DPF
manufacturers that produce synthetic
HTDPF systems. The DPF
manufacturers agreed with us to update
their DPF system specifications to
specifically advise their customers that
the synthetic HTDPF cannot be used
where the exhaust gas temperature at
the filter media exceeds 650 °F. We
posted on the internet links to these
updated specification sheets from the
manufacturers.
To help further resolve this issue,
manufacturers have developed exhaust
gas heat exchangers, both air to air and
air to water type heat exchangers that
can either be installed in the exhaust
prior to the DPF media or be built in as
part of the DPF canister to maintain the
exhaust gas temperature at or below 650
°F. The addition of a heat exchanger
makes the use of the HTDPF feasible on
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a wider variety of vehicles that have
duty cycles that could create exhaust
gas temperatures at the DPF media in
excess of 650 °F. Instead of the machine
manufacturer or mine operator being
concerned that the engine’s duty cycle
does not exceed 650 °F, a heat
exchanger system can be built in to the
exhaust system prior to the DPF to limit
the exhaust gas temperature at the filter
media to 650 °F.
Several commenters made reference
to a joint NIOSH Partnership study at
the Stillwater Mine. This study did a
paper analysis of the equipment and
based on some basic information,
assigned each piece of equipment into a
category to describe the potential for
DPF application. The rulemaking record
does not include the results of this
study, and it is our understanding from
NIOSH that this study is incomplete at
this time. Therefore, this study was not
considered by us in reaching our
determination in this final rule.
However, we do believe that the type
of approach used by NIOSH is a good
beginning step that each mine should
take when considering the use of DPF
control technology. Once a mine
operator categorizes its equipment based
on general assumptions, they could then
begin a more in-depth study of each
piece of equipment that may need a DPF
system installed, and finally, determine
which system or systems could be
feasible. Again, the NIOSH Filter
Selection Guide provides mine
operators with a step by step approach
to determine the best ‘‘fit’’ for a machine
to reduce the DPM emissions.
One commenter discussed feasibility
issues with applying DPF systems to
their mine’s equipment which included
Schedule 31 equipment. The commenter
stated
FMC’s fleet falls into the category that does
not support DPF’s due to duty-cycle and
manufacturers specifications. To date, FMC
has found only one filter manufacturer that
is willing to try their disposable filters on our
fleet. Specific challenges/concerns include
flammability of disposable filters, low engine
duty cycle, and Schedule 31 hurdles that
have yet to be addressed.
The commenter referenced the NIOSH
work conducted at the Stillwater Mine
where NIOSH categorized equipment for
DPF application as was discussed
above.
We believe that the issues raised by
the commenter have been fully
addressed in this preamble and in
previous preambles which include
flammability of disposable filters and
the types of DPFs that can be used based
on an engine’s duty cycle.
The commenter references his
Schedule 31 equipment. Schedule 31 is
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terminology used to refer to permissible
equipment approved by us for use in
gassy mines. Similar types of diesel
powered equipment that are used in this
mine are also used in underground coal
mines in areas where methane gas may
be present. We do not agree with the
commenter that DPF systems are not
available for permissible equipment.
Underground coal mines have been
retrofitting similar permissible
equipment since 2001 to reduce DPM
emissions from this type of equipment.
To date, approximately 300–400
disposable type DPF systems have been
installed on permissible equipment in
coal underground. We believe that the
equipment referred to by the commenter
can be installed with a DPF system. We
have information posted on our Web
site on retrofitting permissible
equipment. Companies such as Dry
Systems Technologies (DST), DBT
Australia Pty Limited, and EJC Mining
Equipment have been supplying this
type of DPF system to the underground
coal permissible fleet. In addition, mine
operators can contact our Technical
Support Approval and Certification
Center for information related to
retrofitting permissible equipment.
One manufacturer testified at the
public hearings that the DPF systems
that they supply to the underground
coal permissible machines are available
in non-permissible (non explosion
proof) configurations for machines in
M/NM mines. They stated that the
technology can be configured for all
horsepower machines and be designed
for numerous machine configurations.
Another area of DPF systems that we
have been investigating is the use of onboard regeneration. On-board
regeneration normally operates in
principle between a passive system and
an active system. In this type of DPF
system, some passive regeneration
occurs depending on duty cycle,
however there is a mechanism for active
regeneration when the duty cycles are
not sufficient. The active regeneration
may be in the form of catalyst, electrical
system, or fuel burner type system.
Several of these systems were discussed
in the preamble to the 2005 NPRM such
as the ArvinMeritor. Other systems are
discussed below that we have become
aware of since the preamble to the
proposed rule.
DPF systems using this type of
technology are becoming more readily
available and feasible due to the
upcoming EPA 2007 on-highway
emission standards. We are aware the
EPA emission standards are more
stringent for reducing both DPM and
NOX. Information on systems being
designed for 2007 on-highway machines
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will include DPF filters and NOX
catalysts. These systems will most likely
require some type of active regeneration
systems to account for low duty cycle
on-highway vehicles. However, at this
time, most engine manufacturers have
not released the technical details of
their systems since they are still in ongoing developments to prepare for the
2007 model year. A combination of
passive and active regeneration will
most likely be used to account for the
various duty cycles of non-road
equipment. The EPA DPM standards
will be forcing more DPF technologies
to the commercial market starting in
2007 which will be available to the
mine operators during the extension of
time allowed for in this final rule.
Recently, MSHA and NIOSH have
been in discussions with an automotive
manufacturer of a commercial pickup
truck and the diesel engine
manufacturer that supplies the diesel
engine for the pickup truck. Currently,
many underground coal mines and
some M/NM mines use commercially
available automotive type pickup
trucks. In 2007 model year, the new
trucks will be sold with DPF systems in
order to comply with the EPA onhighway standards. However, some
underground coal operators became
concerned with the new DPF systems on
these pickup trucks. The concern relates
to regeneration based on a mining duty
cycle. The manufacturers also have not
yet released all the details on the DPF
systems. Engine and machine
manufacturers are doing extensive
testing for on-highway applications.
MSHA and NIOSH have agreed with the
manufacturers to perform laboratory and
field test on the new pickup trucks once
the trucks are available for mining. This
work will be done during the extension
of time allowed for in this final rule.
This type of technology will become
more widespread, even in the mining
industry, as the EPA DPM emission
standards become effective. In addition,
the California Air Resources Board
(CARB) continues work with their
‘‘Verification Procedure, Warranty and
In-Use Compliance Requirements for InUse Strategies to Control Emissions
from Diesel Engines’’. This program
verifies DPF systems for installation on
machines in California. CARB maintains
a Web site at: https://arb.ca.gov/diesel/
verdev/home/home.htm.
Most of the systems being developed
for EPA have also been developed for
California’s program. Some commenters
stated that we should wait till the EPA
standards and technology becomes
available. However, we believe that the
delayed timeframe of the final limit will
permit the DPF technology to become
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more universal in the mining industry.
The mining industry should use its
resources during this delay to resolve
implementation issues on mining
vehicles to meet the final limit.
We are aware of the following DPF
technologies that are either
commercially available or being further
investigated by MSHA and NIOSH.
Many of these systems have been
discussed by us in preambles for the
2005 Final Rule (70 FR 32935) and the
2005 NPRM (70 FR 53284) and we are
updating the discussions to include the
new information that we have. The
extension of time offered by this final
rule will allow for more work to be done
on these promising systems for
implementation into the mining
industry market.
a. ArvinMeritor System. In the 2005
proposed rule, we noted that the
ArvinMeritor system, which utilizes
active regeneration of the DPF, offers
great potential for underground mines
in further reducing DPM exposures. The
ArvinMeritor system utilizes an onboard fuel burner system to regenerate
DPFs. This system actively regenerates
the filter media during normal
equipment operations by causing the
fuel to ignite the burner and thereby
increase the exhaust temperature in the
filter system. Consequently, this system
does not require the host vehicle to
travel to a regeneration station to
regenerate the DPF. The condition of the
DPF is monitored via sensors. We also
stated that while this product was
successfully evaluated at Stillwater’s
Nye Mine, we recently learned that the
manufacturer had decided to
concentrate on working with Original
Equipment Manufacturers (OEMs)
where they would be selling 50 units or
more to one customer rather than selling
one or two units to individual
customers for retrofit application. It is
our current understanding that this
system is still commercially available
for purchase in smaller quantities from
ArvinMeritor distributors and local
dealers.
b. Johnson Matthey’s CRT System.
The Johnson Matthey CRT System is a
DPF utilizing passive regeneration. As
stated above, passive regeneration works
by using the exhaust gas generated by
the engine to burn the DPM. Normally,
DPF manufacturers utilize catalyst
technology to lower the temperature
needed for successful passive
regeneration. By lowering the exhaust
gas temperature needed for passive
regeneration, a broader range of
machines will have the necessary duty
cycle to generate the exhaust gas
temperature needed to burn the DPM.
However, when a platinum coating is
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used as the catalyst, it can also increase
the nitrogen dioxide (NO2) emissions
from the engine exhaust. In mines with
low ventilation rates, the increased NO2
emissions can also result in increased
NO2 exposures to potentially dangerous
levels for miners. We discussed this
issue in the 2005 final rule (70 FR
32924–26).
In 2004, the NIOSH Pittsburgh
Research Laboratory issued a contract to
Johnson Matthey to develop a system
that can regenerate at lower exhaust gas
temperatures and control NO2
emissions. The system is based on
Johnson Matthey’s CRT system and
promotes regeneration at lower
temperatures. Such DPFs are widely
used in urban bus applications and are
capable of passively regenerating DPFs
at the temperatures commonly seen in
the exhausts of underground mining
equipment (above 250 °C for at least
40% of the operation time).
The laboratory evaluation of the
systems continues under NIOSH
contract by the Center for Diesel
Research (CDR) at the University of
Minnesota. The objective is to examine
performance and suitability of the
systems relative to heavy-duty diesel
engines in underground mining
applications, with specific focus on the
effectiveness of controlling NO2. If the
results of laboratory evaluations show
that the system is suitable for use in
underground applications, NIOSH
would continue to study this DPM
control with a field evaluation in an
underground mine. However, at this
time the laboratory data is still
incomplete, and NIOSH continues to
work with the lab and Johnson Matthey
on this promising technology.
c. Diesel Particulate ReactorTM. We
have begun testing in our diesel
laboratory a high performance DOC that
contains a substrate which is a catalyst
treated, woven stainless steel alloy
fabric cartridge. This Reactor is being
tested as a stand alone unit, in
combination with a HTDPF, and with a
synthetic fuel called Synpar 200. Our
preliminary laboratory data using the
Reactor and the Synpar 200 synthetic
diesel fuel has shown an effective whole
DPM removal efficiency approaching 50
percent without any adverse changes in
other engine emissions. We are aware
that several mines are planning on
trying one or several of the
combinations listed. One underground
nonmetal mine has equipped about 80%
of its fleet of about 50 pieces of diesel
equipment with the Reactor, and reports
no operational or maintenance
problems. We will include on our DPM
Single Source Page our efficiency
numbers for DPM removal when they
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become available. NIOSH has also
contracted with the Center for Diesel
Research to do additional testing on the
Reactor and the Synpar 200 synthetic
diesel fuel at this time.
d. Fleetguard. This company has
partnered with other DPF companies
that market such products as a
Longview Lean NOX Catalyst DPF. The
Longview Lean NOX Catalyst combines
NOX reduction plus a DPM reduction
system.
One underground coal mine operator
is planning on receiving a unit to
investigate and install on a piece of
mobile equipment. The system specifies
a minimum exhaust gas temperature of
260°C at least 25 percent of operating
time in order for regeneration to occur.
We also understand that this device may
have the ability for active regeneration.
MSHA and NIOSH plan to work with
the coal mine operator to monitor the
device once it is installed.
Since the system utilizes NOX
reduction, we are planning on testing
this device in our diesel laboratory to
determine the amount of NOX reduction
and to determine if there would be any
adverse effects on engine emissions
from this control scheme. NIOSH is also
planning on testing this device at a M/
NM mine, that is, if the work at the
underground coal mine proves
promising for application in the mining
industry.
e. Rypos. Rypos utilizes a sintered
metal filter media for DPM filtration.
The system uses electrical current for
active regeneration. Initially, the system
was used on stationary generator
systems. Rypos has successfully tested a
prototype system on a surface grader.
Electrical power for filter regeneration
was obtained from a second alternator
on the grader that was dedicated
exclusively to the DPF. At this time,
Rypos is discussing with us and NIOSH
development of a system for mobile
mining equipment. We will update the
mining community on our work with
this device.
f. Huss. We are aware that a M/NM
mine operator has purchased a Huss
system with a ceramic DPF using active
regeneration. However, we have not
received any information on the
application of this DPF to the machine
at the mine or its performance. If and
when we do, we will inform the mining
community through the DPM Single
Source Page.
g. Other DPF Systems. We continue to
work with DPF manufacturers that are
listed on our Web site at: https://
www.msha.gov/01-995/Coal/DPMFilterEfflist.pdf. The DPF manufacturers
that have submitted data to us and are
listed on our Web site are: CleanAir
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Systems, DCL International, Engine
Control Systems, Catalytic Exhaust
Products, Nett Technologies, Donaldson
Company, and Filter Services and
Testing Corporation. We understand
that there are other DPM control
technologies that could be available but
the other manufacturers have not
contacted us. We continue to discuss
and evaluate the latest DPM control
technologies for applicability with the
mining market through this Technical
Support Directorate.
h. Diesel Engine Replacements.
Several commenters stated that the
mines have been replacing older, dirtier
engines with newer, EPA Tier engines.
The EPA Tier engine requirements force
engine manufacturers to build engines
that comply with more stringent
emission standards for NOX, DPM, and
CO over a time period. The Tier
schedule normally requires the larger
horsepower engines to meet more
stringent emission standards first, then
the smaller horsepower engines. At this
time, all new engines being sold in the
United States in all horsepower ranges
are meeting a minimum of a Tier 2 EPA
emission standard.
We agree that this trend which the
mine operators are following to replace
older engines has been a feasible
approach to reduce DPM exposure to
meet the interim limit. However, in
order to meet the final limit, mine
operators must continue to evaluate
their engine inventories to determine
which engines need to be replaced as
they become older, and new cleaner
engines are available.
In addition, if mine operators are
considering adding a DPF system to a
machine that is equipped with a high
DPM emitting engine, they may first
need to repower the machine with an
engine having lower DPM emissions. In
some cases, a Tier 1 engine may need
to be replaced with a Tier 2 engine to
allow for a successful application of the
DPF. A lower DPM emitting engine
would enable the machine to operate for
a longer period between regenerations,
or before a disposable DPF would need
to be replaced. Interruptions to mine
production activities to accommodate
regeneration or to replace a disposable
filter can be avoided when the engine
and DPF are properly matched to each
other.
To further emphasize this point, one
commenter discussed the application of
installing disposable DPF systems on
Toyota pickup trucks. The mine
operator stated that the cost of replacing
the disposable DPF is cost prohibitive.
However, we are aware that the engine
model used in that Toyota truck is an
old model that may be out of production
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at this time. The truck engine described
is a 128 hp engine. Based on
information gathered by us, we believe
that this engine may have a DPM
emissions output of between 0.8 and 0.9
g/bhp-hr. This is considered a dirty
engine and is higher than a Tier 2
engine standard. This would require
more frequent DPF replacements when
using disposable filters, or more
frequent active regenerations, or the use
of two DPFs as was discussed by the
commenter, thus increasing the cost. A
current Tier 2 engine in this horsepower
range has a maximum DPM emission
rate of 0.22 g/bhp-hr. An engine
replacement or vehicle replacement
could reduce the DPM output from each
engine by up to 90 percent.
We believe that there are engines that
could be used to repower the truck. As
further discussed later in this section on
Economic Feasibility, based on the cost
estimates that the commenter presented,
the cost savings of switching engines or
even purchasing newer pickup trucks
with cleaner engines could pay for the
engine or truck in a minimal time frame.
In addition, more stringent EPA onhighway emission standards come into
effect with on-highway vehicle models
starting in 2007. The more stringent
standards will require engine
manufacturers to install a DPF system
on all on-highway diesel powered
vehicles. The 2007 model pickups that
will be sold in the United States will
then have DPF systems installed at the
factory.
As discussed previously in this
section, we are working with an engine
manufacturer and a pickup
manufacturer, NIOSH, and a coal mine
operator to evaluate the technology
being incorporated. We plan on testing
the new engine/DPF system in our
Diesel laboratory as soon as an engine/
DPF system can be made available. The
coal mine operator is concerned about
the ability of the DPF system to
regenerate. MSHA and NIOSH will be
conducting in-mine studies to
determine the feasibility of the
regeneration process on the pickup
trucks in both coal and M/NM mines.
The extended period of time allowed for
in this final rule should provide the
additional time needed for this
evaluation.
i. Alternative Fuels and Ultra LowSulfur Fuels. In our 2005 NPRM, we
stated that during our compliance
assistance efforts, we observed several
mines using alternative fuels, including
water emulsion fuels and biodiesel
fuels, both of which are EPA approved
fuels. We subsequently tested these
alternative fuels to determine if they
could decrease tailpipe DPM emissions.
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In each application the change to an
alternative fuel had a positive impact on
reducing engine emissions and miners’
exposures to DPM. In some cases,
reductions of 50 to 80+ percent were
measured. While we found notable
benefits, the use of alternative fuels can
also cause equipment operation issues
for mine operators. These operational
issues have included initial clogging of
the fuel filters when biodiesel is used,
reduction of horsepower with the use of
water emulsion fuels, and management
of proper fueling of the correct fuel into
specific machines. While these
operational issues could be overcome,
we believe that the mining industry
needs the additional time offered by this
final rule to work through
implementation issues on a case-by-case
basis.
The most common problem with
alternative fuels is lack of geographic
proximity of most mines to a fuel
distributor. There are only three cities
that are served by a water-emulsion fuel
blender/distributor: Cleveland, Ohio,
Houston, Texas, and Los Angeles,
California. Biodiesel fuel is more widely
available throughout the country than
water-emulsion fuel, but some mines,
particularly in the intermountain west
and the west coast, may be 200 miles or
more from the nearest biodiesel
producer or distributor. Thus, mine
operators in these isolated areas could
incur significantly increased fuel
transportation costs if they utilized
biodiesel fuel at their mines.
Fuel manufacturers are building
distribution centers near mining areas to
reduce the transportation costs, but
these centers will take some additional
time to complete. Limited distribution is
also a feasibility issue for metal and
nonmetal mine operators who seek to
obtain ultra low sulfur fuel. However, as
discussed elsewhere in this preamble,
the commercial availability of ultra low
sulfur fuel (less than 15 ppm sulfur
content) will increase during 2006 and
beyond when on-road vehicles, and
shortly after that, nonroad diesel
engines in the United States will be
required by the EPA to use only this
type of diesel fuel. For these reasons, we
believe the additional time provided in
this final rule will allow mine operators
the additional time they will need to
comply is warranted.
j. Water Emulsion Fuels. In the 2005
NPRM, we explained that water
emulsion fuels, such as PuriNox, are
blends of diesel fuels and water. The
water is held in suspension with a
surfactant. The water in the fuel reduces
the engine combustion temperature
resulting in reduced NO2 and reduced
DPM emissions. However, the added
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water also reduces the engine’s
horsepower. While the per gallon price
of the water emulsion fuel is the same
as standard fuel, we are aware of
increases in engine consumption of
these fuels by as much as 15 percent.
However, continued increased use in
mines is currently limited due to lack of
fuel availability in most mining regions.
Manufacturers of this fuel must install
centralized blender facilities in order to
make the fuel more available and
economically feasible for use by the
metal and nonmetal mining industry.
We also stated that we had observed
some engines using water emulsion
fuels. One issue appears to be with the
use of very efficient water separators
used on engine fuel systems to remove
water from the fuel lines. We advised
that a very efficient water separator will
actually remove the water from the
emulsion, thus affecting the engine’s
performance. An engine manufacturer
that has experienced this with its
engines has recommended replacing the
more efficient water separator with a
less efficient one.
Another issue identified by some
mine operators is that some small
machines cannot run, or run poorly, on
this fuel. We are not aware of any
testing that has been done to prove or
disprove this. This may or may not be
due to less complex fuel systems that
cannot handle a change in fuel
properties.
Since water emulsion fuels have been
associated with horsepower loss, mines
will have to determine through their
own in-mine testing if their machines
can continue to operate efficiently even
with the power loss. Some situations
where the power loss could affect a
machine’s productivity occur at
multilevel underground mines at high
elevations. Also, mines that require the
use of permissible engines with prechamber combustion, such as the metal
and nonmetal gassy mines, may need to
determine any additional effects on
these types of engines.
Several commenters noted that
PuriNox, a proprietary diesel fuel
water emulsion product manufactured
by the Lubrizol Corporation, will no
longer be available in North America
after calendar 2006. We regret this
decision by Lubrizol, as we have
documented very significant DPM
reductions at mines that have
experimented with, or permanently
switched to PuriNox fuel. Since most
mines have been successful in attaining
the interim limit using low DPM
emission engines, environmental cabs,
and upgraded ventilation, very few
mines have switched to PuriNox fuel,
thus limiting demand for this product.
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It’s very limited geographic available in
the three cities identified above also
limited demand. It is possible that more
mines might have switched to PuriNox
to attain the final DPM limit, if it were
still available when the final limit
becomes effective. However, as noted
below, many of the DPM reduction
benefits we have observed at mines
using a water-emulsion fuel can also be
achieved using high biodiesel content
fuel blends.
k. Biodiesel Fuels. As noted above, the
use of high biodiesel content fuel blends
has resulted in significant DPM
reductions of up to 80% or more at
mines that have experimented with or
switched entirely to such fuel blends.
Even in blends as low as 20%, DPM
reductions of nearly 40% have been
documented. Actual DPM reductions
depend on engines, duty cycles, etc., but
reductions of at least 60% would be
expected when fuel blends of B90 to
B100 are used.
Biodiesel fuels are more readily
available than water emulsion fuels. As
noted below, biodiesel is currently
available in every state except Alaska.
The costs and therefore the demand for
biodiesel have been related primarily to
federal excise tax credits that have been
available since 2004 to blenders of this
fuel. The tax credits are passed along
from the fuel blender to the purchaser
in the form of reduced fuel costs. With
current tax credits, biodiesel can be an
attractive fuel alternative for the mining
industry. In the late summer and fall of
2005, and again in the spring of 2006,
due to market induced price swings for
standard #2 diesel fuel, the price of
biodiesel in many parts of the country,
with the tax credit applied, was lower
than standard diesel.
Several commenters expressed
general agreement with our statements
in the 2005 NPRM regarding the use of
biodiesel fuel as an effective means of
reducing DPM emissions (70 FR 53287).
One commenter listed various other
advantages of biodiesel, including
reduced emissions of carbon monoxide,
carbon dioxide, polycyclic aromatic
hydrocarbon (PAH) compounds, oxides
of sulfur, and total hydrocarbons, as
well as better lubricity, higher flash
point for increased fuel handling safety,
and higher cetane number for better
cold starts. However, some commenters
asserted that biodiesel fuel is not a
technologically feasible engineering
control because it is not widely
available in the eastern and western
states, it causes unacceptable power
loss, it is subject to gelling in cold
weather, and it causes engine
maintenance problems. These
commenters also mentioned higher fuel
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costs as an impediment to increased
usage of biodiesel. Technological
feasibility issues relating to biodiesel
fuel and economic feasibility issues are
discussed in this section.
Examples of the specific concerns
expressed by commenters who doubt
the technological feasibility of biodiesel
fuel included a mining industry
organization that stated, ‘‘While the use
of biodiesel showed some promise in
reducing EC at some mines, biodiesel
caused reduced horsepower problems
described by mine operators and is not
widely distributed nor accessible at a
reasonable cost to many mining
operations.’’ This commenter went on to
say, ‘‘* * * there is very little
availability of biodiesel in the Eastern or
Western United States, where many of
the mining operations are located that
will be impacted by the proposed rule.’’
A large Montana platinum mining
company that consumes about 1,000,000
gallons of diesel fuel per year
commented that, ‘‘* * * cold weather
concerns were evaluated to determine
the necessary storage requirements to
reduce the potential for the fuel to gel.’’
This commenter continued by stating
that biodiesel cold flow properties in
100% form is not good below 45 degrees
and would require some type of heating
to make it flow. The regional supplier
does not have the infrastructure to
support this product due to the current
low demand and newness of the
product. This mine operator also
evaluated the requirements for storing
biodiesel on-site at the mine, and
indicated that a 10,000 gallon tank
would be needed for diesel, a 15,000
gallon tank would be needed for
biodiesel, and a 10,000 gallon tank
would be needed for the blended
product, at a combined cost of over
$250,000.
Another commenter stated that,
‘‘There may be adverse effects on engine
performance and maintenance that need
careful consideration before selecting
biodiesel as an alternative technology.’’
Another commenter stated that,
‘‘Cummins recommends a biodiesel fuel
mix of no greater than 5%, but that
mixture does not result in a significant
DPM reduction.’’
We agree that these commenters have
concerns based on their current
assessments of the biodiesel fuel. The
extension of time allowed for in this
final rule for meeting the final limit will
assist mine operators in working
through these operational issues if they
decide to use biodiesel. Many of the
biodiesel issues when resolved will
apply to the entire mining industry. One
example of this would be the logistics
for transferring biodiesel fuel during the
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winter. Once the logistics for
transferring the biodiesel in winter are
resolved, all mines can use the
information. This may be as simple as
locating one or more companies that can
ship biodiesel using insulated rail cars
or tankers, or provide a service for
warming up the fuel prior to delivery at
the mine. We can provide these vendors
on our Web site for the entire mining
community for their use.
We are aware of several mines that are
using very high biodiesel content
blended fuels (near 100% biodiesel),
and they have reported no operational
or maintenance issues that were
unanticipated or presented any
difficulty for the respective mine. B100
has approximately 5%–7% less energy
content than standard #2 petroleum
diesel, and this difference is reflected in
correspondingly lower horsepower
output of an engine running on B100.
Mine operators that are using high
biodiesel fuel blends report that this
horsepower loss is noticeable on some
equipment, but manageable, and the
power difference has not impacted
production.
Biodiesel fuel acts as a solvent, and
can loosen sediment in the fuel tanks
and fueling systems of equipment that
has run previously on standard diesel.
This sediment can clog fuel filters for a
period of time until the fuel system is
fully cleaned, which typically takes a
few weeks. During this period, fuel
filters need to be changed more
frequently than normal to avoid loss of
engine power or stalling. This solvent
effect has a long lasting benefit,
however, in that the fuel system and
injectors run cleaner as long as biodiesel
fuel is used. One mine operator reported
that their diesel engines have never run
as well as they are now that the mine
switched to a high biodiesel content
blended fuel. He attributed the better
performance to the higher lubricity of
biodiesel and the cleaning effect on the
fuel injectors.
The solvent properties of high
biodiesel content fuel blends may
adversely affect certain elastomeric
components associated with an engine’s
fueling system, such as hoses and
gaskets. Users need to contact the
respective engine manufacturer to find
out which components, if any, need to
be replaced with their biodieselcompatible counterparts. The extension
of time allowed for under this final rule
will provide the necessary time to make
these contacts.
The solvent properties of the fuel may
also remove certain types of paint if the
fuel remains in contact with a painted
surface for a prolonged period. This
property of biodiesel does not render
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the fuel infeasible. It is simply an
attribute of the fuel of which users need
to be aware and take appropriate
precautions. Likewise, because of its
somewhat higher viscosity, a property
related to its better lubricity, high
biodiesel fuel blends may tend to more
easily pass over the rings and dilute the
engine oil. For this reason, it may be
advisable when using high biodiesel
fuel blends to shorten engine oil change
intervals.
Biodiesel is subject to oxidation,
microbial growth, and other conditions
during long term storage. Manufacturers
typically recommend precautions be
taken such as fuel turnover, tank
mixing, and anti-oxidant treatments if
fuel is to be stored for longer than 6
months. Prior to use, biodiesel fuels
stored for longer than 6 months should
also be tested for acid number,
sediment, and viscosity to insure it
remains within specifications. In its
publication, ‘‘Biodiesel Handling and
Use Guidelines, DOE–GO–102006–2288.
Second Edition, March 2006,’’ the U.S.
Department of Energy indicates that,
‘‘the least stable B100 could be stored
for up to 8 months, while the most
stable could be stored for a year or
more.’’ Nonetheless, the National
Biodiesel Board recommends biodiesel
fuels be used within 6 months of
purchase. Instituting these precautions
in using biodiesel may take mine
operators some additional time to
implement thus justifying the delay
allowed for in this final rule. For mining
operations that consume large amounts
of diesel fuel and receive fresh fuel
shipments from reputable suppliers on
a frequent basis, long term storage issues
are not a major concern.
We agree with the comments
regarding the cold flow properties of
biodiesel presenting storage and
handling challenges. Neat soy-diesel (a
100% biodiesel fuel made from soybean
feedstock) has a cloud point of 32
degrees Fahrenheit, and a pour point of
28 degrees Fahrenheit. The cloud point
is the temperature at which crystals
begin to form in the fuel, causing the
potential for clogged fuel filters. The
pour point is the temperature at which
the fuel begins to gel and becomes
difficult to pump. At temperatures
approaching the cloud point, neat soydiesel needs to be heated to prevent
handling difficulties.
Many industrial chemicals have
similar cold weather handling
properties, and practical means have
been developed to enable routine
storage and transfer of these chemicals
at any temperature. The most common
method for off-loading such materials
from transportation vessels is to heat the
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tank. For example, steam can be applied
at the railhead to rail tank cars that are
specially designed to facilitate this
process. Transportation vessels, either
rail or truck, can also be moved into a
heated building for unloading. Fixed
storage tanks can be heated, placed
inside a heated building, or in the case
of underground mines, storage tanks can
be placed underground. To prevent fuel
from gelling during equipment
operations, the equipment’s fuel tanks,
fuel lines, and fuel filters can be heated,
either using recycled engine heat, or
using an external heating source, as
might be required if equipment is
parked outside the mine overnight.
Such provisions are common in some
parts of the world for all diesel
equipment.
Although the properties of biodiesel
may necessitate special transportation,
storage, and handling procedures by
mine operators, the precautions that
would need to be taken to address these
properties are straightforward and
technologically unsophisticated, such as
more frequent fuel filter changes during
the initial change-over period, heating
transportation and storage tanks, etc.
The process of mixing standard diesel
and biodiesel to achieve a particular
biodiesel blend, such as B20, B35, or
B50 (20%, 35%, and 50% biodiesel with
the remainder standard diesel,
respectively), though not
technologically challenging, would
normally be done by the fuel distributor.
It is also significant that biodiesel is
a ‘‘drop in’’ replacement for standard
diesel in any diesel engine. The only
engine modification that may be
necessary in some engines is to insure
that all elastomeric fuel system
components (hoses, gaskets) are
biodiesel compatible, however, any
components that are not compatible can
be easily replaced. For these reasons, of
the many DPM controls that are
available to underground M/NM mine
operators, switching to biodiesel fuel
may involve the fewest difficult
implementation issues. The
consequences of failing to implement
the precautions listed above could be
quite significant. But information
regarding these implementation issues
is well defined and widely distributed
(MSHA will include this important
information on its DPM Single Source
Page), and fully addressing them would
be technologically and economically
feasible for most, if not all mine
operators.
We agree with comments that the
availability of biodiesel fuel is more
limited than standard diesel, especially
in the eastern and western states.
However, we believe that biodiesel will
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be more readily available in more areas
of the country by the effective date of
this final rule, even though its use may
increase fuel transportation costs for
some mines. Biodiesel is available from
over 1,400 commercial petroleum
distributors and over 750 retail stations
across the country. The only state
without in-state access to biodiesel is
Alaska. The operator of a large
underground metal mine in Alaska,
however, reported that their fuel is
shipped from Seattle, and their supplier
has access to biodiesel.
Regarding the availability of biodiesel
in the eastern and western states, we
acknowledge that most biodiesel
production is concentrated in the
Midwest, however as noted above, it is
available in the contiguous 48 states,
and Hawaii and biodiesel production
and availability nationally is growing
rapidly. Production of biodiesel in the
U.S. grew from about 25 millions
gallons in 2004 to about 75 million
gallons in 2005, and significant further
production growth is expected in the
future, including plants in currently
underserved areas like Wyoming,
Montana, Washington, California,
Colorado, and Texas in the western part
of the U.S., and Tennessee, Kentucky,
Pennsylvania, Virginia, North Carolina,
and New York in the east. This expected
increased availability of biodiesel fuel
by 2008 in currently underserved areas
of the country supports our decision to
phase-in the final DPM limits in three
steps from 308EC µg/m3 in May 2006 to
350TC µg/m3 in January 2007 to 160TC
µg/m3 in May 2008. Biodiesel plants
currently under construction are rated at
329 million gallons of annual
production capacity, and plants in the
pre-construction phase will add an
additional 518 million gallons of annual
production capacity.
The Montana platinum mining
company referenced above stated that,
‘‘No manufacturers of biodiesel have
been located in the proximity of the
mine, making availability and delivery a
significant concern.’’ While there may
be no biodiesel manufacturers in
proximity to the mine at the present
time, a 15,000,000 gallon annual
capacity biodiesel plant is scheduled to
go online in Culbertson, MT in March
2007, and there is currently a
commercial biodiesel distributor about
140 miles from the mine site in
Bozeman, MT. This distributor, which
receives its supply of biodiesel via rail
cars, has the capability to supply the
mine’s required 1,000,000 gallons per
year, and it is equipped to use steam to
heat the cars for off-loading during the
winter months.
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Another commenter that expressed
concern about the lack of biodiesel
availability was a gold mine operator in
the Elko, Nevada area. This operator
said, ‘‘B20 is available in Salt Lake City,
approximately 300 miles away.’’ While
this is undoubtedly true, there is also a
commercial biodiesel distributor at
Battle Mountain, Nevada, about 120
miles from the mine that can supply any
grade of biodiesel from B2 to B100. This
distributor also receives its biodiesel via
rail cars. It does not currently have the
capability to apply steam to cars in the
winter months to facilitate cold weather
off-loading. However, a representative
for the distributor indicated that such a
capability would be provided if a
customer entered into a supply contract
providing for sufficient fuel volumes; a
requirement that this mine should be
able to satisfy within the time
prescribed for the effective date of the
final limit.
A trona mine operator also expressed
concern over the availability of
biodiesel fuel near the mine in
southwestern Wyoming. However, there
is a commercial distributor of all grades
of biodiesel fuel in Jackson, WY
approximately 185 miles from the mine,
and another commercial distributor in
Richmond, UT approximately 180 miles
from the mine. These fuel distributors
are likely farther from the mine than the
mine’s current distributor, and
shipments of fuel from these
distributors would be subject to higher
transportation costs. Although the mine
operator would have to determine the
feasibility of receiving biodiesel from
such distance, we believe that the
biodiesel industry will resolve these
logistic problems in time for the
effectiveness of the final limit in May
2008. The Biodiesel Board included
comments to the 2005 NPRM stating
how distribution of biodiesel fuel is
expanding throughout the United States,
which helps to make the final limit
feasible as prescribed in the final rule.
In response to a commenter’s
concerns about engine warranties, the
engine manufacturers do not warrant
their engines against fuel related
problems, either biodiesel or standard
petroleum diesel. Regarding the
commenter’s concern relating to their
Cummins engines, the Cummins on-line
customer assistance fact sheet on
biodiesel states that,
Given the current understanding of bio
fuels and blending with quality diesel fuel,
it would be expected that blending up to a
5% volume concentration should not cause
serious problems. For customer’s intent on
blending bio fuels above 5% volume
concentration, the following concerns
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represent what is currently known in the
industry.
This on-line fact sheet goes on to
identify specific areas of concern,
including possible adverse effects on
engine performance and fuel system
integrity/durability, low temperature
operability, heat content, oil change
intervals, effects on elastomeric fuel
system components, and a variety of
issues related to long term storage, such
as fuel stability, oxidation, corrosion,
microbial growth, and fuel acid content.
These issues are potentially significant,
and if not appropriately addressed,
could result in serious operational
problems and engine damage. However,
as noted above, we believe that
solutions to these issues could be
implemented by the extension of time
offered by this final rule, so mine
operators should not be impeded from
utilizing high biodiesel content fuel
blends.
Regarding engine warranties, the
Cummins on-line fact sheet states that,
Cummins neither approves or disapproves
of the use of biodiesel fuel. Cummins is not
in a position to evaluate the many variations
of biodiesel fuels or other additives, and their
long-term effects on performance, durability
or emissions compliance of Cummins
products. The use of biodiesel fuel does not
affect Cummins Material and Workmanship
warranty. Failures caused by the use of
biodiesel fuels or other fuel additives are
NOT defects of workmanship and/or
materials as supplied by Cummins Inc. and
CANNOT be compensated under the
Cummins’ warranty.
With respect to engine warranties,
Cummins treats biodiesel no differently
than it treats standard petroleum-based
diesel. Most of the engine manufacturers
have similar warranty positions.
A trona mine operator reported that
they had obtained DPM sample results
for their mine that exceeded the 160TC
µg/m3 final DPM limit despite using a
B20 biodiesel fuel blend (20% biodiesel
mixed with 80% standard petroleum
diesel fuel). A stone mine operator
reported similar results with B20 fuel.
These commenters question whether
biodiesel is a feasible control, since they
were not able to attain compliance with
the 160TC µg/m3 final DPM limit using
this fuel.
Based on extensive in-mine testing
and both personal and area sampling at
mines that have either experimented
with, or switched permanently to
biodiesel fuel blends, we believe
significant DPM reductions would not
have been expected with biodiesel
blends as low as B20. In our
evaluations, we only began to see
significant DPM reductions at B35 or
higher, with higher biodiesel content
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producing lower DPM levels. The DPM
reductions of 60% to 80% that we have
documented were achieved with fuel
blends of 98% to 99% biodiesel. Thus,
we continue to believe that biodiesel is
a feasible DPM control that is capable of
achieving significant reductions (as
defined in the 2005 rule (70 FR 32868,
32916)) in DPM exposure when this fuel
is used in neat form (100% biodiesel) or
in sufficiently high blends with
standard petroleum diesel fuel.
Several commenters also mentioned
that they were considering, or had
switched to ultra low sulfur (15 ppm)
diesel fuel. As expected, these
commenters did not report significant
DPM reductions after the switch to this
fuel. The primary benefit of ultralow
sulfur diesel is to enable advanced
emission reduction technologies that
utilize catalysts that would be poisoned
by higher sulfur content fuel.
l. Installation of Environmental Cabs.
Environmental cabs are a proven means
to reduce worker exposure to DPM.
While much of the construction-type
equipment used in underground stone
mines comes equipped with
environmental cabs, the cabs on
specialty mining equipment used in
underground hard rock mining are less
common, particularly in mines with
narrow drifts or low seam heights. As
mine operators realize the benefits of
cabs, more and more pieces of
equipment are being purchased or
retrofitted with environmental cabs.
These cabs provide protection for
workers not only from diesel particulate
but also from noise and dust.
Only a few comments were received
on the subject of environmental cabs.
These comments typically agree that
environmental cabs can be effective in
reducing the occupant’s DPM
exposures, but applications may be
limited by three factors: retrofitting cabs
is not always possible, especially on
some older machines, there may not be
adequate clearance for cabs in certain
confined areas of some mines, and cabs
offer no protection for miners who must
work outside a cab. A comment received
from a mining industry organization
was typical:
Environmental cabs are effective. However,
they can not be retrofitted to all mining
equipment. Further, there are some jobs in
underground mines where miners work
outside of equipment and cabs would
provide them no protection.
Another industry organization stated,
Simply put, fully enclosed environmental
cabs provide superb protection to equipment
operators from exposure to DPM. However,
they provide no protection to miners working
alongside such equipment. Furthermore,
installation of fully enclosed environmental
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cabs can only be accomplished where the
resulting larger profile of the equipment fits
properly within the heading size in the mine
where such equipment is operated.
We agree in general with these
comments and we believe that a cab’s
feasibility needs to be evaluated on a
case-by-case basis as to exactly which
equipment is suitable for retrofit of a
cab, or whether space limitations in
certain areas at a particular mine would
prevent utilization of equipment with
cabs. In these respects, questions
regarding the feasibility of using cabs as
an engineering control to prevent DPM
exposure are no different than questions
regarding the feasibility of using cabs for
control of dust or noise exposures.
m. Ventilation. All underground
M/NM mines rely on ventilation to
dilute and carry away diesel particulate
matter and toxic gases as well as to
provide fresh air to the miners. Based on
the comments received from mine
operators and from our own
observations during mine inspections
and compliance assistance mine visits,
it is clear that ventilation is a key
component of nearly every mine’s DPM
control strategy.
However, the extent to which it is
feasible for ventilation system
performance to be improved or
upgraded, either to obtain compliance
with the final DPM limit or to obtain
compliance in combination with other
controls, is disputed by some
commenters. One commenter from a
gold mine in Nevada stated that,
‘‘Ventilation is near its capacity. Further
increases are likely to create fugitive
dust problems from haulage vehicles.’’
Another commenter addressing
conditions at a different multilevel
metal mine indicated that increasing
airflows in that mine’s small and widely
distributed working places would be
difficult. This commenter also disputed
our observation in the preamble to the
2005 final rule that a major multimillion dollar ventilation upgrade at
that mine was not a DPM compliance
related expense (70 FR 32934–32936).
Another commenter from a mining
industry organization stated that a
notable characteristic of underground
stone mines is their large open spaces
(room and pillar mining) that are
ventilated naturally. To introduce
forced ventilation in mines presently
ventilated naturally would entail
enormous costs in mine structures that
would be needed to direct the
ventilation inside the mine.
These comments represent the
extremes in ventilation practice in the
underground M/NM mining industry.
Deep multilevel mines, due to a variety
of factors, typically have complex,
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costly, and sophisticated ventilation
systems, often designed by a
professional mine ventilation engineer,
and usually operated and managed by
engineers with specific mine ventilation
training and experience. These systems
normally consist of a network of main,
booster and auxiliary fans, and a
complex array of interconnected shafts,
raises, and ventilation control
structures. In contrast, room and pillar
stone mines typically have very simple
ventilation systems which may not have
been designed at all. Such systems may
rely entirely on natural ventilation
alone, and those that do incorporate
forced ventilation are often simple
blowing or exhausting systems, or may
consist of nothing more than one or a
few free standing booster fans
underground. They are normally
operated or managed by the mine
foreman or manager, and it is rare for
such individuals to have had any
professional training in mine ventilation
engineering.
At most multilevel metal mines, high
ventilation system costs provide a major
economic incentive to operators to
optimize system design and
performance, and therefore, there are
typically few if any feasible upgrades to
main ventilation system elements that
these mines haven’t already
implemented, or would have
implemented anyway, whether or not
the DPM rule existed. Accordingly, and
though it remains an option that might
be attractive in new development, we
expect very few mines of this type to
implement major ventilation system
upgrades to achieve compliance with
this rule.
Despite the built-in incentives to
design and operate efficient ventilation
systems, however, we have observed
aspects of ventilation system operation
at such mines that can be improved,
usually relating to auxiliary ventilation
in stopes. Auxiliary fans are sometimes
sized inappropriately for a given
application, being either too small (not
enough air flow) or too large (causing
recirculation). Auxiliary fans are
sometimes poorly positioned, so that
they draw a mixture of fresh and
recirculated air into a stope. Auxiliary
fans are sometimes connected to
multiple branching ventilation ducts, so
that the air volume reaching a particular
stope face may be considerably less than
the fan is capable of delivering. Perhaps
most often, the ventilation duct is in
poor repair, was installed improperly, or
has been damaged by blasting or passing
equipment to the extent that the volume
of air reaching the face is only a tiny
fraction of that supplied by the fan. We
believe that these and similar problems
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exist at many mines, even if the main
ventilation system is well designed and
efficiently operated.
Without extensive on-site study, we
are unable to assess the validity of the
commenter’s assertion that the mine’s
ventilation is near its capacity, but such
a condition would not be unusual, at
least with respect to major ventilation
system elements like shafts and main
fans. Short of a major ventilation system
upgrade such as a new shaft sinking or
main fan installation or repowering, it
would be more likely that auxiliary
ventilation system performance could
be improved.
Regarding the issue of fugitive dust,
which is mineral dust that is entrained
in and carried by the ventilation air
stream, if ventilation increases are
required to reduce DPM levels, but such
increased ventilation would be so great
as to pick up dust from the mine floor
or muck piles, it may be necessary for
the mine operator to apply water more
frequently to haul roads and working
places, or use dust control chemicals to
manage corresponding fugitive dust
levels. Mine operators frequently face
trade-offs like this, and we are confident
this problem can be successfully
handled within the prescribed time
frames of this final rule. For example,
mines that currently water their haul
roads once a shift, may need to water
their haul roads twice a shift.
Regarding the comment relating to the
difficulty of increasing ventilation in
small and widely distributed working
places, we conducted an extensive
study of the auxiliary ventilation
systems at this mine. The company
ventilation engineer stated that the
stope ventilation systems were designed
to deliver a minimum of 12,000 cfm to
the faces. The 12,000 cfm airflow would
dilute emissions for a 100 hp loader
(PI¥5000 cfm) to 321EC µg/m3. This
value would increase by the level of
DPM in the stope intake. During this
survey, several of the stope ventilation
systems failed to provide that level of
airflow to the faces, and in fact, some
systems lost over 90% of their air
volume before reaching the end of the
vent duct. This was primarily due to
long ventilation tubing lines and poor
maintenance of the ventilation tubing.
Also, it was noted during the survey
that improper fan placement at the
mouth of the stopes allowed exhaust air
to be recirculated back to the face before
being diluted by the footwall lateral
airflow.
This commenter also responded to
our analysis of a major ventilation
upgrade at this mine, characterizing it as
‘‘suspect,’’ but offering no specific
comments or corrections. The mine in
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question had instituted a major upgrade
of the ventilation system including new
aircourses, new vent raises, and new
and redeployed main and booster
ventilation fans. The $9,000,000
upgrade increased total mine airflow by
34% to 840,000 cfm while reducing
total fan power requirements by 1,000
hp through more efficient deployment
of booster fans.
As a result of further discussions with
personnel at the mine, we had
determined that the upgrade had several
objectives in addition to DPM control,
including greater system efficiency such
as eliminating an excessive number of
booster fans (some competing with each
other for air), the need to accommodate
increased production, the need to
ventilate a ramp used by trucks to haul
ore upgrade from the levels below the
bottom of the shaft, and the desire to
increase the number of ventilation
intakes into the mine, thereby providing
more fresh air emergency escape routes
and reducing intake aircourse air
velocities (for reduced dust entrainment
and enhanced miner comfort). We were
told that the mine had ‘‘overreached’’
the existing ventilation system, and that
the upgrade was overdue, even without
consideration for DPM levels in the
mine. Based on this information, and in
response to comments from this mine
operator addressing the August 14, 2003
proposed rule on the interim DPM limit,
we had suggested that the total cost of
the ventilation upgrade should be only
partially DPM-related. We also pointed
out that the cost of the upgrade needed
to be annualized because the asset had
an expected useful life of many years,
resulting in a yearly cost that was a
small fraction of the $9,000,000
expense. We disagree with the
characterization of our analysis as
‘‘suspect,’’ because we believe it is fully
supported by the facts, and because the
commenter provided no explanations or
corrections regarding our data or
methods.
Room and pillar stone mine
ventilation is entirely different than
multilevel metal mine ventilation.
Ventilation at stone mines was
addressed extensively in the preamble
to the 2005 final rule (70 FR 32931–
32932). We agree that ventilation system
upgrades may not be the most cost
effective DPM control for many mines,
and for others, ventilation upgrades may
be entirely impractical. However, at
many other mines, perhaps the majority
of mines affected by this rule,
ventilation improvements would be an
attractive DPM control option, either
implemented by itself or in combination
with other controls. The additional time
provided under this final rule will
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provide mine operators more time to
explore these options.
Indeed, during our DPM compliance
assistance visits, we have observed that
ventilation upgrades have been
implemented at many mines in the
stone sector for DPM control. Nearly
every stone mine visited by us had
completed, had begun, or was planning
to implement ventilation system
upgrades.
At many high-back room-and-pillar
stone mines, we observed ventilation
systems that were characterized by (1)
inadequate main fan capacity (or no
main fan at all), (2) ventilation control
structures (air walls, stoppings, curtains,
regulators, air doors, brattices, etc.) that
are poorly positioned, in poor
condition, or altogether absent, (3) free
standing booster fans that are too few in
number, too small in capacity, and
located inappropriately, and (4) no
auxiliary ventilation for development
ends (working faces). At some mines,
the ‘‘piston effect’’ of trucks traveling
along haul roads underground, along
with natural ventilation pressure,
provide the primary or only driving
forces to move air.
In naturally ventilated mines,
temperature-induced differences in air
density between the surface and
underground result in natural air flows
through mine openings at different
elevations. Warmer and lighter mine air
rises up out of a mine during the colder
winter months, which draws in cooler
and heavier air at lower elevation mine
openings. In the summer, cooler and
denser mine air flows out of lower
elevation openings, which draws
warmer less dense air into higher
elevation openings. Under the right
conditions, such air flows can be
significant, but they are usually
inadequate by themselves to dilute and
carry away DPM sufficiently to reduce
miners’ exposures to the interim limit.
The other principal shortcoming of
natural ventilation is the inherent lack
of a method of controlling air flow
quantity and direction. Ventilation air
flows can slow or stop when
temperature differences between the
surface and underground are small
(common in the spring and fall), and the
flow direction reverses between summer
and winter, and sometimes even
between morning and afternoon.
Mine operators normally supplement
natural ventilation with booster fans
underground. However, if overall air
flow is inadequate, as is usually the case
with naturally ventilated mines, and
when mine elevation differences or
surface and underground temperature
differences are small, booster fans are
largely ineffective.
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28955
The all too frequent result of these
deficiencies is a ventilation system that
is plagued by insufficient dilution of
airborne contaminants, short circuiting,
recirculation, and airflow direction and
volume that are not controllable by the
mine operator. Mines experiencing
these problems could benefit greatly
from upgrading main, booster, and/or
auxiliary fans, along with the
construction and maintenance of
effective ventilation control structures.
Consequently, we have urged the
mining industry to utilize mechanical
ventilation to improve overall air flows
and to enable better control of
ventilating air.
Ventilation fan upgrades for the stone
mining sector are usually relatively
inexpensive due to the low mine
resistance associated with large
openings. In many of these mines, a
250,000 cfm air flow can be obtained at
less than 1 inch of water gage pressure.
This air flow can be provided by a 50
horsepower motor.
We agree with the commenter that the
major cost in these applications is
usually distribution of the air flow
underground to insure that adequate air
quantities reach the working faces rather
than short-circuiting to a return or
recirculating around free-standing
booster fans. Good air flow distribution
requires such practices as installing or
repairing ventilation control structures
(brattice line, air curtains, etc.) or
changes in mine design to incorporate
unmined pillars as air walls. Such
ventilation control structures are not
complex to install, and since they
usually have a very long useful life,
when the cost of such controls is
annualized, the yearly cost is only a
fraction of the initial acquisition and
installation costs.
Despite the commenter’s suggestion to
the contrary, a great many underground
stone mines are currently ventilated
with main and booster fan systems. The
necessary ventilation control structures
have also been installed in a great many
such mines to facilitate the efficient and
effective distribution of ventilation air
underground. One commenter, a stone
producer with seven underground
mines, reported that, ‘‘All of [their]
mines have performed major ventilation
upgrades,’’ including ventilation
surveys by an outside contractor,
installation of larger main fans,
installation of new and larger portable
fans that are used at active headings, use
of larger booster fans, and the
installation of ‘‘new ventilation
stoppings and curtains at various
locations throughout the mine at all
mines.’’ Clearly, based on this
company’s experiences and our
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analyzed using the NIOSH 5040 method
and calculated using the MSHA
Sampling Method to determine
exposure, which does not take into
account significant IH factors such as
shift length over 480 minutes, average
pump flow rates using pre-sample
calibration and post-sample calibration
figures, and other environmental factors
such as temperature and pressure. We
disagree that the MSHA Sampling
observations at many other mines, the
technological feasibility of this type of
DPM engineering control is well
established for the stone sector of the
underground M/NM mining industry,
although it may take some time for
mines to make the necessary changes.
n. DPM Sampling Issues. A trona
mine operator, in reporting their DPM
sampling results in their comments,
indicated that these samples were
Carbon Concentration (µg/m3 ) =
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Where:
C is the mass of carbon, expressed in
micrograms, deposited on the filter
per square centimeter of filter
surface
A is the area of the filter onto which
DPM is deposited, expressed in
square centimeters
1,000 L/m3 is a unit conversion factor to
convert liters to cubic meters (the
pump flow rate is expressed in
liters per minute, whereas the DPM
concentration is expressed in
micrograms per cubic meter)
1.7 Lpm is the pump flow rate,
expressed in liters per minute
480 min is the number of minutes in an
8-hour work shift
We account for work shifts longer or
shorter than 8 hours (480 minutes) by
shift-weighting all sample results. The
shift-weighting process is explained in
the DPM Compliance Guide, which is
also posted on the M/NM DPM Single
Source Page and is summarized below:
‘‘Average full shift airborne concentration’’
means that a miner’s exposure is determined
by measuring the average concentration of
airborne DPM to which the miner is exposed
over a full work shift, regardless of shift
length. Temporary excursions above a limit
are permitted from time to time during the
shift, as long as the average over the entire
shift is within the limit. The term, ‘‘average
eight hour equivalent full shift airborne
concentration,’’ refers to our longstanding
practice of ‘‘shift-weighting’’ when applying
compliance limits for airborne contaminants
to exposures that occur over a time period
that is different from a standard 8-hour shift.
Our compliance limits are normally based on
8 hours of workplace exposure to a
contaminant and 16 hours of recovery time
in the absence of the contaminant. The
workplace 8-hour shift weighted average
(SWA) exposure is computed as the mass of
DPM on the filter divided by the 8-hour
sample volume, which is 0.816 cubic meter
for a sample flow rate of 1.7 liters per minute.
Thus, our DPM sampling and
analytical procedures do account for
work shifts that are longer than 8 hours.
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C (µg /cm 2 ) ∗ A (cm 2 ) ∗ 1, 000 L/m3
1.7 Lpm ∗ 480 min
Regarding the other industrial hygiene
factors which the commenter claims are
not addressed, our sampling procedures
on p. T–3 requires pre-sample
calibration of the sampling pump, and
on p. T–6, requires post-sample
calibration of the sampling pump. The
pre-sample and post-sample calibrations
are required to be performed in
accordance with the procedures
outlined in Chapter C of the M/NM
Health Inspection Procedures
Handbook. Since our pump calibration
devices measure true volumetric flow,
day to day variations in atmospheric
pressure due to weather changes are
irrelevant. However, pressure effects
from calibrating a pump at one elevation
and sampling at a significantly different
elevation can be important.
Accordingly, among the many
requirements relating to the use of
sample pumps contained in the M/NM
Health Inspection Procedures Handbook
is one specifying that pump calibrations
must be performed within 1,000 feet of
the elevation where sampling will be
conducted, or if not, that the specified
procedures for adjusting pump flow rate
for elevation must be followed. Our
inspectors are also required to measure
and record the temperature where
sampling occurs. Our DPM sampling
field notes form has a space for
temperature that must be filled in for
every sample taken.
B. Economic Feasibility
We have determined that phasing in
the final DPM limit of 160TC µg/m3 as
prescribed in the final rule is
economically feasible for the M/NM
mining industry. Economic feasibility
does not guarantee the continued
viability of individual employers, but
instead, considers the industry in its
entirety. In United Steelworkers of
America v. Marshall, 647 F.2d 1189,
1265 (1980) regarding OSHA’s statutory
criteria for establishing economic
feasibility, the Court recognized that:
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Frm 00034
Method fails to account for these
industrial hygiene (IH) factors.
Our DPM sampling procedures are
posted on the M/NM DPM Single
Source Page, which is linked to our
internet home page. Exposures are
determined from the sampling data in
accordance with the formula on page T–
7 of the sampling procedures, as shown
below:
Fmt 4701
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The most useful general judicial criteria for
economic feasibility comes from Judge
McGowan’s opinion in Industrial Union
Dep’t, AFL–CIO v. Hodgson, supra. A
standard is not infeasible simply because it
is financially burdensome, 499 F.2d at 478,
or even because it threatens the survival of
some companies within an industry:
Nor does the concept of economic
feasibility necessarily guarantee the
continued existence of individual employers.
It would appear to be consistent with the
purposes of the Act to envisage the economic
demise of an employer who has lagged
behind the rest of the industry in protecting
the health and safety of employees and is
consequently financially unable to comply
with new standards as quickly as other
employers. * * *
Id. (footnote omitted). A standard is feasible
if it does not threaten ‘‘massive dislocation’’
to, AFL–CIO v. Brennan, supra, 530 F.2d at
123, or imperil the existence of, American
Iron & Steel Institute v. OSHA, supra, 577
F.2d at 836, the industry. No matter how
initially frightening the projected total or
annual costs of compliance appear, a court
must examine those costs in relation to the
financial health and profitability of the
industry and the likely effect of such costs on
unit consumer prices. Id. More specifically,
Industrial Union Dep’t, AFL–CIO v. Hodgson,
supra, teaches us that the practical question
is whether the standard threatens the
competitive stability of an industry, 499 F.2d
at 478, or whether any intra-industry or interindustry discrimination in the standard
might wreck such stability or lead to undue
concentration. Id. at 478, 481. Granting
companies reasonable time to comply with
new PEL’s might not only enhance economic
feasibility generally, but, where the agency
makes compliance deadlines uniform for
competing segments of industry, can also
prevent such injury to competition. Id. at
479–481. United Steelworkers of America,
AFL–CIO–CLC v. Marshall, (OSHA Lead) 647
F.2d 1189, 1265 (D.C. Cir. 1980). To prove
economic feasibility, ‘‘OSHA must construct
a reasonable estimate of compliance costs
and demonstrate a reasonable likelihood that
these costs will not threaten the existence or
competitive structure of an industry, even if
it does portend disaster for some marginal
firms.’’ Steelworkers, 647 F.2d at 1272. As
with technological feasibility, OSHA is not
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required to prove economic feasibility with
certainty, but is *981 **153 required to use
the best available evidence and to support its
conclusions with substantial evidence. See
id. at 1267.
In a separate case involving review of
an OSHA standard, the D.C. Circuit
Court stated that:
‘‘Congress does not appear to have
intended to protect employees by putting
their employers out of business—either by
requiring protective devices unavailable
under existing technology or by making
financial viability generally impossible.’’ See
Industrial Union Dep’t., 499 F.2d at 467 (D.C.
Circuit 1974).
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A standard would not be considered
economically feasible if an entire
industry’s competitive structure were
threatened. Id. at 478; See also, AISI–II,
939 F.2d 975, 980 (DC Cir. 1991); United
Steelworkers, 647 F.2d at 1264–65;
AISI–I, 577 F.2d 825, 835–36 (1978).
This would be of particular concern in
the case of foreign competition, if
American companies were unable to
compete with imports or substitute
products. The cost to government and
the public, adequacy of supply,
questions of employment, and
utilization of energy may all be
considered when analyzing feasibility.
In determining whether these factors
might reasonably be significant in
analyzing the economic feasibility of a
rule, MSHA has relied on a 1% ‘‘screen’’
of the yearly costs industry is estimated
to incur to comply with a rule relative
to annual industry revenues. When
yearly costs are less than 1% of annual
revenues, MSHA views that the costs of
the rule are below the threshold
necessary to conclude that such an
extensive analysis is necessary to
establish the economic feasibility of the
rule. In that case, MSHA presumptively
concludes that the rule is economically
feasible.
This final rule will continue to
require mine operators to establish, use
and maintain all feasible engineering
and administrative control methods to
reduce a miner’s exposure to the
applicable final limit. It affords mine
operators the flexibility to choose
engineering and administrative controls,
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or a combination of controls to reduce
a miner’s exposure to DPM. When
engineering and administrative controls
do not reduce a miner’s exposure to the
DPM limit, the controls are infeasible, or
controls do not produce significant
reductions (as defined in the 2005 rule
(70 FR 32868, 32916)) in DPM
exposures, operators must continue to
use all feasible engineering and
administrative controls and supplement
them with respiratory protection.
Though mine operators may choose to
use an engineering control or an
administrative control to reduce a
miner’s exposure, or a combination
thereof, existing § 57.5060(d) prohibits a
mine operator from using respiratory
protection in lieu of feasible controls.
Mine operators must establish a
respiratory protection program when
controls are infeasible. Section
57.5060(d), as promulgated under the
2005 rule, incorporates by reference
MSHA’s current respiratory protection
program requirements for metal and
nonmetal mines at §§ 56.5005(a) and (b)
and 57.5005(a) and (b). These provisions
include requirements for selection, fittesting, and maintenance of respirators.
In addition, mine operators must follow
the requirements under paragraphs
(d)(1) and (d)(2) of the 2005 rule for
appropriate filters for respirators. If we
confirm that mine operators have met
all of the abovementioned requirements
for addressing a miner’s overexposure,
and the miner’s exposure continues to
exceed the final limit (not counting
respirators), we will not issue a citation
for an overexposure. Instead, we will
continue to monitor the circumstances
leading to the miner’s overexposure,
and as controls become feasible, we will
require the mine operator to install and
maintain them to reduce the miner’s
exposure to the final limit. We believe
that existing controls used to reduce
miners’ exposures to the current interim
limit can be used in helping mine
operators achieve compliance with the
final limits. Therefore, in determining
the economic feasibility of engineering
and administrative controls that the M/
NM underground industry will have to
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use under this final rule and using the
2001 REA as a basis, we compared the
cost of controls that are used to comply
with the existing DPM limit of 308EC µg/
m3 to that of the newly promulgated
final limits. These controls include
diesel particulate filters (DPFs),
ventilation upgrades, oxidation catalytic
converters, alternative fuels, fuel
additives, enclosures such as cabs and
booths, improved maintenance
procedures, newer engines, various
work practices and administrative
controls. Our comparison included costs
of retrofitting existing diesel-powered
equipment and regeneration of DPFs.
On the basis of information in the
rulemaking record, including our
current enforcement experience, we
have determined that the final rule is
economically feasible for the
underground M/NM mining industry as
a whole, as was the 2005 final rule. In
the 2005 final rule, we determined that
the 308EC µg/m3 interim limit is
economically feasible. To determine
whether this final rule is economically
feasible, we analyze economic
feasibility from two different
perspectives. First, we analyze whether
the new requirements of the final rule
(medical evaluation and transfer) are
economically feasible. Second, we
analyze whether the additional cost of
moving from the interim limit of 308EC
µg/m3 to the final limit of 160TC µg/m3
is economically feasible.
Analyzed from the first perspective,
the additional yearly costs of the final
rule are $69,170. The derivation of the
costs of medical evaluation and transfer
provisions of the final rule are
explained in Section IX.A of this
preamble. The total yearly compliance
cost of these new provisions for the
underground M/NM mines that use
diesel equipment is only 0.001% of the
annual revenues for these mines, well
below the 1% ‘‘screen’’ that we use as
a presumptive benchmark of economic
feasibility. Hence, we conclude that this
final rule is economically feasible for
underground M/NM mines that use
diesel equipment. Table V–1 shows
these calculations.
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Analyzed from the second
perspective, the additional yearly costs
for underground M/NM mines to move
from the interim limit to the final limit
of 160TC µg/m3 are $8,454,853. The
derivation of these costs of achieving
the 160TC µg/m3 final limit, given that
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the 308EC µg/m3 interim limit is in
effect, are provided in Section IX.B of
this preamble. The total yearly cost of
meeting the final limit for the
underground M/NM mines that use
diesel equipment is only 0.175% of the
annual revenues for these mines, well
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below the 1% ‘‘screen’’ that we use as
a presumptive benchmark of economic
feasibility. Hence, we conclude that the
final limit is economically feasible for
underground M/NM mines that use
diesel equipment. Table V–2 shows
these calculations.
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In circumstances where the use of
further controls may not be
economically viable, the standard
provides for a hierarchy of control
strategy that allows specifically for the
cost impact to be considered on a caseby-case basis. Our DPM enforcement
policy, therefore, takes into account the
financial hardship on a mine-by-mine
basis, which we believe effectively
accommodates mine operators’
economic concerns, particularly those of
small mine operators.
Whether controls are feasible for
individual mine operators is based in
part upon legal guidance from decisions
of the independent Federal Mine Safety
and Health Review Commission
(Commission) involving enforcement of
MSHA’s noise standards for M/NM
mines, 30 CFR 56.5–50 (revised and
recodified at 30 CFR 62.130). According
to the Commission, a control is feasible
when it: (1) Reduces exposure; (2) is
economically achievable; and (3) is
technologically achievable. See
Secretary of Labor v. A.H. Smith, 6
FMSHRC 199, 201–02 (1984); Secretary
of Labor v. Callanan Industries, Inc., 5
FMSHRC 1900, 1907–09 (1983).
In determining the economic
feasibility of an engineering control, the
Commission has ruled that we must
assess whether the costs of the control
are disproportionate to the ‘‘expected
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benefits,’’ and whether the costs are so
great that it is irrational to require
implementation of the control to
achieve those results. The Commission
has expressly stated that cost-benefit
analysis is unnecessary to determine
whether a control is feasible.
Consistent with Commission case law,
we consider three factors in determining
whether engineering controls are
feasible at a particular mine: (1) The
nature and extent of the overexposure;
(2) the demonstrated effectiveness of
available technology; and (3) whether
the committed resources are wholly out
of proportion to the expected results. A
violation under the final standard will
entail an agency determination that a
miner was overexposed, that controls
are feasible, and that the mine operator
failed to install or maintain such
controls. According to the Commission,
an engineering control may be feasible
even though it fails to reduce exposure
to permissible levels contained in the
standard, as long as there is a significant
reduction in a miner’s exposure. Todilto
Exploration and Development
Corporation v. Secretary of Labor, 5
FMSHRC 1894, 1897 (1983).
We will consistently utilize our
longstanding enforcement procedures
that we currently use for enforcement of
our interim DPM limit and for our other
exposure-based standards at M/NM
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mines. As a result, we will consider the
total cost of the control or combination
of controls relative to the expected
benefits from implementation of the
control or combination of controls when
determining whether the costs are
wholly out of proportion to results. If
controls are capable of achieving a 25%
reduction criterion, we will evaluate the
cost of controls and determine whether
their costs would be a rational
expenditure to achieve the expected
results.
We continue to emphasize that the
concept of ‘‘a combination of controls’’
is not new to the mining industry. It is
our consistent practice not to cost
controls individually, but rather to
combine their expected results to
determine if the 25% significant
reduction criterion, as discussed earlier
in this section, can be satisfied. We
heavily weigh the potential benefits to
miners’ health when considering
economic feasibility and do not
conclude economic infeasibility merely
because controls are expensive. Mine
operators have the responsibility for
demonstrating to us that the costs of
technologically feasible controls are
wholly out of proportion to their
expected benefits.
In situations where we find that the
mine operator has not installed all
feasible controls, we will issue a citation
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and establish a reasonable abatement
date. Based on a mine’s technological or
economic circumstances, the standard
gives us the flexibility to extend the
period within which a violation must be
corrected. If a particular mine operator
is cited for violating the DPM final limit,
but that operator believes that the
standard is technologically or
economically infeasible for that
operation, the operator ultimately can
challenge the citation in an enforcement
proceeding before the Commission.
We have found that most of the
practical and effective DPM controls
that are available, such as DPFs,
ventilation upgrades, enclosed cabs
with filtered breathing air, alternative
diesel fuels, low-emission engines, and
various work practice and
administrative controls, have the
potential to achieve a 25% reduction in
DPM exposure. The actual percentage
reduction obtained varies from
application to application depending on
the nature of the exposure and the
specific choice of control or controls
applied. For example, a DPF might
reduce DPM tailpipe emissions from a
piece of diesel-powered equipment by
95%. However, the equipment
operator’s actual exposure could be
reduced by more than 95% if an
enclosed cab with filtered breathing air
is also provided, or the reduction could
be less than 95% if other dieselpowered equipment without filtered
exhaust is operated in the same area.
We have consistently advised the
industry that DPM controls should be
selected based on a thorough analysis of
the circumstances and conditions at
each mine. This final rule affords each
mine operator the flexibility to select
the DPM controls that are appropriate
for their site-specific conditions. We
have also advised that similar
equipment may require different DPM
controls due to different duty cycles or
operating conditions. For example, a
platinum-catalyzed passivelyregenerating DPF might be successfully
applied on one piece of equipment, but
it may fail on a similar piece of
equipment owing to different duty
cycles. Even if applied on similar
machines with similar duty cycles, such
a DPF might be successfully applied on
one machine but be unsuitable for the
other because it is operated in an area
of the mine having marginal ventilation,
which could result in elevated NO2
exposures.
Our compliance cost estimates from
the 2001 final rule (not adjusted for
inflation) ranged from $31,373 per year
for the smallest nonmetal mines (based
on fewer than 20 miners and 2.2 pieces
of diesel-powered equipment per mine)
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to $659,987 for the largest precious
metals mines (based on over 500 miners
and 133 pieces of diesel-powered
equipment per mine). Our average
estimated compliance cost for the
industry as a whole to achieve the
interim and final limits was about
$128,000 per year per mine in 1998
dollars, or about 0.68 percent of the
mine’s annual revenues, on average. Of
that amount, about $90,000 per mine, on
average, was our estimated yearly
compliance cost to meet the interim
limit of 400TC µg/m3. These estimates
were reduced by a negligible amount in
the 2005 final rule, due largely to the
elimination of the provisions on DPM
control plan and required approval from
the Secretary to use respiratory
protection. As shown in Table IX.5 of
this preamble, the estimated compliance
cost to move from the interim limit to
the final limit of 160TC µg/m3 is about
$50,000 per mine in 2004 dollars.
The 2001 final rule established DPM
limits that were to be phased-in in two
steps over five years, starting with 308EC
µg/m3, which is comparable to the 400TC
µg/m3 that became effective July 20,
2002, 18 months after promulgation,
followed by a final limit of 160TC µg/m3
that was to become effective three-andone-half years later. Our intent with
respect to the phased-in DPM limits in
the 2001 rule and in subsequent
rulemaking was to provide the industry
with adequate time to familiarize itself
with DPM control technology so mine
operators could make informed
decisions regarding selection and
implementation of controls, train miners
properly on the use and maintenance of
the controls before the limits became
effective, and spread the cost of controls
over a multi-year period. As noted
above, our Regulatory Economic
Analysis (REA) for the 2001 final rule
determined that total annual
compliance costs would average
$128,000 per mine for the industry as a
whole, primarily for DPM controls.
These costs represented about 0.68% of
annual industry revenue. We believed
that the multi-year phase-in of the DPM
limits would serve to reduce the
economic impact on affected mines by
encouraging purchases of controls
gradually over several years.
At the time the 2001 final rule was
issued, based on the availability of
controls we understood could be
implemented by mine operators to
attain compliance with the respective
limits, we believed the phase-in
schedule of 18 months to reach the
interim limit and five years to reach the
final limit would provide sufficient time
for the entire industry to attain
compliance. However, based on the
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comments received from the mining
industry, other data in the DPM
rulemaking record, information received
from NIOSH, our compliance assistance
reports and activities, and our
experience with enforcing the interim
limit, we began to question whether it
was feasible for the industry to attain
compliance with the final limit by
January 20, 2006. As we discussed in
the preamble to the 2005 NPRM, the
applications engineering and related
technological and economic
implementation issues that we believed
would have been easily resolved by then
were more complex and extensive than
previously thought. We still believed
the mining industry could reach
compliance with the 160TC µg/m3 final
limit; however, we had determined that
the original schedule for attaining the
final limit was too ambitious for a
significant portion of this industry.
In the 2005 NPRM, we acknowledged
the implementation issues and proposed
modifying our phase-in schedule with
the intention of establishing a more
realistic regulatory timetable for
reaching the final limit. Rather than
requiring compliance with the 160TC µg/
m3 final limit by January 20, 2006, we
proposed phasing-in the final limit in
five steps over a five year period, and
in 50TC µg/m3 reductions for each year.
The initial final limit would have been
308EC µg/m3 on January 20, 2006; 350TC
µg/m3 on January 20, 2007; 300TC µg/m3
on January 20, 2008; 250TC µg/m3 on
January 20, 2009; 200TC µg/m3 on
January 20, 2010; and finally 160TC µg/
m3 on January 20, 2011. Our goal in
proposing this five-year phase in was to
provide the additional time we believed
the industry needed to attain the final
160TC µg/m3 limit, while at the same
time, assuring steady progress would be
made during that period to reduce
miner exposures to DPM. In the NPRM,
we asked for comments on this schedule
for phasing in the final limit, and on
other issues.
After analyzing the information and
data obtained from the comments we
received on the 2005 NPRM, we have
extended the amount of time we believe
the industry will need to attain
compliance with the 160TC µg/m3 final
limit beyond what was promulgated in
the 2001 final rule. Based on this new
information and data, we now believe
that requiring compliance with the final
limit in three steps over two years,
namely 308EC µg/m3 by May 20, 2006,
350TC µg/m3 by January 20, 2007, and
160TC µg/m3 by May 20, 2008, is
feasible. This timeframe for
implementing the final limits will
produce the maximum degree of miner
protection from DPM exposure that is
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both technologically and economically
feasible for the M/NM underground
mining industry, as a whole, to achieve.
We continue to believe that
establishing a final limit lower than
160TC µg/m3 is not economically
feasible for the industry. Reducing the
final limit below 160TC µg/m3 would
require costly ventilation upgrades,
replacement of most older mining
equipment, and considerably increased
use of DPFs on large numbers of, if not
on all, underground diesel powered
equipment.
In our 2005 NPRM, where we
proposed our five-year phase in of the
final limit, we tentatively concluded
that the 2001 160TC µg/m3 final
concentration limit presented a
significant challenge to a large portion
of the underground M/NM mining
industry and that compliance may not
be feasible by January 2006. We also
stated that:
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Our experience since January 2001 has
raised questions on technological feasibility
for the mining industry as a whole, rather
than for a small number of individual mines,
to meet the 160 TC concentration limit by
January 20, 2006.
We specifically requested comments on
the economic feasibility of the final
concentration limit of 160TC µg/m3 and
our proposed phase-in approach.
We also acknowledged in the 2005
NPRM that significant compliance
difficulties may be encountered at some
mines due to implementation issues and
the cost of purchasing and installing
certain types of controls. We requested
additional information regarding these
technological difficulties and whether
they would increase the cost to comply
with the final concentration limit above
that estimated in the 2001 final rule.
In addition, we proposed to eliminate
§ 57.5060(c)(3)(i) which prohibits new
mines from applying for special
extensions and requested comments on
the benefits (including cost savings) of
doing so. Lastly, we requested
comments on the costs to mine
operators for implementing a rule
requiring medical evaluation and
transfer of miners. In response to these
requests, we received numerous
comments on the economic feasibility of
meeting a final limit of 160TC µg/m3
within the proposed phase-in
timeframes, as well as on other
provisions of the proposed rule, which
we discuss in detail below.
We believe that the reduction from
308EC µg/m3 to 350TC µg/m3 in January
2007 will provide necessary incentive
and experience for mine operators to
continue to work out their remaining
feasibility issues and not to delay
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implementation of further engineering
and administrative controls until the
final 160TC µg/m3 limit becomes
effective in May 2008.
We believe that the current
rulemaking record fully supports the
economic feasibility of the initial phasein final limit of 308EC µg/m3, and the
final limit of 160TC µg/m3. We have no
new data or information in the
rulemaking record justifying change to
our 2005 cost estimates for the interim
limit of 308EC µg/m3. We stated in our
2005 final rule that a PEL of 308EC µg/
m3 was economically feasible for the M/
NM mining industry and provided
considerable discussion in support of
our position.
Regarding the 2001 final limit of
160TC µg/m3, we stated in the 2005
final rule that the evidence in the
current DPM rulemaking record was
inadequate for us to make
determinations regarding revision of the
final DPM limit at that time. We
requested comments on the feasibility of
the mining industry to comply with a
final limit of less than 308EC µg/m3.
Although we did not revise the final
limit in the 2005 final rule, we did
revise the special extension requirement
to provide one year, renewable,
extensions of time for mine operators in
which to comply with the final limit,
based on either economic or
technological constraints, but continued
to prohibit newer mines from applying
for extensions (70 FR 32966).
Additionally, in this 2006 final rule, we
have removed the prohibition on newer
mines from applying for a special
extension. Consequently, all mine
operators will be able to apply for a oneyear, renewable special extension of
time to comply with each of the final
limits, including the final limit of 308EC
µg/m3, 350TC µg/m3, and 160TC µg/m3.
The rulemaking record provides
numerous examples of successful use of
effective DPM controls. Our
enforcement sampling record from
November 2003 to January 2006 shows
that 82% of the 1,798 samples we
collected were below the 308EC µg/m3
interim limit, 78% were below the
January 2007 final limit of 350TC µg/m3,
and 46% were below the May 2008 final
limit of 160TC µg/m3. Additionally, 46%
of the mines sampled had at least one
sample over 308EC µg/m3, 55% over
350TC µg/m3, and 82% of the mines
had at least one sample over 160TC µg/
m3. It should be noted that we do not
consider these sample results to
necessarily represent typical or average
exposures for the industry as a whole
because we do not randomly select the
miners to be sampled. Following good
industrial hygiene practice, our
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sampling procedures dictate that when
we conduct enforcement sampling, we
sample those miners whom we believe
will have the highest exposures. Thus,
typical or average exposures for the
industry as a whole would likely be
lower than these values. We have
determined that the degree of
compliance demonstrated in our
enforcement sampling and the cost of
available control technology support our
conclusion that the final limits are
economically feasible for the industry as
a whole within the prescribed
timeframes. Our enforcement sampling
results also demonstrate the magnitude
of the compliance difficulties the M/NM
mining industry would have
experienced in meeting the 160TC µg/m3
final limit by the May 2006 effective
date.
We provide for consideration of
compliance difficulties on a mine-bymine basis in our existing use of
hierarchy of controls and provisions on
special extensions, which apply to the
final limits. We are satisfied that the
rule itself and our DPM enforcement
policy take into account the financial
difficulties on an individualized basis,
which we believe will effectively
accommodate an individual mine
operator’s economic concerns,
particularly those of small mine
operators.
We further recognize that there
currently are significant implementation
issues, both economic and
technological, that would make it
infeasible for the industry to comply
with the existing 160TC µg/m3 final limit
by May 2006. In our 2005 NPRM, we
proposed a five-year phase in of the
final limit to address the remaining
feasibility issues and asked for
comments on the technological and
economic feasibility of this approach.
Based on our analysis of the comments
received, the entire rulemaking record,
our current enforcement strategy for
enforcing the final limits, and our
experience with DPM control
technology and costs, we believe that
compliance with the 160TC µg/m3 final
limit can be achieved in a shorter
timeframe than the five years that we
proposed. We are encouraged by the
considerable progress we have seen to
date in reducing DPM levels and in the
many successful implementations of
DPM controls addressed in the
following discussion.
As stated in our 2005 final rule, ‘‘The
trends in DPM control technology
development, especially DPFs, indicate
that manufacturers are creating more
innovative designs. MSHA believes that
more cost effective control methods are
on the horizon.’’ Another new
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development that supports reducing the
proposed five year phase-in of the final
limit to the two year phase-in
established in this rule is the significant
DPM emission reductions achieved
through the use of high biodiesel
content fuel blends, coupled with the
federal excise tax credit for biodiesel,
and the rapidly growing availability of
this alternative diesel fuel throughout
the country. Although we acknowledge
the high cost of some DPM controls, we
do not believe they are significantly
different from our estimated compliance
costs in the 2001 final rule, and we have
identified many lower cost options.
In the 2001 final rule, we estimated
that the yearly cost of the rule would be
about 0.68% of annual industry
revenues, which was less than the 1%
‘‘screen’’ for costs relative to revenues
that we use as a presumptive benchmark
of economic feasibility (66 FR 5889). In
the 2005 final rule, we determined that
the 308EC µg/m3 interim limit was
economically feasible for the M/NM
mining industry. In Table IX.5 of this
preamble, we estimate that the total
yearly costs for the underground M/NM
mines using diesel equipment to move
from the current 308EC µg/m3 interim
limit to the 350TC µg/m3 and 160TC µg/
m3 final limits contained in this rule are
$8,454,853. As previously shown in
Table V–2 of this preamble, these yearly
costs are less than 0.2% of annual
industry revenues, well below our 1%
‘‘screen’’ that we use as a presumptive
benchmark of economic feasibility.
In this rulemaking to consider a
phased-in approach to the final
exposure limit of 160TC µg/m3, we used
economic feasibility information from
the entire rulemaking record supporting
the 2001 final rule, the 2005 final rule,
comments in response to the 2005
NPRM, and our experience gained with
control technology since 2001. We also
used information obtained subsequently
and entered into the rulemaking record,
including data from the published
literature, data developed by us through
MSHA Technical Support
investigations, public comments and
testimony, and our enforcement
experience relating to the interim PEL of
308EC µg/m3.
As stated above, we received
numerous comments on the economic
feasibility of the 2005 NPRM. Some
commenters disagreed with our
analytical method and the data we used
to estimate compliance costs, and
suggested that actual compliance costs
will be much higher than our estimates.
Consequently, they disputed our
tentative conclusion that compliance
with the phased-in final limits as
proposed will be economically feasible
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for the industry as a whole. Other
commenters stated that no delay is
justified because there is strong
evidence in the rulemaking record that
full compliance with the 160TC µg/m3
final limit is both technologically and
economically feasible at this time for the
industry as a whole. Still other
commenters indicated that it was
impossible to estimate the industry’s
compliance costs for attaining the final
exposure limit at this time. This is
because they contend that feasible
technology for complying with this limit
is not yet available and will not be
available in the foreseeable future.
Comments relating to our economic
feasibility determinations regarding the
final limit are discussed in this section.
Comments addressing technological
feasibility were discussed previously in
this section.
A few commenters stated that
compliance with the final DPM limit
would be cost prohibitive for their
mines, and that business failure could
result from their attempt to comply. Our
technological and economic feasibility
assessments of the final rule lead us to
a different conclusion with respect to
the possibility that business failures will
occur as a result of implementing the
final DPM limit.
Several commenters suggested that
our ‘‘prior economic feasibility
conclusion is based on improper
sampling and analysis, inaccurate and
incomplete data, and incorrect
assumptions.’’ Regarding the issue of
sampling and analysis, our economic
feasibility assessment for the 2001 final
rule was based on personal,
occupational, or area sampling using a
respirable dust sampler equipped with a
submicron impactor, and analysis of
samples for TC (EC plus OC) in
accordance with NIOSH Analytical
Method 5040. The DPM rulemaking
record contains evidence supporting the
positions of both MSHA and NIOSH
regarding the performance of the SKC
sampler. Among the conclusions drawn
from the 31-Mine Study and included in
the preamble to the 2005 final rule were
the following (70 FR 32871):
• The analytical method specified by the
diesel standard gives an accurate measure of
the TC content of a filter sample and the
analytical method is appropriate for making
compliance determinations of DPM
exposures of underground metal and
nonmetal miners.
• SKC satisfactorily addressed concerns
over defects in the DPM sampling cassettes
and availability of cassettes to both MSHA
and mine operators * * *
• The submicron impactor was effective in
removing the mineral dust, and therefore its
potential interference, from DPM samples.
Remaining interference from carbonate is
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removed by subtracting the 4th organic peak
from the analysis. No reasonable method of
sampling was found to eliminate
interferences from oil mist or that would
effectively measure DPM levels in the
presence of environmental tobacco smoke
(ETS) with TC as the surrogate * * *
MSHA has found that the use of EC
eliminates potential sampling interference
from drill oil mist, tobacco smoke, and
organic solvents, and that EC consistently
represents DPM. In comparison to using TC
as the DPM surrogate, using EC would
impose fewer restrictions or caveats on
sampling strategy (locations and durations),
would produce a measurement much less
subject to questions, and inherently would be
more precise. Furthermore, NIOSH, the
scientific literature, and the MSHA
laboratory tests indicate that DPM, on
average, is approximately 60 to 80%
elemental carbon, firmly establishing EC as a
valid surrogate for DPM.
Some industry comments contained
in Section VII of the 31-Mine Study
final report state that, ‘‘Fears about
using Method 5040 have been allayed,
but potential interference from ETS, oil
mist, and ANFO are too great to permit
using TC as a measure of DPM. Single
samples and area samples are
inappropriate.’’ As noted below, our
enforcement sampling procedures were
subsequently changed to incorporate
personal sampling only, and the DPM
surrogate was changed to EC to
eliminate potential non-DPM sources of
OC from interfering with DPM
determinations based on TC.
Regarding the effectiveness of the SKC
DPM sampler with integral submicron
impactor in the presence of ore dust, the
industry comments contained in Section
III–B of the 31-Mine Study final report
state that, ‘‘The impactor works in most
applications.’’ The industry comments
on this section also stated that, ‘‘The
industry is perplexed about possible
continued interference in gold mines
with graphitic ores.’’ However, the 31Mine Study final report states that, ‘‘For
typical samples collected in gold mines,
the interference from elemental carbon
from gold ore would be less than 1.5
µg/m3.’’
In the 2005 final rule, we modified
our compliance sampling strategy to
utilize personal sampling only, which is
the sampling strategy used by us for
determining compliance with our other
full-shift exposure-based standards for
airborne contaminants, and we changed
the DPM surrogate from TC to EC for the
interim limit. The change to EC as the
DPM surrogate was made to eliminate
the potential for sampling interferences
from non-diesel sources of OC, such as
drill oil mist or tobacco smoke, from
causing erroneous TC analytical results.
Our 2005 final rule on the interim DPM
exposure limit incorporated these
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changes, as does the current rulemaking,
with the exception that we will
undertake a separate rulemaking to
convert from TC limits to EC limits for
the 350TC µg/m3 and 160TC µg/m3 final
limits.
Regarding the use of inaccurate or
incomplete data for determining
economic feasibility, some commenters
suggested that the 2001 economic
feasibility assessment should have been
based on a representative sampling of
all the underground mines affected by
the rule. These commenters take the
position that since the standard affects
mines producing 24 different major
commodities, our 2001 assessment
should have included consideration for
the impact of the standard on a
representative sample of mines
producing each commodity. The
commenters also suggest that our
practice of comparing the industry-wide
cost of compliance to the industry’s
annual revenue is inappropriate. They
indicate that this method ignores the
fact that international commodity
markets determine the viability of mines
by setting market prices for their
production, and that annual revenues of
hundreds of millions, if not billions, of
dollars have not prevented the domestic
underground M/NM mining industry
from shrinking in recent years.
We believe that the method we used
to determine economic feasibility is
valid. In the 2001 final rule, we
subdivided the industry both by mine
size class and commodity sector. The
mine size classes were under 20
employees, 20 to 500 employees, and
over 500 employees. The commodity
sectors grouped mines according to the
commodity produced. The commodity
sectors were stone, precious metals,
other metals, evaporates, and other. The
resulting matrix comprised the five
commodity groups with three mine size
classes within each commodity group.
Compliance costs were estimated for
mines within each size class and
commodity group based on mining
methods and equipment common for
those specific types and sizes of mines.
Using this methodology, all
underground M/NM mines were
included in our economic analysis, even
though compliance costs were not
necessarily determined on a mine by
mine or individual commodity by
individual commodity basis.
Compliance cost estimates were
included for each of the major
provisions of the standard, such as DPM
controls to attain the DPM limit (DPM
filters, equipment cabs, and ventilation),
newly introduced engines, paperwork
costs associated with applying for a
special extension, tagging and
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examination of equipment suspected of
needed emissions maintenance,
training, etc.
Some commenters believe that we
made incorrect assumptions in
performing our economic feasibility
assessments. The Regulatory Economic
Analysis (REA) for the 2001 final rule
was based on our determination that the
most significant compliance cost
component would be the cost of DPM
controls to meet the respective DPM
limits, accounting for 96% of the total
cost of compliance. Our cost estimates
for these controls were originally based
on a compliance strategy that assumed
that the interim limit would be attained
primarily by replacing engines,
installing oxidation catalytic converters,
and ventilation improvements. We
further assumed that the final limit
would be attained primarily by adding
environmental cabs with filtered
breathing air and installing DPM filters.
We recognized that mine operators had
the flexibility to choose the engineering
and administrative controls that best
suited their mine-specific circumstances
and conditions. However, for costing
purposes, the above compliance
strategies were assumed. Based on
extensive industry comments on the
Preliminary Regulatory Economic
Analysis (PREA) for our 1998 proposed
rule, we modified our cost estimates to
favor diesel particulate filter systems
and cabs for compliance with the
interim limit, and more filters,
ventilation and the turnover of engines
for compliance with the final limit. Our
2001 REA was based on this modified
compliance strategy.
The modified compliance strategy
results in estimated industry-wide
compliance costs that we believed were
economically feasible for the industry as
a whole. The original estimate of $19.2
million in annual compliance costs was
revised upward to $25.1 million as a
result of the comments received on the
1998 proposed rule. Our economic
analysis for the 2005 final rule on the
interim limit actually showed a slight
decrease in compliance costs of $3,634
annually, primarily due to reduced
recordkeeping requirements from
elimination of the DPM control plan and
required approval from the Secretary to
use respiratory protection (70 FR
32944). The 2005 final rule analysis,
however, did not address the economic
impact of the final DPM limit of 160TC
µg/m3.
The commenters further stated that
the compliance strategy used for
developing compliance cost estimates
was based on, ‘‘incorrect assumptions of
applicable and feasible controls.’’
However, as discussed extensively in
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the technological feasibility section of
this preamble and throughout the
rulemaking record, we have established
the feasibility of the various controls
that are required to attain compliance
with the new final limits in accordance
with the phased-in dates.
Through the comments received
during our DPM rulemakings,
compliance assistance visits to mines,
and our enforcement experience with
the 2001 and 2005 final rules, we have
learned that the vast majority of mine
operators have acquired at least a few
EPA Tier 1 and Tier 2 engines, and
many have fleets that are comprised of
40% to 50% or more of such engines.
Despite disagreeing with our proposed
rule, a stone mining operator with seven
underground mines commented that all
new equipment purchased at two of
their mines were supplied with EPA
Tier 3 engines, and they have plans to
similarly upgrade the remaining
equipment at those mines. Three other
stone mining operators who also
disagreed with our proposed rule,
nonetheless, volunteered similar
information. One reported they had
recently acquired a new loader, drill,
and scaler, all with EPA Tier 2 engines.
Another reported acquiring two new
haulage trucks in 2005 at a cost of over
$600,000. The third operator indicated
that,
Before the initial inventory was even
required, we immediately replaced our
1970’s haul trucks with trucks built in the
1990’s. Later we removed a 1992 loader for
a 1999 loader with a Tier 2 engine. We have
recently purchased a newer roof-scaler with
a Tier 2 engine. We have retrofitted one of
our drills with a Tier 2 engine, and are
looking at buying a new drill to replace our
second drill.’’
Use of low emission engines has also
been common in the western multilevel
metal mines. Despite opposing our
proposed rule, one mine operator said
that replacement of old engines with
new cleaner engines, where practicable,
began in 2003. Such engine
replacements have now become a
primary focus of our efforts to control
DPM. Another operator who opposed
our proposed rule indicated they have
conducted a proactive engine campaign
to replace higher DPM emitting engines
with newer EPA Tier 1 and Tier 2 rated
engines. To date, 68% of the
underground equipment is powered by
EPA Tier 2 rated engines. A third
operator who also disagreed with our
proposed rule reported they have
repowered eight pieces of equipment at
their mine. A mining industry
organization commented that, ‘‘* * * as
our members replace their old engines
with new cleaner engines, that effort
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will reduce the DPM exposures of
miners.’’ A comment from another mine
operator indicated that during the last
two years, they had, ‘‘purchased fifteen
Tier 2 engines that, along with thirty
Tier 1 engines, constitute 42% of the
current underground fleet and 54% of
the total horsepower.’’
Some commenters noted they have
also made improvements to their
ventilation systems, such as upgraded
auxiliary ventilation systems, more
booster fans, and better maintenance of
ventilation control structures. Examples
include a mining company that operates
several underground stone mines,
which commented,
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All [of our] mines have performed major
ventilation upgrades, which include
installation of new larger portable fans that
are used at active headings to help direct air
flow, installation of larger main ventilation
fans at two mines, installed larger booster
fans in the duct tubing at three mines,
installed new ventilation stoppings and
curtains at various locations throughout the
mine at all mines, [and] replaced less
efficient ventilation fans with high volume/
low pressure fans.
Another stone mine operator reported
they had, ‘‘installed a third vertical air
shaft in our mine, we have added
brattice cloth for over 25 rooms and
adjusted brattice cloth throughout our
mine, changed traffic patterns, and
utilized portable fans.’’
Western multilevel metal mine
operators also upgraded ventilation
systems. One operator of several
underground gold mines reported
upgrading a spray chamber, developing
a new entrance drift and mine portal,
and using large auxiliary fans to
increase heading ventilation. A large
base metal mine operator reported
purchasing 17 new auxiliary fans that
were one-third more powerful than the
existing fans and also upgrading
ventilation system maintenance.
A few mine operators have completed
major ventilation system upgrades,
including new ventilation shafts and fan
installations. However, it is not clear
whether all operators that reported such
upgrades did so entirely to attain
compliance with the DPM interim or
final limit. For example, despite the
mine operator’s claims to the contrary,
our detailed analysis of a ventilation
system improvement project costing
over $9,000,000 at a western multilevel
metal mine indicated that some or most
of these upgrades would have been
necessary anyway to accommodate
planned production increases and other
non-DPM related purposes. One
outcome of this ventilation upgrade was
a 1,000 horsepower reduction in the
ventilation system’s total electrical
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power requirements, achieved through
more efficient deployment of booster
fans. Over 60% of the overall $9,000,000
project cost, when annualized, was
offset by this electrical power cost
savings.
Through the comments submitted to
the rulemaking record, the NISOH DPM
workshops in 2003, and our compliance
assistance visits to mines affected by the
rule, we have learned that, although
many of the metal mines have
experimented with DPM filters,
comparatively few are relying on filters
as their primary means of complying
with the interim limit. Also,
environmental cabs are in widespread
use throughout the industry; however,
comparatively few such cabs have been
retrofitted to existing equipment as a
primary means of compliance with the
interim limit. Indeed, several
commenters provided information on
the high cost of retrofitting cabs to
existing equipment, indicating why cab
retrofits were not the first option for
attaining compliance. Since the final
rule is performance-oriented and gives
mine operators flexibility to choose the
DPM engineering and administrative
controls that are best suited to their
unique circumstances and conditions, it
is not surprising that other compliance
strategies have also been employed,
such as utilization of alternative diesel
fuel (high biodiesel content blends and
diesel-water emulsions) and
implementation of a wide array of work
practice and administrative controls.
But by far the most common strategies
employed throughout the industry to
attain compliance with the interim limit
have been low DPM emitting engines
and ventilation improvements, which
were the basis for our original
compliance cost estimates.
One commenter suggested that we
conduct a full regulatory impact
analysis to assess the true economic cost
of our proposal. This commenter
disagreed with the manner in which we
updated the 2001 REA, since significant
changes have occurred since then in the
American economy, namely changes in
fuel prices due to war and natural
disasters. This commenter also believes
that DPM controls are more costly than
we projected and questioned whether
these controls are effective. Overall, this
commenter believes that we grossly
underestimated compliance costs in our
2001 final rule. We are unaware of a
change in the American economy
presented by the commenter other than
the price of fuel, which we agree has
gone up since 2001. However, the
commenter did not relate a rise in fuel
prices with the economic feasibility of
industry compliance with the subject
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rule. The recent rise in diesel fuel prices
does not affect the 1% ‘‘screen’’ for
compliance costs relative to industry
annual revenue that we use as a
presumptive benchmark of economic
feasibility. Higher fuel prices would
actually make the purchase of low DPMemitting engines more attractive because
they also have better fuel economy
compared to the older technology high
DPM emission engines. More
importantly, we also note that the prices
of the various commodities that are
produced in underground M/NM mines
have also gone up since 2001. For
example, between 2001 and 2005, the
price of gold increased 108%, zinc 53%,
platinum 64%, crushed stone 11%, lead
40%, and rock salt 19%. The
commenter has not established that the
industry’s relative financial position
compared to 2001, if it has changed at
all, has been so altered by a general rise
in prices that compliance with the final
rule is economically infeasible.
In responding to the commenter’s
second point, the technological
feasibility of DPM controls was
discussed in detail previously in this
section of the preamble. In the 2005
NPRM, we proposed a five year phasein of the final DPM limit to allow mine
operators the extra time they would
need to overcome technological and
economic implementation issues with
DPM controls. Based on new
information, primarily relating to DPM
filters and biodiesel fuel, we have
shortened the final limit phase-in period
from five to two years. However, we
believe this compliance schedule,
coupled with provisions in the final rule
relating to special extensions of time in
which to meet the final limit, will
enable the entire industry to attain
compliance.
Regarding the comments concerning
the role of international commodity
markets in determining the viability of
mines by setting market prices for their
production, our use of industry annual
revenue tacitly incorporates the effects
of ever-changing commodity prices. As
prices rise, industry annual revenue
rises, and as prices fall, industry annual
revenue falls. Although commodity
prices are indirectly incorporated into
our analysis, however, for purposes of
determining the economic feasibility of
a rule, the dollar amount of the
industry’s annual revenue is not by
itself determinative. Both prices and
production determine industry annual
revenue. Compliance costs that are only
a small percentage of industry revenue
help to establish economic feasibility.
We have customarily used yearly
compliance costs of greater than 1% of
annual industry revenue as our
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screening benchmark for determining
whether a more detailed economic
feasibility analysis is required. The
commenters correctly point out that
despite hundreds of millions, if not
billions, of dollars of industry annual
revenue, business failures can and do
occur, and over a period of decades, the
characteristics of an industry can
change markedly. However, by utilizing
the 1% of annual revenue screening
benchmark, we assure that a new MSHA
rule will not significantly affect the
viability of an industry.
While it is true that individual
business failures can and do occur, and
that over a period of many years,
substantial portions of a domestic
industry can be adversely affected by,
for example, international competition,
MSHA believes it is highly improbable
that such events would be set into
motion by a rule imposing costs equal
to or less than 1% of industry annual
revenue. Threats to an entire industry’s
competitive structure and resulting large
scale dislocations within an industry
sector are typically caused by
fundamental changes in technology,
permanent downward pressure on
demand for a commodity due, for
example, to the introduction of a
superior substitute material, world-wide
or regional business cycles, etc.
A commenter suggested that the
economic feasibility analysis in the 31Mine Study was flawed because our
unit prices for commodities were
significantly in error. For example, rock
salt for highway de-icing (the primary
market for the three rock salt mines
included in the study) reportedly sold
for about $20–$25 per ton when the
analysis was made. Yet, this commenter
went on to say that our estimates for
revenues and likely annual production
levels for the three salt mines appeared
to indicate that a price of about $50–$70
per ton was used in our analysis.
We are not persuaded by commenter’s
view that the economic feasibility
analysis for the 31-Mine Study is
invalid because we used erroneous
commodity prices. For the 31-Mine
Study, we did not have access to actual
annual revenue data for the 31 mines in
the study, so we indirectly estimated
annual revenues using our data on the
number of employee work hours in 2000
for each mine, the total number of
employee work hours reported to us in
2000 by all mines producing that
commodity, and data from the U.S.
Geological Survey on the industry-wide
value of mineral production by
commodity for the year 2000. We
estimated annual revenues for a
particular mine by determining the
industry-wide production value per
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employee hour for the specific
commodity each mine produced, and
multiplying that amount by the number
of annual employee work hours
reported to us for that mine. This
methodology assumes that each mine’s
annual revenues would be roughly
proportional to each mine’s share of the
industry’s total employee work hours.
Thus, our estimates, while not
necessarily exact for each mine, were a
reasonable approximation for those
mines based on industry averages. This
methodology does not explicitly
incorporate a cost per ton factor.
However, implicit in this methodology,
based on the U.S. Geological Survey’s
estimates of rock salt production in
2000 of 45,600,000 metric tons valued at
$1,000,000,000, would be a cost per
metric ton of $21.93 (equivalent to
$19.89 per short ton), which is actually
slightly less than the commenter’s
estimated price of $20 to $25 per ton.
Thus, we have no information about
how the commenter came up with a
price of $50–$70 per ton of salt
purportedly used in our analysis. As
demonstrated above we implicitly used
a cost per metric ton of $21.93.
Several commenters stated that our
compliance cost estimates in the ‘‘31Mine Study’’ were unrealistically low
because we didn’t recommend major
ventilation upgrades for any of the
mines in the study. Other comments
relating to the ‘‘31-Mine Study’’ were
that the mines included in the study
were not representative of the industry
as a whole, that we voided 25% of the
samples collected, that we eliminated
four mines from the study, and that we
significantly underestimated
compliance costs for the Stillwater Mine
near Nye, MT, which was one of the
mines included in the study. In
responding to the question of major
ventilation upgrades, we noted in the
preamble to the 2005 final rule (70 FR
32921) that we did not specify any
major ventilation upgrades in the 31Mine Study because, based on the study
methodology, the analysis did not
indicate the need for major ventilation
upgrades in order to attain compliance
with either the interim or final DPM
limits at any of the 31 mines. We further
went on to explain that the purpose of
specifying controls for each mine in this
study was simply to demonstrate that
feasible controls capable of attaining
compliance existed, and to provide a
framework for costing such controls on
a mine-by-mine basis. We explicitly
stated in the final report that the DPM
controls specified for a particular mine
did not necessarily represent the only
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28965
feasible control strategy, or the optimal
control strategy for that mine.
Since the completion of the 31-Mine
Study, we have observed that mine
operators in the stone industry, for
example, have chosen to attain
compliance without utilizing DPFs.
These operators instead have opted to
upgrade ventilation (usually by adding
or re-positioning booster fans and
installing or repairing ventilation
control structures such as air curtains
and brattices); install low-emission
engines; utilize equipment that is
supplied by the original equipment
manufacturer (OEM) with cabs with
filtered breathing air; initiate a variety of
work practices that contribute to
reducing personal exposures to DPM;
and in a few cases, use alternative diesel
fuels such as bio-diesel fuel blends and
diesel/water emulsions.
Regarding the question of the 31
mines being unrepresentative of the
industry as a whole, we note that the
mines were selected jointly by us and
the DPM litigants, and all parties
collaborated in the study design.
Although an attempt was made to
include a variety of commodities in the
study, the selected mines were not ever
intended by us or the collaborators to be
a statistically representative sample of
the industry.
In a related comment, an industry
organization asserted that our
subsequent ‘‘baseline’’ sampling was
‘‘similarly non-representative.’’ The
sampling to which this commenter
refers was conducted by us in 2002 and
2003 in accordance with a provision of
the second partial settlement agreement.
As described in the preamble to the
2005 final rule (70 FR 32873–32874),
Under the second partial DPM settlement
agreement, MSHA agreed to provide
compliance assistance to the M/NM
underground mining industry for a one-year
period from July 20, 2002 through July 19,
2003. As part of its compliance assistance
activities, MSHA agreed to conduct baseline
sampling of miners’ personal exposures at
every underground mine covered by the 2001
final rule. Our baseline sampling began in
October 2002 and continued through October
2003. During this period a total of 1,194 valid
baseline samples were collected. A total of
183 underground M/NM mines are
represented by this analysis * * * MSHA
[included] 320 additional valid samples [in
the analysis of baseline sample data] because
MSHA decided to continue to conduct
baseline sampling after July 19, 2003 in
response to mine operators’ concerns.
We are unclear as to why the
commenter would characterize the
baseline sampling as ‘‘nonrepresentative,’’ as it included all
underground M/NM mines that were in
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operation during this period of over one
year.
Regarding voided samples, of the 464
samples obtained at the 31 mines, 106
were voided. A key consideration in the
sampling conducted at the 31 mines was
to insure, to the extent possible, that
samples were not contaminated by nondiesel sources of airborne carbon.
Testing had verified that the submicron
sampler would remove mineral dust
contamination (limestone, graphite,
etc.), but tobacco smoke, drill oil mist,
and possibly vapors from ANFO loading
could contaminate a sample filter with
non-diesel organic carbon. Thus, in
accordance with the study protocol that
had been jointly developed and
approved by both us and the litigants,
any sample that was known to have
been, or could potentially have been
contaminated with such an interferant
was voided. Of the 106 voided samples,
61 were voided due to interferences.
There were also some samples that were
voided for other reasons, such as
laboratory error (2 samples), sample
pump failure (22 samples), or
incomplete sample or sampling the
wrong location (21 samples). Including
any of these 106 voided samples in the
data analysis would have cast doubt on
the validity of the study.
In response to the comment that four
mines were eliminated from the study,
of the 31 mines selected to participate;
only one was eliminated. This mine was
not eliminated per se. DPM samples
were obtained at this mine; however,
none of these samples were included in
the data analysis because they all had to
be voided due to interferences.
The underestimation of compliance
costs for the Stillwater Mine in the 31Mine Study was also discussed in the
preamble to the 2005 final rule (70 FR
32924). We acknowledged that the DPM
compliance costs for this mine would
probably be significantly higher than we
reported in this study because, as we
explained previously, our analysts, at
the time the 31-Mine Study was
conducted, had been supplied with
inaccurate information regarding this
mine’s diesel equipment inventory.
Based on updated equipment inventory
data, we subsequently revised our
analysis and corresponding cost
estimates. The revised annual estimated
compliance cost for the Stillwater Mine
of $935,000 was reported in the
preamble to the 2005 final rule (70 FR
32943). Although, this amount is
considerably higher than the estimate
from the 31-Mine Study, it is
significantly less than the estimated
compliance cost for a precious metals
mine of this size as detailed in our REA
for the 2001 final rule.
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Several commenters repeated their
concerns expressed in previous public
comments that the 2001 final rule and
subsequent economic feasibility
assessment for the 31-Mine Study relied
on quantitative analyses supported by a
‘‘flawed’’ computer simulation program.
They believe that the Regulatory
Economic Analyses for all of our DPM
rulemakings, from the original 2001
final rule to and including the current
rulemaking, are invalid because they
incorporate analytical results obtained
from this program.
As discussed in the section on
technological feasibility, the computer
program in question, referred to as the
DPM Estimator, is a Microsoft Excel
spreadsheet program that calculates the
reduction in DPM concentration that
can be obtained within an area of a mine
by implementing individual, or
combinations of engineering controls.
The two specific ‘‘flaws’’ identified by
the commenters are, ‘‘assumptions of
the availability of filters that would fit
the entire fleet of equipment in use, and
assumptions of perfect ventilation
conditions throughout the industry.’’
We have responded previously to both
of these comments, as well as to other
criticisms of the Estimator. We have
shown that suitable DPM filters were,
and continue to be, available to mine
operators that are capable of attaining
the final DPM limits within the
timeframes established in the final rule,
and that the Estimator does
appropriately account for complex
ventilation effects. Our responses to the
previous criticisms on the Estimator and
to the comments on the Estimator
submitted to this rulemaking are
detailed in the technological feasibility
section of this preamble.
A number of comments related either
directly or indirectly to activities at the
Stillwater Mine near Nye, MT. The
Stillwater mine is a large multilevel
platinum mine that operates 24/7 with
a workforce of over 900 miners. The
Stillwater Mining Company currently
utilizes 288 pieces of diesel equipment
in its underground mine. The company
has been installing EPA Tier 1 and Tier
2 engines since 2001, and at present,
approximately 16% of its engines are
Tier 1, and 52% are Tier 2. One Tier 3
engine is in operation, and three
additional Tier 3 engines were expected
in late January 2006. The company has
also upgraded its diesel engine
maintenance program. Cabs have been
installed on a few pieces of equipment
which are operated in areas of the mine
where the size of the mine openings
provides sufficient clearance for a cab.
The company has experimented with a
variety of DPM filter systems, including
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platinum washcoated passively
regenerating filters, active on-board
filters, active off-board filters, a fuel
burner type active regenerating system,
and disposable filter element systems.
The company has also evaluated a
diesel-water emulsion fuel and various
biodiesel blends, and the company has
made significant improvements to the
mine’s ventilation system in recent
years.
Most of the comments relating to this
mine, submitted both by the mine
operator and various other mining
companies and organizations, suggest
that the failure to attain full and
consistent compliance with the interim
DPM limit at this mine, despite vigorous
and sustained efforts by the company,
are evidence that neither the interim
DPM limit nor the final DPM limit are
technologically feasible. They also point
out that the funds expended by the
company thus far in its effort to attain
compliance have been excessive, and
that this experience therefore
demonstrates the economic infeasibility
of the rule as well.
We have found through our Technical
Support assistance and enforcement
experience that this mine operator, in
time, could achieve more consistent
compliance with the DPM interim limit
and attain the final DPM limits if they
would install effective engineering and
administrative controls. Although this
mine operator has experimented with a
number of DPM control technologies,
some of these trials were of quite
limited scope and duration. Several
were conducted as a part of
collaborative studies with the NIOSH
Pittsburgh Research Laboratory under
the auspices of the NIOSH M/NM Diesel
Partnership. While it is true that this
mine operator has evaluated numerous
DPM control technologies, only a few
have been the subject of sustained and
intensive applications engineering
efforts that we believe are required to
resolve the associated site-specific and
application-specific implementation
challenges. To mention a few examples,
this operator is not currently utilizing
fuel burner DPFs, biodiesel, or wateremulsion fuels. Their use of high
temperature disposable diesel
particulate filters (HTDPFs) has been
hampered by the use of HTDPFs on
equipment having very high DPM
emission engines, which causes the
filters to load up quickly and create
possible fire hazards. This operator has
not utilized heat exchangers in
conjunction with HTDPFs, which would
enable their use on a much broader
range of equipment. They have
expended far greater effort to optimize
passive DPF applications compared
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with active DPF applications, even
though they indicate that the vast
majority of their equipment is not
suitable for application of passive DPFs.
Through an extensive MSHA Technical
Support study of their ventilation
system, we had observed numerous
problems with auxiliary ventilation
systems in stopes. MSHA is continuing
to work with Stillwater to resolve these
compliance issues.
Regarding the question of economic
feasibility, although the mine operator
has incurred substantial costs, as
mentioned earlier we do not believe that
these costs would be excessive for a
mine of this type and size based on
expected compliance costs detailed in
the Regulatory Economic Analysis
(REA) for the 2001 final rule. In the
preamble to the 2005 final rule (70 FR
32934–32936), compliance costs for this
mine were analyzed in detail. This
analysis indicated that when this
operator’s actual expenditures were
annualized at a 7% annualization rate,
the operator’s yearly compliance costs
for the interim limit were less than
expected based on the estimates
contained in the REA for the 2001 final
rule for a precious metals mine of this
size.
Two compliance cost issues at this
mine were discussed in detail in the
preamble to the 2005 final rule: the cost
of implementing an active DPF program,
and the cost of a major ventilation
system upgrade. In that preamble, we
presented several options for deploying
active diesel particulate filters at this
mine. These options were developed in
response to a comment from this mine
operator submitted to the 2003 NPRM
that the cost of implementing an active
DPF program for this mine would
exceed $100 million over ten years. Our
deployment options were functionally
equivalent, and the estimated costs were
less than $400,000 per year. In the
preamble to the 2005 final rule (70 FR
32935–32936), we said,
MSHA does not believe the particular plan
developed by Stillwater is the optimal means
of utilizing active DPM filters at this mine.
Various alternative approaches for utilizing
active filters exist which would be far less
costly.
Since excavating regeneration stations
accounted for over 96% of the total cost of
implementing Stillwater’s active filter plan,
alternatives that do not include such
excavation costs would have a significant
cost advantage over Stillwater’s plan. It is
somewhat curious that Stillwater developed
its active DPF plan on the basis of this
particular on-board active regeneration
system, despite the extraordinarily high cost
of excavating the regeneration stations, and
Stillwater’s prior experience with premature
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failure of the on-board heating elements built
into the filters.
A lower cost alternative to Stillwater’s
approach utilizes an on-board fuel burner
system to regenerate filters. The
ArvinMeritor system was used at this mine
in 2004 with excellent results. It actively
regenerated the filter media during normal
equipment operations, regardless of
equipment duty cycle, with no elevated
levels of potentially harmful NO2, and
without having to travel to a regeneration
station to regenerate its filter.
Another less costly alternative would be to
utilize off-board regeneration instead of onboard regeneration. In off-board regeneration,
a dirty filter is removed and replaced with a
clean filter at the beginning of each shift.
During shift change, the dirty filters are then
transported by the equipment operator or a
designated filter attendant to a central
regeneration station or stations.
Such stations could be a fraction of the size
of the regeneration stations envisioned in
Stillwater’s plan, because they would only
need to accommodate the filters, not the host
vehicles. Since the host vehicles would not
need to travel to the regeneration stations, the
travel distance from normal work areas to the
regeneration stations would be less
important, greatly lessening the need for
frequent construction of new regeneration
stations as the workings advance. It is very
likely that such stations could be co-located
in existing underground shops, unused muck
bays, unused parking areas, or other similar
areas.
Off-board regeneration might not be
practical on larger machines due to the size
of the filters. For larger machines that are not
suitable for passive regenerating filters, the
fuel burner approach might be preferable. But
many of the machines targeted for active
filtration are quite small, having 40 to 80
horsepower engines. Active filters for these
engines are correspondingly small, and could
be easily and quickly removed and replaced
using quick-disconnect fittings. Another
lower cost option would be to utilize
disposable high-temperature synthetic fabric
filters, especially on smaller, light duty
equipment such as pickups, boss buggies,
and skid steers. Depending on equipment
utilization, such filters might only need to be
replaced once or twice per week.
In its comments on our 2005 NPRM, the
mine operator states that equipment
identified for use with active
regeneration systems has been limited to
equipment that is parked on the surface
at the end of the shift. This would allow
the DPF to be removed and placed in a
regeneration station. Unfortunately, not
all equipment can be brought to the
surface for regeneration due to logistical
issues, according to this mine operator.
The commenter, however, provided no
rationale explaining why active
regeneration should be limited only to
equipment that is brought to the surface
at the end of the shift, as active
regeneration can easily be accomplished
underground. Furthermore, later in the
same section, the commenter
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28967
acknowledges that underground
regeneration is possible. The commenter
states that for units that must be
regenerated underground, additional
excavations to house the regeneration
equipment and to provide parking
during regeneration would be required.
These additional excavations are neither
practical nor economically feasible,
according to this commenter.
These comments neither acknowledge
nor refute the recommended options we
provided in the 2005 final rule preamble
and as summarized above.
In another part of their comments to
this rule, the mine operator discusses
their experiences with disposable filter
element type diesel particulate filters,
and indicates that the costs of utilizing
this system are excessive because the
useful life of the filter is so short. The
example provided by the mine operator
was a particular model Toyota truck.
The commenter operates many such
Toyota trucks, which can be configured
for a variety of service and support
applications. According to the mine
operator’s analysis, the annual cost of
maintaining a disposable element filter
system on this type of vehicle is
$40,000, which this mine operator
characterized as ‘‘cost prohibitive.’’ In
response, we note that the Toyota truck
used in this example is equipped with
a model 1HZ engine, which has very
high diesel particulate emissions
between 0.8 and 0.9 g/bhp–hr. Table 6
in this mine operator’s comments
indicated that the DPM emissions for
this engine were 0.22 g/bhp–hr. At 0.8
g/hp–hr, the 128 hp engine on the
subject vehicle would generate 102 g/hr
of DPM. A 10 inch diameter, 26 inch
long filter with a capacity for capturing
and storing 8 g of DPM per inch of filter
length could thus store 208 g of DPM.
Even with two such filters installed on
the subject vehicle, the filters would
become fully loaded after only (208 × 2)/
102 = 4.08 hours, or about 4 hours and
5 minutes. The mine operator’s reports
of filters that, ‘‘burnt out,’’ may be
caused by continued operation of the
subject vehicle after the filter has been
fully loaded.
The problem with this application is
the engine, not the filter system. If this
engine were replaced with a modern
low emission engine, filter loading
would occur at a fraction of the rate
experienced with the current high
emission engine. The cost of the engine
would be partially offset through lower
fuel consumption, and the cost of
maintaining the disposable filter system
would drop by 70% to 90% because the
truck could be operated for many more
hours before the filter would become
fully loaded and need replacement. By
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optimizing the total system, including
the engine and the filter, associated
costs could be significantly reduced.
Regarding the major ventilation
upgrade, in its comments on the 2003
NPRM, Stillwater provided information
and costs relating to a major $9,000,000
ventilation upgrade they stated was a
DPM-related compliance expense. In the
preamble to the 2005 final rule (70 FR
32934–32935), we disputed this claim.
We determined that the expense was
only partially DPM-related and that this
operator was also able to obtain a
significant electrical power cost savings
as a result of more efficient deployment
of booster fans. Over 60% of the overall
$9,000,000 project cost, when
annualized, was offset by this electrical
power cost savings. In its comments on
the current rulemaking, additional
general information on the mine’s
ventilation system is provided, as are
plans for future upgrades, but our
analysis was not refuted. Another
commenter observed that our analysis of
the $9,000,000 ventilation upgrade was,
‘‘suspect,’’ but provided no factual
information to corroborate their
position.
Two commenters noted that our 2001
estimate of the cost of compliance for
the industry as a whole of $25.1 million
per year was too low. One commenter,
a mining industry organization,
provided no rationale or explanation to
support this comment. The other
commenter, a stone mining operator,
presented estimated compliance costs
for this mine and extrapolated these
costs to the rest of the industry. This
operator stated that it cannot accept our
projections that this final rule will not
have an annual effect of $100 million or
more on the economy. A figure of $100
million divided by 200 M/NM mines
would result in $500,000 per mine. This
commenter believes that its cost
estimates for new or newer equipment
in its small mine show capital
contribution of over three times our
figure.
This mine operator then listed the
following estimated equipment costs:
dsatterwhite on PROD1PC76 with RULES
•
•
•
•
•
•
•
•
Drill ...................................
Powder truck ....................
Scaler ................................
Loader ...............................
Truck 1 ..............................
Truck 2 ..............................
Truck 3 ..............................
Total ..................................
$350,000
$50,000
$350,000
$250,000
$225,000
$225,000
$225,000
$1,675,000
Upon examination, we have
determined that this commenter’s
analysis does not account for several
important factors. First, replacement of
equipment that is near the end of its
useful life and would have been
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replaced in the near future anyway
would not be considered a DPM-related
compliance cost, or at most, only
partially DPM-related. It is extremely
improbable that an entire inventory of
underground equipment would need to
be replaced all at once purely for DPM
compliance. The oldest equipment in a
mine’s inventory, which would
normally be the worst polluters, would
be the first that would need to be
replaced in the course of the normal
equipment turnover process. The cost of
replacing such worn out equipment
would not be considered DPM
compliance-related, because it would
have occurred anyway, with or without
a DPM rule. The newest equipment,
typically mid to late-1990’s model year
or newer, would most likely not need to
be replaced right away, as this
equipment would have EPA Tier 1 or
Tier 2 engines, and as a consequence,
would be low, or at worst moderate
polluters. Thus, new equipment
purchased strictly for DPM compliance,
if any, would typically be limited to
only a portion of a mine’s overall
equipment inventory.
Second, it is very unlikely that the
wholesale replacement of equipment is
the most cost effective DPM control
strategy for this, or any mine. For
example, rather than replacing all
equipment, an operator could replace
just one or two pieces of equipment (if
any equipment at all needed to be
replaced), utilize diesel particulate
filters, upgrade ventilation, switch to a
high biodiesel content fuel blend,
implement various administrative
controls, or use some combination of
these strategies. Indeed, this same
commenter earlier in their comments
stated that buying new equipment is
costly. There may be less expensive
alternatives to improve DPM levels,
such as ventilation or alternative fuels.
This commenter indicates that they,
‘‘have not tried diesel particulate filters
due to cost and negative performance
history reported by producers and
manufacturers.’’ However, as discussed
extensively in the previous section of
this preamble and throughout the
rulemaking record, diesel particulate
filters are a technologically and
economically feasible DPM control once
mine operators work through their
implementation issues. The commenter
indicated that they are considering the
use of a B99 biodiesel fuel blend. As
noted elsewhere in this preamble, use of
high biodiesel fuel blends has been
quite successful at other M/NM mines
in significantly reducing DPM
exposures.
By overlooking lower cost DPM
control alternatives, this mine operator’s
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assertion of economic infeasibility of the
final limit of 160TC µg/m3, even in 2011,
is questionable. A fundamental concept
upon which the Regulatory Economic
Analysis (REA) for the 2001 final rule
was based is that mine operators will
choose the lowest cost method of
attaining compliance with the
applicable DPM limits. If a mine
operator chooses other than the lowest
cost method for compliance, any
resulting determination of economic
feasibility would be seriously flawed.
We acknowledge that the process of
attempting to install various alternative
control technologies may be imprecise
at best, and that testing multiple designs
can be inherently cost-inefficient
because some designs will inevitably be
found to be unsuitable for a particular
purpose. However, we continue to
emphasize that mine operators can
obtain compliance assistance from our
District Managers, or utilize our DPM
Single Source Page and access the
internet-hosted DPF Selection Guide to
help streamline this process. Economic
feasibility is based on the assumption
that optimal, lowest-cost controls are
implemented to attain compliance
taking into account recognized
implementation difficulties. In the cost
estimates for this final rule, we have
included cost related to operator
evaluation of different technologies in
an effort to determine the most effective
method for compliance.
Third, the equipment listed by the
commenter would be expected to have
a long useful life, possibly up to 20
years. Thus, the total first year
acquisition cost of this equipment is an
incorrect representation of the
corresponding yearly cost to the
operator. Even in the unlikely event that
a mine operator would need to purchase
all new major underground equipment
in a single year, we would first need to
determine that these controls are
economically feasible for the operator.
Moreover, when the $1,675,000 cost of
this equipment is amortized over a 10year period (to account for depreciation)
at a 7% discount rate, the annualized
cost to the operator is $238,482. This
annualized cost is 48% of the
commenter’s threshold of $500,000 per
year that, according to the commenter’s
calculations, would be required, on
average, to generate industry-wide
annual compliance costs greater than
$100,000,000.
A mining industry organization stated
that even though the Mine Act is a
‘‘technology forcing’’ statute, the
projections that we made in this rule
‘‘go far beyond this into the realm of
pure theory.’’ They go on to state that,
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Underground stone mines cannot make
purchasing decisions based on hypotheses as
to what technologies may be available during
the coming decade when there is scant
evidence to support MSHA’s assertions.
dsatterwhite on PROD1PC76 with RULES
We disagree with the commenter’s
position regarding our conclusions on
economic feasibility. As we discussed
extensively in this preamble,
technologically and economically
feasible DPM controls are available,
however, mine operators will need to
resolve these implementation issues to
meet the final limit of 160TC µg/m3. In
the 2005 NPRM, we stated that mine
operators may need more time to
comply with the final rule due to
implementation issues, including cost
implications. We nonetheless believe
that in time, most of these
implementation issues can be overcome,
especially by May 2008. The five
principal engineering controls discussed
throughout this preamble—DPFs,
equipment for ventilation upgrades,
environmental cabs, alternative fuels,
and low emission engines—are all
commercially available off-the-shelf
from many suppliers. The final rule,
however, provides mine operators with
additional time to work through their
individual implementation issues.
These individual issues, when viewed
as a whole, result in our need to phasein the 160TC µg/m3 final limit.
Several mine operators and an
industry organization commented on
the costs associated with DPFs.
Comments included:
Average operating life of the Englehard
DPF utilized at Stillwater is 3000–4000 hours
at a cost ranging from $7,000–$8,500 per
unit. [Note: This mine operator reported the
average unit cost of 103 passive systems
installed since 2004 plus those planned for
installation in 2006 is $7,170.]
For equipment not compatible with passive
regeneration systems, active regeneration
systems have been researched and tested at
Stillwater. The cost for these systems have
ranged from $4,000–$8,000 per unit. [Note:
This mine operator reported the average total
acquisition, installation, and maintenance
cost for 10 active off-board filter systems and
4 regeneration stations sufficient for filtering
the DPM emissions from 5 vehicles was
$95,000, resulting in a per vehicle cost of
$19,000.]
The passive regeneration filter systems we
have purchased range from $6,600 to $8,700
each. These filters also have backpressure
monitors costing roughly $700 each.
Installation on equipment usually will cost
about $1,000.
Costs for our passive regeneration filters
systems will be borne over the filter life,
which in our experience has ranged between
2,500 and 9,000 hours with most falling
around 6,000 hours.
The last quote we received for an on-board
active regeneration filter was $28,000,
excluding the regeneration station which
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would cost an additional $8,600 and a
backpressure monitor estimated at $1,100, for
a total cost of $37,700 excluding freight and
installation.
What many NSSGA members are
experiencing is that they do not have any
way of establishing the true costs of diesel
particulate filters because, setting aside the
direct costs and questionable results related
to filter usage, the filters affect equipment in
ways that are adverse but cannot be readily
quantified.
We agree that the cost for passive
regeneration diesel particulate filters for
typical production equipment (loaders
or trucks with 300 hp to 500 hp engines)
would range from about $7,000 to about
$8,500. A number of industry
commenters agree that passive
regenerating filter systems are feasible
for equipment that operates at a
sufficiently demanding duty cycle.
Typical comments were:
Practical experiences with equipment that
have the capability to operate with passive
regeneration systems indicate this type of
control can reduce DPM exhaust emissions.
At the present time, however, we are
increasingly confident that passive
regeneration filter technology can be effective
in the mine’s larger horsepower production
units.
Turquoise Ridge believes that properly
sized and fitted filters can reduce DPM
emissions, and the Turquoise Ridge Mine is
now at the sustained level of production to
begin testing.
Both DPM filter vendors and mine
operators are now gaining experience in the
application of DPM filters underground.
Some progress is being made. For example,
the application of passive regeneration filter
technology is becoming effective on larger
horsepower production units. However,
NMA agrees with MSHA’s observation in the
preamble of the NPR that ‘[r]elying on
[filters] to be installed on older, higher DPM
emitting engines may also introduce
additional implementation issues since
[filter] manufacturers normally do not
recommend adding [filters] to older engines.’
Furthermore, the application of DPM filters
to equipment with medium- to low-duty
cycle engines remains problematic.
Industry objections to active filter
systems center on operational aspects
that result in higher overall costs for
applying this type of control. These
systems are very efficient in capturing
and retaining DPM, and the hardware
costs of such systems, though higher
than a comparable passive system, are
not excessive for many mine operators.
An example of active off-board
regeneration DPF system costs was
provided by the commenter who
indicated that ten filter systems and four
off-board regeneration stations cost
$95,000. This cost included acquisition,
installation, and maintenance, and was
sufficient for filtering the DPM
emissions from five utility and support
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28969
type vehicles. Assuming the filters
would last two years and the
regeneration stations would last five
years, the per vehicle yearly cost, when
annualized at a discount rate of 7%
would be $8,963. The cost of an active
on-board regeneration DPF system was
quoted by another commenter at
$28,000 plus an additional $1,100 for a
backpressure monitor and $8,600 for the
regeneration station, for a total of
$37,700. The per vehicle yearly cost for
this system, when annualized at a
discount rate of 7% would be $18,192.
We believe the difference in costs
between these systems relates more to
the engine horsepower they are
intended to filter rather than the type of
regeneration employed. The unit cost
for this second active DPF system is
about the same as we estimated in the
31-Mine Study for a similar system. For
that study, we estimated an active
system for a 400 hp to 500 hp engine
would cost $18,000 and the associated
regeneration station would cost another
$20,000 for a total of $38,000.
Rather than the cost of the systems
themselves, operators’ comments
primarily addressed the associated
implementation issues, such as the
required frequency of regeneration,
travel time to a regeneration station,
providing locations for regeneration
stations, equipping regeneration stations
with the necessary facilities and
utilities, equipment downtime while
regenerating, etc. and the perceived
increased labor and infrastructure costs
associated with applying active filter
technology. These concerns have
limited more widespread utilization of
active systems. Comments concerning
these logistical issues included:
Active filters require that equipment be
idled for a considerable period of time either
with on-board regeneration, or with an off
board filter change-out system * * * In
addition, active systems require considerable
space * * * The record to date has identified
other feasibility problems with DPFs that
include physical size of filter systems, the
short life span of filter elements, the required
downtime for regeneration of active
regeneration systems, the need for
regeneration stations with electric power and
compressed air supply near producing zones
for active regeneration systems * * *
Practical experience with active
regeneration systems has not indicated these
control options are economically feasible for
the Stillwater diesel fleet * * * Initial
operating time before the unit is required to
be removed and placed on a regeneration
station is, at best, 10–15 hours. However,
experience has shown this time can be as
little as 4 hours before off-board regeneration
is required. Due to the low utilization of the
active DPF before the system needed to have
active regeneration, two active DPFs were
purchased to ensure the equipment would be
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operational for the next shift. This option has
proven to be cost prohibitive; it is unrealistic
to logistically store spare active DPFs and
regeneration stations for even the small
fraction of equipment that has the capability
to operate with active DPFs * * * For units
that must be regenerated underground,
additional excavations to house the
regeneration equipment and to provide
parking during regeneration would be
required. These additional excavations are
neither practical nor economically feasible.
Additionally, moving equipment to the
regeneration stations is time consuming,
unproductive, and cost prohibitive.
One active regenerative DPF system,
specifically DCL Mine-X Black Out Soot
filter, was tested on a Tamrock 1400, 8 yard3
scoop over an 8 month period. Because of
filter limitations, the scoop was only
operational for 7 to 8 hours per shift before
the backpressure increases caused the need
for filter regeneration. This rendered the
equipment unusable for the remainder of our
normal 11 hour production shift. The active
regeneration system was determined to be
impractical because it was not effective for an
entire shift and could not be regenerated
between shifts (regeneration typically took
between 2 and 5 hours).
The feasibility of equipping medium-to
low-duty cycle engines with passive and
active regeneration DPF filter systems
continue to be evaluated by Greens Creek
Mine personnel. However, the need for fixed
locations for installation of equipment used
for active filter regeneration poses serious
logistical problems due to the spread out
nature of the mine’s layout.
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Other mine operators have not even
attempted to utilize diesel particulate
filter systems because of perceived
logistical problems and associated costs.
Typical comments from these operators
who have had no first hand experience
with diesel particulate filters included:
* * * the current methods to achieve
compliance are not economically feasible or
present other hazards to employees,
specifically some of the filtration technology
that we’ve investigated. I would state that we
have not tried those technologies as of yet.
As I said, the current filtering technology is
a capital cost and a long-term operating cost
that’s difficult to absorb in the operations.
We’ve talked about what filters mean and
what filters do and how they work and what
they are. We’ve closely watched how that
technology has moved forward. As of this
point, even the employees don’t see a benefit
in doing that. Mainly because the
maintenance that they’re going to be required
to do to change filters, to move filters around,
is going to cause them to pull out the ladder
and climb the ladder and work around the
hot exhaust and move the heavy thing back
down, you know, the ladder, put it where it
needs to go. And they’re exposed physically
to something—these guys are smart. They
understand these are real physical hazards
I’m exposed to try and get filters on and off.
We have not gone to diesel particulate
filters. In our hierarchy of controls, quite
honestly diesel particulate filters would be
our last choice. First of all, just from a
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practical perspective, there is still issues with
the types of filters you might use and if you
are making the engines—if the engines are
inefficient to start with and you have to use
a—you want to use a diesel particulate filter
as the correction method, it could very well
be that because of the inefficiency of the
engine, it makes the filters a lot more difficult
to deal with. Because they’re going to clog
up, they’re going to create problems for you
and it’s just going to increase the difficulties
of implementing a program. So we looked at
diesel particulate filters as the last resort. It
certainly may be one that we want to take,
but it’s not one that we would choose to go
at early * * * One of the things also about
diesel particulate filters and off board
regeneration is you’re talking about
increasing the labor cost.
There’s no way around it. It’s going to take
more people.
We believe that active regenerating
filter technology is available to enable
compliance with the final limit.
However, these commenters have
highlighted some of the implementation
issues we believe will be encountered
by a great many mine operators that may
need to utilize this technology to attain
compliance with the final rule. The
additional time required to resolve these
issues is provided by the two-year phase
in of the final limits incorporated in this
final rule.
We continue to advise that the
‘‘toolbox approach’’ be used for
compliance with this rule, and that
DPM controls be carefully selected on
the basis of attaining compliance at the
lowest cost. However, where
circumstances indicate that active
regenerating DPM filtration would be
the optimum control method, we
believe that the application of such a
system would be economically feasible
over time. We do intend to continue to
assess feasibility of effective controls on
a case-by-case basis.
We do not dispute that implementing
an active regenerating filter program at
an underground mine will create
logistical and implementation
challenges, and that mine operators will
need to incur costs to solve these
problems. As mines begin to solve these
implementation issues, however, most
should be able to reduce miners’
exposure to DPM in the process. We
acknowledge that a certain amount of
trial and error experimentation may be
unavoidable before an optimum
selection is made. However, we do not
believe this evaluation and selection
process is economically infeasible for
mine operators to successfully complete
over time.
We believe that the applications
engineering process followed by mine
operators for overcoming
implementation issues with passive DPF
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systems establishes a realistic model for
overcoming implementation issues with
active DPF systems. The early attempts
at applying passive DPF systems in M/
NM mines were inefficient and costly.
Applications and duty cycles were not
fully characterized, inappropriate filters
were selected, installation methods
were crude, and system maintenance
requirements were not well understood,
leading to short filter life and a variety
of related problems. The final rule’s
phased-in final DPM limits provide the
additional time required by the industry
to successfully address these issues.
With respect to the above specific
comments, while it is true that active
filter regeneration can require several
hours, the associated piece of diesel
equipment need not be idled for that
entire period. As one mine operator
indicated, two filter elements can be
acquired for each piece of diesel
equipment so that one element can be
in use while the other element is being
regenerated. Using quick disconnect
couplings in the equipment’s exhaust
system, swapping out the active DPF
elements could be accomplished
quickly with very little physical effort.
Equipment downtime in the context of
this active filter regeneration scenario
would be measured in minutes rather
than hours.
Nonetheless, the subject mine
operator declared this strategy to be
‘‘cost prohibitive,’’ due to the need to
purchase two filters for each piece of
equipment and the required space to
store the extra filter elements. We
disagree with this conclusion. First, the
annualized yearly cost of providing two
filters for each piece of equipment is not
significantly greater than the annualized
yearly cost of providing a single filter
for each piece of equipment because
each filter, being used only on every
other shift, will last twice as long as it
would have if it were used on every
shift. Second, there would be no need
for storing extra filters since filters
would simply be swapped back and
forth between the regeneration station
and the piece of diesel equipment.
We agree that there will be costs
associated with providing facilities and
utilities such as electrical power and
compressed air for the regeneration
stations. However, we believe these
costs will be small or negligible in the
context of implementing such a system,
or at worst, should not be economically
infeasible. As noted above, we believe
an optimally deployed active
regeneration system would utilize
existing locations with utilities already
in place as regeneration stations,
thereby simplifying implementation and
minimizing associated costs. Although
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several commenters have identified this
requirement as a compliance cost, the
actual magnitude of these costs has not
been presented.
The size of active DPF filter elements
has been discussed previously.
Typically, active systems would be
applied to smaller support and utility
equipment that does not operate at a
severe enough duty cycle to permit
passive regeneration. Smaller
equipment requires smaller DPF filter
elements that can be handled without
specialized materials handling
equipment or lifting aids. Unlike
passive systems that usually have to be
installed as close as possible to the
engine manifold so that the exhaust is
hot when it reaches the filter, there is
greater flexibility in installing active
DPF systems on a piece of equipment,
usually enabling convenient access for
swapping out filters. In rare cases where
filter elements may be too large to be
conveniently handled by the equipment
operator, accommodation could be
made, such as providing lifting aids at
the regeneration station or the exhaust
could be divided into dual separately
filtered branches with a smaller filter on
each branch. Implementing either of
these options by May 2008 would incur
some cost, but not so great as to
approach economically infeasible.
In instances where filters load up
with soot and require regeneration
before the end of a shift, a possible
solution is to utilize a larger filter that
has more soot storage capacity. The
mine operator that was able to run an
actively filtered loader for only 7 to 8
hours of an 11 hour shift could utilize
a 40% larger filter to extend the loader’s
operating time to the full shift duration
of 11 hours. Adding more filter capacity
could also be accomplished by dividing
the exhaust into dual separately filtered
branches, as was done at the mine
referenced above that used a dual
element disposable filter system on its
Toyota support and utility vehicles.
Another option for extending the
operating time of an active filter is to
replace the diesel engine with one that
produces less DPM. For example,
replacing a 100 horsepower Tier 1
compliant engine with the equivalent
Tier 2 engine would reduce DPM
emissions by over 60%. While a given
active filter on a Tier 1 engine may
require regeneration before the end of
the shift, the same filter on a Tier 2
engine might operate for the entire shift
or longer. A similar situation exists at
the Stillwater Mine in Nye, MT with
respect to the disposable filter element
systems on their Toyota trucks. As
discussed earlier in this section, a
possible solution to the problem of these
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filters loading up to quickly is to replace
the engines with a model that produces
significantly lower DPM emissions.
Again, there are some costs associated
with these approaches, but we do not
believe they would reach the level of
economic infeasibility.
Regarding the feasibility of providing
space for regeneration stations and
parking areas, we refer to our analysis
of the active regeneration system
proposed by the Stillwater Mining
Company and discussed in the preamble
to the 2005 final rule (70 FR 32934–
32936). The rationale supporting our
suggested alternative active regeneration
system for this mine remains our
current position, and given the extra
time afforded by the phased-in final
limit included in the final rule, we
believe a similar optimization process
can be used at other mines to solve a
number of implementation challenges.
We do not dispute that mine operators
have had less success with active
regenerating filter systems compared to
passive systems. As noted above, we
believe this result is largely due to
greater experimentation, trial and error,
and applications engineering by mine
operators on passive systems. During
the remaining period before
enforcement of the final limit of 160TC
µg/m3 begins, mine operators will have
sufficient time to meet these challenges
and successfully apply active
regeneration systems.
Several commenters have said that
they favor passive regeneration over
active regeneration. For example, one
mine operator said, ‘‘Research and
testing of DPF regenerations systems has
concluded that passive regeneration
systems are preferred over active
regenerations systems.’’ As a result,
most mine operators who have
evaluated DPFs have concentrated their
efforts on passive systems. We realize,
however, that mine operators who have
successfully implemented passive
regeneration filter systems have had to
work long and hard to overcome
difficult implementation issues. One
mine operator commented, ‘‘The
process of achieving filter reliability has
been arduous * * *’’ The product of
these sustained efforts has been longer
filter life, acceptance and support by
operating and maintenance personnel,
and the streamlined integration of
passive filters into these mines’ overall
operating procedures, all of which we
believe could contribute to controlling
costs.
We are confident that such efforts,
applied to active systems, can achieve
similar results. These systems are
widely used in other industries, and
they have been used successfully on a
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28971
limited basis in M/NM mining. Their
successful use on a more widespread
basis in the mining industry is possible,
but not without time and similar
dedicated efforts by mine operators to
solve the mine-specific and applicationspecific logistical and implementation
issues discussed above. This point was
emphasized by NIOSH in its opinion
submitted on June 25, 2003 and
repeated in its comments on the current
rule that:
With regard to the availability of filters and
the interim standard, the experience to date
has shown that while diesel particulate filter
(DPF) systems for retrofitting most existing
diesel-powered equipment in underground
metal and nonmetal mines are commercially
available, the successful application of these
systems is predicated on solving technical
and operational issues associated with the
circumstances unique to each mine.
Operators will need to make informed
decisions regarding filter selection,
retrofitting, engine and equipment
deployment, operation, and maintenance,
and specifically work through issues such as
in-use efficiencies, secondary emissions,
engine backpressure, DPF regeneration, DPF
reliability and durability.
When these implementation issues
are resolved, we believe an inevitable
consequence will be significantly
reduced costs due to decreased waste,
fewer damaged or failed filters,
increased efficiency and effectiveness of
filter system installations, operations,
and maintenance, acceptance by miners,
minimal adverse effects on equipment
operations, and smoother integration of
filter regeneration into the mining
process.
Two commenters provided
information on the costs of utilizing low
DPM emission engines. One mine
operator said, ‘‘Since 2001, Stillwater
has performed a proactive engine
campaign to replace the higher DPM
emitting engines with the newer EPA
Tier I and Tier II rated engines.’’ This
commenter also provided a table of the
costs incurred in 2004 and 2005 for
engine replacements and upgrades
showing that 48 new engines were
installed at a total cost of $576,000
(average cost of $12,000 each) and 98
engine upgrades (electronic engine
governors) were completed at a total
cost of $198,000 (average cost of $2,020
each). Several other commenters
indicated they had replaced engines or
had purchased new equipment with low
DPM emission engines, but the only
other commenter to provide cost data on
engines said they had completed eight
‘‘engine repowers’’ at a total cost of
$120,000, for an average cost of $15,000.
As we have suggested throughout the
DPM rulemakings, utilization of low
DPM-emitting engines is an excellent
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way of reducing DPM concentrations
underground. Depending on the specific
emissions from the original and
replacement engines, DPM reductions of
up to 90% or more are possible.
However, we acknowledge that
replacing engines can be costly,
especially when the replacement engine
requires significant adaptations to the
host vehicle to accommodate physical
size constraints, new plumbing and
wiring harnesses, etc. Comments on the
1998 Preliminary Regulatory Economic
Analysis (PREA) suggested such ‘‘nonlike-for-like’’ retrofits could cost up to
$60,000. Although costs may reach
$60,000 in certain extreme or worst case
situations, we believe in reality, that the
costs quoted above of $12,000 to
$15,000 are more typical. When
amortized over the 10 year life of an
engine, the annualized yearly cost of a
$15,000 engine at a discount rate of 7%
is $2,136.
We also received comments to the
1998 PREA indicating that mining
equipment at underground M/NM
mines can have a useful life of up to 20
years. However, engines typically last
only half that long or less, meaning that
engine replacement is a routine
procedure that is necessary to maintain
mine production levels. We do not view
replacing a worn out or blown engine
with a new low DPM engine as a DPM
related compliance cost. It is not clear
from the commenters’ data whether the
subject engines were replaced due to the
normal engine turnover process or
whether serviceable engines were
replaced solely for DPM compliance
purposes.
We also note that the new low DPM
emitting engines provide other
significant benefits to mine operators.
The electronic maintenance diagnostics
reduce maintenance-related downtime,
and the fuel savings between a non-EPA
Tier rated engine and an EPA Tier 2
engine can be 10%–15% or more. For a
400 horsepower engine that normally
consumes 8 gallons of fuel per hour
(approximately 50% duty cycle), a 10%
reduction in fuel consumption over
3,000 annual operating hours results in
a 2,400 gallon fuel savings per year. At
a diesel fuel cost of $2.00 per gallon, the
new $15,000 Tier 2 engine would
almost pay for itself in 3 years due to
lower fuel consumption. At a diesel fuel
cost of $2.30 per gallon, if an old engine
was replaced with one that consumed
15% less fuel and was operated for
6,000 hours per year, the payback
period for the $15,000 replacement
would be less than one year. In fact, the
current price of diesel fuel (in May
2006) has risen to approximately $2.90
per gallon.
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A mining company that operates two
gold mines in Nevada commented that,
Our estimate of the total cost of measures
taken to achieve compliance with the current
interim standard [interim DPM limit] is
approximately $1.68 million annually ($8.4
million since 2001). Our experience indicates
that MSHA’s 2001 cost estimates
dramatically understated the costs of
compliance.
This commenter then itemized the
compliance costs incurred at their two
mines since 2001 as follows:
• Engine repowers (8 @
$15,000) ............................
• Cab installed on KMS 608
• Cabs on 2 new loaders @
$43,000 each .....................
• Cabs on 3 new loaders @
$48,000 each .....................
• 1225 South Meikle Spray
Chamber ............................
• Rodeo Betze Portal Drift ..
• Rodeo Betze Port Drift
Vent Intake .......................
• Increase size of auxiliary
fans ....................................
• Higher power cost,
$560,000/yr × 3 yrs ..........
• Total costs since 2001 ......
$120,000
$43,000
$86,000
$144,000
$139,000
$1,200,000
$1,300,000
$750,000
$1,680,000
$5,462,000
The sum of the items listed by the
commenter, $5,462,000, is about 65% of
the $8.4 million amount the commenter
claims was spent to attain DPM
compliance. Without a thorough study
of these elements, and based on the
limited information provided by this
mine operator in their comments, we are
not able to verify that all of these costs
are DPM-related. For example, we
determined at another precious metals
mine that claimed DPM-related
ventilation upgrades were actually
justified on the basis of other needs,
such as planned production increases
and the desire to improve overall
ventilation system efficiency. Of the
approximately $5.46 million in claimed
DPM compliance costs itemized above,
over $5.07 million, or 93% are
ventilation related. Likewise, installing
cabs on mobile equipment or acquiring
new equipment with OEM cabs can also
solve dust and noise overexposure
problems and improve operator comfort.
However, even if all the listed costs
were entirely justified solely on the
basis of complying with the DPM rule,
when the individual cost elements are
amortized at a discount rate of 7% over
their expected life, annualized yearly
costs to the operator are about $980,000.
The estimated yearly compliance cost
for a medium sized gold mine was
determined in the Regulatory Economic
Analysis (REA) for the 2001 final rule to
be $171,778 (not adjusted for inflation)
based on an inventory size of 24 pieces
of diesel equipment. In their comments,
this mine operator indicated they are
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currently operating 154 pieces of diesel
equipment for mining and support
activities. In 2002, this operator
reported 236 pieces of diesel equipment
in its diesel equipment inventory. Using
the lower number and applying a ratio
multiplier of 6.4 (154/24) to the
$171,778 compliance cost estimate from
the 2001 REA results in an estimated
compliance cost for the commenter’s
two mines of $1,099,379. Thus, this
commenter’s actual annualized
compliance cost of $980,000 is about
89% of the expected annualized
compliance cost for gold mines of this
size, as estimated for the 2001 final rule.
Under the new final rule, the mine
operator’s compliance costs would be
expected to decrease due to the phasein of the final DPM limits.
This same mine operator urged us to
update our compliance cost estimates
based on the current price of diesel fuel.
They indicated that,
In 2001, when the proposed limit was
adopted, diesel costs were approximately
$1.40 per gallon. Currently, diesel prices are
in the range of $2.39 per gallon, an increase
of over 70%. Available control technologies,
particularly filters, reduce horsepower and
increase fuel consumption and costs to
accomplish the same work. The agency’s cost
estimates should acknowledge current diesel
fuel prices.
Since 2001, a major component of
DPM compliance strategies that are
being widely adopted throughout the
industry, including by this operator, is
the use of modern low emission
engines, which in addition to
significantly lowering DPM emissions,
also reduces fuel consumption by 10%
to 15% compared to older, high DPM
emission engines. We also note that the
fuel penalty of using a properly sized
diesel particulate filter is very small.
Even the fuel burner system, which
combusts diesel fuel in the exhaust to
raise the exhaust gas temperature
sufficient for filter regeneration, only
increases fuel consumption by about
1%.
We received comments on the costs of
environmental cabs from gold mines in
Nevada. One company indicated they
had retrofitted five fully enclosed cabs
onto haulage trucks and loaders, and
that as a result, the operators of this
equipment were in compliance with the
final limit. These cabs were installed
during major re-builds on the subject
equipment at a cost of $30,000 to
$50,000 each. Another operator
indicated they had installed
environmental cabs on six loaders at a
cost of $43,000 to $48,000 each. These
unit costs are higher than we originally
estimated for environmental cabs in the
REA for the 2001 final rule. However,
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our original cost estimate applied to the
industry in general and to all
equipment. We expected the cost of
retrofitting cabs onto purpose-built
underground mining equipment to be
substantially higher than the cost of
cabs installed at the factory on
construction-type equipment by the
OEM. The costs quoted by the
commenters reflect this expected
difference. It is also important to note
that the costs of these retrofitted cabs
are only a small part of overall
compliance costs for these mines, and
their overall compliance costs are less
than expected based on the REA for the
2001 final rule.
We received several comments on the
cost of biodiesel fuel. These comments
generally fell into three categories: the
cost of the fuel itself, the biodiesel tax
credit, and the cost of infrastructure for
fuel storage and handling. Regarding the
cost of the fuel itself, typical comments
were:
Fuel prices will have a substantial impact
as Bio-Fuel cost is over $1.00 per gallon
higher than diesel.
[Biodiesel] * * * is not widely distributed
or accessible at a reasonable cost to many
mining operations.
Our current diesel fuel supplier has
indicated that the cost for bio-diesel fuel
* * * would be priced at a premium of 20
to 25 cents per gallon for a B20 blend.
Regarding the tax credit, typical
comments included:
We are now considering a B99, with the
hope that the current $1.00 per gallon tax
credit remains to help control costs.
The economic feasibility of alternative
fuels depends upon uncertain government
price supports that are due to expire in the
near future.
Regarding the cost of infrastructure
upgrades, typical comments included:
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Cost analysis concerning on-site storage
was conducted with a regional supplier and
proved cost prohibitive. The cost of the
infrastructure to support biodiesel at the
mine would include a 10,000 gallon tank for
diesel, 15,000 gallon tank for biodiesel, and
a 10,000 gallon tank for the blended product.
The cost for this system would be in excess
of $250,000.
[The higher cost per gallon for biodiesel]
does not include costs for specialized
transport during the winter season to keep
the biodiesel fuel from gelling. Further, we
would have to install separate fuel tankage to
segregate biodiesel fuels from other fuels
* * *
We agree with the commenters who
indicated that the cost of biodiesel is
typically about $1.00 per gallon more
than standard diesel fuel, though this
has not always been the case. Prices for
standard diesel and biodiesel are
determined by the market, and when the
price of standard diesel fuel spiked in
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the late summer and fall of 2005, the
price difference between standard diesel
and biodiesel was considerably less
than $1.00 per gallon. But the $1.00 per
gallon price difference quoted by the
commenters is more typical. However,
the net cost of biodiesel to mine
operators is significantly affected by the
federal excise tax credit for biodiesel
fuels, which applies to fuel blenders
(typically the fuel distributor), and is
valued at $0.01 per gallon per
percentage of biodiesel in a fuel blend
for biodiesel made from agricultural
feedstock (such as soy biodiesel).
Because the cost of biodiesel is typically
approximately $1.00 per gallon more
than standard diesel, the credit of $0.01
per gallon per percent biodiesel has
nominally eliminated the cost difference
between standard diesel and biodiesel.
For example, if standard diesel is $2.00
per gallon, and the cost of biodiesel
before the excise tax credit is applied is
$3.00 per gallon, a 98% biodiesel fuel
blend (98% biodiesel mixed with 2%
standard diesel) with the tax credit
applied would cost:
[$2.00/gal × 2%] + [$3.00/gal ×
98%]¥[98% × $0.01] = $2.00/gal. Thus,
a gallon of the 98% blend of biodiesel,
after the tax credit is applied, would
cost the same as a gallon of standard
diesel.
This tax credit, which has been in
effect since 2004, was scheduled to
expire in 2006, but has been extended
through 2008. It is impossible to predict
whether the credit will be extended
beyond 2008, as its further extension is
subject to Congressional action. It is also
impossible to predict the future price
difference between standard diesel and
biodiesel, as the prices of both
commodities are determined by market
forces. The only factor affecting the
price of either fuel that can be predicted
with any degree of certainty is the
supply of biodiesel. Biodiesel
production in the United States has
grown from 0.5 million gallons in 1999
to an estimated 75 million gallons in
2005. Production growth between 2004
and 2005 alone was 300%, from 25
million gallons to 75 million gallons.
Annual production capacity that is
currently under construction is 329
million gallons. Biodiesel production
plants in the pre-construction phase
will have an annual capacity of an
additional 529 million gallons. To the
extent that increased supply tends to
attenuate upward pressure on price, the
expected effect of this large increase in
biodiesel supply would be to moderate
price increases, if any, or possibly serve
to lower the price. Another indicator of
future price trends is the capacity of
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28973
individual plants. At present, only 13 of
52 plants have an annual capacity of 10
million gallons or more. In contrast, of
the plants currently under construction
or in the pre-construction phase, 27
have an annual capacity of 10 million
gallons or more, including several
ranging from 30 million to 80 million
gallons of annual capacity. To the extent
that larger plants can reduce costs
through economies of large scale
production, the growth of larger plants
will also attenuate upward price
pressure. Thus, even without the tax
credit, we expect the price difference
between standard diesel and biodiesel
to shrink over time. Our determination
of whether biodiesel fuel is a feasible
DPM control at a particular mine,
however, does not depend on extension
of the federal excise tax incentive.
Regarding the issue of infrastructure
upgrades to accommodate biodiesel, we
agree that some upgrades may be
necessary at some mines. For example,
due to the cold weather properties of the
fuel, storage tanks at mines that
experience sub-freezing temperatures
would need to be heated, moved to a
heated indoor space, or moved
underground. Some mines that are using
high biodiesel content fuel blends have,
or are planning such changes. There
may also be costs incurred by the fuel
distributor. Some distributors are
already capable of off-loading, handling,
and storing biodiesel in cold weather.
However, those that do not have this
capability would need to acquire the
necessary infrastructure upgrades, and
the associated costs would reasonably
be passed along to their biodiesel
customers. However, such costs,
whether incurred by the mine operator
or the fuel distributor and passed on to
the mine operator, would largely be onetime expenses that would be amortized
over a period of many years. For
example, although we dispute the
commenter’s assertion that
infrastructure upgrades to support
biodiesel at their mine would cost
$250,000, even this amount, when
amortized over 20 years, results in an
annualized yearly cost of $23,598. We
assume a tank already exists at the mine
for standard diesel, so it is not clear why
another tank is necessary. We also
question why a tank for blended fuel is
needed, as greater DPM reductions are
obtained when biodiesel content is
maximized. While it is true that
biodiesel needs to be blended with
standard diesel to qualify for the federal
excise tax credit, the IRS has
determined that a 99.9% blend
(nominally 10 gallons of standard diesel
mixed with 10,000 gallons of biodiesel)
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satisfies this requirement. Such a
blending process would not require a
separate blending tank. Thus, the
commenter’s $250,000 cost estimate for
infrastructure to support biodiesel
appears high. However as noted above,
even if this cost is supportable, the total
cost, when amortized over the life of the
asset, results in an annualized yearly
cost of $23,598. It is also significant to
note that this commenter’s fuel
consumption is about 80,000 gallons per
month. The corresponding costs for
infrastructure upgrades at an average or
typical mine would be much lower.
Depending on circumstances at a
given mine, there may also be a need to
provide vehicle fuel tank heaters, fuel
line heaters, and fuel filter heaters.
These items are commercially available
at reasonable costs. For example, the
MSRP for an Artic Fox model AF–F–203
14″ to 29″ in-tank fuel warmer is
$169.27, the MSRP for an Artic Fox
model AF–D3085–2180 24V, 600W, 12
ft heated fuel line is $614.86, and the
MSRP for a Diesel Therm fuel filter
heater is $180.81.
The operator of two large stone mines
commented that there are occupations at
their mines such as roof bolters that
require personnel to work outside of a
cab near the mine roof where DPM
concentrations would be expected to be
the highest. Due to the high cost of
major ventilation upgrades, this
commenter asked that consideration be
given to allowing such miners to utilize
PPE for compliance with the DPM limit.
Another stone mine operator made a
similar comment, asking:
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Is it economically sensible to expend
monies to ensure compliance with the DPM
rule for 15 employees exposed to the
polluted air when they venture outside of the
cab and can use PPE? MSHA also did not
allow the most cost-effective method of use
of PPE and other administrative controls to
reach the final limit.
In responding to these comments, we
note first that mine operators have
available engineering control options
other than cabs and ventilation, and
second, that under certain
circumstances, PPE is allowed as a
means of compliance. Under
§ 57.5060(d), mine operators have been
granted great flexibility in choosing
controls to attain compliance, and are
not limited to only cabs or ventilation.
The operator of the two large stone
mines has acknowledged having had
success with alternative diesel fuels,
and has also acquired new equipment
with low emission engines. However,
they have not utilized diesel particulate
filters on any equipment, and it is not
clear whether expanded use of low
emission engines or the use of
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administrative controls might also be
possible.
As noted previously in the
technological feasibility section, it is a
widely accepted principle of industrial
hygiene that PPE is inherently inferior
compared to engineering and
administrative controls for reducing
exposures, so the requirement to
implement all feasible engineering and
administrative controls before PPE
could be utilized as a means of
compliance was promulgated in the
2005 final rule and is applicable to this
final rule. We also note that, in
accordance with our DPM sampling
procedures, a miner’s exposure to DPM
is determined through full-shift
personal sampling. This sampling
procedure integrates or averages a
miner’s exposure throughout the shift so
that an occasional exposure to a high
concentration to DPM will not cause the
full shift sample to exceed the DPM
limit if the majority of the miner’s
exposure is sufficiently below the limit.
Given adherence to this sampling
procedure, it is highly unlikely that any
of the, ‘‘15 employees exposed to the
polluted air when they venture outside
of the cab,’’ would be overexposed to
DPM on a full-shift basis if their
excursions outside their cabs were brief,
and their cabs were properly maintained
and provided with filtered breathing air.
The operator of the two large stone
mines included cost estimates for a new
ventilation shaft and fan for one of its
mines. They indicated the cost of a 16foot diameter shaft at $1,000 per vertical
foot and 800 to 1,200 feet deep would
be $800,000 to $1.2 million, and that
when fan costs are added, the total cost
approaches $1.5 million. We note that
the upper end of the range of the
commenter’s estimated cost for a new
shaft and fan of $1,500,000, would not
necessarily be considered economically
infeasible for a stone mine of this size.
The cost of this shaft and fan, when
amortized over 20 years at a discount
rate of 7%, results in an annualized
yearly cost to the operator of $142,000.
The estimated total yearly compliance
cost for a medium sized stone mine was
determined in the Regulatory Economic
Analysis (REA) for the 2001 final rule to
be $150,738 based on an inventory size
of 17 pieces of diesel equipment. In
2002, this mine operator reported a total
diesel equipment inventory of 60 pieces
of diesel equipment at the subject mine.
Applying a ratio multiplier of 3.5 (60/
17) to the estimated $150,738
compliance cost from the 2001 REA
results in an estimated yearly
compliance cost for the mine of
$527,583. Thus, if a new ventilation
shaft and fan are installed to attain
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compliance at the subject mine, the
annualized yearly cost of $142,000 for
this major ventilation upgrade, though
significant, is less than 30% of the
expected total yearly compliance cost
for a stone mine of this size.
Not all commenters disagreed with
the economic feasibility of the rule. One
commenter said,
In January 2001, MSHA estimated that
compliance with the rule would cost
approximately $25.1 million on an annual
basis (66 FR 5889). MSHA estimated that
73% of those costs would be expended to
comply with the interim level and 27%, or
just $6.6 million annually, to comply with
the final limit. MSHA found these costs to be
economically feasible. They represent less
than one percent of industry revenues.
Nothing in the record suggests that these
compliance costs have increased. If anything,
advances in technology and the availability
of substitute fuels mean the likely costs of
compliance have decreased since the 2001
estimates were completed.
Another commenter said,
A standard is not infeasible simply because
it is financially burdensome, or even because
it threatens the survival of some companies
within an industry. MSHA estimated that the
annual cost of the final rule was $25.1
million or $128,000 annually for an average
underground metal and nonmetal mine. (70
FR 53282) The NPRM does not contain any
data suggesting that these minimal costs
would be significantly greater than originally
estimated, let alone that costs would be so
high to threaten the economic viability of the
industry.
The DPM rulemaking record contains
considerable comments supporting the
need for more time to effectuate controls
that are economically feasible for mine
operators. In the cost estimates for this
final rule, we have included cost related
to operator evaluation of different
technologies in an effort to determine
the most effective method for
compliance.
A number of comments were received
on the cost of medical evaluations.
Under the final rule, a miner is required
to wear respiratory protection if the
miner is overexposed to DPM and all
feasible engineering and administrative
controls are installed. Prior to being fit
tested or assigned to a task where
respiratory protection is required, the
miner must be evaluated by a physician
or other licensed healthcare professional
to determine whether the miner is
medically capable of wearing a
respirator in the mine. As shown in
Table IX.1 later in this preamble, the
estimated yearly cost to the
underground M/NM mining industry of
this medical evaluation requirement is
about $20,000. Comments on medical
evaluation included:
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• Prior to any miner being placed into a
respirator, steps are taken to ensure that the
miners are medically fit for wearing a
negative pressure respirator. A formal
medical evaluation is conducted prior to
being fit tested and annually thereafter. To
date, approximately 65 miners needed
additional evaluation to receive clearance to
wear a negative pressure respirator. The
average cost for the additional medical
evaluation was $250/visit. Estimated annual
cost for medical clearance has been $16,000.
• MSHA seeks comments on whether the
final rule should include a provision
requiring a medical evaluation to determine
a miner’s ability to use a respirator before the
miner is fit tested or required to work in an
area of the mine where respiratory protection
must be used. Barrick already complies with
this proposed requirement. Each of our
employees undergoes a medical evaluation
before being fitted with a respirator * * *
Based on currently available data, we
estimate that the average cost per person for
medical evaluations for our Goldstrike
operations is $660.
• Greens Creek also conducts its own
pulmonary function tests on individuals
required to wear respirators under our
respiratory protection program. That program
includes proper fit testing. We have on-site
technicians who are certified to conduct
these tests, however, the analysis of the
pulmonary function tests is provided by a
licensed healthcare provider. The tests cost
roughly $17.00 per individual.
• At our mines, we provide a medical
exam and certification of the ability to wear
a respirator upon hire * * * If the miner’s
health conditions change preventing the safe
use of a respirator, then additional tests can
be provided including spirometry and if
indicated, a medical examination. We have
not had a case where a miner’s health
changed preventing the wearing of a
respirator, that the miner was not aware of
the health condition. We do not object to
annual spirometry testing following
guidelines developed and supervised by a
medical doctor or other medical professional.
We do object to the added expense of
requiring a medical exam every year if there
are no indicators of a medical necessity,
either by the miner’s own request or the
conditions mentioned.
Mine operators that provided
comments on the cost of medical
evaluations for respirator users already
routinely conduct such evaluations.
Based on the significant disparity in
quoted costs from $17 to $660 per
miner, it appears that some operators’
evaluations are quite basic, consisting of
a simple pulmonary function test and
possibly the completion of an employee
questionnaire, whereas other operators
are apparently conducting actual
medical examinations. No commenters
provided information suggesting that
the requirement for medical evaluations
would be economically infeasible.
Although we require a medical
evaluation to determine a miner’s ability
to wear a respirator before using a
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respirator, we only require a reevaluation when the mine operator has
reason to believe that conditions have
changed which could adversely affect
the miner’s ability to wear a respirator.
We also will accept prior medical
evaluations to the extent the mine
operator has a written record and there
have not been any changes that will
adversely affect the miner’s ability to
wear a respirator. We believe that this
approach will minimize the economic
burden on the mine operator in
conducting medical evaluations while
still protecting the miner.
VI. Summary of Benefits
In Chapter III of the Regulatory
Economic Analysis in support of the
2001 final rule (2001 REA), we
demonstrated that the DPM final rule for
M/NM mines will reduce a significant
health risk to underground miners. This
risk included the potential for illnesses
and premature death, as well as the
attendant costs to the miners’ families,
the mine operators and society at large.
We have incorporated into this
rulemaking record the previous DPM
rulemaking records, including the risk
assessment to the 2001 final rule.
Benefits of the 2001 final rule include
continued reductions in lung cancers. In
the long run, as the mining population
turns over, we estimated that a
minimum of 8.5 lung cancer deaths will
be avoided per year. We noted that this
estimate was a lower bound figure that
could significantly underestimate the
magnitude of the health benefits. For
example, the mean value of all eight
quantitative estimates examined in the
2001 final rule was 49 lung cancer
deaths avoided per year.
Other benefits noted in the 2001 REA
were reductions in the risk of premature
death from cardiovascular,
cardiopulmonary, or respiratory causes
and reductions in the risk of sensory
irritation and respiratory symptoms.
However, we did not include these
health benefits in our estimates because
we could not make reliable or precise
quantitative estimates of them.
Nevertheless, we noted that the
expected reductions in the risk of death
from cardiovascular, cardiopulmonary,
or respiratory causes and the expected
reductions in the risk of sensory
irritation and respiratory symptoms are
likely to be substantial.
The 2001 risk assessment used the
best available data on DPM exposures at
underground M/NM mines to quantify
excess lung cancer risk. ‘‘Excess risk’’
refers to the lifetime probability of dying
from lung cancer during or after a 45year occupational DPM exposure. This
probability is expressed as the expected
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excess number of lung cancer deaths per
thousand miners occupationally
exposed to DPM at a specified mean
DPM concentration. The excess is
calculated relative to baseline, agespecific lung cancer mortality rates
taken from standard mortality tables. In
order to properly estimate this excess, it
is necessary to calculate, at each year of
life after occupational exposure begins,
the expected number of persons
surviving to that age with and without
DPM exposure at the specified level. At
each age, standard actuarial adjustments
must be made in the number of
survivors to account for the risk of dying
from causes other than lung cancer.
Occupational exposure is assumed to
begin at age 20 and to continue, for
surviving miners, until retirement at age
65. The accumulation of lifetime excess
risk continues after retirement through
the age of 85 years.
Table IV–9 in Section IV of this
Preamble, taken from the 2001 risk
assessment, shows a range of excess
lung cancer estimates at mean exposures
equal to the final DPM limit. The eight
exposure-response models employed
¨
were based on studies by Saverin et al.
(1999), Johnston et al. (1997), and
Steenland et al. (1998). All of the
exposure-response models shown are
monotonic (i.e., increased exposure
yields increased excess risk, though not
proportionately so). Thus, despite
evidence from recent sampling of
substantial improvements attained since
the 1989–1999 sampling period
addressed by the 2001 risk assessment,
underground M/NM miners are still
faced with an unacceptable risk of lung
cancer due to their occupational DPM
exposures.
Another principal conclusion of the
2001 risk assessment was:
By reducing DPM concentrations in
underground mines, the rule will
substantially reduce the risks of material
impairment faced by underground miners
exposed to DPM at current levels.
DPM levels have declined since
MSHA’s first sampling period (from
1989 to 1999). MSHA expects that
further improvements will continue to
significantly reduce the health risks
identified for miners. There is clear
evidence of DPM’s adverse health
effects, not only at pre-2001 levels but
also at the generally lower levels
currently observed at many
underground mines. These effects are
material health impairments as
specified under section 101(a)(6)(A) of
the Mine Act. During the time period
from November 1, 2003 to January 31,
2006, 1798 valid personal compliance
samples from all mines covered by the
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2001 rule were collected. From these
samples collected, 18% (324) of samples
exceeded 308EC µg/m3, 22% (396)
exceeded 350TC µg/m3, and 64% (1151)
exceeded 160TC µg/m3. Because the
exposure-response relationships shown
are monotonic, MSHA expects that
industry-wide implementation of the
final limit of 160TC µg/m3 will
significantly reduce the risk of lung
cancer and other adverse health effects
among miners.
This final rule would amend the 2001
final DPM rule by phasing in the final
limit over a two-year period to address
feasibility constraints that have arisen.
By phasing in the final limit to address
the feasibility issues, this final rule
would contribute to the realization of
the benefits mentioned above. In
addition, the medical evaluation and
transfer provisions of this final rule
would provide further benefits by
ensuring that miners who are required
to wear a respirator are able to do so
safely, thereby obtaining the full health
protection available from that
equipment.
VII. Section 101(a)(9) of the Mine Act
Section 101(a)(9) of the Mine Act
provides that: ‘‘No mandatory health or
safety standard promulgated under this
title shall reduce the protection afforded
miners by an existing mandatory health
or safety standard.’’ We interpret this
provision of the Mine Act to require that
all of the health or safety benefits
resulting from a new standard be at least
equivalent to all of the health or safety
benefits resulting from the existing
standard when the two sets of benefits
are evaluated as a whole. The U.S. Court
of Appeals for the D.C. Circuit approved
such a ‘‘net effects’’ application of
Section 101(a)(9). Int’l Union, UMWA v.
Federal Mine Safety and Health Admin.,
407 F. 3d 1250, 1256–57 (D.C. Cir.
2005).
We conclude that this final rule will
not reduce protection afforded miners
under the 2001 final rule. The phase-in
period of the 2001 final limit of 160TC
µg/m3 is not feasible for the mining
industry as a whole in May 2006, but we
could not justify a greater reduction in
the final limit than 350TC µg/m3 before
May 2008. Feasibility issues with
respect to operator compliance are
discussed above. Moreover, we intend
to convert the final limits of 350TC µg/
m3 and 160TC µg/m3 in a separate
rulemaking by January 2007. As we said
in the 2005 NPRM, if we do not
complete this rulemaking by that time,
we will use the EC equivalent as a check
to validate that an overexposure to the
350TC µg/m3 final limit is not the result
of interferences. This enforcement
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policy, which is based on the Second
Partial Settlement Agreement and data
in the rulemaking record, would be the
same that we used to implement the
400TC µg/m3 interim limit before we
converted it to 308EC µg/m3 in the June
2005 final rule. Whereas we have
evidence that we can obtain an accurate
sample analysis of the final limit of
350TC µg/m3, there is no evidence in
the rulemaking record suggesting that
the 1.3 conversion factor is appropriate
for substantially lower limits, such as
the final limit of 160TC µg/m3. In the
2005 NPRM, we stated that we have an
additional concern with whether an
effective sampling strategy exists to
enforce the final limit of 160TC µg/m3
with TC as the surrogate. Evidence after
January 2001 suggests that without an
appropriate conversion factor, which we
do not have presently, there is no
practical sampling strategy that would
adequately remove organic carbon
interferences that occur when TC is
used as the surrogate without the ability
to confirm the sample results with an
EC analysis. Thus, we acknowledge that
it is questionable whether the final limit
with a TC surrogate of 160TC µg/m3
would provide more protection for
miners than the final limits of 350TC µg/
m3 when we use the 1.3 conversion
factor to confirm an overexposure. We
have the burden of proof in court to
demonstrate that an overexposure to
DPM actually occurred and the sample
result is not due to interferences. If we
were to enforce the final DPM limit of
160TC µg/m3, we would need to validate
a TC sample result, which cannot be
done without an appropriate conversion
factor for EC at that level. Discussion of
the complexity of developing an
appropriate conversion factor for the
final limit is discussed in Variability of
the Relationship Between EC and TC.
We requested comments in the 2005
NPRM on whether a five-year phase-in
period for lowering the final limit to
160TC µg/m3 complies with Section
101(a)(9) of the Mine Act. A number of
commenters objected to our 2005 NPRM
that would have delayed
implementation of the final limit of
160TC µg/m3 until 2011. They stated
that the 2005 NPRM would weaken
protection provided by the 2001 final
rule, a consequence that Section
101(a)(9) prohibits, since the lower level
can be met in some jobs in underground
metal and nonmetal mines, if not in all
jobs. They believe that the 2005 NPRM
violates the law since we would be
raising the final limit above 160TC µg/m3
and extending the timeframe for its
applicability. In response, we
emphasize that we determined that it is
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presently infeasible for the mining
industry to comply with 160TC µg/m3,
and we have no data to confirm in court
that a 160 TC sample is not the result
of interferences.
Regarding feasibility, we chose May
2008 for the effective date of the final
limit to correspond with when we
believe mine operators, especially small
mine operators, will be able to find
effective approaches to utilizing
available DPM control technology so
that they will be capable of meeting the
standard. Over the five years since the
2001 final rule was promulgated, both
MSHA and the mining industry have
gained considerable experience with the
implementation, use, and cost of DPM
control technology. We have reviewed
this experience, and our own
enforcement data, and conclude in the
final rule that effective DPM controls
will be feasible and commercially
available to mine operators by 2008.
Other commenters stated that the
proposed five year phase-in period, a
longer phase-in period, or a decision to
adopt the current interim limit of 308EC
µg/m3 as a final standard would all
comply with Section 101(a)(9) of the
Mine Act, and that we should take no
action to require reductions below the
current interim standard. These
commenters also noted that our inability
to enforce a final limit of 160TC µg/m3
is critical because Section 101(a)(9) is
predicated on the assumption that the
existing standards are enforceable, and
therefore, ensure the health of miners.
They do not believe that the final limit
of 160TC µg/m3 would provide any more
protection than the 308EC µg/m3, and
that many mines will not be able to
comply with the 160TC µg/m3 due to
economic and technological feasibility
issues. These commenters further stated
that most miners at these sites will be
required to wear respirators for
extended periods of time.
We disagree with these commenters.
As discussed above under Section V.A.
Technological Feasibility, and Section
V.B., Economic Feasibility, we are
confident that feasible technology exists
to reduce miners’ exposures to DPM to
the final limit by May 2008. Although
most mines can feasibly comply with
the existing DPM final limit of 308EC µg/
m3 we expect that some miners will
continue to have to wear respiratory
protection under the final limit of 160TC
µg/m3. By phasing in the 160TC µg/m3
final limit over two years, we believe
that many existing compliance
difficulties can be successfully resolved
as mine operators are able to access
alternative fuels and become more adept
and familiar with DPFs.
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Similarly, some commenters stated
that the proposed standard is based on
the wrong exposure matrix, is infeasible,
and should be withdrawn. They believe
that implementation of the 160TC µg/m3
final limit would result in widespread
experimentation with unproven and
untested control technology that
presents new and potentially significant
risks to miners. In these commenters’
views, such a result would violate the
Mine Act and should not be permitted.
We responded to these control
technology issues in our feasibility
discussion of this preamble at Section
V. It is important to note, nevertheless,
that we stated in the 2005 NPRM that
implementation issues may adversely
affect the feasibility of using DPFs to
reduce exposures despite the results
reported in NIOSH’s Phase I Isozone
Study. Under the prescribed timeframes
of the final rule, mine operators should
be able to resolve their unique
implementation issues with DPFs.
Moreover, proper selection of available
filters will resolve the problem with
risks to miners from increased levels of
nitrogen dioxide. As we stated
previously, we are confident that the
current rulemaking record includes
sufficient scientific data to retain the
final limit of 160TC µg/m3.
More importantly, we have no
evidence to substantiate deleting the
final limit, especially when miners’
exposures are expected to further
decline over time, based on our
enforcement sampling results. The 2001
risk assessment and its updates confirm
the serious health risks to miners from
exposure to DPM, and we intend for the
mining industry to continue to reduce
miners’ exposures to the final limit of
160TC µg/m3 by May 2008.
Additionally, although some mines may
experience implementation difficulties
in meeting the DPM limits, the final rule
allows for instances where mine
operators may request special
extensions of time in which to comply
with the final limits in situations where
controls may be technologically or
economically infeasible. Finally, our
longstanding enforcement policy
considers an individual mine operator’s
ability to feasibly comply with the
applicable limit. If we determine that
the mine operator has installed all
feasible controls and has placed affected
miners in an appropriate respiratory
protection program, we will not issue a
citation for an overexposure.
Another commenter stated that due to
the scientific uncertainty that DPM
poses, we should wait for the outcome
of the NIOSH/NCI study to help identify
the appropriate exposure limit. The
commenter also stated that we are
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violating the requirements of Section
101(a)(6)(A) by proceeding with the
rulemaking. We disagree. We have
discussed our data to support our
position to proceed with requiring the
mining industry to continue to take the
initiative to further reduce miners’
exposures to DPM. Throughout this
rulemaking, we expressed our intent to
phase in the final limit of 160TC µg/m3
over time rather than in 2006. With
regard to the collaborative study
between NIOSH/NCI, if the study
becomes available, we will assess it to
determine if it provides additional
information about the relationship
between DPM exposure levels and
disease outcomes. NIOSH, in its recent
comments to our 2005 final rule, stated
that, ‘‘In summary, new peer-reviewed
publications addressing the health
effects of exposure to diesel exhaust
continue to support MSHA’s 2001 risk
analysis and its 2005 updated
information on health effects.’’
Considering the foregoing, we do not
believe that it is in the best interest of
miners’ health to delay beyond the
implementation dates of the final rule.
A number of other commenters
believe that the five year phase-in
period would have complied with
101(a)(9) of the Mine Act unless this
rulemaking is not completed before May
20, 2006, the existing effective date of
the 160TC µg/m3 final limit. They stated
that the Mine Act provision applies only
upon the effective date of a requirement
rather than the promulgation date of the
standard. Consequently, they advise that
if the Secretary were to allow the 160TC
µg/m3 final limit to take effect on May
20, 2006 then the Mine Act would
prohibit any subsequent reduction or
phase-in period. We do not agree with
these commenters’ interpretation of the
Mine Act. We refer the commenters to
our explanation in this section as to
why we must phase in the final limit of
160TC µg/m3, and why we do not believe
that we have violated our mandate
under Section 101(a)(9) not to reduce
protection afforded by an existing
standard.
VIII. Section-by-Section Analysis
A. PEL § 57.5060(b)
Section 57.5060(b) in the 2001 final
rule established a final concentration
limit of 160TC µg/m3 which was
scheduled to become effective on
January 20, 2006. The final limit
restricts total carbon (TC)
concentrations in underground mines in
areas where miners normally work or
travel. Total carbon is the sum of
elemental and organic carbon. In the
2001 final rule, we chose TC as the
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surrogate for measuring DPM
concentrations. In our 2005 final rule,
we changed the surrogate for the interim
concentration limit measured by TC to
a comparable permissible exposure limit
(PEL) measured by elemental carbon
(EC), which renders a more accurate
DPM exposure measurement. We also
committed to revising the 2001 final
concentration limit of 160TC µg/m3 in
future rulemaking. Currently, the 160TC
µg/m3 final limit is to become applicable
on May 20, 2006.
In our 2005 NPRM, we recommended
staggering the effective dates for
implementing the final limit, to be
phased-in over a five-year period, and
decreased approximately 50 micrograms
each year until the final limit of 160TC
µg/m3 would be reached in January
2011. This proposal was based on our
position that the industry was
encountering economic and
technological implementation issues
that could affect feasibility, while
seeking to further reduce miners’
exposures (70 FR 53283). These
implementation issues surfaced
following promulgation of the 2001 final
rule. We stated in the 2005 NPRM that
the mining industry, as a whole, may
need additional time to address these
implementation issues and find
effective solutions for implementing
additional DPM controls (70 FR 53284).
We also proposed changing the final
concentration limit to final permissible
exposure limits (PELs), and we noted
that special extensions of time in which
to comply with the final PELs under
existing § 57.5060(c) would apply to
each of the phased-in final limits,
including the initial final limit of 308EC
µg/m3. We explained that mine
operators could apply to the District
Manager if they were seeking additional
time to come into compliance with each
of the final limits, due to technological
or economic constraints. We requested
comments on the impact of granting
extensions for compliance with
exposure limits that are greater than the
160TC µg/m3 final limit.
In the 2005 NPRM, we also asked the
mining community to provide us their
views on whether five years is the
correct timeframe for reducing miners’
exposures to 160TC µg/m3. Additionally,
we requested information on whether
the proposed annual 50 microgram
reductions of the final DPM limit are
appropriate or, in the alternative, should
the final rule include an approach such
as one or two reductions. We asked
whether our reduction scheme for the
final limit of 50 micrograms of TC each
succeeding year, from 400TC µg/m3
(converted to a comparable limit of
308EC µg/m3) is feasible, and whether
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it will provide additional time for the
implementation of controls,
development of distribution centers for
alternative fuels, and consideration of
the economic impact of the proposed
phased-in approach (70 FR 53288).
Finally, we emphasized our need for
information and views on the mining
industry’s current experiences with
feasibility of compliance with a lower
limit than the interim PEL of 308EC µg/
m3. In addition to our requests for
comments, we notified the mining
community that we were committed to
initiating a separate rulemaking to
determine the correct TC to EC
conversion factor for the phased-in final
limits. As discussed later in the
subsection ‘‘Variability of the
Relationship Between EC and TC’’, we
will address those comments in our
future rulemaking. We further stated in
the 2005 NPRM that in the event that we
did not complete this subsequent
rulemaking to establish a conversion
factor before January 20, 2007, the date
of the first proposed reduction of the
final limit, we were considering using
the current 1.3 conversion factor that we
use to establish the interim DPM PEL of
308EC µg/m3 to convert the phased-in
final DPM TC limits to EC equivalents.
As we did with the interim TC limit
pursuant to the Second Partial
Settlement Agreement, we would use
the EC equivalents as a check to validate
that an overexposure is not the result of
interferences until this issue is
addressed in future rulemaking.
In development of this final rule, we
also considered public comments
related to the final limit which we
received in response to the 2002
ANPRM to revise the DPM limits. Some
commenters to the ANPRM
recommended that we propose separate
rulemakings for revising the interim and
final DPM limits to give us an
opportunity to gather further
information to establish a final DPM
limit. In the 2003 NPRM, we agreed
with these commenters and solicited
other information from the mining
community that would lead to an
appropriate final DPM standard.
Moreover, we announced our intention
to publish a separate rulemaking to
amend the existing final concentration
limit in § 57.5060(b).
To assist us in achieving this
objective, we requested comments on an
appropriate final limit to replace the
160TC µg/m3 concentration limit, and
asked for information on an appropriate
surrogate for measuring miners’ DPM
exposures. We concluded our request
for information by clarifying that
revisions to the final DPM concentration
limit would be included in a separate
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rulemaking. The public comments in
response to our requests are reflected
below in this section.
Based on feasibility with respect to
compliance and an effective strategy for
implementing the final limits, we
believe the mining industry as a whole
can reduce DPM levels to the 2001 final
limit of 160TC µg/m3 by May 20, 2008.
We have determined that M/NM
underground mines using diesel
powered equipment are capable of
reducing miners’ exposures to 160TC µg/
m3 by May 20, 2008, rather than on
January 20, 2011. As proposed, the
initial final limit will be the same as the
current interim limit of 308EC µg/m3 and
will remain in effect through January 19,
2007. On January 20, 2007, the final
limit will be reduced, as we proposed,
to 350TC µg/m3, which represents a 50
microgram reduction. This limit, and
the 160TC µg/m3 final limit, will be TC
limits rather than EC limits, since we do
not have current data establishing a
conversion factor from TC to EC. We
discuss the complexity of developing a
conversion factor later in this section
under ‘‘Variability of the Relationship
Between EC and TC.’’
As we did with the 400TC µg/m3
interim limit pursuant to the Second
Partial Settlement Agreement, we will
use the EC equivalent as a check to
validate that an overexposure to the 350
TC limit is not the result of interferences
(67 FR 47296, 47298). We will
implement an enforcement policy for
the 350TC µg/m3 final limit that will use
EC as an analyte to ensure that a citation
based on the 350TC µg/m3 limit is valid
and not the result of interferences.
Under our policy, we will first develop
an appropriate error factor to account
for variability in sampling and analysis
from such things as pump flow rate,
filters, and the NIOSH Analytical
Method 5040. If the TC measurement is
below 350TC µg/m3 plus the error factor,
we will not issue a citation for an
overexposure. If the TC measurement is
above 350TC µg/m3 times the error
factor, we would look at the EC
measurement from the sample obtained
through the NIOSH Analytical Method
5040, and multiply EC by a factor of 1.3
to produce a statistical valid estimate of
what the TC result is without
interferences. If the TC measurement is
above this estimate, we would not issue
a citation when the EC measurement
times the multiplier is below the TC
analysis.
The 1.3 multiplier that we will use to
estimate TC (i.e., EC × 1.3 = estimated
TC) is derived from NIOSH’s
determination that TC is 60–80% EC.
We will announce our enforcement
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policy in our updated DPM Compliance
Guide.
As we stated in the 2005 proposed
rule, we will continue to cite a violation
of the DPM limit only when we have
solid evidence that a violation actually
occurred. Accordingly, we will apply
the existing error factor to the first
phased-in final limit of 308EC µg/m3 to
determine that an overexposure to the
final limit has occurred. The error
factors for the first step-down limit of
350TC µg/m3 and second step-down
limit of 160TC µg/m3 will be slightly
different.
We will continue to base our
compliance determinations on a single,
personal sample, taken over the miner’s
full shift as specified in existing
§ 57.5061, Compliance determinations.
Also, under existing § 57.5060(d), we
will continue to require mine operators
to install all feasible engineering and
administrative controls to reduce
miners’ exposures to DPM. When such
controls do not reduce a miner’s
exposure to the DPM limit, controls are
infeasible, or controls do not produce
significant reductions (as defined in the
2005 rule (70 FR 32868, 32916) in DPM
exposures, operators must continue to
use all feasible engineering and
administrative controls and supplement
them with respiratory protection. When
respiratory protection is required under
the final standard, mine operators must
establish a respiratory protection
program that meets the specified
requirements. See the discussion of
respirator use in Section VIII.C. Medical
Evaluation and Transfer.
We have determined that these new
final limits are both technologically and
economically feasible for the M/NM
mining industry to achieve as
scheduled. Feasibility data, however, do
not support delaying the applicability of
the 160TC µg/m3 final limit until 2011,
nor do they support application of the
160TC µg/m3 final limit as early as May
2006. Regarding feasibility, we chose
May 2008 for the effective date of the
final limit to correspond with when we
believe mine operators, especially small
mine operators, will be able to find
effective approaches to utilizing
available DPM control technology so
that they will be capable of meeting the
standard. Over the five years since the
2001 final rule was promulgated, both
MSHA and the mining industry have
gained considerable experience with the
implementation, use, and cost of DPM
control technology. We have reviewed
this experience, and our own
enforcement data, and conclude in the
final rule that effective DPM controls
will be feasible and commercially
available to mine operators by 2008. We
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continue to acknowledge that our 2001
feasibility projections for the ability of
the M/NM mining industry to comply
with the final limit of 160TC µg/m3 by
January 2006 were incorrect.
In the 2005 proposed rule, we
continued to project that many mine
operators would have to use DPFs to
reduce DPM levels to the final
concentration limit. We believe that
DPFs can be a very effective engineering
control throughout the mining industry
for reducing miners’ exposures to DPM,
provided mine operators address their
implementation issues. These
implementation issues include such
decisions as DPF media selection,
sizing, regeneration scheme, and
installation.
The rulemaking record includes
updated data and promising information
from the Biodiesel industry on the
progress of increasing mine operators’
access to this fuel. Accessing biodiesel
fuels has been a feasibility issue for M/
NM mine operators primarily due to the
lack of sufficient distribution centers.
The growing trend on demand and
supply of alternative fuels; availability
of special extensions; enforcement of
our hierarchy of controls strategy;
additional time for the mining industry
to continue to resolve their existing
maintenance and other implementation
issues with control technology;
ventilation upgrades; continued
introduction of cleaner engines; and
current enforcement data support both
the economic and technological
feasibility of the final limits as
prescribed in this final rule. Although
the risk assessment indicates that a
lower DPM limit, lower than 160TC µg/
m3, would enhance miner protection, it
is infeasible for the underground M/NM
mining industry to reach a lower final
limit.
We acknowledge in the Technological
Feasibility discussion in Section V of
this preamble that our projections for
availability of alternative fuels were
underestimated in the 2005 proposal.
We also considered our updated
enforcement data from November 2003
to January 2006 which show that 82%
of the 1,798 samples we collected were
below the initial final limit of 308EC µg/
m3, 78% were below the January 2007
final limit of 350TC µg/m3, and 46%
were below the May 2008 final limit of
160TC µg/m3. We remain committed to
assuring that mine operators continue
the significant progress they have
already demonstrated in reducing
miners’ exposures to DPM.
We received a number of comments
from the mining community on our
proposed revisions to the final limits.
Establishing a standard that focuses
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control efforts on diminishing the DPM
level in air breathed by a miner is
supported by some commenters in
labor. These commenters stated, ‘‘We
agree that personal sampling gives a
better representation of real exposure,
and we support the change in the final
rule.’’ A number of industry
commenters stated that we should
rescind the 160TC µg/m3 final limit,
since they believe that it is unjustifiable
and infeasible, and urged us to adopt as
the final limit the current interim
exposure limit of 308EC µg/m3 currently
in place. We disagree, primarily because
the 2001 risk assessment concludes that
exposure to DPM could result in a
material impairment of miners’ health
and functional capacity, including lung
cancer, and that our analysis has
concluded that controls significantly
reducing DPM exposure are both
technologically and economically
feasible. Moreover, in the 2005 NPRM,
when we decided that we should
consider phasing in the final limit of
160TC µg/m3, we acknowledged
complications with feasibility and
stated the following:
We believe that wider use of alternative
fuels and filter technology can make the
160TC µg/m3 final limit feasible if a
staggered phase-in approach is adopted. By
lowering the exposure limit in intervals over
five years beginning in January 2007, market
forces should have sufficient time and
incentive to adjust to the new standard.
Specifically, a reliable alternative fuel
distribution system should induce mine
operators to adopt this relatively low-cost
method to achieve compliance. The
development and distribution of alternative
fuels is also encouraged by existing tax
credits. We believe that regional distribution
networks are beginning to emerge. We seek
data on alternative fuel distribution systems
(70 FR 53283–84).
We received comments on the
availability of distribution systems and
other means of DPM exposure controls
and have discussed them in detail in
Section V of this preamble. Our
sampling data, compliance experience,
and comments in the rulemaking record
lead us to conclude that reductions
below the 308EC µg/m3 limit are
achievable by the phase-in dates
specified.
Another industry commenter
suggested that the proposed five-year
phase-in of the final limit would drive
technology development but would not
allow sufficient time for further research
and development, and in-field testing.
This commenter did state, however, that
a two-phase approach would allow
mine operators to implement changes in
mining techniques and strategies and
would provide for continued protection
of miners. Some other commenters state
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that if we pursue our proposed course,
or worse, allow the 160TC µg/m3 limit to
take effect immediately, it would result
in an infeasible rule with which the
underground M/NM mining industry
could not comply. They believe that this
could potentially subject mines to
closure orders, and require miners to
wear respirators to protect against what
many regard as undemonstrated adverse
health effects. These commenters also
urge that we retain the interim limit of
308EC µg/m3, limit pending results of
NIOSH/NCI study.
Another mine operator noted that the
proposed phase-in of the final limit is
an improvement, but agreed with some
other commenters that we need to stay
the interim and final limits and wait for
completion of the NIOSH/NCI Study.
We have sufficient evidence in the DPM
rulemaking record which supports the
need for us to lower miners’ current
exposures to DPM beginning in January
2007. We will, however, continue to
closely monitor the progress of the
NIOSH/NCI joint study, and when the
results of this study become available,
we will carefully consider them.
As discussed at length in Section V.
addressing feasibility of the final rule,
we now have more definitive
information on availability of alternative
fuels and the implementation issues that
mine operators face to warrant the time
frames under this final rule. We,
therefore, cannot justify further delays
of implementing the applicability of the
160TC µg/m3 beyond May 2008.
We also considered that the mining
industry has had since January 2001 to
work through many of their
implementation issues. By now mine
operators have implemented more
effective controls to meet the interim
limit. These controls can be used to
assist in reducing miners’ exposures
even further, ultimately resulting in
successful achievement of the final
limits. We acknowledge that the mining
industry as a whole still needs more
time to meet the 160TC µg/m3 final limit
and believe May 2008 will give them an
appropriate amount of time for
implementing additional controls
needed to comply with the final limit.
Most industry commenters, however,
emphasized that compliance with the
interim limit of 308EC µg/m3 still poses
feasibility issues for the mining industry
as a whole. Some other industry
commenters added that the proposed
reductions are infeasible for 90% of the
industry.
We disagree with these commenters.
Our data in the 2005 final rule
demonstrate that compliance with the
interim limit is both technologically and
economically feasible (70 FR 32915,
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32939). Moreover, our updated
compliance sampling results
demonstrate that most mines are
presently capable of meeting the interim
limit of 308EC µg/m3. Like in the 2005
final rule, compliance with this final
rule also relies on our traditional
hierarchy of controls enforcement
strategy (70 FR 32915–16) discussed
above. Thus, this regulatory scheme
adequately accomplishes control of
exposure under circumstances where an
individual mine operator cannot reduce
a miner’s exposure to the final limit
solely by use of engineering and
administrative controls, including work
practices.
One commenter took the position that
we should retain the current interim
limit of 308EC µg/m3 based on EPA’s
timeframe for industry to develop
cleaner burning engines for diesel
engines regulated by EPA. The
commenter stated that the Tier 4
engines mandated by EPA are to be
available in the very near future and are
designed to reduce the DPM levels by at
least 90%. Tier 4 engines that are greater
than 130 hp are to be available in 2011;
engines from 56 to 130 hp will be
available in 2012; and 19 to 56 hp will
be available in 2013. This includes the
availability of very low sulfur fuel as
well. According to the commenter, this
Tier 4 technology deals with the source
of DPM exposures; however, they
believe that the final DPM limit should
not be reduced until these engines are
available and tested in the underground
mine environment. They also remark
that if MSHA believes that the
technology will eventually catch up to
its DPM final limit, then the phase-in
schedule should coincide with the EPA
mandated schedule for clean engines. In
response, the EPA specifically exempts
underground mining diesel powered
equipment, as we addressed in the 2001
final rule (Control of Emissions of Air
Pollution From Nonroad Diesel Engines,
40 CFR Parts 9, 86, and 89 (1998)).
However, § 57.5067, Engines, allows the
mine operator to introduce EPA
certified diesel engines into mines using
either an on-highway vehicle that is a
1994 model year or newer, a Tier 1
nonroad diesel engine, or a Tier 2
nonroad engine dependent on the
horsepower. Also in the 2001 final rule,
we documented through our risk
assessment the need for us to proceed
presently to reduce miners’ exposures.
The final rule requires the mining
industry to continue to make progress in
further reducing DPM levels in
underground M/NM mines.
The EPA standards referred to by the
commenter only include newly
manufactured diesel engines based on
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EPA’s implementation dates with no
requirements on engine retrofits. As
discussed in the Technological
Feasibility section of this preamble, the
EPA’s emission regulations will
significantly reduce DPM through the
use of DPFs installed on newly
manufactured engines. We agree that
this technology will benefit the mining
industry by offering mine operators the
opportunity to purchase this technology
in the form of new and used machines
over time. However, we do not believe
that it would be cost effective for the
mining industry to purchase all new
equipment when the EPA engines
become available in order to get the
DPM controls that will be mandated by
the EPA as suggested by the commenter.
We do believe however, that the EPA
standards will make it easier for mine
operators over time to purchase diesel
engines and machines which are
equipped with DPFs which should
decrease the need to retrofit DPFs. The
MSHA DPM final rule provides mine
operators with an opportunity to
purchase some on-highway vehicles
which will include DPFs but will not be
available until January 2007. As
discussed in Section V of this preamble,
this will initially include automotive
pickup trucks and other utility trucks.
In addition, EPA is mandating the use
of ultra low sulfur diesel fuel, less than
15 ppm, for on-highway vehicles
starting in mid 2006. This fuel will not
be required by MSHA; however this
may be the only economical diesel fuel
to purchase over the coming years based
on availability. Eventually by 2010, 15
ppm sulfur fuel will be required for all
nonroad diesel powered vehicles and
due to the EPA requirements, we
anticipate that 15 ppm sulfur fuel will
be the only available diesel fuel to
purchase. Even though 15 ppm sulfur
fuel does directly reduce DPM or EC, it
will be needed for compatibility with
specialized catalyst formulations used
by engine manufacturers for DPM and
nitrous oxide reductions.
A number of industry commenters
noted that experience of both MSHA
and the industry under the DPM rules
demonstrate an evolving learning
process regarding controlling diesel
exhaust. It is in this context that these
commenters stated that they support the
proposed staggered effective date
schedule for implementation of the final
limit, provided that we address their
other concerns related to the final limit.
They believe that it would be more
appropriate to promulgate a two-step
phased-in approach for the final limit
ending on January 20, 2011, rather than
an annual, 50 microgram reduction of
the final limit. These commenters
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recommended that the first reduced
final limit be the EC equivalent of 250TC
µg/m3 on January 20, 2009. The final EC
equivalent of 160TC µg/m3 would
become effective on January 20, 2011.
They suggest that this schedule would
more realistically take into account the
purchasing decisions by the mining
industry to buy new equipment and
engineering controls designed to
ultimately achieve compliance with the
final limit. In this final rule, we based
our timetable on definitive information
on availability of alternative fuels and
the implementation issues that mine
operators face in complying with the
final limit of 160TC µg/m3. We discussed
this at length in Section V, Feasibility,
of this final rule.
Organized labor commented that
exposure to DPM causes cancer, and
lawful or not, they believe that delay
will cost miners’ lives, since they are
breathing these fumes at toxic levels.
These commenters discussed what they
believe to be our protracted rulemakings
to revise the 2001 final rule. They also
expressed their disagreement with us in
changing the applicability of the 2001
final limit of 160TC µg/m3, and not
including medical evaluation and
transfer protection for miners. They
stated, among other things, that:
On September 7, 2005, the agency
proposed to postpone the final PEL by five
more years, reducing it instead by small
steps. The agency also suggested there might
be difficulties converting the 160 µg/m3 TC
limit to an appropriate EC limit, and
proposed to leave that determination to yet
another rulemaking. The final standard has
now been delayed until May 20, but MSHA
clearly intends to delay it far longer,2
ostensibly on the grounds of feasibility, and
based primarily on unsubstantiated claims
from the mine operators. These proposed
changes would significantly weaken the rule
by permitting the continued exposure of
miners to levels of DPM the agency has found
to be unacceptable * * *
MSHA made a promise to underground M/
NM miners in 2001. It told them that help
was on the way and that they would someday
be protected from choking levels of diesel
exhaust. Relief would come slowly, and
exposures would be reduced in steps, but by
January 2006, a protective standard would be
in place. MSHA now proposes to break that
promise.
Instead, MSHA should withdraw the
proposal to delay the 160 µg/m3 TC limit, and
revise its effective date to no later than July
20, 2006. The USW has no objection to
converting the standard to one based on EC
at some time in the future, when the data
exists to do so. For the time being, TC and
EC measurements should be taken
2 The USW did not object to the 5 month delay;
it was necessary to allow the rulemaking process to
be as complete as possible. However, we object
strenuously to the 5 year delay.
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simultaneously, so that MSHA or NIOSH can
calculate a proper conversion factor when the
time comes. (USW, AB29–COMM–117)
As we stated earlier in this preamble,
data continue to support our 2001 risk
assessment. That risk assessment
establishes a material impairment of
health or functional capacity to miners
from exposure to DPM. We have
incorporated into this rulemaking
record the previous DPM rulemaking
records, including the 2001 risk
assessment. In the 2005 NPRM, we
discussed the decline in miners’
exposures to DPM from a mean of
808DPM µg/m3 (646TC µg/m3
equivalent) prior to the implementation
of the 2001 standard, to a mean of 233TC
µg/m3 based on enforcement sampling at
that time (70 FR 53283). More recent
enforcement data show that miners’
exposures to DPM continue to decline.
Nevertheless, we continue to believe
that mine operators’ experiences with
control technology confirm that it is
infeasible for us to implement the 160TC
µg/m3 final limit earlier than May 2008.
We believe that these data dictate the
need to afford the mining industry more
time to work through their
implementation and maintenance issues
with DPFs, and to allow sufficient time
for construction of more biodiesel fuel
distribution centers.
Some industry commenters strongly
suggest that feasibility of the final DPM
limits must be based on fair and
effective implementation of existing
§ 57.5060(c) regarding special
extensions of time in which to comply
with the final DPM limit. It is their
contention that many mines will be
unable to meet the lower DPM limit of
160TC µg/m3, even if staggered over a
five-year period as the agency proposed.
Some other mine operators stated that
the special extension process ‘‘is not a
feasible means of salvaging the
infeasible 160TC µg/m3, or the
unworkable and unsupported yearly
‘phase-in’ proposal.’’
Section 57.5060(c) allows mine
operators to apply to the MSHA District
Manager for additional time to meet the
final DPM limits due to economic or
technological constraints. Mine
operators must demonstrate infeasibility
of compliance to the District Manager
before they can qualify for a special
extension. The feasibility considerations
for the District Manager in granting
special extensions are very similar to
those for determining feasibility under
our hierarchy of controls enforcement
scheme. Given the progress the mining
industry has shown in reducing DPM
levels thus far, we do not believe that
the industry, as a whole, will be unable
to meet the lower DPM limit of 160TC
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µg/m3 by May 2008. Initially, we expect
to have greater numbers of miners
overexposed to the final limit, than with
the interim limit. However, we believe
that miners in this category will decline
over time as mine operators introduce
improved engines and continue to
resolve their implementation and
maintenance problems with DPFs and
access problems with biodiesel.
These industry commenters also point
out that we should develop, in their
views, an accurate, scientifically
supportable conversion factor to change
the current TC-based final limit of 160TC
µg/m3 to an EC-based limit. We intend
to use the best available evidence to
develop a proposed rule to
appropriately and accurately convert the
final DPM limit in the near future.
We received comments from the
mining industry on establishing an
appropriate surrogate for the DPM final
limit. In our 2005 final rule, we changed
the surrogate for the interim limit by
changing from a concentration limit
measured by TC to a comparable PEL
measured by EC, which renders a more
accurate DPM exposure measurement,
and committed to revising the final
concentration limit in a future
rulemaking. The final rule adopts 308EC
µg/m3 as the initial final limit, but
retains TC as the surrogate for the 350TC
µg/m3 and 160TC µg/m3 final limits. We
will initiate a separate rulemaking to
determine the correct TC to EC
conversion factor for the phased-in final
limit of 160TC µg/m3.
Several commenters to the proposed
rule continue to question the
applicability of the 2001 risk assessment
when using a surrogate measure of
elemental carbon to regulate exposures
to DPM. These commenters also
question the accuracy of the NIOSH
Analytical Method 5040 and expressed
disapproval for our using EC as a
surrogate. In contrast, a number of other
commenters objected to MSHA not
enforcing a limit of 160TC µg/m3
immediately. We refer the commenters
to the preamble to the 2005 final rule
(70 FR 32868) for our position on these
issues. Commenters presented some
new information, however, in response
to the 2005 NPRM.
NIOSH Analytical Method 5040
Validation and Accuracy
The guidelines for development and
evaluation of analytical methods are
documented in the NIOSH publications
NIOSH Manual of Analytical Methods,
Chapter E (NIOSH 2nd Supplement
Publication No. 98–119) and Guidelines
for Air Sampling and Analytical Method
Development and Evaluation (NIOSH
Publication No. 95–117). These
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documents are guidelines that are used
in the process of determining that an
analytic method accurately measures
what it purports to measure. NIOSH
validation criteria state that the NIOSH
Analytical Method 5040 provides a
result that differs no more than ±25%
from the true value 95 times out of 100.
The NIOSH Analytical Method 5040
validation is documented in several
publications. These publications
include:
(1) Chapter Q of the NIOSH Manual
of Analytical Methods (NMAM), DHHS
(NIOSH) Publication No. 94–113,
(2) Occupational Monitoring of
Particulate Diesel Exhaust by NIOSH
Analytical Method 5040, Birch, Applied
Occupational and Environmental
Hygiene, Vol. 17(6):400–405, 2002,
(3) Diesel Particulate Matter (as
Elemental Carbon) 5040, Issue 3: March
15, 2003, NIOSH Manual of Analytical
Methods (NMAM), Fourth Edition.
In addition to the above documented
validations, there are additional peerreviewed studies providing evidence
that the NIOSH Analytical Method 5040
method is valid. In a study published by
Noll, et al., in January 2005 evaluating
sampling results of DPM cassettes, the
authors report a 95% upper confidence
limit Coefficient of Variation (CV) of 7%
when analyzing samples for EC and 6%
for TC. In this same study, NIOSH
reported good agreement and precision
between EC for DPM samples using SKC
impactor and respirable samples in both
laboratory and field studies. The CVs for
EC measurements between SKC
impactors and respirable samples
ranged from 0.2% to 12.3% when taking
measurements in an underground mine.
The CVs for EC ranged from 3.5% to
5.4% when samples were taken in a
laboratory chamber. Two studies
published in 2004 (Noll, et al., 2004 and
Birch, et al., 2004) reported results from
investigating sampling for EC in the
presence of coal dust using submicron
impactors. The results show good
agreement between submicron EC and
respirable samplers for collecting DPM
samples.
Error Factor
In accordance with generally accepted
good industrial hygiene practice and
MSHA policy, we develop methodspecific error factors to assure that a
personal exposure result is more than
likely to represent an overexposure.
These error factors account for normal
and expected variability inherent in any
analytic method and sampling protocol
and provide a basis for interpretation of
sampling results. When we interpret
sampling results and make a
determination of compliance, we apply
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the error factor to the result to gage
whether the sample indicates a true
overexposure. We use the validated
NIOSH Analytical Method 5040 for
diesel particulate matter to analyze our
personal exposure samples collected for
compliance determinations.
The NIOSH criteria and guidelines
used for method validation do not
directly apply to the development of
error factors. However, similar statistical
procedures to develop analytical
methods can also be used to develop
error factors. The commenters fail to
recognize other differences between
validation of methods and development
of error factors.
Error factors are developed to
compare an infinite number of sampling
results to a specific target value of the
analyte whereas the method validation
protocol specifies a range of 0.1 to 2
times a specific value. Many other
differences exist between the two
procedures.
We believe the NIOSH Analytical
Method 5040 is most appropriate for use
in a mining environment because:
(1) The results from the additional
method validation efforts by NIOSH
using samples collected in mines, as
mentioned above, show the method is
valid, and
(2) The data we used are generated
from miners’ samples and analyzed in
our laboratory (using multiple
analyzers) and other laboratories
account for variability in the
determination of the error factor.
In response to commenters’ concerns
that ‘‘MSHA has developed this Error
Factor as though the NIOSH Analytical
Method 5040 were perfectly accurate for
measurements of EC,’’ we refer the
commenter to item (2) above. We have
incorporated inter-laboratory variability
and inter-instrument variability into the
calculation of the error factor that does,
in fact, address accuracy. By
incorporating this type of variability we
account for some possible biases. It was
stated in the 31-Mine study that, based
on the available data from all
laboratories, the estimated coefficient of
variation for analytical TC
measurements declines from 12.7% to
8.0% at TC loadings corresponding to 8hour equivalent concentrations of 160
µg/m3 and 400 µg/m3, respectively.
These estimates are approximately 60
percent greater than those based on the
MSHA and NIOSH data alone. Intraand inter-laboratory analytical
imprecision appears to be similar to
other airborne contaminants’ monitoring
methods used by us and other
regulatory agencies.
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Specific Issues Raised by Commenters
on Elemental Carbon Variability of the
Relationship Between EC and TC
Industry commenters raised the
following specific issues regarding the
use of EC as a surrogate for DPM
exposure. Commenters asserted that the
EC content of DPM is neither stable nor
predictable and thus the proposed
conversion of TC limits to EC limits is
not feasible.
We have addressed this issue in the
2005 final rule (70 FR at 32945–32951),
and we continue to support using EC as
the most suitable surrogate for
measuring DPM. Our 2005 final rule (70
FR 32868) establishes the measurement
of DPM using EC as a direct measure of
total DPM. Using EC as the surrogate
permits personal sampling of miners
(such as those who smoke, operate
jackleg drills, or load ANFO) that would
otherwise be difficult or impossible
using the OC components in the
calculation of TC. Several commenters
also noted that the ratio of EC:TC in
DPM can vary widely. One commenter
pointed out that EC appeared to make
up nearly all of the TC at the mine with
which he was affiliated. This
commenter stated that replacing a 400TC
µg/m3 limit with a 308EC µg/m3 limit
would impose a much more stringent
standard at that mine. Another
commenter noted that a 308EC µg/m3
limit would be less protective of miners
than the 400TC µg/m3 limit in cases
where the ratio of EC comprised less
than 78% of the TC. One industry
association submitted comments
authored by a consultant who
emphasized that the highly variable
nature of the EC to OC ratio introduces
‘‘large and important uncertainties in
the exposure assessments needed to
sustain QRA [i.e., quantitative risk
assessment].’’
We addressed these concerns
regarding variability previously in our
discussion of the Relationship Between
EC and TC in our preamble to the 2005
final rule (70 FR 32894–32899). In the
2005 NPRM we solicited comments
about converting the final phased-in
limits based on TC measurements to
corresponding EC limits. In the 2005
NPRM, we also notified the mining
community that we would initiate a
separate rulemaking to determine what
the correct TC to EC conversion factor
would be for the phased-in TC final
limits below 308EC µg/m3. We requested
comments on whether the record
supports an EC PEL without regard to
any conversion factor, the appropriate
conversion factor if one is used, and any
other scientific approaches for
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converting the existing TC limit to an
appropriate EC limit.
Several commenters agreed with our
use of the 1.3 conversion factor for the
interim limit and the first phased-in
final limit of 400TC µg/m3 (308EC µg/
m3), but did not believe sampling
evidence supported its use at a lower
PEL. One commenter recommended we
either use the EC number from the lab
evaluation, or use a compliance strategy
similar to the method used by the
Agency in 2004 for the interim limit of
400TC µg/m3.
Several commenters agreed that more
work is required to develop an
appropriate conversion factor from TC
to EC for the final limits. They stated it
was reasonable to expect sampling and
analysis variability to increase, and
accuracy and precision to decrease at
lower EC levels. They further stated that
MSHA data demonstrate that no
accurate conversion factor exists for the
highly variable ratio of TC to EC at
levels below the interim standard and
that this ratio becomes even more
unstable once diesel equipment is
modified by installation of DPM
filtering devices.
Other commenters also believed more
research is needed to determine an
appropriate conversion factor and noted
that recent evidence indicated the EC to
TC relationship may change depending
on various factors such as fuel type,
engine duty cycle, and the control
technologies being used.
A number of commenters stated that
an accurate, scientifically supportable
conversion factor was essential to their
acceptance of a staggered effective date
schedule. One of them further stipulated
the need for peer review of the
conversion factor. Other commenters
believe that the EC content of DPM is
not stable or predictable so the proposed
conversion of TC limits to EC limits is
not feasible and that the measurement of
EC is not accurate.
Organized labor commented that the
only proper course of action for MSHA
would be to leave the standard at 160
µg/m3 TC until an equally protective
standard based on EC can be
established. They said that leaving the
standard at 308 µg/m3 EC, or going to an
EC level not equivalent to 160 µg/m3 TC
would violate the ‘‘no-less protection’’
restriction under section 101(1)(9) of the
Mine Act.
We maintain that the 31-Mine Study
data establish that a conversion factor of
1.3 is appropriate for both the initial
and final limit of 308EC µg/m3. As we
determined in the 2005 final rule, we
believe that the limit of 308EC µg/m3 is
equally protective of miners’ health and
equally feasible for the mining industry
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to meet. Although the EC:TC ratio can
exhibit considerable variability in
specific cases, we concluded that
application of the 1.3 conversion factor,
pursuant to the Second Partial
Settlement Agreement, achieves the goal
of equal protection and feasibility at the
308EC µg/m3 final PEL.
We are considering various
alternatives for converting the 350TC µg/
m3 and 160TC µg/m3 final limits to
comparable EC limits. We will consider
all comments in this rulemaking record
concerning the relationship between EC,
OC and TC in a separate rulemaking to
determine the most appropriate
conversion of the final TC limits.
Presently, we believe that the DPM
rulemaking record is inadequate for us
to make determinations regarding a
more appropriate conversion factor
other than 1.3 for the 350TC µg/m3 final
PEL. If a rulemaking to establish a
conversion factor is not completed
before January 20, 2007, we intend to
use the 1.3 conversion factor to convert
the 350TC µg/m3 final limit to an EC
equivalent. We will use the EC
equivalents as a check to validate that
an overexposure is not the result of
interferences as we did with the 400TC
µg/m3 interim limit pursuant to the
Second Partial Settlement Agreement 67
FR 47296, 47298). We discussed this
concept earlier in this section.
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Measurement of EC
Some commenters stated that any
carcinogenic effect of DPM is due
entirely to the organic fraction. We
believe this assumption is speculative.
This assumption contradicts findings
reported by Ichinose et al. (1997b) and
does not take into account the
contribution that inflammation and
active oxygen radicals induced by the
inorganic carbon core of DPM may have
in promoting lung cancers. Indeed,
identifying the toxic components of
DPM, and particulate matter in general,
is an important research focus of a
variety of government agencies and
scientific organizations (see, for
example: Health Effects Institute, 2003;
Environmental Protection Agency,
2004b).
In focusing on the carcinogenic agents
in OC, the commenters seem to have
ignored non-cancer health effects
documented in the 2001 risk
assessment—e.g., immunological,
inflammatory, and allergenic responses
in healthy human volunteers exposed to
300DPM µg/m3 (i.e., ≈ 240TC µg/m3) for as
little as one hour (66 FR at 5769–70,
5816–17, 5820, 5823, 5837, 5841, 5847).
We discussed this also in our 2005 final
rule (70 FR 32898,32899).
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The implication of non-organic
chemicals in a chemical pathway
explaining the induction of lung
carcinogenesis indicates that organic
and inorganic chemical compounds,
acting together, contribute to the
toxicity of DPM. Identification of a
single carcinogenic component of DPM
(whether EC, OC, or some combination
of chemicals in DPM) is not germane to
the issue of whether DPM actually
causes adverse health effects as
established by the 2001 risk assessment
and its updates. This rule reduces the
adverse health risks associated with
miners’ exposure to DPM and not just
those associated with the EC or OC
fractions of DPM.
The NIOSH Analytical Method 5040
characterizes compounds found in DPM
into several classes of substances. These
classifications are convenient categories
and do not distinguish hazardous
compounds from other compounds. As
stated by NIOSH (Birch, 1996),
‘‘[M]ethods that speciate EC and OC are
considered operational (Cadle and
Groblicki, 1980) in the sense that the
method itself defines the analyte.’’
The possible chemical pathways
causing adverse health effects
(including lung cancer) include both
organic and inorganic chemical
elements. Since we believe that both
organic and inorganic chemicals
contribute to the overall toxicity of DPM
our use of EC as a surrogate is intended
to control miners’ exposure to whole
DPM. As NIOSH stated:
Elemental carbon is the superior measure
of exposure to particulate diesel exhaust
because elemental carbon constitutes a large
portion of the particulate mass, it can be
quantified at low levels, and its only
significant source in many workplaces is the
diesel engine. Selection of an elemental
carbon marker also was based on previous
work by Fowler (1985), who evaluated
various analytes as indices of ‘‘overall diesel
exposure.’’ (Birch, 1996)
We have not obtained additional
information, either provided in
comments or from peer-reviewed
literature, to change our position that
the EC and OC fractions of DPM
contribute to the adverse health effects
of miners caused by exposure to DPM
found in diesel exhaust and that EC is
the superior measure of exposure to
DPM.
The 308EC µg/m3 final PEL established
by this rule is intended to be
commensurate with the interim TC limit
of 400 micrograms established under the
2001 rule—i.e., to be equally protective
and equally feasible as well as the 308
µg/m3 interim EC PEL established by the
2005 final rule. Although the EC:TC
ratio can exhibit considerable variability
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28983
in specific cases, we concluded that
application of the 1.3 conversion factor,
as suggested in the Second Partial
Settlement Agreement, achieves equal
protection and feasibility at the 308EC
µg/m3 final PEL.
In the 2005 NPRM we solicited
comments about converting the final
phased-in limits based on TC
measurements to corresponding EC
limits. We have discussed the
relationship between EC and TC and
conclude the relationship of EC:TC is
adequate to promulgate a personal
exposure limit of 308EC µg/m3 final PEL.
However, we are considering various
alternatives for converting the 350TC µg/
m3 and 160TC µg/m3 final limits to
commensurate EC limits. We will
consider all comments in this
rulemaking record concerning the
relationship between EC, OC and TC in
a separate rulemaking to determine the
most appropriate conversion of the final
TC limits. Presently, we believe that the
DPM rulemaking record is inadequate
for us to make determinations regarding
a more appropriate conversion factor
other than 1.3 for the 350TC µg/m3 final
PEL. If a rulemaking to establish a
conversion factor is not completed
before January 20, 2007, we intend to
use the 1.3 conversion factor to convert
the 350TC µg/m3 final limit to an EC
equivalent. We will use the EC
equivalents as a check to validate that
an overexposure is not the result of
interferences as we did with the 400TC
µg/m3 interim limit pursuant to the
Second Partial Settlement Agreement
(67 FR 47296, 47298). We discussed this
concept earlier in this section.
Other commenters asserted that
measurement of EC is not accurate and
the inherent inaccuracies are not
accounted for by the MSHA ‘‘error
factor.’’ NIOSH Analytical Method 5040
has been validated. The Error Factor
accounts for uncontrollable components
of measurement except for the
variability inherent in EC:TC ratios. We
have shown these ratios vary between
mines and within mines. The
commenters obtained additional
information from us and presented a
new analysis addressing the validity of
the NIOSH Analytical Method 5040.
Based on this new analysis, they
concluded that ‘‘* * * the MSHA Error
Factor described in the proposed Final
Rule is too small to meet the statistical
goals (i.e., ‘95-percent confidence’)
adopted by the Agency.’’ We disagree.
We have demonstrated the
mathematical fallacies of the
commenters’ position in the 2005 final
rule. We show it is plausible to have 32
percent of sampling clusters with the
experimental design specified by Cohen,
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Federal Register / Vol. 71, No. 96 / Thursday, May 18, 2006 / Rules and Regulations
et al., 2002 with an inherent coefficient
of variation (CV) of 12% and still be
consistent with the NIOSH accuracy
criterion. The Monte Carlo analysis we
performed shows that the commenters’
data are consistent with NIOSH
validation criteria even though the
commenters’ collection procedures and
analyses were substandard.
The commenters’ experimental design
and results as presented to the 2003
NPRM were critiqued in the 2005 final
rule. No explanation has been provided
by these commenters as to why the
submitted data were restricted to 75EC
µg/m3 to 200EC µg/m3 and whether
additional basket data falling outside of
this range were collected. The samples
were collected without the submicron
impactor. The sample results are,
therefore, inappropriate to address this
rulemaking. The study reference does
not indicate the type of filter holder and
cyclone attachment configuration or if
the mineral-dust-related carbonate that
occurs in the organic portion of the
analysis was subtracted off the OC
determination. When using a filter
holder with an internal cyclone
connection, the cyclone nozzle acts as
an impactor jet and mineral dust is
deposited in the center of the filter. This
inferior sampling equipment
arrangement gives a high level of
mineral dust in the center of the filter,
and a non-uniform deposit of material
on the filter surface. A non-uniform
deposit precludes any analysis of
duplicate sample punch repeatability.
Additionally, three of the seven mines
in the referenced study produced either
limestone or trona. Both of these
minerals contain carbonates which are
evolved in the organic portion of the
analysis. The referenced study indicates
that up to 15 mg/m3 of total mineral
dust was present at one of the mines.
Failure to remove this mineral dust by
use of an impactor may affect the ability
of the analytical analysis to discern
between OC and EC, thus introducing
an artificially high variability of results.
No information is provided on
sampling times or filter loadings (µg/
cm2), both of which affect expected
analytical variability. Commenters
provided no information as to whether
multiple punches were used to
determine EC concentrations similar to
what we do in our analyses. Only
summary data, consisting of the EC
measurement range, mean, standard
deviation (SD), and coefficient of
variation (CV), were provided for each
group of ‘‘four or five’’ samples. No
confidence intervals or other measures
of statistical uncertainty were provided
for their summary statistics. The
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commenters failed to address these
issues.
Some commenters presented a new
analysis addressing the validity of the
NIOSH Analytical Method 5040. The
new Monte Carlo simulation study
results are not persuasive. The
commenters’ statement that ‘‘MSHA
employed its Monte Carlo simulation to
support the conclusion that their
sampling and analytical method was
adequately precise and therefore
feasible’’ misrepresents our inferences.
We used a Monte Carlo simulation to
show that, even with all the
uncertainties in the quality of the
referenced study and conjectures made
by the commenter, it is possible for
those results to have been generated by
a valid analytical method. We generally
agree with the commenters insofar as
hypothetically generated data seem to
only obscure the discussion of realworld data that document analytical
precision.
Industry commenters believed that
our analysis of more than 600 EC
samples (punch-repunch) show that the
results are neither precise nor
reproducible. This issue was addressed
in the preamble to the 2005 final rule.
We continue to rely on our previous
analysis of the commenters’ statement.
The commenters’ analysis of the punchrepunch data used in the calculation of
the error factors for the PELs is
incorrect. We summarize our critique of
the commenters’ analysis here in
response to their new analyses of their
updated data set.
1. The commenter’s analysis of the
punch-repunch data is now closer to the
mathematical definition of a Coefficient
of Variation (CV). Their calculation of a
‘‘difference between punches, to the
average of the two punch results’’
presents artificially larger variations in
the analytic method compared with
those with properly calculated CVs. We
point out that the commenters did not
follow the guidelines specified in
NIOSH validation guidelines. The
calculation used by the commenters to
show large variability is misleading and
inconsistent with their own criticisms,
and overstates the variation of the
NIOSH Analytical Method 5040
instrumentation.
2. Although the commenters adjust
their calculation of the difference
between punches by the mean of the
punches, they fail to make meaningful
statistical inferences of the results. They
simply tabulate instances in which the
‘‘% Difference’’ exceeds a specified CV.
The CV values used for their
demonstration thresholds do not
represent an upper bound on individual
deviations or differences.
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Approximately one-third of individual
errors (without regard to direction)
would normally be expected to exceed
the corresponding CV.
This is why we multiply the
appropriate CVs used in calculating the
error factor (EF) by a ‘‘Confidence
Coefficient’’ when establishing a 1tailed confidence error factor for
noncompliance determinations along
with other sources of uncontrollable
variability of the measurement system.
Industry commenters also contended
that there is no NIST ‘‘standard’’ for
defining EC for analysis and
measurement, thus accurate
measurement is not feasible. The
National Institute of Standards and
Technology (NIST) provides two
Standard Reference Materials that
define not only EC but also TC. These
reference materials are well
characterized to help determine the
operating characteristics of NIOSH
Analytic Method 5040 and others. NIST
Standard Reference Material 1649a
(Urban Dust) provides a Certified
Concentration Value for TC. NIST
provides an Information Concentration
Value for the fraction of EC (EC/TC)
contained in this standard material.
Although components of the material
assigned Information Concentration
Values are not as well characterized as
those with certified Concentration
Values, they are valuable sources of
information used by laboratories to
validate and assure proper operation of
analytic methods.
NIST Standard Reference Material
8785 (Air Particulate Matter on Filter
Media) has been available since July 8,
2005 and provides the means to
compare methods and laboratories for
the measurement of EC. This reference
material has value-assignments for TC,
EC, and OC measured according to two
thermal-optical methods: the NIOSH
and IMPROVE (Interagency Monitoring
of Protected Visual Environments)
protocols. Our laboratory utilizes these
NIST Standard Reference Materials as
part of a comprehensive quality
assurance program.
Health Implications of Using EC
Commenters also asserted that EC is
not a constituent of diesel exhaust that
is suspected of causing lung cancer, and
the MSHA risk analysis of diesel
exhaust is inapplicable to the proposed
EC limits. The particulate component of
combustion products produced by a
diesel engine is characterized by the
analytic method as primarily either EC
or OC. The analytic decomposition of
DPM defines which components are
characterized as EC or OC without
specifically determining the exact
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chemical, physical, or carcinogenic
chemicals found in DPM (NIOSH
Analytical Method 5040, March 15,
2003). Diesel particulate matter is firmly
characterized as a hazardous substance
and we do not further characterize DPM
into hazardous components and nonhazardous components. The final rule
intends to limit exposures to total DPM
rather than any single constituent of
DPM. The NIOSH Analytical Method
5040 characterizes compounds found in
DPM into two classes of substances.
These classifications are convenient
categories and do not distinguish
hazardous compounds from other
compounds. As stated by NIOSH (Birch,
1996), ‘‘[M]ethods that speciate EC and
OC are considered operational (Cadle
and Groblicki, 1980) in the sense that
the method itself defines the analyte.’’
The assumption that any carcinogenic
effect of DPM is due entirely to the
organic fraction is speculative. This
assumption contradicts findings
reported by Ichinose et al. (1997b) and
does not take into account the
contribution that inflammation and
active oxygen radicals induced by the
inorganic carbon core of DPM may have
in promoting lung cancers. Indeed,
identifying the toxic components of
DPM, and particulate matter in general,
is an important research focus of a
variety of government agencies and
scientific organizations (see, for
example: Health Effects Institute, 2003;
Environmental Protection Agency,
2004b). The 2001 risk assessment
discusses possible mechanisms of
carcinogenesis for which both EC and
OC would be relevant factors (66 FR at
5811–5822). Multiple routes of
carcinogenesis may operate in human
lungs—some requiring only the various
organic mutagens in DPM and others
involving induction of free radicals by
the EC core, either alone or in
combination with the organics (70 FR
32898).
The implication of non-organic
chemicals in a chemical pathway
explaining the induction of lung
carcinogenesis indicates that organic
and inorganic chemical compounds,
acting together, contribute to the
toxicity of DPM. Identification of a
single carcinogenic component of DPM
(whether EC, OC, or some combination
of chemicals in DPM) is not germane to
the issue of whether DPM actually
causes adverse health effects as
established by the 2001 risk assessment
and its updates. This rule reduces the
adverse health risks associated with
miners’ exposure to DPM and not just
those associated with the EC or OC
fractions of DPM.
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We have not obtained additional
information, either provided in
comments or from peer-reviewed
literature, to change our position that
the EC and OC fractions of DPM
contribute to the adverse health effects
of miners caused by exposure to DPM
found in diesel exhaust and that EC is
the superior measure of exposure to
DPM.
B. Special Extensions § 57.5060(c)(3)(i)
In our 2005 final rule addressing the
interim limit, we revised the
requirements at § 57.5060(c) regarding
special extensions of time in which to
meet the final DPM limit. We retained
the requirement in § 57.5060(c)(3)(i),
however, that the mine operator must
specify in the application whether
diesel-powered equipment was used in
the mine prior to October 29, 1998. The
purpose of the 2001 restriction was to
limit special extensions to underground
mines that operated diesel-powered
equipment prior to October 29, 1998.
We chose this date because we released
the NPRM to our 2001 final rule on that
date. We reasoned that some mines in
operation prior to that date could
experience compliance difficulties
relating to such factors as the basic mine
design, use of older equipment with
high DPM emissions, etc., and that as a
result, some of these mines may require
additional time to attain compliance
with the 2001 final concentration limit.
Also, we envisioned that mines opened
after that date would be using cleaner
engines to help them comply with the
final limit. Furthermore, we stated in
the 2005 proposal that we had reason to
believe that our 2001 assumptions were
incorrect, and that it was unnecessary to
limit extensions to mines operating
diesel equipment prior to October 29,
1998.
We believe the consequence of such a
conclusion does not compromise the
level of health protection afforded under
the existing prohibition. This is because
it is optional as to whether a mine
operator applies for a special extension
under current § 57.5060(c). Special
extensions involve considerable
paperwork for mine operators, but they
result in a document that a mine
operator can rely on for a period of one
year (renewable) to demonstrate to our
inspectors that we have determined that
it is infeasible for that particular mine
operator to achieve compliance with the
final limit using engineering and
administrative controls. If affected
miners are included in a respiratory
protection program which meets the
requirements of § 57.5060(d), the mine
operator is in compliance and no
citation will be issued. To qualify for a
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28985
special extension, a mine operator must
demonstrate infeasibility, which is the
same test which we use for enforcement
of § 57.5060(d) at mines that don’t have
a special extension. Current § 57.5060(d)
requires mine operators to install, use,
and maintain all feasible engineering
and administrative controls to achieve
compliance. If we determine that
reaching the final limit is infeasible for
technological or economic reasons, and
over-exposed miners are in an
appropriate respiratory protection
program, the operator is deemed to be
in compliance and we will not issue a
citation. We will periodically check to
determine current DPM exposures and
the ability of the mine operator to
implement new control technology.
We received no comments objecting
to deleting § 57.5060(c)(3)(i).
Commenters supporting the deletion
stated that they saw no reason to limit
special extensions to those mine
operators who were operating diesel
equipment prior to the arbitrary date of
October 29, 1998. They also stated that
there would be no reduction in the level
of health protection from a standard that
was not feasible, nor with which health
risks were never associated. Another
commenter stated that if this restriction
is left in the DPM standard, mines that
are just starting will not be allowed to
file for a special extension. They
claimed that in their case, if they were
to develop a new mine, they would have
essentially the same constraints as far as
mine opening dimensions, maximum air
volumes, and equipment as their
existing mines have. Consequently, they
would not necessarily have lower DPM
levels in a new mine. For this reason,
they believe that it is critical that we
allow new mines the same opportunity
to qualify for special extensions after
taking all reasonable steps to reduce
DPM emissions.
Other commenters agreed that we
should delete § 57.5060(c)(3)(i) from the
existing DPM standard, but provided no
information as to whether elimination of
this requirement would result in a
reduction in the current level of health
protection afforded to miners.
We also received numerous comments
recommending that we make other
changes to the special extension
provisions. These commenters
suggested that the final rule include:
Comprehensive criteria for granting a
special extension; specific language to
expand the application of an extension
to the entire mine or to portion(s) of a
mine; additional procedures for the
District Manager to consider in making
a determination of whether to grant a
special extension; requirements that the
District Manager include reasons for any
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denial of a special extension; and,
procedures allowing appeal of the
District Manager’s determination to the
Administrator, and ultimately, to the
independent Federal Mine Safety and
Health Review Commission.
In the 2005 proposed rule, we
informed the public that the scope of
revision to § 57.5060(c) was limited to
the removal of paragraph (c)(3)(i).
Accordingly, such changes would be
beyond the scope of this rulemaking.
Consequently, the final rule does not
reflect consideration of the above stated
issues. We note that we made
comprehensive revisions to § 57.5060(c)
in the 2005 final rule.
Some other commenters discussed
how the special extension procedures
enhance feasibility and that the courts
have recognized that such procedures
can resolve individual problems with
feasibility. The commenter refers us to
the United Steelworkers of America v.
Marshall, 647 F. 2d 1189, 1266 (1980).
We address this comment under our
discussions on feasibility.
Based on the comments received
supporting the deletion of
§ 57.5060(c)(3)(i), and our discussions
above, we have deleted this provision
from the DPM standard. For the forgoing
reasons, we do not believe that deletion
of this provision reduces miners’
current level of health protection, and
there were no comments submitted to
the contrary.
C. Medical Evaluation and Transfer
§ 57.5060(d)
In the preamble to the 2005 NPRM,
we requested comments from the
mining community on whether we
should include in the final rule a
provision requiring a medical
evaluation to determine a miner’s ability
to use a respirator before the miner is fit
tested or required to work in an area of
the mine where respiratory protection
must be used. In addition, we asked for
comments on whether the final rule
should contain a requirement for
transfer of a miner to an area of the mine
where respiratory protection is not
required if a medical professional has
determined as a result of the medical
evaluation that the miner is unable to
wear a respirator for medical reasons.
Further, we asked whether we should
amend the existing respiratory
protection requirement at § 57.5060(d)
by adding new paragraphs (d)(3) and
(d)(4) to address medical evaluation and
transfer rights for miners. We
particularly wanted to know if the final
rule should include the following
language:
(3) The mine operator must provide a
medical evaluation, at no cost to the miner,
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to determine the miner’s ability to use a
respirator before the miner is fit tested or
required to use the respirator to work at the
mine.
(4) Upon notification from the medical
professional that a miner’s medical
examination shows evidence that the miner
is unable to wear a respirator, the miner must
be transferred to work in an existing position
in an area of the same mine where respiratory
protection is not required.
(i) The miner must continue to receive
compensation at no less than the regular rate
of pay in the classification held by that miner
immediately prior to the transfer.
(ii) The miner must receive wage increases
based upon the new work classification.
We also requested comments in the
preamble to the proposed rule on
whether a transfer provision in the final
rule should include issues of
notification to the District Manager of
the health professional’s evaluation and
the fact that a miner will be transferred;
the appropriate time frame within
which the transfer must be made;
whether a record of the medical
evaluation conducted for each miner
should be maintained along with the
correct retention period; medical
confidentiality; and any other relevant
issues such as costs to mine operators
for implementing a rule requiring
medical evaluations and transfer of
miners. Our current DPM requirements
for respiratory protection at § 57.5060(d)
do not include requirements for medical
evaluation of miners before they are
required to work in an area where
respiratory protection must be worn, or
transfer of miners who are medically
unable to wear respirators.
Section 101(a)(7) of the Mine Act
authorizes medical evaluation and
transfer protection for miners, and
states, in pertinent part:
Where appropriate, such mandatory
standard shall also prescribe suitable
protective equipment and control or
technological procedures to be used in
connection with such hazards and shall
provide for monitoring or measuring miner
exposure at such locations and intervals, and
in such manner so as to assure the maximum
protection of miners. In addition, where
appropriate, any such mandatory standard
shall prescribe the type and frequency of
medical examinations or other tests which
shall be made available, by the operator at his
cost, to miners exposed to such hazards in
order to most effectively determine whether
the health of such miners is adversely
affected by such exposure. Where
appropriate, the mandatory standard shall
provide that where a determination is made
that a miner may suffer material impairment
of health or functional capacity by reason of
exposure to the hazard covered by such
mandatory standard, that miner shall be
removed from such exposure and reassigned.
Any miner transferred as a result of such
exposure shall continue to receive
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compensation for such work at no less than
the regular rate of pay for miners in the
classification such miner held immediately
prior to his transfer. In the event of the
transfer of a miner pursuant to the preceding
sentence, increases in wages of the
transferred miner shall be based upon the
new work classification.
Existing § 57.5060(d) requires that
mine operators comply with the
respiratory protection requirements
under § 57.5005(a) and (b) (control of
exposure to airborne contaminants) of
our air quality standards for M/NM
underground mines. Sections
57.5060(d)(1) and (d)(2) designate
acceptable respirator filters under the
standard. Section 57.5005(a) requires
that respirators be furnished and miners
use the protective equipment in
accordance with training and
instruction. Currently, we do not require
mine operators to provide miners with
medical evaluation before they wear a
respirator and transfer protection in the
event that they cannot wear one.
Existing § 57.5005(b) for control of
miners’ exposures to airborne
contaminants requires that mine
operators establish a respiratory
protection program consistent with the
(ANSI Z88.2–1969) ‘‘American National
Standard for Respiratory Protection
—‘‘ANSI Z88.2–1969, ‘‘American
National Standards Practices for
Respiratory Protection.’’ The final rule,
however, adopts our approach taken in
the proposed preamble
recommendations along with additional
requirements which we deem necessary
to protect miners. These additional
requirements address issues related to
medical confidentiality, evaluation of a
miner’s ability to wear a PAPR,
reevaluation of miners, and
recordkeeping requirements, along with
other revisions to clarify our intent
under the standard.
We believe that there is adequate
evidence in the rulemaking record
establishing the need for medical
evaluation of miners. We incorporated
into the DPM rulemaking record the
Occupational Safety and Health
Administration’s (OSHA) data from its
rulemaking record supporting its
generic respiratory protection standard
at 29 CFR 1910.134 related to the health
risk to persons from using respirators
with certain medical conditions. Based
on their data, OSHA concluded, and
MSHA agrees, that use of a respirator
may place a physiological burden on a
worker while wearing such a device.
Depending on the medical condition of
the person, this burden could result in
illness, injury, and in some instances,
even death. OSHA also concludes that
common health problems can cause
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difficulty in breathing while a person is
wearing a respirator. Most healthy
persons, however, will not have
physiological problems wearing
properly chosen and fitted respirators.
The final rule amends the existing
DPM respiratory protection standard at
§ 57.5060(d) by adding requirements for
mine operators to provide, at no cost to
the miner, a confidential medical
evaluation by a physician or other
licensed health care professional
(PLHCP) to determine the miner’s
ability to use a respirator before the
miner is fit tested or required to work
in an area of the mine where respiratory
protection must be used. When these
conditions occur the miner must be
reevaluated to determine the miner’s
ability to use the respirator.
Also included in the final rule is the
right of miners to discuss their medical
evaluations with the PLHCP before the
PLHCP submits to the mine operator a
copy of the PLHCP’s medical
determination. The mine operator must
have a written record of the most recent
medical evaluation to confirm that the
miner was evaluated. We believe that
the final rule includes a practical
approach for requiring medical
evaluations that lessens the compliance
burden on mine operators without
compromising miners’ health.
In addition, the final rule includes
requirements for transferring a miner to
an existing job in an area of the mine
where respiratory protection is not
required if a PLHCP has determined that
the miner’s medical condition precludes
the miner from safely wearing any
required respirator, including a powered
air-purifying respirator (PAPR). The
details of this requirement are discussed
below in this preamble. We believe that
compliance with the final rule will
enhance miner protection.
Section 57.5060(d)(3) of the final rule
requires that the mine operator provide
a confidential medical evaluation by a
PLHCP to determine the miner’s ability
to use a respirator before the miner is
required to be fit tested or to use a
respirator at the mine. The mine
operator must provide the medical
evaluation to the miner and pay the cost
of each of the miner’s medical
evaluations. Mine operators must make
certain that the PLHCP administers the
testing in a manner that protects the
confidentiality of the miner being
evaluated.
If the PLHCP determines that the
miner is able to wear a negativepressure respirator, the mine operator
must provide it and require the miner to
wear it under our existing respiratory
protection requirements. On the other
hand, if the PLHCP concludes that the
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miner is unable to wear a negativepressure respirator, the mine operator
must make certain that the PLHCP also
determines the miner’s ability to wear a
PAPR. If the PLHCP finds that the miner
can wear a PAPR, the mine operator
must provide the PAPR and require the
miner to wear it.
The miner must be evaluated by a
PLHCP prior to the miner wearing the
respirator for any duration or frequency
of respirator use, including prior to fit
testing of the respirator. This is because
we intend that a miner not be assigned
to tasks in the mine that require use of
a respirator unless a PLHCP makes a
written determination that the miner is
physically able to perform the work to
which the miner is assigned while using
the respirator. For enforcement
purposes, we will use the results of the
most recent written determination of the
PLHCP to assess compliance with this
provision. Whereas we have chosen not
to include a specific protocol for how
evaluations must be conducted, we
expect the PLHCP to conduct an
evaluation based on the individual
miner’s medical information.
As part of the PLHCP’s determination,
§ 57.5060(d)(4) requires that the mine
operator provide the miner with an
opportunity to discuss their evaluation
results with the PLHCP before the
PLHCP submits the written
determination to the mine operator. If
the miner disagrees with the
determination of the PLHCP, the miner
has up to 30 days to submit to the
PLHCP additional evidence of their
medical condition. Depending upon the
miner’s medical history, it may be
critical for the miner to discuss any
discrepancies or errors in a PLHCP’s
determination. The miner, however,
may at any time provide additional
medical information to the mine
operator if the miner believes that it
may impact the miner’s ability to wear
a respirator.
Section 57.5060(d)(5) requires the
mine operator to obtain a written
determination from the PLHCP
regarding the miner’s ability to wear a
respirator. The mine operator must
make certain that the PLHCP provides a
copy of the determination to the miner.
Though the rule does not specify a
timeframe in which the mine operator
must have the PLHCP provide a copy to
the miner of his or her medical
determination, we intend for the mine
operator to exercise diligence in getting
this important information to the miner.
Section 57.5060(d)(6) requires the
mine operator to reevaluate the miner
when the operator has reason to believe
that conditions have changed such as
when the miner is assigned to a new
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28987
task requiring a significantly greater
degree of physical exertion, or the miner
is assigned to work at a lower level of
a deep mine that is hotter and imposes
greater physiological stress. We expect
the mine operator to exercise sound
judgment when deciding whether the
miner must be reevaluated by a PLHCP.
Section 57.5060(d)(7) requires that
upon written notification that the
PLHCP has determined that the miner is
unable to wear a respirator (including a
PAPR), the miner must be transferred
within 30 days of the PLHCP’s
determination to work in an existing
position in an area of the same mine
where respiratory protection is not
required. Congress specifically included
in Section 101(a)(7) of the Mine Act that
when transfer of a miner is required
under this section that their
compensation must be as we
specifically stated in this final rule. As
a result, the miner must continue to
receive compensation at no less than the
regular rate of pay in the classification
held by that miner immediately prior to
the transfer. However, wage increases of
the transferred miner must be based on
the new work classification.
Under § 57.5060(d)(8) of the final rule,
the mine operator must maintain a
record of the identity of the PLHCP and
the most recent written determination of
each miner’s ability to wear a respirator
for the duration of the miner’s
employment plus six months thereafter.
In response to our 2005 NPRM, we
received numerous comments on issues
related to medical evaluation of
respirator wearers and transfer of miners
medically unable to wear respirators.
We requested comments in the 2005
NPRM regarding whether we should
amend existing § 57.5060(d) addressing
respiratory protection requirements by
adding regulatory language to provide
miners medical evaluations and transfer
rights pursuant to Section 101(a)(7) of
the Mine Act. One mine operator
commented that they still face
significant challenges to compliance
with the interim limit. They currently
require miners to wear respirators when
performing certain tasks that have been
a significant source of DPM exposure.
Based on their own samples, they
believe that the use of respiratory
protection would increase under the
final limit and be required of all miners
through the entire shift. They also stated
their concern for the burden this would
place on affected miners and noted that
mandatory respirator usage for the
entire shift would compromise miners’
acceptance of the rule and their ability
to safely remain productive. Further,
they believe that most companies that
have a formal respiratory protection
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program are currently conducting
medical evaluation in the program, and
consequently, should not have to
perform medical evaluation ‘‘solely to
comply with the rule.’’ Some other mine
operators commented that they perform
medical evaluations of a miner’s ability
to wear a respirator during preemployment examination, and annually
thereafter for workers who must wear
respirators, but did not believe it was
necessary to require medical evaluations
through regulation.
Although some mine operators are
already conducting medical evaluations
before fit testing and requiring miners to
wear respirators, not all underground
M/NM mine operators using diesel
powered equipment are conducting
voluntary medical evaluations. We
believe that the data establishing the
need for the evaluations support a
uniform approach for requiring
reevaluations.
We agree with the commenters who
acknowledged that existing voluntary
medical evaluations currently provided
by some mine operators do not establish
uniform protection for all miners
covered under the DPM standard. These
commenters also stated that simply
because some mine operators have
provided miners this protection does
not justify why others should continue
to be denied them. These commenters
support the need for including medical
evaluation in the final rule and stated
that voluntary medical evaluation
programs in the industry show that
mine operators, acting in good faith, can
easily implement a respirator program,
including transfer rights, without
practical or financial difficulty.
One commenter recommended that
we defer requiring medical evaluation
and transfer until we are able to
establish an accurate database on the
number of miners projected to be
affected. Our 2005 NPRM preliminary
estimates of the number of miners that
may be affected resulted from the
available data in the rulemaking record
at the time of the proposal. We have
since received comments from several
mine operators who included their
current costs for medical evaluations
and the number of miners affected. We
used this information in assessing our
cost analysis for the Regulatory
Economic Analysis (REA) supporting
this final rule.
Several other commenters voiced
concern over worker acceptance of
respirators in general, but believed that
medical evaluations were a good idea.
Organized labor stated that there is
substantial evidence in the record of the
relevant OSHA hearings to support
medical evaluations, and requested that
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we incorporate that evidence into this
record as well. We have incorporated
these data into the DPM rulemaking
record. As stated earlier, OSHA
acknowledges within its current
standards addressing respiratory
protection at 29 CFR 1910.134(e) that
use of a respirator may place a
physiological burden on workers while
using them. At a minimum, OSHA
requires employers to provide medical
evaluations before an employee is fit
tested or required to use respiratory
protection. Employers are required to
have a physician or other licensed
health care professional have the worker
complete a questionnaire, or in the
alternative, conduct an initial medical
examination in order to make the
determination. If the worker has a
positive response to certain specified
questions, the employer must provide a
follow-up medical examination. The
questionnaire is contained in the body
of the OSHA rule. The preamble to the
OSHA final rule states:
Specific medical conditions can
compromise an employee’s ability to tolerate
the physiological burdens imposed by
respirator use, thereby placing the employee
at increased risk of illness, injury, and even
death (Exs. 64–363, 64–427). These medical
conditions include cardiovascular and
respiratory diseases (e.g., a history of high
blood pressure, angina, heart attack, cardiac
arrhythmias, stroke, asthma, chronic
bronchitis, emphysema), reduced pulmonary
function caused by other factors (e.g.,
smoking or prior exposure to respiratory
hazards), neurological or musculoskeletal
disorders (e.g., ringing in the ears, epilepsy,
lower back pain), and impaired sensory
function (e.g., a perforated ear drum, reduced
olfactory function). Psychological conditions,
such as claustrophobia, can also impair the
effective use of respirators by employees and
may also cause independent of physiological
burdens, significant elevations in heart rate,
blood pressure, and respiratory rate that can
jeopardize the health of employees who are
at high risk for cardiopulmonary disease (Ex.
22–14). One commenter (Ex. 54–429)
emphasized the importance of evaluating
claustrophobia and severe anxiety, noting
that these conditions are often detected
during respirator training. [See 63 FR 1152,
01/08/1998]
Organized labor also stated:
* * * In all of our certification programs
we have included blood pressure and
spirometry measurements. In respirator
certification for a group of electrical workers,
we identified 7.5% who had abnormal
spirometry and were not given a respiratory
certificate until they had received further
medical evaluation and a repeat of the
spirometry.
This observation was [sic] supported in a
study of nurses working in a hospital close
to the World Trade Center at the time of the
disaster. Although exhibiting no respiratory
symptoms on their questionnaires, 10 of 110
nurses had abnormal spirograms and were
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referred to a Pulmonologist for further
evaluation.
In our evaluation of World Trade Center
Rescue workers, we have found similar
discrepancies between the questionnaire and
spirometry.
A report by S. Levine et al. (MMWR Sept.
10, 2004) notes that 33% [sic] had abnormal
spirometry but wheeze was [sic] only
reported in 0.9%. (David Parkinson, MD,
United Steelworkers Consultant,
Occupational Physician)
The final rule does not include a
protocol to guide the PLHCP on how to
conduct medical evaluations as the
OSHA standard does, but places the
responsibility on the mine operator to
provide an appropriate medical
evaluation by a PLHCP to determine the
miner’s ability to use a respirator before
the miner is required to be fit tested or
to use a respirator at the mine.
We intend that a ‘‘physician or other
licensed health care professional
(PLHCP)’’ be a physician, physician’s
assistant, nurse, emergency medical
technician or other person qualified to
provide medical or occupational health
services, as we have defined a ‘‘health
professional’’ under our Hazard
Communication standards at 30 CFR
47.11. We will accept the license as
proof of qualification to perform the
medical evaluation. We specified that
the health care worker be licensed to
ensure an acceptable level of
competency, but have not specified
which states’ licensing to accept. As we
said in our preamble to the final rule (64
FR 49578) on Health Standards for
Occupational Noise Exposure at 30 CFR
Part 62, ‘‘* * * although some state
licensing requirements are more
stringent than others, even the least
rigorous of the state requirements will
provide an acceptable level of
competence * * * [for audiologists].’’
NIOSH commented that in other
industries where respirators were used,
they supported the requirements
specified in the OSHA Respiratory
Protection Standard (29 CFR 1910.134),
with the exception of:
(a) The use of irritant smoke for qualitative
respirator fit testing, and (b) unsupervised
medical evaluations conducted by health
care professionals who are not licensed for
independent practice to perform or supervise
medical evaluations.
We also received comments from
mine operators who stated that they
already conduct medical evaluations, or
at the very least, pulmonary function
tests, during pre-employment
examinations. From the mine operators
who commented on their frequency of
these examinations, several commenters
stated that they test annually, another
tests every three years, while another
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performs them bi-annually. Others
noted that the tests were initially
performed during pre-employment
examinations, and thereafter, were
conducted whenever a miner was about
to be required to wear a respirator. One
commenter that provides a medical
exam upon employment and annually
thereafter stated:
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If the miners health conditions change
preventing the safe use of a respirator, then
additional tests can be provided including
spirometry and if indicated, a medical
examination. We have not had a case where
a miner’s health changed preventing the
wearing of a respirator, that the miner was
not aware of the health condition. We do not
object to annual spirometry testing following
guidelines developed and supervised by a
medical doctor or other medical professional.
We do object to the added expense of
requiring a medical exam every year if there
are no indicators of a medical necessity,
either by the miners own request or the
conditions mentioned.
The final rule requires that miners be
reevaluated when the mine operator has
reason to believe that conditions have
changed which could adversely affect
the miner’s ability to wear the
respirator. We believe that the final rule
provision is more appropriate and cost
effective than a restrictive schedule of
frequency of reevaluation to detect or
confirm the miner’s ability to safely
wear respiratory protection. We do not
envision, in most instances, that miners
will be in a respiratory protection
program for an extended length of time.
We recognize, however, that more
miners may have to wear respirators
when the PEL is reduced to 160TC mg/
m3. We received no comments in
support of establishing the need for a
specific frequency, but we did receive
several comments opposing them. Also,
a miner should alert the mine operator
whenever the miner experiences
changes in his or her health that could
impact his or her ability to safely wear
a respirator. Mine operators have the
responsibility for conducting a
reevaluation where a change in
workplace conditions may result in a
substantial increase in the physiological
burden that respirator use places on the
miner. For example, a change in the
miner’s work task may require greater
physical exertion or a change in the
work environment could increase the
stress on the miner.
A mine operator stated that the use of
PAPRs was not practical in most mining
applications. They believe that the need
for battery charging stations for the
PAPRs, storage facilities and
maintenance would significantly
increase the cost of a respiratory
protection program. NIOSH commented
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that PAPRs have some of the same
limitations as negative-pressure
respirators in that both impede
communication, hearing, vision, and
require periodic replacement of the
purifying elements, as well as other
disadvantages. NIOSH further stated:
* * * In addition, the battery must be
recharged on a daily basis so that the blower
will deliver enough respirable air to the
respiratory inlet covering. Batteries have a
limited useful life and cannot be recharged
indefinitely. The blower’s high speed motor
can wear out and require replacement; if the
blower fails in a loose-fitting PAPR, the
wearer will be without respiratory protection.
Other disadvantages include the weight and
bulk of the PAPR with its blower and battery,
which can hinder movement; complex
design; and the need for a higher level of
maintenance than a negative pressure
respirator.
NIOSH also commented, however,
that under normal use, PAPRs do not
impose the resistance to breathing that
is associated with negative-pressure
respirators and that for a miner who has
a medical condition placing the miner at
risk from using a negative-pressure
respirator, use of a PAPR is a potential
alternative to transfer of duties.
Another commenter stated that
anybody who is working underground
at their operations is provided a
pulmonary function check to make sure
that they are capable of wearing a
respirator. That commenter was not
aware of anyone being found unable to
do so. Several industry commenters
stated that they performed medical
evaluations for testing the ability of
miners to wear a negative-pressure
respirator during pre-employment and
annually thereafter. One commenter
noted that although they had found a
few miners who were unable to wear
negative-pressure respirators initially,
each of them responded to medical
treatment and subsequently was found
medically able to wear a negativepressure respirator.
Another commenter specified that
they have pulmonary function tests
performed on anyone entering a
respiratory protection program (about 10
miners), and had no one who was
determined to be unable to wear a
negative-pressure respirator. While a
commenter, on behalf of organized
labor, stated that only a few miners
would be unable to wear a negativepressure respirator, most of these miners
would be able to wear a PAPR. A
medical testing company that provides
pulmonary function and respiratory fits,
primarily for compliance with OSHA
regulations testified that, in their
experience, ‘‘with maybe a hundred
workers, anywhere from three to five
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28989
[workers] could not go to work because
of their lung problems over the years.’’
They also stated that they had not found
any workers unable to wear an airsupplying respirator or powered airpurifying respirator, as long as they
were clean-shaven. We agree with these
commenters that few miners will be
unable to wear a PAPR while
performing their tasks in a mine.
In the event that a miner is medically
unable to wear a negative-pressure
respirator, § 57.5060(d)(3) requires the
mine operator to make certain that a
PLHCP evaluates the miner’s ability to
use a PAPR, such as those that are
integrated into a hard hat. Although a
determination needs to be made that the
miner is medically able to wear a PAPR,
it is likely that most miners could wear
a PAPR. We believe that such
respirators are an effective option for
persons who cannot wear a negativepressure respirator and, in most
instances, will negate the need to
transfer the miner.
One commenter suggested that mine
operators be required to provide PAPRs
to miners who are medically unable to
wear a negative-pressure respirator, and
not be required to transfer the miner to
another position at equal pay unless the
miner was unable to wear either a
negative-or positive-pressure respirator.
Most commenters favored leaving the
choice to the mine operator. NIOSH
suggested transfer be reserved for those
who could not use either a negativepressure respirator or a PAPR. Final
§ 57.5060(d)(7) requires transfer of
miners when the PLHCP determines
that the miner cannot wear a respirator,
including a PAPR. If the PLHCP finds
that the miner cannot wear a negativepressure respirator, the mine operator
must make certain that the PLHCP tests
the miner’s ability to wear a PAPR.
Pursuant to existing § 57.5060(d), if the
mine operator can wear a PAPR, the
mine operator has an obligation to
provide it and require the miner to wear
it.
One commenter stated that as the
DPM standard becomes more stringent
and respirator usage increases, the
medical evaluation would need to be
adapted to evaluate the miner’s ability
to wear the respirator for the full shift
during high workload duties. The
commenter believes this would increase
the number of miners that are unable to
successfully pass the medical
evaluation, increasing the need for
transfer or termination. Although we
agree that the number of miners
required to use respirators would
increase as the DPM final limit is
lowered, we do not believe that it would
result in any significant increase in the
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number of transfers, because most
miners could wear a PAPR if they
cannot wear a negative pressure
respirator.
Most commenters stated that in the
event that we require medical transfer of
a miner, they opposed creating a job for
the transferred miner. They strongly
believe that transfer rights should be
limited to those circumstances where a
position is available where respiratory
protection is not required, and the
miner is qualified for that position.
Several of these commenters stated that
not giving consideration to miners’
skills or qualifications could result in a
miner being transferred into a position
where they are unqualified to perform
the work. As a result, this could create
a threat to the safety of the transferred
miner as well as to other miners.
We concluded in final § 57.5060(d)(7)
that the miner must be transferred to an
existing job in an area of the same mine
where respiratory protection is not
required. We believe that the
rulemaking record is insufficient to
establish justification for requiring mine
operators to create jobs for transferred
miners. The mine operator is in the best
position to determine if a miner is
qualified to perform the job to which the
miner is transferred based upon the
tasks involved. We would, however,
expect the mine operator to provide
necessary task training under our
existing standards at 30 CFR part 48.
Several small mine operators were
particularly concerned with the
difficulty of moving people to different
positions within their small workforce.
One operator said they often do crosstraining, but that their labor market was
limited and it was becoming more
difficult to find people willing to work
underground. Our primary objective
under this standard is to prevent miners
from being required to use a respirator
before the miner is determined to be
medically able to wear the respirator.
Section 101(a)(7) of the Mine Act, and
the data confirming the potential health
consequences of using a respirator with
certain illnesses and other medical
conditions, lead us to disagree with
these commenters.
Several mine operators commented
that available positions were limited for
transferred miners due to terms of labor
contracts. One mine operator with
several properties said it might be
difficult to find an available job at their
mine having about 25 employees, but
that they would consider offering a
position at one of their other properties
if a position was available there.
Another mine operator said that they
might not be able to find a job
underground, but that one on the
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surface might be available. The final
standard does not prohibit mine
operators from transferring a miner to an
existing job on the surface of the same
mine. Mine operators, however, must
make certain that they comply with the
compensation requirements in
§ 57.5060(d)(7)(i) and (ii). Moreover,
they must make certain that the new
miner is not overexposed to DPM on the
new job and is not required to use
respiratory protection, until such time
that a subsequent medical evaluation by
a PLHCP determines that the miner is
able to use the respirator.
One mine operator stated that most of
their underground miners would be
required to wear respirators, and as a
consequence, the availability of
alternative positions would be
extremely limited. The commenter
stated that the rate of pay should not be
tied to the position held by the worker
prior to the transfer but should be based
on the new position because wage scales
for underground workers are typically
higher than for comparable above
ground positions. Several other
commenters also wanted the wage rate
for a transferred miner to be based on
the new position. Again, we emphasize
that the final rule adopts our statutory
mandate articulated in the Mine Act
regarding compensation of transferred
miners. Under § 57.5060(d)(7)(i),
transferred miners are to receive ‘‘no
less’’ than the regular rate of pay that
they received in the job classification
that they were in immediately before the
transfer. Under § 57.5060(d)(7)(ii), mine
operators must base increases in wages
of transferred miners on the new work
classification.
We received several comments
regarding an appropriate regulatory
response to when a miner cannot meet
the requirements of wearing a respirator
while performing their duties, and there
is no available work that the restricted
miner is qualified to perform. Some
commenters suggested that the miner
should be considered medically unfit
for duty and terminated subject to their
company policies, collective bargaining
agreements, and State or Federal laws.
One commenter stated that they did not
have transfer rights in their contracts,
but had been assured that if the
circumstance arose, their human
resources department would see
whether the miner could be moved to an
available job. In response, the final rule
does not require mine operators to
create a job for miners who need to be
transferred.
Organized labor stated its strong
support for medical evaluation and
transfer. They believe that since a mine
operator who assigns a miner to work in
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a respirator without a medical
evaluation puts that worker’s life at risk,
we have an obligation to protect miners
from such harm. We agree that medical
evaluation and transfer requirements are
a necessary component to the existing
DPM respiratory protection program,
and we have included this protection in
the final rule for improving miners’
health.
In our preamble to the 2005 final rule,
we stated our belief that a requirement
for medical evaluation of respirator
wearers and transfer of miners unable to
wear respirators was inappropriate for
that rulemaking (70 FR 32957). At that
time, we believed that these
requirements would have minimal
application, particularly considering the
extent to which mine operators were
voluntarily implementing such
provisions and the limited long term use
of respirators envisioned under the
interim rule. We are now persuaded that
under the final limit, this is no longer
the case.
Notwithstanding the continuation of
some voluntary use of these programs in
the mining industry, we are concerned
that more miners may be required to
wear respirators for longer periods of
time as the final limit is lowered, and
therefore, medical evaluation and
transfer should not remain an elective.
If, however, we fail to include transfer
rights for miners unable to wear
respiratory protection, the effect may be
worse than not requiring a medical
evaluation at all. The mine operator,
acting on false information given by the
miner to protect his or her job, is then
in the position of assigning a respirator
to a miner who cannot safely wear it.
The best course of action for miner’s
health is to remove the fear of reprisals
to the degree necessary to allow the
miner to truthfully and fully participate
in a medical evaluation.
We realize that particularly at a small
mine, an alternative position may not
exist. Under this circumstance, we
believe that the mine operator is best
suited to determine how to
accommodate that miner based on
existing employment rights pursuant to
collective bargaining agreements, and
state and federal laws, etc. The final
rule, however, prohibits a mine operator
from allowing a miner to voluntarily
work in an area where respiratory
protection is required without a
respirator and when the miner is
medically unable to wear a respirator.
We received one comment objecting
to notification to the District Manager of
the health professional’s evaluation and
the fact that a miner will be transferred.
We have not included notification
requirements in the final rule due to our
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objective to limit the paperwork burden
on mine operators, and due to the fact
that our inspectors have access to mine
operators’ records and can determine
that miners have been transferred.
NIOSH recommended that mine
operators be required to maintain
records of miners’ medical evaluations,
respirator use, and transfers required
under this rule and that the records be
kept confidential and in a secure
location. The final rule requires mine
operators to keep a record of the identity
of the PLHCP and the most recent
written determination of each miner’s
ability to wear a respirator for the
duration of the miner’s employment
plus six months. It is important that we
note that our compliance specialists
have access to these records pursuant to
Section 103(h) of the Mine Act, and
operators must make these records
available to the authorized
representatives of the Secretary of
Labor.
NIOSH recommended that the
timeframe for transfer be as rapid as
possible if a miner is experiencing acute
health effects from exposure. The final
rule requires the mine operator to
transfer the affected miner within 30
days of the final determination by the
PLHCP that the miner is unable to wear
a respirator. We anticipate most
overexposures to be chronic rather than
acute, and therefore, have given greater
latitude in the time for compliance.
A number of commenters stated that
where miners’ exposures cannot be
reduced below the applicable final
limit, the standard should provide that
the mine operator may assign other
miners who must wear respiratory
protection to work in the affected area
to reduce the amount of time that any
given miner must wear respiratory
protection. We do not agree. Allowing
this practice fails to eliminate the
hazard of DPM exposure and results in
placing more miners at risk. We do
believe that a two-year phase-in
approach of the final limit of 160TC µg/
m3 will resolve many of the existing
feasibility issues as discussed in the
feasibility section of this preamble.
Although the number of miners required
to wear respirators is likely to increase
initially under the 160TC µg/m3 final
limit, with the use of biodiesel and
other available DPM controls, we project
that the number of miners in respiratory
protection should decrease over time.
In the 2005 NPRM, we estimated that
medical evaluation and transfer
requirements would affect about 50
miners annually for evaluation, about 3
miners annually for transfer, and cost
about $40,000 annually. We asked for
comments on costs to mine operators for
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implementing a rule requiring medical
evaluations and transfer of miners.
One mine commented that they have
a formal medical evaluation conducted
prior to being fit tested and annually
thereafter. Their average cost for an
evaluation to be able to wear a negativepressure respirator was $250 per miner.
They also estimated that the cost for
them to provide a PAPR for miners
unable to wear a negative-pressure
respirator would be approximately
$700. One large gold mine commented
that they believed approximately 70%
(480) of their 686 underground
personnel would require respiratory
protection in meeting the final 160 TC
limit.
Another commenter said they have
onsite technicians who are certified to
conduct these tests (medical
evaluation), however, the analysis of the
pulmonary function tests is provided by
a licensed healthcare provider. Their
cost for the pulmonary function tests is
roughly $17.00 per individual. Another
company estimated that the average cost
per person for medical evaluations is
$660. The range for costs varied widely
depending on the types of tests
performed and whether the cost of the
respirator itself was included. We have
considered these new data in our REA
in support of the final rule and have
revised our costs estimates.
As explained in section IX.A. of this
preamble, a total of 680 miners will
require a medical evaluation in the first
year after the rule takes effect to meet
the 350TC µg/m3 limit. An additional
244 miners will require a medical
evaluation when the 160TC µg/m3 takes
effect. The estimated yearly medical
evaluation and transfer costs to mine
operators to meet the requirements of
the final rule are $69,170.
D. Diesel Particulate Records
§ 57.5075(a)
The recordkeeping requirements of
the DPM standards contained in
§§ 57.5060 through 57.5071 are listed in
a table entitled ‘‘Table 57.5075(a)—
Diesel Particulate Matter Recordkeeping
Requirements.’’ The table lists the
records the operator must maintain
pursuant to §§ 57.5060 through 57.5071,
and the retention period for these
records.
The final rule also makes a confirming
change to the Table in § 57.5075(a)
which includes a record of the identity
of the physician or other licensed health
care professional (PLHCP) and the most
recent written determination of each
miner’s ability to wear a respirator for
the duration of the miner’s employment
plus six months.
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As discussed in detail under section
VIII.C. Medical Evaluation and Transfer,
we have determined that medical
evaluation and transfer requirements are
a necessary component to the existing
DPM respiratory protection program,
and have included this requirement for
improving miners’ health in the final
rule. Thus, we are amending the
existing DPM respiratory protection
standard at § 57.5060(d) by adding a
provision requiring a medical
evaluation to determine a miner’s ability
to use a respirator before the miner is fit
tested or required to work in an area of
the mine where respiratory protection
must be used.
The final rule also includes
requirements for transferring a miner to
an existing job in an area of the mine
where respiratory protection is not
required if a PLHCP has determined that
the miner’s medical condition precludes
the miner from safely wearing any type
of respirator, including a PAPR.
Under paragraph (d)(8) the mine
operator must maintain a record of the
identity of the PLHCP and the most
recent written determination of each
miner’s ability to wear a respirator for
the duration of the miner’s employment
plus six months. We consider this
document to be a medical record and
our retention requirements are
consistent with other medical records
that we require mine operators to
maintain, such as those specified in our
existing Hearing Conservation Program
requirements in 30 CFR 62.171. By
requiring the operator to retain a copy
of these documents, it will help protect
miner’s health and assist with
compliance with § 57.5060(d). This new
recordkeeping requirement will be
incorporated into existing Table
57.5075(a)—Diesel Particulate
Recordkeeping Requirements.
IX. Regulatory Costs
Section IX.A discusses the costs
attributable to this final rule. These
costs arise from new provisions for
medical evaluation and transfer. Section
IX.B discusses the costs of
implementing the 160TC µg/m3 final
limit, given that the existing 308EC µg/
m3 interim limit is in effect. The move
from the existing higher limit to the
lower final limit results from a series of
final rules, including both this final rule
and two prior rules. Other than the costs
for medical evaluation and transfer
(estimated in Section IX.A and reported
in Section IX.B), the costs presented in
Section IX.B are not attributable to this
final rule. All costs are reported in 2004
dollars.
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If a respirator is needed, the mine
operator would have to provide a
negative-pressure respirator. However, if
the PLHCP determines that the miner
cannot wear a negative-pressure
respirator but can wear a positivepressure respirator, then the mine
operator would be required to provide a
powered air-purifying respirator (PAPR)
to the miner.
To estimate the cost of these medical
evaluation and transfer provisions, for
the 308EC µg/m3, 350TC µg/m3, and
160TC µg/m3 limits, MSHA made the
following assumptions:
In each year that medical evaluations
are required for a mine, it would take a
mine health and safety specialist,
earning $52.31 per hour, 1 hour to
prepare information for the PLHCP.3
The cost of a medical evaluation is
$50. This medical evaluation consists of
a medical questionnaire or interview
with the PLHCP and a simple
pulmonary function test.
Four miners per mine in mines with
fewer than 20 employees will need to
use respirators and therefore require a
medical evaluation in the first year that
respirators are required for mines that
need them.4 Twelve miners per mine in
mines with 20–500 employees will need
to use respirators and therefore require
a medical evaluation in the first year
that respirators are required for mines
that need them.5 Thirty miners per mine
in mines with over 500 employees will
need to use respirators and therefore
require a medical evaluation in the first
year that respirators are required for
mines that need them.6
Based on these assumptions a total of
680 miners will require a medical
evaluation in the first year after the rule
takes effect to meet the 308EC and 350TC
µg/m3 limits. An additional 244 miners
will require a medical evaluation at the
beginning of the third year when the
160TC µg/m3 limit takes effect.
Because of turnover, new miners will
require medical evaluations in years
subsequent to the first year in which
respirators are first used. In each year
after the first year, approximately 0.28
additional miners per mine will require
a medical evaluation in mines with
fewer than 20 employees. In each year
The mine operator would have to
transfer the miner to an existing
position in the same mine where
respiratory protection is not required if
the PLHCP determined that the miner
was unable to wear either a negativepressure respirator or a PAPR. The mine
operator would be required to
compensate the miner at no less than
the regular rate of pay received by the
miner immediately before the transfer.
after the first year, approximately 0.84
additional miners per mine will require
a medical evaluation in mines with 20–
500 employees. In each year after the
first year, approximately 2.1 additional
miners per mine will require a medical
evaluation in mines with 20–500
employees.7
In ten percent of the cases, the PLHCP
will determine that additional tests are
needed for the miner’s medical
evaluation. These additional tests may
include X-rays and cardio-pulmonary
tests. The cost of the additional tests is
$250.
Five percent of the miners required to
wear a respirator will need a PAPR. A
PAPR costs approximately $1,000 and
has a useful life of about 5 years.
At any point in time, approximately
1⁄2% of the number of miners using
respirators will need to be transferred.
The total is expected to be fewer than
five transferred employees at any one
time for the entire mining industry. The
normal hourly wage rate in an existing
position where respiratory protection is
not required averages 20% less than the
miner’s hourly wage rate in the position
where respiratory protection is required,
taking into account the rare cases where
there is no position in the mine to
which the miner can be transferred. A
miner works 2,000 hours per year on
average. The average remaining work
life of a miner is 20 years.
Based on the preceding assumptions,
Table IX–1 summarizes the costs of
medical evaluation and transfer by mine
size for 308EC µg/m3, 350TC µg/m3, and
160TC µg/m3 limits. The estimated
yearly medical evaluation and transfer
costs to mine operators to meet the
requirements of the final rule are
$69,170 in 2004 dollars.8 The costs
shown in Table IX–1 are the only costs
attributable to this final rule.
3 MSHA assumes that the wage of a health and
safety specialist is the same as the wage of a mine
supervisor. The wage is reported in 2004 dollars.
4 This estimate is based on the assumption of two
two-person crews for one shift in mines with fewer
than 20 employees.
5 This estimate is based on the assumption of
three two-person crews for each of two shifts at
mines with 20–500 employees.
6 This estimate is based on the assumption of five
two-person crews for each of three shifts at mines
with over 500 employees.
BILLING CODE 4510–43–P
A. Costs of Medical Evaluation and
Transfer
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The medical evaluation and transfer
provisions would require the mine
operator to provide a medical evaluation
by a physician or other licensed health
care professional (PLHCP) to each miner
required to wear a respirator. MSHA
will accept a prior medical evaluation to
the extent the mine operator has a
written record and there have not been
any changes that will adversely affect
the miner’s ability to wear a respirator.
For those miners who do not have an
existing medical evaluation, we expect
that the mine operator would need to
provide the PLHCP with information,
including the types and weights of the
respirator that the miner will use, the
duration and frequency of respirator
use, the expected physical work effort,
additional protective clothing and
equipment worn, and temperature and
humidity extremes that may be
encountered. The mine operator would
also need to provide additional medical
evaluations if: the miner’s supervisor
notifies the PLHCP of medical signs or
symptoms related to the miner’s ability
to use a respirator; the PLHCP informs
the mine operator that the miner needs
to be reevaluated; information from the
respiratory protection program indicates
a need for miner reevaluation; or a
change in workplace conditions occurs.
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7 These numbers are based on a turnover rate of
7% for the four miners per mine in mines with
fewer than 20 employees, the 12 miners per mine
in mines with 20–500 employees , and the 30
miners per mine in mines with over 500: 4 × 0.07
= 0.28; 12 × 0.07 = 0.84; 30 × 0.07 = 2.10.
8 The spreadsheets underlying the development
to the cost estimates presented in this section, as
well as in Sections V, X, and XI of this preamble,
are posted on MSHA’s Web page.
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This subsection discusses all the costs
of reducing the existing 308EC µg/m3
interim limit to the 160TC µg/m3 final
limit. These costs arise from both this
final rule and the existing 2001 and
2005 final DPM rules for metal/
nonmetal mines. Most of the costs
estimated in this subsection are not
attributable to this final rule. The costs
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described and explained in this
subsection are presented for purposes of
completeness and clarity and to support
the Agency’s finding of feasibility for
the final limit, as shown in Section V.
In Chapter IV of the Regulatory
Economic Analysis in support of the
January 19, 2001 final rule (2001 REA),
we estimated that underground M/NM
mine operators would incur yearly costs
to comply with the DPM final rule of
$25,149,179 (p. 106). Of this amount,
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$6,612,464 was the discounted (from
2006 to 2001) yearly cost of compliance
with the final limit. The yearly cost for
compliance with the final limit
beginning in 2006 was estimated as
$9,274,325 (p. 58). If we adjust for the
change in the number of mines and also
adjust for inflation (from 1998 dollars,
in which the costs of the 2001 rule were
reported, to 2004 dollars), this yearly
cost becomes $9,259,519. These
calculations are shown in Table IX–2.
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This final rule would amend the
January 19, 2001 final DPM rule by
phasing in the 160TC µg/m3 final limit
over an additional two-year period, from
May 20, 2006 to May 20, 2008, to
address feasibility issues that have
surfaced since the 2001 final rule. The
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discounted present value of the
reduction in the cost estimate for this
two-year phase-in period is $15,467,387.
The annualized value of this reduced
cost estimate, using an annualization
rate of 7%, is $1,082,717 in 2004
dollars. Table IX–3 shows these
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calculations, as well as the breakdown
by mine size of this reduced cost
estimate. Because of feasibility issues
associated with currently meeting the
160TC µg/m3 limit, this reduction in
cost estimate is not properly attributable
as a cost saving due to this final rule.
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The process of evaluating and
implementing DPM control technologies
has been more difficult, time
consuming, and costly for some mine
operators than we had initially
anticipated in the 2001 final rule. For
example, some mine operators that
initially installed a passive regeneration
system on a machine learned through
trial and error that the machine did not
have a consistent duty cycle that would
support passive regeneration, so they
had to alter their regeneration strategy to
incorporate an active regeneration
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system. Another mine operator, who
initially tried a high-temperature
disposable particulate filter (HTDPF)
without exhaust gas cooling prior to the
filter media, needed to add a heat
exchanger prior to the filter media to
meet the manufacturer’s exhaust gas
temperature specifications. Yet another
mine operator, who used biodiesel fuel
during the summer months, needed to
make changes to the fuel delivery
system during the winter months in
order to deal with the lower ambient
temperatures.
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These evaluation and implementation
costs, it should be noted, do not involve
testing the workability of the known
methods for reducing DPM emissions.
Rather, the evaluation is for determining
the suitability of the various existing
DPM-control technologies for minespecific applications and integrating
such technology into the mining and
maintenance process. While the
industry has provided examples of its
experience with implementation
difficulties, they provided limited
information as to the magnitude of these
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particular costs. Accordingly, the costs
associated with evaluating various
methods to achieve compliance are
difficult to quantify.
Evaluation costs typically will not
involve all diesel equipment. For
example, we would expect a mine
operator to evaluate filters on one or a
few pieces of diesel equipment,
probably during maintenance shifts. We
therefore expect that costs of evaluation
will be only a fraction of MSHA’s
estimated costs of achieving the final
limit. Accordingly, based on its
technical expertise and experience with
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DPM controls, MSHA estimates that, for
the average mine that has evaluation
costs, annual costs of evaluating
alternative methods of compliance are
25% of the previously estimated
compliance costs for mines to reduce
the 308EC µg/m3 limit to the 160TC µg/
m3 limit.
Not all the diesel mines will incur
evaluation costs, beyond the costs
previously estimated, to comply with
the rule. Many mines are already in
compliance or can achieve compliance
using technologies already proven to
work in these mines. MSHA estimates
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that during the first two years of the
rule, 50% of mines will experience
evaluation costs. Further, MSHA
estimates that during the third and
fourth years of the rule, 10% of mines
will continue to experience evaluation
costs. These evaluation costs are being
recognized in this final rule, as needed
to achieve the final limit. However,
these costs were not caused by, or
attributable to, this final rule. These
costs would exist even in the absence of
this final rule. These cost estimates are
shown in Table IX–4.
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effect. Table IX–5 also includes the costs
of the medical evaluation and transfer
provisions discussed in Section IX.A of
this preamble and the costs of the
special extensions for the final limit
provided for in the 2005 DPM final
rule.9 The yearly cost of implementing
the 160TC µg/m3 final limit is
$8,454,853. The economic feasibility of
the 160TC µg/m3 final limit, as reflected
in these revised cost estimates, is
discussed in Section V.B.
X. Regulatory Flexibility Act
Certification and Small Business
Regulatory Enforcement Fairness Act
(SBREFA)
A. Definition of a Small Mine
Pursuant to the Regulatory Flexibility
Act (RFA) of 1980 as amended by the
Small Business Regulatory Enforcement
Fairness Act (SBREFA), we have
analyzed the impact of the final rule on
small businesses. Further, we have
made a determination with respect to
whether or not we can certify that the
final rule would not have a significant
economic impact on a substantial
number of small entities that are
covered by the final rule. Under the
SBREFA amendments to the RFA, we
must include in the rule a factual basis
for this certification. If a rule would
have a significant economic impact on
a substantial number of small entities,
we must develop a regulatory flexibility
analysis.
9 The cost savings due to other provisions of the
2005 DPM final rule are not included in the
estimates here because they have already accrued
to mine operators in achieving the interim limit.
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Under the RFA, in analyzing the
impact of a rule on small entities, we
must use the Small Business
Administration (SBA) definition for a
small entity or, after consultation with
the SBA Office of Advocacy, establish
an alternative definition for the mining
industry by publishing that definition in
the Federal Register for notice and
comment. We have not taken such an
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Table IX–5 integrates all the cost
estimates and cost adjustments
discussed in this subsection to provide
an updated estimate of the cost for the
industry to comply with the 160TC µg/
m3 final limit, given that the existing
308EC µg/m3 interim limit is already in
Federal Register / Vol. 71, No. 96 / Thursday, May 18, 2006 / Rules and Regulations
action and hence are required to use the
SBA definition. The SBA defines a
small entity in the mining industry as
an establishment with 500 or fewer
employees.
We have also looked at the impacts of
our rules on a subset of mines with 500
or fewer employees—those with fewer
than 20 employees, which we and the
mining community have traditionally
referred to as ‘‘small mines.’’ These
small mines differ from larger mines not
only in the number of employees, but
also in economies of scale in material
produced, in the type and amount of
production equipment, and in supply
inventory. Therefore, their costs of
complying with our rules and the
impact of our rules on them will also
tend to be different. It is for this reason
that ‘‘small mines,’’ as traditionally
defined by us as those employing fewer
than 20 workers, are of special concern
to us.
This analysis complies with the legal
requirements of the RFA for an analysis
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XI. Paperwork Reduction Act
This final rule addresses information
collection requirements under OMB
Control Number 1219–0135 that have
been submitted to the Office of
Management and Budget (OMB) for
review under 44 U.S.C. 3504(h) of the
Paperwork Reduction Act of 1995, as
amended.
The paperwork costs presented in this
section are a subset of the total costs
presented in Table IX–1 and reflect only
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B. Factual Basis for Certification
MSHA’s analysis of impacts on ‘‘small
entities’’ begins with a ‘‘screening’’
analysis. The screening compares the
estimated compliance costs of a rule for
small entities in the sector affected by
the rule to the estimated revenues for
the affected sector. When estimated
compliance costs are less than one
percent of the estimated revenues, the
Agency believes it is generally
appropriate to conclude that there is no
significant economic impact on a
substantial number of small entities.
When estimated compliance costs
exceed one percent of revenues, it tends
to indicate that further analysis may be
warranted.
As shown in Table X–1, using either
MSHA’s traditional definition of a small
mine (those having fewer than 20
employees) or SBA’s definition of a
small mine (those having 500 or fewer
employees), the estimated yearly costs
of this final rule for small underground
M/NM mines that use diesel-powered
equipment is less than 0.01 percent of
their estimated yearly revenues, well
below the level suggesting that this rule
might have a significant economic
impact on a substantial number of small
entities. Accordingly, we have certified
that this final rule will not have a
significant economic impact on a
substantial number of small entities
covered by the final rule.
those costs which relate to burden hours
that are a result of the final rule. Both
paperwork burden hours and costs were
derived from the spreadsheets (posted
on our Web page) used to estimate the
costs in Table IX–1.
MSHA estimates that the final rule
would create 3,687 burden hours for the
first year, 299 burden hours for the
second year, 1,120 burden hours for the
third year, and 371 burden hours each
year after the third year. This is
equivalent to an annualized value of
1,261 burden hours per year and related
annualized burden costs of $28,905 per
year. On a per-mine basis, the
annualized paperwork burden is 7.5
hours and $172 per year.
The paperwork burden to the mine
operator is attributable primarily to
§ 57.5060(d)(3), to prepare and provide
information to the PLHCP and to send
the miner to the PLHCP for a medical
evaluation to determine the miner’s
of the impacts on ‘‘small entities’’ while
continuing our traditional definition of
‘‘small mines.’’ We conclude that we
can certify that the final rule would not
have a significant economic impact on
a substantial number of small entities
that are covered by this rulemaking. We
have determined that this is the case
both for mines affected by this
rulemaking with fewer than 20
employees and for mines affected by
this rulemaking with 500 or fewer
employees.
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28999
ability to use a respirator. The
annualized paperwork and cost burden
to the mining industry for this provision
is 1,140 hours and $26,330 per year. The
remaining paperwork burden is
attributable to § 57.5060(d)(4), which
allows miners to submit additional
evidence of their medical condition to
the PLHCP, and to § 57.5060(d)(8),
which requires mine operators to
maintain a record of the identity and
written determination of the PLHCP.
The annualized paperwork and cost
burden to the mining industry for these
two provisions is 103 and 17 hours per
year, and $2,190 and $385 per year,
respectively.
The total paperwork hour and cost
burden is summarized in Table XI–1 by
first year, second year, third year, and
each year after the third year.
XII. Other Regulatory Considerations
accuracy and completeness of this
environmental assessment when this
rule was first proposed, and received no
comments relevant to this
environmental assessment. We find,
therefore, that the final rule has no
significant impact on the human
environment. Accordingly, we have not
provided an environmental impact
statement.
D. Executive Order 12630: Government
Actions and Interference With
Constitutionally Protected Property
Rights
This final rule does not implement a
policy with takings implications.
Accordingly, Executive Order 12630,
Governmental Actions and Interference
with Constitutionally Protected Property
Rights, requires no further agency action
or analysis.
This final rule does not include any
Federal mandate that may result in
increased expenditures by State, local,
or tribal governments; nor does it
increase private sector expenditures by
more than $100 million annually; nor
does it significantly or uniquely affect
small governments. Accordingly, the
Unfunded Mandates Reform Act of 1995
(2 U.S.C. 1501 et seq.) requires no
further agency action or analysis.
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B. National Environmental Policy Act
We have reviewed this final rule in
accordance with the requirements of the
National Environmental Policy Act
(NEPA) of 1969 (42 U.S.C. 4321 et seq.),
the regulations of the Council on
Environmental Quality (40 U.S.C. 1500),
and the Department of Labor’s NEPA
procedures (29 CFR part 11). This final
rule has no significant impact on air,
water, or soil quality; plant or animal
life; the use of land; or other aspects on
the human environment. We solicited
public comment concerning the
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C. The Treasury and General
Government Appropriations Act of
1999: Assessment of Federal
Regulations and Policies on Families
This final rule has no affect on family
well-being or stability, marital
commitment, parental rights or
authority, or income or poverty of
families and children. Accordingly,
Section 654 of the Treasury and General
Government Appropriations Act of 1999
(5 U.S.C. 601 note) requires no further
agency action, analysis, or assessment.
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E. Executive Order 12988: Civil Justice
Reform
This final rule was written to provide
a clear legal standard for affected
conduct, and was carefully reviewed to
eliminate drafting errors and
ambiguities, so as to minimize litigation
and undue burden on the Federal court
system. Accordingly, this final rule
meets the applicable standards provided
in Section 3 of Executive Order 12988,
Civil Justice Reform.
F. Executive Order 13045: Protection of
Children From Environmental Health
Risks and Safety Risks
This final rule has no adverse impact
on children. Accordingly, Executive
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A. The Unfunded Mandates Reform Act
of 1995
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Federal Register / Vol. 71, No. 96 / Thursday, May 18, 2006 / Rules and Regulations
Order 13045, Protection of Children
from Environmental Health Risks and
Safety Risks, as amended by Executive
Orders 13229 and 13296, requires no
further agency action or analysis.
G. Executive Order 13132: Federalism
This final rule does not have
‘‘federalism implications,’’ because it
does not ‘‘have substantial direct effects
on the States, on the relationship
between the national government and
the States, or on the distribution of
power and responsibilities among the
various levels of government.’’
Accordingly, Executive Order 13132,
Federalism, requires no further agency
action or analysis.
H. Executive Order 13175: Consultation
and Coordination With Indian Tribal
Governments
This final rule does not have ‘‘tribal
implications,’’ because it does not ‘‘have
substantial direct effects on one or more
Indian tribes, on the relationship
between the Federal government and
Indian tribes, or on the distribution of
power and responsibilities between the
Federal government and Indian tribes.’’
Accordingly, Executive Order 13175,
Consultation and Coordination with
Indian Tribal Governments, requires no
further agency action or analysis.
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I. Executive Order 13211: Actions
Concerning Regulations That
Significantly Affect Energy Supply,
Distribution, or Use
Regulation of the M/NM sector of the
mining industry has no significant
impact on the supply, distribution, or
use of energy. This final rule is not a
‘‘significant energy action,’’ because it is
not ‘‘likely to have a significant adverse
effect on the supply, distribution or use
of energy * * * (including a shortfall in
supply, price increases, and increased
use of foreign supplies).’’ Accordingly,
Executive Order 13211, Actions
Concerning Regulations That
Significantly Affect Energy Supply,
Distribution, or Use, requires no further
agency action or analysis.
J. Executive Order 13272: Proper
Consideration of Small Entities in
Agency Rulemaking
We have thoroughly reviewed this
final rule to assess and take appropriate
account of its potential impact on small
businesses, small governmental
jurisdictions, and small organizations.
As discussed in Chapter V of the REA,
we have determined and certified that
this final rule will not have a significant
economic impact on a substantial
number of small entities. We solicited
public comment concerning the
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accuracy and completeness of this
potential impact when the rule was first
proposed. We took appropriate account
of comments received relevant to the
rule’s potential impact on small entities.
Accordingly, Executive Order 13272,
Proper Consideration of Small Entities
in Agency Rulemaking, requires no
further agency action or analysis.
XIII. Information Quality
In accordance with the Information
Quality Act and the Department of
Labor Information Quality Guidelines,
we are responding to the substantive
information quality request of the
Methane Awareness Resource Group
(MARG) as part of other information/
data related comments received in the
record to this rulemaking. Some of the
commenters’ issues are limitations of
models, such as the 31-Mine Study and
the Estimator model. No better data
were offered by commenters and we
find that that information remains the
best available. We also conclude that
some of the corrections requested were
policy solutions rather than information
corrections, thus they will not be
addressed in our response.
We received a number of comments
from the mining industry suggesting
that our risk assessment does not
comply with the present requirements
under the data quality guidelines to use
the best available, peer reviewed
science. In addition, industry
commenters stated that the DPM rule
does not comply with the congressional,
Office of Management and Budget
(OMB) and the Department of Labor
(DOL) information quality guidelines
because the DPM rule is not supported
by an adequate scientific basis, and it
fails to meet the reproducibility
standard required for disseminating
influential information. Moreover, these
commenters stated that OMB requires
agencies in their own data quality
guidelines to submit for public
comment data on which we rely or
disseminate. The guidelines also
establish administrative mechanisms
that allow affected persons to seek or
obtain correction of disseminated
information if they believe such
information does not comply with either
the OMB or MSHA guidelines.
Throughout the DPM rulemakings, we
have given serious consideration to the
issues raised by commenters. As a
result, we have made some adjustments
to our data and provided comprehensive
responses in this preamble. For
example, we conducted the 31-Mine
Study, which resulted from a joint
protocol of government, the mining
industry and organized labor, to address
and correct, where necessary, the
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following issues with regard to our 2001
data:
—The validity, precision and feasibility of
the sampling and analysis method
specified by the diesel standard (NIOSH
Method 5040);
—The magnitude of interferences that occur
when conducting enforcement sampling
for total carbon as a surrogate for diesel
particulate matter (DPM) in mining
environments; and,
—The technological and economic feasibility
of the underground metal and nonmetal
(MNM) mine operators to achieve
compliance with the interim and final
DPM concentration limits.
—The parties developed a joint MSHA/
Industry study protocol to guide sampling
and analysis of DPM levels in 31 mines.
The parties also developed four
subprotocols to guide investigations of the
known or suspected interferences, which
included mineral dust, drill oil mist, oil
mist generated during ammonium nitrate/
fuel oil (ANFO) loading operations, and
environmental tobacco smoke (ETS). The
parties also agreed to study other potential
sampling problems, including any
manufacturing defects of the DPM
sampling cassette (70 FR 32871).
(Executive Summary, Report on the 31Mine Study)
MSHA requested that NIOSH peer
review the draft Report on the 31-Mine
Study, and NIOSH’s conclusions were
placed in the rulemaking record and
published in the 2005 final rule (70 FR
32871).
We are confident that we have set
forth the evidence and rationale behind
our decisions to establish a rule
amending the existing DPM standard
that meets the statutory requirements for
promulgating this health standard as
required under the Federal Mine Safety
and Health Act of 1977 (Mine Act) in
Section 101(a)(6)(A). We have presented
and discussed with commenters in
Federal Register notices, in preambles
and at public hearings, the evidence
supporting our decision to revise the
existing rule restricting miner exposure
to DPM.
With regard to the 2001 DPM risk
assessment, we relied on peer-reviewed
scientific studies. Of particular note, is
that the two quantitative meta-analyses
of lung cancer studies supporting our
risk assessment were peer reviewed and
published in scientific journals. (Bhatia,
Rajiv, et al., ‘‘Diesel Exhaust Exposure
and Lung Cancer,’’ Journal of
Epidemiology, 9:84–91, January 1998,
and Lipsett M., and Campleman, Susan,
‘‘Occupational Exposure to Diesel
Exhaust and Lung Cancer: A MetaAnalysis,’’ American Journal of Public
Health, (89) 1009–1017, July 1999). We
informed the public as early as
September 25, 2002, in the 2002
ANPRM for the 2005 final rule at M/NM
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mines, in the 2003 NPRM, in the 2005
final rule and again in the 2005
proposed rule that we would
incorporate the existing rulemaking
record into the record of this
rulemaking, including the 2001 risk
assessment. In that risk assessment, we
carefully laid out the evidence available
to us, including shortcomings inherent
in that evidence. Although not required
by law to do so, we had the 2001 risk
assessment independently peerreviewed, published the evidence and
tentative conclusions for public
comment, and incorporated the
reviewers’ recommendations. We were
open to considering any new scientific
data relating to the risk assessment.
Commenters were encouraged in the
instant rulemaking to submit new
scientific data related to the health risk
from exposure to DPM. Some
commenters did submit new evidence
and we have included those documents
in the record for consideration.
Other commenters stated that we need
to stay the interim and final limits and
wait for completion of the NIOSH/NCI
Study. They believe that any regulatory
effort before the completion of the study
is not in compliance with the DOL
Guidelines that define influential
information: ‘‘In rulemaking, influential
information is scientific, financial, or
statistical information that the agency
believes will have a clear and
substantial impact on the resolution of
one or more key issues in an
economically significant rulemaking, as
that term is defined in section 3(f)(1) of
Executive Order 12866 (DOL
Guidelines, p. 6).’’
We have a statutory obligation to
consider in a rulemaking the best
available evidence. (Section
101(a)(6)(A)). Though the NIOSH/NCI
Study is ongoing, at this time, we are
confident that the current rulemaking
record includes credible scientific data
to establish occupational exposure
limits for DPM. The scientific basis for
the health risk of exposure to DPM is
supported by the rulemaking record in
both the 2001 and 2005 rules. We will
continue to closely monitor the progress
of the NIOSH/NCI joint study, and when
the results of this study become
available, we will carefully consider
them.
Commenters stated that our statement
that TC cannot be measured accurately
and our change to a new surrogate, EC,
undermines our 2001 justifications for
our diesel rules, including the exposure
limits. They reasoned that we regulated
TC, and that we based our 2001
determinations of risk, benefits, impacts
and feasibility on TC as a surrogate for
DPM. In response, our rules limit
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miners’ exposures to DPM, not to TC.
TC was chosen as the surrogate for
measuring that exposure in the 2001
final rule. In concert with the Second
Partial Settlement Agreement, we
proposed in 2003 to ‘‘[r]evise the
existing diesel particulate matter (DPM)
interim concentration limit measured by
total carbon (TC) to a comparable
permissible exposure limit (PEL)
measured by elemental carbon (EC)
which renders a more accurate DPM
exposure measurement.’’ (68 FR 48668).
As proposed, our 2005 final rule (70 FR
32868) establishes the measurement of
DPM using EC as a direct measure of
total DPM. The 2001 risk assessment
establishes a material impairment of
health or functional capacity to miners
from exposure to DPM and does not
distinguish between adverse health
effects specific to either the EC or OC
fractions of DPM. The measurement of
that exposure, whether using TC, EC or
OC as a surrogate, is not related to the
material impairment of health endpoints
identified in the 2001 risk assessment
and in subsequent literature updates.
Our discussion in Section VIII.A. of this
preamble of the variability of the EC:TC
ratio addresses total adverse health risks
of DPM. The analysis of the EC:TC ratio
is presented in that section, and in the
preamble to our 2005 final rule (70 FR
32894–32899). The 2001 risk assessment
discusses possible mechanisms of
carcinogenesis for which both EC and
OC would be relevant factors (66 FR at
5811–5822). Multiple routes of
carcinogenesis may operate in human
lungs, some requiring only the various
organic mutagens in DPM and others
involving induction of free radicals
regardless of whether the source is the
EC fraction, OC fraction, some other
unidentified component, or a
combination of components. We
recognize that identifying the toxic
components of DPM, and particulate
matter in general, is an important
research focus of a variety of
government agencies and scientific
organizations (see, for example: Health
Effects Institute, 2003; Environmental
Protection Agency, 2004b).
We are still considering various
alternatives for converting the 350TC µg/
m3 and 160TC µg/m3 final limits to
commensurate EC limits. We will
consider all comments in this
rulemaking record concerning the
relationship between EC, OC and TC in
a separate rulemaking to determine the
most appropriate conversion of the final
TC limits. Presently, we believe that the
DPM rulemaking record is inadequate
for us to make determinations regarding
a more appropriate conversion factor
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29001
other than 1.3 for the 350TC µg/m3 final
PEL.
Some commenters suggested that the
data used in the 31-Mine Study and the
analytical method used (NIOSH Method
5040) should be subjected to peer
review. However, MSHA, organized
labor, and the mining industry, through
the negotiations process, jointly
developed the protocol for conducting
the 31-Mine Study. All of the parties
agreed on the protocol following
numerous discussions among industry,
labor, and government experts, and had
an opportunity to comment and make
changes to the document. Thereafter, we
conducted the study, following the
agreed upon protocol, and published its
results. Industry was given an
opportunity to publish their separate
results simultaneously with the
government. During this rulemaking,
industry submitted to us through the
notice and comment process their
conclusions on the 31-Mine Study in a
report titled, ‘‘Technical and Economic
Feasibility of DPM Regulations.’’ The
industry report is contained in the
rulemaking record, and we considered it
in reaching determinations for the 2005
final rule. We have been transparent
about the design of the study and
methods of analysis.
Commenters also stated that we
disseminated information that relies on
non-representative sampling and is
therefore in violation of the Information
Quality Guidelines. The information
they refer to was obtained in the
previously discussed 31-Mine Study
and also during our baseline sampling.
Under the Second Partial DPM
Settlement Agreement, we agreed to
provide compliance assistance to the M/
NM underground mining industry for a
one-year period from July 20, 2002
through July 19, 2003. As part of our
compliance assistance activities, we
agreed to conduct baseline sampling of
miners’ personal exposures at every
underground mine covered by the 2001
final rule.
A total of 1,194 valid baseline
samples were collected. A total of 183
underground M/NM mines are
represented by this analysis. We used
the results of this sampling in our
preamble to the 2005 final rule to
estimate current DPM exposure levels in
underground M/NM mines using diesel
equipment (70 FR 32873–32883) and in
the risk assessment for this final rule.
The sampling results also assist mine
operators in developing compliance
strategies based on actual exposure
levels. Most commodities were well
represented in this analysis with the
average number of valid samples per
mine ranging from 6.0 to 8.2 (average
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across all mines is 6.5 samples per
mine).
MSHA compliance specialists
collected baseline samples in the same
manner they have been instructed to use
for collecting samples for enforcement
purposes. It is expected that personal
exposure to DPM will fluctuate due to
variations in day to day operations in a
mine. Reported levels of DPM are
representative of the exposures of
miners identified as having the highest
risks of overexposures to DPM during
our compliance assistance work. In an
ideal situation, and with unlimited
resources, every potentially exposed
miner would be individually sampled. It
is not necessary or practical, however,
to sample all miners on a mine property
in order to evaluate personal exposures.
Suspected and potential health hazards
may be reasonably and adequately
evaluated by sampling the maximum
risk miner in a work area. Compliance
specialists strive to characterize the
higher exposure levels during typical
work shifts. The baseline samples are
representative of the conditions
experienced on work shifts during the
defined compliance assistance period.
MSHA has obtained the best available
information for characterizing recent
activities at the relevant M/NM mines.
Commenters questioned the accuracy
and validity of the NIOSH Analytical
Method 5040. NIOSH validation criteria
state that the NIOSH Analytical Method
5040 provides a result that differs no
more than ±25% from the true value 95
times out of 100. The NIOSH Analytical
Method 5040 validation is documented
in several publications. See our
discussion of this in Section VIII.A. of
this preamble for additional peerreviewed studies providing evidence
that the NIOSH Analytical Method 5040
method is valid. In a study published by
Noll, et al., in January 2005 evaluating
sampling results of DPM cassettes, the
authors report a 95% upper confidence
limit Coefficient of Variation (CV) of 7%
when analyzing samples for EC and 6%
for TC. In this same study, NIOSH
reported good agreement and precision
between EC for DPM samples using SKC
impactor and respirable samples in both
laboratory and field studies. Two
studies published in 2004 (Noll, et al.,
2004 and Birch, et al., 2004) reported
results from investigating sampling for
EC in the presence of coal dust using
submicron impactors. The results show
good agreement between submicron EC
and respirable samplers for collecting
DPM samples.
Commenters also stated that we
calculated the error factors for our
analytical method assuming no related
methodological inaccuracies. We
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develop method-specific error factors to
assure that a personal exposure result is
more than likely to represent an
overexposure. These error factors
account for normal and expected
variability inherent in any analytic
method and sampling protocol and
provide a basis for interpretation of
sampling results. When we interpret
sampling results and make a
determination of compliance, we apply
the error factor to the result to gauge
whether the sample indicates a true
overexposure. We use the validated
NIOSH Analytical Method 5040 for
diesel particulate matter to analyze our
personal exposure samples collected for
compliance determinations.
The NIOSH criteria and guidelines
used for method validation do not
directly apply to the development of
error factors. However, similar statistical
procedures to develop analytical
methods can also be used to develop
error factors. The commenters fail to
recognize other differences between
validation of methods and development
of error factors. We discuss our error
factor in detail in Section VIII.A. of this
preamble.
Commenters further questioned
whether the NIOSH Method 5040 has
been commercially tested. As in the
preamble to the 2003 NPRM, we
discussed in detail our findings
regarding the NIOSH Method 5040 in
the 31-Mine Study discussion in the
preamble to the 2005 final rule (70 FR
32870–32871) and in Section VIII of this
preamble. NIOSH’s peer review of the
31-Mine Study also concludes that the
analytical method specified by the
diesel standard gives an accurate
measure of the TC content of a filter
sample and that the analytical method
is appropriate for making compliance
determinations of DPM exposures of
underground M/NM miners. NIOSH
confirmed this position by letter of
February 8, 2002, in which NIOSH
stated that,
MSHA is following the procedures of
NIOSH Method 5040, based on our review of
MSHA P13 (MSHA’s protocol for sample
analysis by NIOSH Method 5040) and a visit
to the MSHA laboratory.
Commenters stated that MSHA’s
former chairman of the DPM
Rulemaking Committee had a conflict of
interest as he was also author of the
ACGIH diesel TLV. In response, our
2001 final rule includes the basis for our
interim limit of 400TC µg/m3 and final
limit of 160TC µg/m3, and states the
following:
Because of the lack of a generally accepted
dose-response relationship, some
commenters questioned the agency’s
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rationale in picking a particular
concentration limit: 160TC µg/m3 or around
200DPM µg/m3. Capping DPM
concentrations at this level will eliminate the
worst mining exposures, and bring miner
exposures down to a level commensurate
with those reported for other groups of
workers who use diesel-powered equipment.
The proposed rule would not bring
concentrations down as far as the proposed
ACGIH TLVR of 150DPM µg/m3. Nor does
MSHA’s risk assessment suggest that the
proposed rule would completely eliminate
the significant risks to miners of DPM
exposure.
In setting the concentration limit at this
particular value, the Agency is acting in
accord with its statutory obligation to attain
the highest degree of safety and health
protection for miners that is feasible. The
Agency’s risk assessment supports reduction
of DPM to the lowest level possible. But
feasibility considerations dictated proposing
a concentration limit that does not
completely eliminate the significant risks
that DPM exposure poses to miners.
The Agency specifically explored the
implications of requiring mines in this sector
to comply with a lower concentration limit
than that being adopted. The results,
discussed in Part V of this preamble, indicate
that although the matter is not free from
question, it still may not be feasible at this
time for the underground metal and
nonmetal mining industry as a whole to
comply with a significantly lower limit than
that being adopted. The Agency notes that
since this rulemaking was initiated, the
efficiency of hot gas filters has improved
significantly, the dpm emissions from new
engines continue to decline under EPA
requirements, and the availability of ultralow sulfur fuel should make controls even
more efficient than at present.
The Agency also explored the idea of
bridging the gap between risk and feasibility
by establishing an ‘‘action level’’. In the case
of MSHA’s noise rule, for example, MSHA
adopted a ‘‘permissible exposure level’’ of a
time-weighted 8-hour average (TWA8) of 90
dBA (decibels, A-weighted), and an ‘‘action
level’’ of half that amount—a TWA8 of 85
dBA. In that case, MSHA determined that
miners are at significant risk of material harm
at a TWA8 of 85 dBA, but technological and
feasibility considerations preclude the
industry as a whole, at this time, below a
TWA8 of 90 dBA. Accordingly, to limit miner
exposure to noise at or above a TWA8 of 85
dBA, MSHA requires that mine operators
must take certain actions that are feasible
(e.g., provide hearing protectors).
MSHA considered the establishment of a
similar ‘‘action level’’ for DPM— probably at
half the proposed concentration limit, or
80TC µg/m3. Under such an approach, mine
operators whose DPM concentrations are
above the ‘‘action level’’ would be required
to implement a series of ‘‘best practices’’—
e.g., limits on fuel types, idling, and engine
maintenance. Only one commenter
supported the creation of an Action Level for
DPM. However, this commenter suggested
that such an Action Level be adopted in lieu
of a rule incorporating a concentration limit
requiring mandatory compliance. The
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Agency determined it is feasible for the entire
underground mining community to
implement these best practices to minimize
the risks of DPM exposure without the need
for a trigger at an Action Level (66 FR 5710).
Consequently, MSHA did not rely on
data from ACGIH in establishing its
2001 final rule.
Commenters leveled several other
criticisms at the Estimator and the 31Mine Study which they believe violate
Data Quality Act requirements and
invalidate our conclusions regarding the
feasibility of the 2001 and 2005 final
rules. The computer program in
question, referred to as the Estimator, is
a Microsoft Excel spreadsheet program
that calculates the reduction in DPM
concentration that can be obtained
within an area of a mine by
implementing individual or
combinations of engineering controls.
This program was the subject of a
Preprint published for the 1998 Society
of Mining Engineers Annual Meeting
(Preprint 98–146, March 1998), and it
was fully described in a peer reviewed
article in a professional journal (Haney
and Saseen, Mining Engineering, April
2000).
Commenters objected to the use of
input data for the Estimator which they
characterized as ‘‘assumed ventilation
air flows that do not reflect reality or
actual MSHA measurements,’’ and
‘‘assumptions regarding perfect mixing
of ventilation air to achieve dilution of
exhaust particulate,’’ which they further
characterized as ‘‘another assumption
that does not reflect reality or actual
measurements.’’ The commenters stated
that these failures are violations of the
Data Quality Act’s reproducibility and
transparency requirements, and that
MSHA admitted to these failures in the
preamble to the 2005 final rule.
Regarding the use of ‘‘assumed
ventilation flows that do not reflect
reality,’’ all data used in Estimator
analysis for the 31-Mine Study were
obtained by MSHA M/NM industrial
hygienists or Health Specialists. The
ventilation inputs were either measured
or estimated by these MSHA personnel.
As stated in the final report of the 31Mine Study, ‘‘Each mine was evaluated
individually, based on the DPM
concentration data obtained for that
mine through sampling, coupled with
the mine-specific equipment, operating
practices, and ventilation observed at
that mine.’’
Of the 31 mines addressed in the
study, ventilation changes were
specified for only five, and those
changes were limited to auxiliary
ventilation systems only. This fact is
very important because when using the
‘‘Column A’’ option of the Estimator,
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which was the only option used in the
31-Mine study, if ventilation changes
are not specified, the prevailing
ventilation in a given area of the mine
is irrelevant to Estimator analysis. The
engineering rationale for this effect was
explained thoroughly in the final report
for the 31-Mine Study (p. 96):
It is significant to note that when
ventilation remains the same before and after
DPM controls are specified in the Estimator
(i.e. the DPM control chosen was not a
change in ventilation), the actual ventilation
value used is irrelevant. This characteristic of
the Estimator applies to any mine ventilation
scheme, but it is particularly important
where ventilation velocity is low, and
ventilation flow is difficult to accurately
measure. Mine ventilation velocity is very
low in large parts of many room and pillar
mines with large cross-section mine
openings. This situation suggests two
possible problems with DPM measurement—
difficulty measuring mine airflow rates, and
non-homogeneous mixtures of DPM in mine
air. DPM concentrations in the ambient air at
these mines can be profoundly affected by
near-stagnant conditions in some areas, as
well as by localized air movement that is
independent of the overall mine ventilation
flow. Such localized air movement can result
from pressure differences created by wind
from moving vehicles, natural ventilation,
diesel engine cooling fans, heat-induced
stratification, etc. In these situations, perfect
mixing of mine air with DPM emissions
would not be expected, hence, the DPM
concentration in ambient mine air could not
be reasonably estimated by simply dividing
the DPM emission rate by the ventilation
flow rate.
In its Column A option, the Estimator does
not calculate DPM concentration by dividing
the DPM emission rate by the ventilation
flow rate. Thus, in MSHA’s view, neither the
difficulty of measuring airflow nor the
imperfect mixing of DPM and mine air is
important. The Estimator accounts for
complex and imperfect mixing of ventilation
air and DPM emissions by assuming that this
mixing, in whatever manner it occurs when
DPM samples are initially collected, would
remain unchanged after DPM controls are
implemented. MSHA considers this to be a
reasonable assumption unless the DPM
control that is specified is itself a major
ventilation change. Since ventilation changes
were not specified for any of the mines where
complex and imperfect mixing was likely to
occur, MSHA considers it reasonable to
estimate a final DPM concentration at these
mines based on applying a proportionality
factor to the DPM concentration originally
measured. The proportionality factor is
simply the ratio of the DPM emission rate
after controls are implemented to the DPM
emission rate before controls are
implemented, and is independent of the
actual airflow present at that location.
Although the Estimator makes simplifying
assumptions, MSHA considers its results
reasonably accurate. The Estimator’s
calculations have been compared to actual
in-mine data, and good agreement has been
achieved.
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The differences between the
Estimator’s user-selectable ‘‘Column A’’
and ‘‘Column B’’ options are addressed
in Section V.A of this preamble and
previously were thoroughly discussed
in the preamble to the 2005 final rule
(70 FR 32920):
The Estimator actually incorporates two
independent means of calculating DPM
levels: one based on DPM sampling data for
the subject mine, and one based on the
absence of such sampling data. Where no
sampling data exist, the Estimator calculates
DPM levels based on a straightforward
mathematical ratio of DPM emitted from the
tailpipe (or DPF, in the case of filtered
exhaust) per volume of ventilation air flow
over that piece of equipment. This is referred
to in the Estimator as the ‘‘Column B’’ option
for calculating DPM concentrations. The
commenters’ observation that the Estimator
fails to account for imperfect mixing between
DPM emissions and ventilating air flows is a
valid criticism of the ‘‘Column B’’ option. For
this and other reasons, the Estimator’s
instructions urge users to utilize the
‘‘Column A’’ option whenever sampling data
are available.’’
In the ‘‘Column A’’ option, the Estimator’s
calculations are ‘‘calibrated’’ to actual
sampling data. Whatever complex mixing
between DPM emissions and ventilating air
flows existed when DPM samples were
obtained, are assumed to prevail after
implementation of a DPM control. This is an
entirely reasonable assumption, and in fact,
there is no engineering basis to assume
otherwise. Indeed, comparisons of ‘‘Column
A’’ Estimator calculations and actual DPM
measurements taken in mines before and
after implementation of DPM controls have
shown good agreement, indicating that
Estimator calculations do adequately
incorporate consideration for complex
mixing of DPM and air flows when the
‘‘Column A’’ option is used. The Estimator
was originally developed with both the
Column A and Column B options because at
the time it was developed (1997), the
specialized equipment required for reliable
and accurate in-mine DPM sampling, such as
the submicron impactor, was not widely
available. Consequently, few mine operators
were able to obtain the in-mine DPM sample
data required for utilizing the Column A
option.
The commenter refers to the ‘‘Column
A option’’ as an alternative use of the
Estimator. However, we have always
recommended that the Column A option
be used if sampling data are available.
As noted above in the excerpt from the
31-Mine Study, we explained fully at
the time the study was released in
January 2003 exactly how the Estimator
was used in that study, and we also
explained its use in the preamble to the
June 2005 final rule. The commenter
states that the sample data used in
Estimator analysis were ‘‘nonrepresentative of routine mining
conditions that can vary greatly at each
mine from day to day, and from mine
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to mine throughout the industry.’’
However, we stated in the 31-Mine
Study final report that we followed
standard MSHA enforcement sampling
procedures to obtain the DPM samples
at the 31 mines. These procedures are
public information, and were well
known by the labor and industry
representatives that collaborated on the
study protocol.
Regarding the question of whether the
data obtained in the 31-Mine Study
were representative of the industry as a
whole, the mines in the study were
jointly selected by MSHA, labor, and
industry representatives. A reasonable
attempt was made to achieve a crosssection of the industry in terms of
commodities and mine sizes. The
MSHA, labor, and industry personnel
who collaborated on the study protocol
were all fully aware at that time that the
study was never intended to be
statistically representative of the
industry as a whole, and this fact was
explicitly stated in the 31-Mine Study
final report.
The commenter suggests that the
study is ‘‘suspect’’ because 25% of the
samples were voided. As was explained
in the 31-Mine Study final report, of the
464 samples obtained at the 31 mines,
106 were voided. A key consideration in
the sampling conducted at the 31 mines
was to ensure, to the extent possible,
that samples were not contaminated by
non-diesel sources of airborne carbon.
Testing had verified that the submicron
sampler would remove mineral dust
contamination (limestone, graphite,
etc.), but tobacco smoke, drill oil mist,
and possibly vapors from ANFO loading
could contaminate a sample filter with
non-diesel organic carbon. Thus, in
accordance with the study protocol that
had been jointly developed and
approved by both us and the litigants,
any sample that was known to have
been, or could potentially have been
contaminated with such an interferent
was voided. Of the 106 voided samples,
61 were voided due to interferences.
There were also some samples that were
voided for other reasons, such as
laboratory error (2 samples), sample
pump failure (22 samples), or
incomplete sample or sampling the
wrong location (21 samples). Including
any of these 106 voided samples in the
data analysis would have cast doubt on
the validity of the study. The study
methodology that resulted in voiding
questionable samples was part of the
mutually agreed upon study protocol,
the rationale for voiding these samples
was well known and supported by all
parties, and it was fully explained in the
study final report.
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For 26 of the 31 mines, ventilation
flow rates did not factor into Estimator
analysis because, as explained above,
they were not relevant to the
computations. For the remaining five
mines, we continue to believe our
estimates of ventilation flow rates were
sufficiently accurate for the purposes of
the study. Both our methods and data
sources were explained thoroughly and
we have responded previously on the
record to these same criticisms of the
Estimator.
Some commenters questioned the
quality of reports of MSHA’s
compliance assistance work at mines
covered under the standard, and
requested that they be stricken from the
rulemaking record because these studies
were conducted without an apparent
protocol or independent peer review.
Also, commenters stated that these
studies have not been published nor
submitted for publication in any
scientific journal. In response, the
compliance assistance reports in the
DPM rulemaking record are not
intended for publication in a scientific
journal, but instead, are accounts of our
experiences at mines where mine
operators requested help from MSHA in
reducing DPM exposures. Under the
second partial DPM settlement
agreement, MSHA agreed to provide
compliance assistance at underground
mining operations using diesel-powered
equipment from July 20, 2002 through
July 19, 2003.
The Technological Feasibility section
of this preamble, Section V.A, discusses
the information and data related to
feasible engineering and administrative
controls currently available for the
mining industry as a whole. Mines have
implemented many of these DPM
controls to meet the interim DPM limit
as shown by our enforcement sampling.
As further discussed in that section, we
expect the industry as a whole will
continue to learn more about the
available control technologies and
implement these control strategies in
order to meet the final limits specified
in this final rule. We recognized that
implementation issues were making it
difficult for some mines to use DPFs and
obtain alternative fuels such as
biodiesel. The extension of time allowed
by this final rule was justified due to the
greater availability of biodiesel fuels, the
variety of DPF systems available, and
the cleaner on-highway diesel engines
that are becoming available.
The data presented in the Feasibility
sections of this rulemaking support the
feasibility of the various DPM control
technologies. This data were derived
from sources such as NIOSH, MSHA,
and the Biodiesel Board. The NIOSH
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work provided mine operators with data
that showed expected DPM reductions
in a diesel laboratory, an isolated zone,
and in production areas. The expected
reductions were presented to assist
mine operators with choosing DPM
controls for implementation in their
mines. We discussed information on
DPFs that can achieve EC reductions
above 90% and informed mine
operators of other products that gave
very minimal reductions. This was done
to give mine operators the ability to
choose a single control or combination
of controls that would be
technologically and economically
feasible and appropriate for their
particular situation to implement in
order to meet the interim limit and the
final limits specified in this final rule.
All of the data collected during the
31-Mine Study and subsequent studies
performed by NIOSH were gathered
using transparent methods, with
protocols agreed upon by industry and
union representatives. NIOSH
performed extensive isolated zone
studies that were developed and
performed through the M/NM Diesel
Partnership (the Partnership). NIOSH’s
reports were reviewed by the industry
and revised based on comments in the
record. Our compliance assistance work
discussed previously in this section and
the data obtained from those studies
were developed with industry
assistance.
The commenters state that our
feasibility determinations for individual
mines and for the industry were based
in part on the results of Estimator
analysis that calculated compliant DPM
concentrations after installation of DPM
filters, thus demonstrating that such
filters could be used by mine operators
to attain compliance with the interim
and final DPM limits. The commenters
object to the use of the Estimator for this
purpose because they believe such
filters did not exist. They charge that
since appropriate filters did not exist,
the methodology for our feasibility
determination failed to meet our Data
Quality requirements.
We disagree with the commenter’s
statement that our, ‘‘assumptions
[regarding the availability of filters] do
not reflect reality.’’ We have provided
extensive discussion throughout the
rulemaking record supporting our
position that diesel particulate filters
suitable for any size diesel engine were
commercially available at the time the
2001 final rule was issued, and that a
greater variety of such filters have
become commercially available since
2001. The commenter states that we
were, ‘‘forced to admit’’ in the 2005
final rule that there was ‘‘insufficient
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evidence of feasibility,’’ thus
contradicting the Estimator and 31-Mine
Study feasibility determinations. The
sentence from the preamble to the 2005
final rule quoted by the commenter
states, in full, ‘‘MSHA acknowledges
that the current rulemaking record lacks
sufficient feasibility documentation to
justify lowering the DPM limit below
308EC µ/m3, at this time.’’ This
statement was not meant to imply that
either the 2001 or 2005 final rule was
infeasible, and it is irrelevant to the
final DPM limit. It states that at that
time, which was June 2005, we did not
believe it was feasible for the industry
as a whole to achieve DPM levels lower
than the interim DPM limit, 308EC µ/m3,
which was the DPM limit in effect at
that time.
The commenter stated that our
explanation for many filter failures
reported by Stillwater and other
companies was that the user or the
manufacturer was at fault, and that if
MSHA had selected the filters, we
would have selected or used them
differently. We have extensively
discussed in our preambles in this
rulemaking record that the user of a DPF
must evaluate and monitor each
application in order to verify that the
DPF is working properly at all times. We
have continually stated that the majority
of the DPF failures that have been
reported have been related to DPF
regeneration. We believe that better
choices in selection and maintenance of
DPFs would result in greater successes.
However, these regeneration issues are
not related to the capability of DPFs to
effectively collect DPM. All of the data
that we have presented on DPFs show
that DPFs effectively collect DPM. Tests
that were performed in the mining
industry have consistently supported
the same conclusions and agree with
data given in the literature. Again, the
failure of the regeneration scheme is the
main cause of a clogged filter. The
proper selection of DPFs has been
discussed in the literature, and NIOSH’s
Filter Selection Guide extensively
provides the information needed for
selection.
The commenter also discusses the
NO2 issues related to DPFs. The data
presented from studies show that
catalyzed DPFs can increase NO2. This
data have been developed with the
Partnership. However, we continue to
believe that the NO2 problems reported
have been ventilation issues and not
specifically a DPF issue. In fact, as
discussed in the Technological
Feasibility section, NIOSH stated that
NO2 elevations experienced were a
result of poorly or marginally ventilated
areas. Our data from the Greens Creek
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study that were developed and reviewed
with industry showed no NO2 issues on
production machines in well ventilated
areas.
Commenters raised several Data
Quality issues relating to our
determinations that the 2001 and 2005
final rules were economically feasible.
They include whether the data used to
make these determinations were
representative of the industry, that
industry annual revenue is an
inappropriate measure of economic
feasibility, that erroneous commodity
prices were used in the 31-Mine Study
to estimate revenue for at least one of
the mines in the study, and that the 31Mine Study incorrectly assumed that
none of the mines in the study required
major ventilation upgrades. They
believe our economic feasibility
conclusions were based on improper
sampling, and inaccurate and
incomplete data.
Each of these issues is discussed in
detail in the Economic Feasibility
section of this preamble. The key
information from that section that
relates to commenters’ Data Quality
concerns is summarized here. Regarding
the first issue, that the subject mines in
the 31-Mine study were not
representative of the industry, this issue
has already been addressed above.
MSHA, labor, and industry collaborated
on the study design, and all parties were
aware at the time that the study mines
were not randomly selected. Thus, the
study results would reasonably
accurately reflect feasibility of the
subject mines, but would not be
statistically representative of the
industry as a whole. The entire process
was transparent, reproducible, and
based on valid assumptions and sound
methods.
Regarding the second issue of whether
industry annual revenue is an
inappropriate measure of economic
feasibility, commenters indicated that
this method ignores the fact that
international commodity markets
determine the viability of mines by
setting market prices for their
production, and that annual revenues of
hundreds of millions, if not billions, of
dollars have not prevented the domestic
underground M/NM mining industry
from shrinking in recent years.
We believe that the method we used
to determine economic feasibility is
valid. We have customarily used
compliance costs of greater than 1% of
industry annual revenue as our
screening benchmark for determining
whether a more detailed economic
feasibility analysis is required. The
commenter correctly points out that
despite hundreds of millions, if not
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billions, of dollars of industry annual
revenue, business failures can and do
occur, and over a period of decades, the
characteristics of an industry can
change markedly. However, by utilizing
the 1% of annual revenue screening
benchmark, we assure that a complete
feasibility analysis will be conducted to
determine whether a new MSHA rule
could potentially affect the viability of
an industry.
While it is true that individual
business failures can and do occur, and
that over a period of many years,
substantial portions of a domestic
industry can be adversely affected by,
for example, international competition,
it is highly improbable that such events
would be set into motion by a rule
imposing costs equal to or less than 1%
of industry annual revenue. Threats to
an entire industry’s competitive
structure and resulting large scale
dislocations within an industry sector
are typically caused by fundamental
changes in technology, permanent
downward pressure on demand for a
commodity due, for example, to the
introduction of a superior substitute
material, world-wide or regional
business cycles, etc. Our practice of
utilizing compliance costs of greater
than 1% of industry annual revenue as
our screening benchmark for
determining whether a more detailed
economic feasibility analysis is required
is reproducible and transparent, and is
based on reasonable assumptions and
sound economic principles.
The third issue raised by the
commenter relating to economic
feasibility was that erroneous
commodity prices were used to estimate
annual revenue for one of the mines in
the 31-Mine Study. The commenter
states that our revenue estimates suggest
we used a price of $50 to $70 per ton
for rock salt for highway de-icing, when
a more reasonable estimate would have
been $20 to $25 per ton.
The commenter did not explain how
they inferred a $50 to $70 per ton price
for rock salt from our analysis, so we are
unable to respond directly to this
comment. However, we did not base our
economic feasibility determination for
the subject mine on this inflated price
for rock salt. For the 31-Mine Study, we
did not have access to actual annual
revenue data for any of the 31
individual mines in the study, so we
indirectly estimated annual revenues
using our data on the number of
employee work hours in 2000 for each
mine, the total number of employee
work hours reported to us in 2000 by all
mines producing that commodity, and
data from the U.S. Geological Survey on
the industry-wide value of mineral
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production by commodity for the year
2000. We estimated annual revenues for
a particular mine by determining the
industry-wide production value per
employee hour for the specific
commodity each mine produced, and
multiplying that amount by the number
of annual employee work hours
reported to us for that mine. This
methodology assumes that each mine’s
annual revenues would be roughly
proportional to each mine’s share of the
industry’s total employee work hours.
Thus, our estimates, while not
necessarily exact for each mine, were a
reasonable approximation for those
mines based on industry averages. Our
analytical methods and data sources
were fully explained in the final report
to the 31-Mine Study. The process was
transparent and reproducible, and the
method was sound. This methodology
does not explicitly incorporate a cost
per ton factor. Implicit in this
methodology, based on the U.S.
Geological Survey’s estimates of rock
salt production in 2000 of 45,600,000
metric tons valued at $1,000,000,000,
would be a cost per metric ton of $21.93
(equivalent to $19.89 per short ton),
which is actually slightly less than the
commenter’s estimated price of $20 to
$25 per short ton.
The final issue relating to economic
feasibility raised by the commenter also
concerns the 31-Mine Study. The
commenter suggests that our
methodology underestimated
compliance costs by failing to
recommend major ventilation upgrades
for any mine in the study. They point
out that a total of only $234,000 was
recommended in the study for minor
ventilation upgrades, whereas the
operator of one of the mines in the study
estimated at least $4.4 million in
ventilation upgrades would be required
at that mine alone to attain compliance.
In response to a similar comment on
our 2003 NPRM, we noted in the
preamble to the 2005 final rule that we
did not specify any major ventilation
upgrades in the 31-Mine Study because,
based on the study methodology, the
analysis did not indicate the need for
major ventilation upgrades in order to
attain compliance with either the
interim or final DPM limits at any of the
31 mines. We went on to explain that
the purpose of specifying controls for
each mine in this study was simply to
demonstrate that feasible controls
capable of attaining compliance existed,
and to provide a framework for costing
such controls on a mine-by-mine basis.
We explicitly stated in the 31-Mine
study final report that the DPM controls
specified for a particular mine did not
necessarily represent the only feasible
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control strategy, or the optimal control
strategy for that mine.
The fact that the operator of one of the
mines in the study estimated costs of
$4.4 million for ventilation upgrades to
attain compliance with the rule does not
invalidate the methodology we used, or
the results we obtained in the 31-Mine
study. It is impossible for us to verify
whether $4.4 million for ventilation
upgrades is a reasonable estimate for the
subject mine because we don’t know
which mine the commenter is referring
to, and no additional supporting
documentation was provided by the
commenter. However, even if this figure
is accurate, it would not necessarily
invalidate our methodology or results.
We have received numerous comments
throughout the rulemaking process that
ventilation upgrades alone would not be
a cost-effective DPM control at many
mines. These comments support our
position that mine operators need to
carefully analyze all DPM control
options in order to select the most costeffective control or combination of
controls to implement at a particular
mine. Although a $4.4 million
ventilation upgrade may be required to
attain compliance at the subject mine, if
ventilation alone was used to attain
compliance, it is more likely that
compliance could be achieved at this
mine at a lower cost if an optimal
combination of controls were
implemented, including low DPMemission engines, environmental cabs
with filtered breathing air, DPM filters,
alternative fuels such as biodiesel, work
practices and administrative controls, as
well as ventilation.
With respect to ventilation upgrades
for the 31 mines, the study methodology
and the sources of all data we used in
performing the feasibility analyses were
thoroughly explained in the 31-Mine
Study final report. The process was
transparent and reproducible, and the
study protocol was developed jointly by
MSHA, labor, and industry
representatives.
XIV. References Cited
AFL–CIO v. Brennan, 530 F.2d 109 (3d Cir.
1975).
American Jobs Creation Act of 2004, H.R.
4520. (Pub. L. 108–357).
American Iron and Steel Institute v. OSHA,
(AISI–I) 577 F.2d 825, 834 (3d Cir. 1978).
AISI–II, 939 F.2d 975, 980 (DC Cir. 1991)
American Textile Manufacturers Institute,
Inc. v. Donovan, 452 U.S. 490, 508–509
(1981).
Al-Humadi, N. H., et al. ‘‘The Effect of Diesel
Exhaust Particles (DEP) and Carbon
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Georgetown Mine, Nally and Gibson,
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Greer Limestone Mine, Greer Limestone
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Hampton Corners Mine, Martin Marietta
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Independence Mine, Rocca Processing, LLC,
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2003.
Inland Quarries, Americold Logistics, LLC,
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2003; dated August 15, 2003.
Jefferson County Stone Mine, Rogers Group,
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Jefferson County Stone Mine, Rogers Group,
Inc., Jefferson County, Kentucky,
PS&HTC-DD–03–312, Dust Compliance
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Kaylor No. 3 Mine, Brady’s Bend
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2003.
Kerford Limestone Mine, Kerford Limestone
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Lyons Salt Mine, Lyons Salt Company,
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M&M Lime Company, Inc. Mine,
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04–416, Diesel Particulate
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Meikle Mine, Barrick Goldstrike Mines, Inc.,
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Diesel Particulate Matter Compliance
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November 23, 2004.
Midas Mine, Newmont Midas Operations,
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Diesel Particulate Matter Compliance
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November 23, 2004.
Murray Mine, Queenstake Resources, U.S.A.,
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dated October 28, 2004.
Oldham County Stone Mine, Rogers Group,
Inc., Oldham County, Kentucky, DPM
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Petersburg Mine, East Fairfield Coal
Company, Limestone Division,
Petersburg, Mahoning County, Ohio,
PS&HTC–DD–06–602, Diesel Particulate
Matter Study, September 27, 2005; dated
November 30, 2005.
Randolph Mine, Hunt Midwest Mining, Inc.,
Diesel Particulate Compliance Assistance
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2003.
Rock Springs Mine, Liter’s Quarry, Inc.,
Diesel Particulate Compliance Assistance
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Stone Creek Brick Company Mine, Marsh A
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PS&HTC–DD–03–320, Diesel Particulate
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Stone Creek Brick Company Mine, Marsh A
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PS&HTC–DD–03–322, Diesel Particulate
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Compliance Assistance Visit, November
18, 2003; dated February 18, 2004.
Table Rock #3 Mine, Table Rock Asphalt
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Torrance Mine, Hanson Aggregates PMA,
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Weeping Water Mine, Martin Marietta
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XV. Regulatory Text
List of Subjects in 30 CFR Part 57
Diesel particulate matter, Metal and
nonmetal, Mine safety and health,
Underground miners.
Dated: May 9, 2006.
Robert M. Friend,
Acting Deputy Assistant Secretary of Labor
for Mine Safety and Health.
For reasons discussed in the
preamble, MSHA amends 30 CFR part
57 as follows:
I
PART 57—SAFETY AND HEALTH
STANDARDS—UNDERGROUND
METAL AND NONMETAL MINES
1. The authority citation for part 57
continues to read as follows:
I
Authority: 30 U.S.C. 811 and 813.
2. Section 57.5060 is amended by:
A. Revising paragraph (b);
B. Removing (c)(3)(i); and
C. Redesignating paragraphs (c)(3)(ii),
(c)(3)(iii), and (c)(3)(iv) as (c)(3)(i),
(c)(3)(ii), and (c)(3)(iii) respectively.
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I
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The revision reads as follows:
§ 57.5060 Limit on exposure to diesel
particulate matter.
*
*
*
*
*
(b)(1) Effective May 20, 2006, a
miner’s personal exposure to diesel
particulate matter (DPM) in an
underground mine must not exceed an
average eight-hour equivalent full shift
airborne concentration of 308
micrograms of elemental carbon per
cubic meter of air (308EC µg/m3).
(2) Effective January 20, 2007, a
miner’s personal exposure to diesel
particulate matter (DPM) in an
underground mine must not exceed an
average eight-hour equivalent full shift
airborne concentration of 350
micrograms of total carbon per cubic
meter of air (350TC µg/m3).
(3) Effective May 20, 2008, a miner’s
personal exposure to diesel particulate
matter (DPM) in an underground mine
must not exceed an average eight-hour
equivalent full shift airborne
concentration of 160 micrograms of total
carbon per cubic meter of air (160TC µg/
m3).
*
*
*
*
*
I 3. Effective August 16, 2006, § 57.5060
is amended by revising paragraph (d)
introductory text and adding paragraphs
(d)(3) through (d)(8).
§ 57.5060 Limit on exposure to diesel
particulate matter.
*
*
*
*
*
(d) The mine operator must install,
use, and maintain feasible engineering
and administrative controls to reduce a
miner’s exposures to or below the
applicable DPM PEL established in this
section. When controls do not reduce a
miner’s DPM exposure to the PEL,
controls are infeasible, or controls do
not produce significant reductions in
DPM exposures, controls must be used
to reduce the miner’s exposure to as low
a level as feasible and must be
supplemented with respiratory
protection in accordance with
§ 57.5005(a), (b), and paragraphs (d)(1)
through (d)(8) of this section.
*
*
*
*
*
(3) The mine operator must provide a
confidential medical evaluation by a
physician or other licensed health care
professional (PLHCP), at no cost to the
miner, to determine the miner’s ability
to use a respirator before the miner is
required to be fit tested or to use a
respirator at the mine. If the PLHCP
determines that the miner cannot wear
a negative pressure respirator, the mine
operator must make certain that the
PLHCP evaluates the miner’s ability to
wear a powered air purifying respirator
(PAPR).
(4) The mine operator must provide
the miner with an opportunity to
discuss their evaluation results with the
PLHCP before the PLHCP submits the
written determination to the mine
operator regarding the miner’s ability to
wear a respirator. If the miner disagrees
with the evaluation results of the
PLHCP, the miner may submit within 30
days additional evidence of his or her
medical condition to the PLHCP.
(5) The mine operator must obtain a
written determination from the PLHCP
regarding the miner’s ability to wear a
respirator, and the mine operator must
assure that the PLHCP provides a copy
of the determination to the miner.
(6) The miner must be reevaluated
when the mine operator has reason to
believe that conditions have changed
which could adversely affect the miner’s
ability to wear the respirator.
(7) Upon written notification that the
PLHCP has determined that the miner is
unable to wear a respirator, including a
PAPR, the miner must be transferred to
work in an existing position in an area
of the same mine where respiratory
protection is not required. The miner
must be transferred within 30 days of
the final determination by the PLHCP.
(i) The miner must continue to receive
compensation at no less than the regular
rate of pay in the classification held by
that miner immediately prior to the
transfer.
(ii) Increases in wages of the
transferred miner must be based upon
the new work classification.
(8) The mine operator must maintain
a record of the identity of the PLHCP
and the most recent written
determination of each miner’s ability to
wear a respirator for the duration of the
miner’s employment plus six months.
*
*
*
*
*
4. Section 57.5075 is amended by
revising paragraph (a) and paragraph
(b)(3) to read as follows:
I
§ 57.5075
Diesel particulate records.
(a) The table entitled ‘‘Diesel
Particulate Matter Recordkeeping
Requirements’’ lists the records the
operator must maintain pursuant to
§§ 57.5060 through 57.5071, and the
duration for which particular records
need to be retained.
TABLE 57.5075(a).—DIESEL PARTICULATE RECORDKEEPING REQUIREMENTS
Section
reference
Record
dsatterwhite on PROD1PC76 with RULES
1. Approved application for extension of time to comply with exposure limits.
2. Identity of PLHCP and most recent written determination of miner’s ability to wear a respirator.
3. Purchase records noting sulfur content of diesel fuel ................................
4. Maintenance log .........................................................................................
5. Evidence of competence to perform maintenance ....................................
6. Annual training provided to potentially exposed miners ............................
7. Record of corrective action ........................................................................
8. Sampling method used to effectively evaluate a miner’s personal exposure, and sample results.
(b) * * *
(3) An operator must provide access
to a miner, former miner, or, with the
miner’s or former miner’s written
consent, a personal representative of a
miner, to any record required to be
maintained pursuant to § 57.5071 or
§ 57.5060(d) to the extent the
VerDate Aug<31>2005
19:52 May 17, 2006
Jkt 208001
Retention time
§ 57.5060(c)
Duration of extension.
§ 57.5060(d)
Duration of miner’s employment plus 6 months.
§ 57.5065(a)
§ 57.5066(b)
§ 57.5066(c)
§ 57.5070(b)
§ 57.5071(c)
§ 57.5071(d)
1 year beyond date of purchase.
1 year after date any equipment is tagged.
1 year after date maintenance performed.
1 year beyond date training completed.
Until the corrective action is completed.
5 years from sample date.
information pertains to the miner or
former miner. The operator must
provide the first copy of a requested
record at no cost, and any additional
copies at reasonable cost.
*
*
*
*
*
[FR Doc. 06–4494 Filed 5–17–06; 8:45 am]
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]]>Agencies
[Federal Register Volume 71, Number 96 (Thursday, May 18, 2006)]
[Rules and Regulations]
[Pages 28924-29012]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-4494]
[[Page 28923]]
-----------------------------------------------------------------------
Part II
Department of Labor
-----------------------------------------------------------------------
Mine Safety and Health Administration
-----------------------------------------------------------------------
30 CFR Part 57
Diesel Particulate Matter Exposure of Underground Metal and Nonmetal
Miners; Final Rule
Federal Register / Vol. 71, No. 96 / Thursday, May 18, 2006 / Rules
and Regulations
[[Page 28924]]
-----------------------------------------------------------------------
DEPARTMENT OF LABOR
Mine Safety and Health Administration
30 CFR Part 57
RIN 1219-AB29
Diesel Particulate Matter Exposure of Underground Metal and
Nonmetal Miners
AGENCY: Mine Safety and Health Administration (MSHA), Labor.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: This final rule revises the May 20, 2006 effective date of the
diesel particulate matter (DPM) final concentration limit of 160
micrograms of total carbon (TC) per cubic meter of air
(160TC [mu]g/m3) promulgated in the 2001 final
rule ``Diesel Particulate Matter Exposure of Underground Metal and
Nonmetal Miners,'' and published in the Federal Register on January 19,
2001 (66 FR 5706) and amended on September 19, 2005 (70 FR 55019).
This final rule increases flexibility of compliance for mine
operators by allowing staggered effective dates for implementation of
the final DPM limit, phased-in over a two-year period, primarily based
on feasibility issues which have surfaced since promulgation of the
2001 final rule.
Furthermore this final rule establishes requirements for medical
evaluation of miners required to wear respiratory protection and
transfer of miners who are medically unable to wear a respirator;
deletes the existing provision that restricts newer mines from applying
for an extension of time in which to meet the final concentration
limit; addresses technological and economic feasibility issues, and the
costs and benefits of this rule.
EFFECTIVE DATE: This final rule is effective on May 18, 2006 except for
amendments to Sec. 57.5060(d), which is effective August 16, 2006.
FOR FURTHER INFORMATION CONTACT: Patricia W. Silvey, Acting Director,
Office of Standards, Regulations, and Variances, MSHA, 1100 Wilson
Blvd., Room 2350, Arlington, Virginia 22209-3939; 202-693-9440
(telephone); or 202-693-9441 (facsimile).
You may obtain copies of this final rule and the Regulatory
Economic Analysis (REA) in alternative formats by calling 202-693-9440.
The alternative formats are either a large print version of these
documents or electronic files that can be sent to you either on a
computer disk or as an attachment to an e-mail. The documents also are
available on the Internet at https://www.msha.gov/REGSINFO.HTM.
SUPPLEMENTARY INFORMATION:
Outline of Preamble
This outline will assist the mining community in finding
information in this preamble.
I. List of Common Terms
II. Background
A. First Partial Settlement Agreement
B. Second Partial Settlement Agreement
III. Rulemaking History
A. Advance Notice of Proposed Rulemaking (ANPRM) on the Interim
and Final Concentration Limits
B. Notice of Proposed Rulemaking (NPRM) on the Interim Limit
C. Final Rule Revising the Interim Concentration Limit
D. September 2005 Notice of Proposed Rulemaking
IV. Risk Assessment
V. Feasibility
A. Technological Feasibility
B. Economic Feasibility
VI. Summary of Benefits
VII. Section 101(a)(9) of the Mine Act
VIII. Section-by-Section Analysis
A. PEL Sec. 57.5060(b)
B. Special Extensions Sec. 57.5060(c)(3)(i)
C. Medical Evaluation and Transfer Sec. 57.5060(d)
D. Diesel Particulate Records Sec. 57.5075(a)
IX. Regulatory Costs
A. Costs of Medical Evaluation and Transfer
B. Costs of Implementing the 160TC [mu]g/
m3 Limit
X. Regulatory Flexibility Act Certification (RFA) and Small Business
Regulatory Enforcement Fairness Act (SBREFA)
A. Definition of a Small Mine
B. Factual Basis for Certification
XI. Paperwork Reduction Act
XII. Other Regulatory Considerations
A. The Unfunded Mandates Reform Act of 1995
B. National Environmental Policy Act
C. The Treasury and General Government Appropriations Act of
1999: Assessment of Federal Regulations and Policies on Families
D. Executive Order 12630: Government Actions and Interference
With Constitutionally Protected Property Rights
E. Executive Order 12988: Civil Justice Reform
F. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
G. Executive Order 13132: Federalism
H. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
J. Executive Order 13272: Proper Consideration of Small Entities
in Agency Rulemaking
XIII. Information Quality
XIV. References Cited
XV. Regulatory Text
I. List of Common Terms
Listed below are the common terms used in the preamble.
31 Mine Study............................................................ Joint MSHA/Industry Study:
Determinations of DPM levels in
Underground Metal and Nonmetal
Mines.
Commission............................................................... Federal Mine Safety and Health Review
Commission.
CV....................................................................... Coefficient of Variation.
DPF...................................................................... diesel particulate filter.
DPM...................................................................... diesel particulate matter.
EC....................................................................... elemental carbon.
ETS...................................................................... environmental tobacco smoke.
Filter Selection Guide................................................... Diesel Particulate Filter Selection
Guide for Diesel-powered Equipment
in Metal and Nonmetal Mines.
First Partial Settlement Agreement....................................... 66 FR 35518 (2001) & 66 FR 35521
(2001): basis for July 5, 2001 NPRM.
MARG..................................................................... Methane Awareness Resource Group.
M/NM..................................................................... metal/non-metal.
MSHA..................................................................... Mine Safety and Health
Administration.
NIOSH.................................................................... National Institute for Occupational
Safety and Health.
NTP...................................................................... National Toxicology Program.
OC....................................................................... organic carbon.
PAPR..................................................................... powered air-purifying respirator.
PEL...................................................................... permissible exposure limit.
PPM...................................................................... parts per million.
QRA...................................................................... quantitative risk assessment.
REA...................................................................... Regulatory Economic Analysis.
[[Page 28925]]
Second Partial Settlement Agreement...................................... 67 FR 47296 (2002): basis for August
14, 2003 NPRM.
SD....................................................................... standard deviation.
SKC...................................................................... SKC, Inc.
TC....................................................................... total carbon (the sum of elemental
and organic carbon).
USWA..................................................................... United Steelworkers of America.
USW...................................................................... United Steelworkers.
[mu]g/cm\2\.............................................................. micrograms per square centimeter.
[mu]g/m\3\............................................................... micrograms per cubic meter.
2001 final rule.......................................................... January 19, 2001 DPM final rule.
Amended 2001 final rule.................................................. 2001 final rule amended on February
27, 2002.
2002 final rule.......................................................... February 27, 2002 final rule.
2002 ANPRM............................................................... Advance Notice of Proposed Rulemaking
published on September 25, 2002.
2003 NPRM................................................................ Notice of Proposed Rulemaking
published on August 14, 2003.
2005 final rule.......................................................... June 6, 2005 final rule.
2005 proposed rule....................................................... Notice of Proposed Rulemaking
published on September 7, 2005.
II. Background
On January 19, 2001, MSHA published a final rule addressing the
health hazards to underground metal and nonmetal miners from exposure
to diesel particulate matter (DPM) (66 FR 5706). The rule established
new health standards for these miners by requiring, among other things,
mine operators to use engineering and work practice controls to reduce
DPM to prescribed limits. It set an interim and final DPM concentration
limit in the underground metal and nonmetal mining environment with
staggered effective dates for implementation of the concentration
limits. The interim concentration limit of 400TC [mu]g/
m3 was to become effective on July 20, 2002. The final
concentration limit of 160TC [mu]g/m3 was
scheduled to become effective January 20, 2006. In the 2001 final rule,
MSHA projected that the mining industry would meet the final
concentration limit in their mines through the use of diesel
particulate filtration devices, ventilation changes, and the turnover
of equipment and engines to less polluting models (66 FR 5713, 5888).
Several mining trade associations and individual mine operators
challenged the final rule and the United Steelworkers of America (USWA)
intervened in the case, which is now pending in the United States Court
of Appeals for the District of Columbia Circuit. The parties agreed to
resolve their differences through settlement negotiations with MSHA and
we delayed the effective date of certain provisions of the standard.
A. First Partial Settlement Agreement
On July 5, 2001, as a result of an agreement reached in settlement
negotiations, MSHA published two notices in the Federal Register. One
notice (66 FR 35518) delayed the effective date of Sec. 57.5066(b)
related to tagging requirements in the maintenance standard. The second
notice (66 FR 35521) proposed a rule to make limited revisions to Sec.
57.5066(b) and added a new paragraph to Sec. 57.5067(b) ``Engines''
regarding the definition of the term ``introduced.'' MSHA published the
final rule on February 27, 2002 (67 FR 9180).
B. Second Partial Settlement Agreement
Settlement negotiations continued on the remaining unresolved
issues in the litigation, and on July 15, 2002, the parties finalized a
written agreement (67 FR 47296, 47297). Under the agreement, the
interim concentration limit of 400TC [mu]g/m3
became effective on July 20, 2002, without further legal challenge.
MSHA afforded mine operators one year to develop and implement good-
faith compliance strategies to meet the interim concentration limit,
and MSHA agreed to provide compliance assistance during this one-year
period. MSHA also agreed to propose rulemaking on several other
disputed provisions of the 2001 final rule. The legal challenge to the
rule was stayed pending completion of the additional rulemakings.
On July 20, 2003, MSHA began full enforcement of the interim
concentration limit of 400TC [mu]g/m3. MSHA's
enforcement policy was also based on the terms of the second partial
settlement agreement and includes the use of elemental carbon (EC) as
an analyte to ensure that a citation based on the 400 TC concentration
limit is valid and not the result of interferences (67 FR 47298). The
policy was discussed with the DPM litigants and stakeholders on July
17, 2003.
III. Rulemaking History
A. Advance Notice of Proposed Rulemaking (ANPRM) on the Interim and
Final Concentration Limits
On September 25, 2002, MSHA published an Advance Notice of Proposed
Rulemaking (ANPRM) (67 FR 60199). MSHA noted in the ANPRM that the
scope of the rulemaking was limited to the terms of the Second Partial
Settlement Agreement and posed a series of questions to the mining
community related to the 2001 final rule. MSHA also stated its intent
to propose a rule to revise the surrogate for the interim and final
concentration limits and to propose a DPM control scheme similar to
that included in our longstanding hierarchy of controls scheme used in
MSHA's air quality standards (30 CFR 56.5001 through 56.5005 and
57.5001 through 57.5005) for M/NM mines. In addition, MSHA stated that
it would consider technological and economic feasibility for the
underground M/NM mining industry to comply with revised interim and
final DPM limits. MSHA determined at that time that some mine operators
had begun to implement control technology on their underground diesel-
powered equipment. Therefore, MSHA requested relevant information on
current experiences with availability of control technology,
installation of control technology, effectiveness of control technology
to reduce DPM levels, and cost implications of compliance with the 2001
final rule.
B. Notice of Proposed Rulemaking (NPRM) on the Interim Limit
In response to our publication of the ANPRM, some commenters
recommended that MSHA propose separate rulemakings for revising the
interim and final concentration limits to give MSHA an opportunity to
gather further information to establish a final DPM limit, particularly
regarding feasibility. In the subsequent notice of proposed rulemaking
(NPRM) published on August 14, 2003 (68 FR 48668), MSHA concurred with
these commenters and notified the public in the NPRM that we would
propose a separate rulemaking to amend the existing final concentration
limit of 160TC [mu]g/m3. MSHA also requested
comments on an appropriate final DPM limit and solicited additional
information on feasibility. The proposed rule also addressed the
interim concentration limit by proposing a
[[Page 28926]]
comparable PEL of 308 [mu]g/m3 based on the EC surrogate and
included a number of other provisions.
C. Final Rule Revising the Interim Concentration Limit
MSHA published the final rule revising the interim concentration
limit on June 6, 2005 (70 FR 32868). This rule changed the interim
concentration limit of 400 [mu]g/m3 measured by TC to a
comparable PEL of 308 [mu]g/m3 measured by EC. The rule
requires MSHA's longstanding hierarchy of controls that is used for
other MSHA exposure-based health standards at M/NM mines, but retains
the prohibition on rotation of miners for compliance. Furthermore, the
rule, among other things, requires MSHA to consider economic as well as
technological feasibility in determining if operators qualify for an
extension of time in which to meet the final DPM limit, and deletes the
requirement for a control plan.
Currently, the following provisions of the DPM standard are
effective: Sec. 57.5060(a), establishing the interim PEL of 308
micrograms of EC per cubic meter of air which is comparable in effect
to 400 micrograms of TC per cubic meter of air; Sec. 57.5060(d),
Addressing control requirements; Sec. 57.5060(e), Prohibiting rotation
of miners for compliance with the DPM standard; Sec. 57.5061,
Compliance determinations; Sec. 57.5065, Fueling practices; Sec.
57.5066, Maintenance standards; Sec. 57.5067, Engines; Sec. 57.5070,
Miner training; Sec. 57.5071, Exposure monitoring; and, Sec. 57.5075,
Diesel particulate records.
D. September 2005 Notice of Proposed Rulemaking
On September 7, 2005, (70 FR 53280) MSHA proposed a rule to phase
in the final DPM limit because MSHA was concerned that there may be
feasibility issues for some mines to meet that limit by January 20,
2006.
Accordingly, the proposed rule considered staggering the effective
date for implementation of the final DPM limit, phased in over a five-
year period, primarily based on feasibility issues which had surfaced
since promulgation of the 2001 final rule. MSHA also proposed to delete
existing Sec. 57.5060(c)(3)(i) that restricts new mines from applying
for an extension of time for meeting the final concentration limit.
MSHA sought comment and data on an appropriate conversion factor for
the final DPM limit, technological implementation issues, and the costs
and benefits of the final rule. In addition, MSHA requested comments on
the appropriateness of including in a final rule a provision for
medical evaluation of miners required to wear respiratory protection
and transfer of miners who have been determined by a medical
professional to be unable to wear a respirator.
MSHA set hearing dates and a deadline for receiving comments on the
September 7, 2005 proposed rule with the expectation that MSHA would
complete the rulemaking to phase in the final DPM limit before January
20, 2006.
After publication of the September 7, 2005 proposed rule, MSHA
received a request from the United Steel, Paper and Forestry, Rubber,
Manufacturing, Energy, Allied Industrial and Service Workers
International Union (USW) for more time to comment on the proposed
rule. The USW explained that Hurricane Katrina had placed demands on
their resources that would prevent them from participating effectively
in the rulemaking under the current schedule for hearings and comments.
MSHA recognized the USW's need to devote resources to respond to the
aftermath of Hurricane Katrina and the impact that would have on their
participation under the current timetable. MSHA also received a request
from the National Stone, Sand and Gravel Association (NSSGA) for
additional time to comment on the proposed rule and for an additional
public hearing in Arlington, Virginia.
Accordingly, due to requests from the USW and NSSGA, MSHA published
a notice on September 19, 2005 (70 FR 55018) that changed the public
hearing dates from September 2005 to January 2006. MSHA also extended
the public comment period from October 14, 2005 to January 27, 2006.
Also on September 19, 2005, MSHA issued a second notice delaying the
applicability of the final concentration limit of 160TC [mu]g/
m3 until May 20, 2006.
Public hearings were held on the proposed rule in Arlington,
Virginia on January 5, 2006; Salt Lake City, Utah on January 9, 2006;
Kansas City, Missouri on January 11, 2006; and Louisville, Kentucky on
January 13, 2006. The comment period was scheduled to close on January
27, 2006. However, the National Mining Association and the Methane
Awareness Resource Group (MARG) Diesel Coalition requested that the
comment period be extended an additional 30 days beyond January 27,
2006 to allow for more time to prepare their comments. Additionally,
the Agency received a request from the National Institute for
Occupational Safety and Health (NIOSH) for a three week extension. On
January 26, 2006, MSHA determined that a three week extension of the
comment period was sufficient to allow additional public comment on the
proposed rule and extended the comment period until February 17, 2006.
What follows is a discussion of the specific revisions to the 2001
DPM standard. The final rule addresses:
Section 57.5060(b) addressing the final dpm concentration
limit;
Section 57.5060(c)(3)(i) addressing special extensions;
Section 57.5060(d)addressing medical evaluation and
transfer; and
Section 57.5075 addressing recordkeeping requirements.
IV. Risk Assessment
A. Introduction
We rely on our comprehensive January 2001 risk assessment published
at 66 FR 5752-5855 (as corrected at 66 FR 35518-35520) to support this
final rule. This risk assessment was updated in the 2005 final rule (70
FR 32868) establishing the 308EC [mu]g/m3 interim
permissible exposure limit (PEL). In the following discussion, we will
refer to the risk assessment published in the 2001 final rule as the
``2001 risk assessment'' and the updates published in the 2005 final
rule as the ``updated 2001 risk assessment.''
The discussion of the 2001 risk assessment in our 2005 final rule
presented our evaluation of health risks associated with DPM exposure
levels encountered in the mining industry and is based on a review of
the scientific literature available through March 31, 2000, along with
consideration of all material submitted during the public comment
periods for the 2001 and 2005 rulemakings.
The 2001 risk assessment was divided into three main sections.
Section 1 (66 FR 5753-5764) contained a discussion of U.S. miner
exposures based on field data collected through mid-1998. Section 2 of
the 2001 risk assessment (66 FR 5764-5822) reviewed the extensive
scientific literature on health effects associated with exposures to
DPM. In section 3 of the 2001 risk assessment (66 FR 5822-5855), we
evaluated the best available evidence to ascertain whether exposure
levels currently existing in mines warranted regulatory action pursuant
to the Mine Act. After careful consideration of all the submitted
public comments, the 2001 risk assessment established three main
conclusions:
1. Exposure to DPM can materially impair miner health or
functional capacity. These material impairments include acute
sensory irritations and respiratory symptoms (including allergenic
responses); premature death from cardiovascular, cardiopulmonary, or
respiratory causes; and lung cancer.
[[Page 28927]]
2. At DPM levels currently observed in underground mines, many
miners are presently at significant risk of incurring these material
impairments due to their occupational exposures to DPM over a
working lifetime.
3. By reducing DPM concentrations in underground mines, the rule
will substantially reduce the risks of material impairment faced by
underground miners exposed to DPM at current levels (66 FR 5854-
5855).
Exposure to DPM can materially impair miner health or functional
capacity. These material impairments include acute sensory irritations
and respiratory symptoms (including allergenic responses); premature
death from cardiovascular, cardiopulmonary, or respiratory causes; and
lung cancer. Scientific evidence gathered after the peer-review of the
2001 risk assessment generally supports our conclusions, and nothing in
our reviews suggests that they should be altered.
Some commenters presented critiques challenging the 2001 risk
assessment and disputing scientific support for any DPM exposure limit,
especially by means of an EC surrogate. Other commenters endorsed the
risk assessment and stated that recent scientific publications support
our conclusions.
Some commenters continue to question the scientific basis for
linking DPM exposures with an increased risk of adverse health effects.
Many of these comments are the same as those addressed in the 2005
final rule. We refer the reader to section VI, DPM Exposures and Risk
Assessment, in the 2005 final rule (70 FR at 32888) for discussions
addressing earlier commenters' positions on the underlying basis of the
risk assessment.
After considering the additional peer-reviewed scientific
literature submitted in response to the proposed rule, and all of the
comments, we did not identify any reason to reduce our concern with
regard to adverse health risks associated with DPM exposure as
identified in the 2001 risk assessment.
Section IV.B, summarizes the DPM exposure data that became
available after publication of the 2001 final rule. Section IV.C,
Health Effects, summarizes additional scientific literature pertaining
to adverse health effects of DPM and fine particulates submitted to the
record since our 2005 final rule. The reader is encouraged to refer to
the 2001 quantitative risk assessment (66 FR 5752-5855) that reviewed
the health effects associated with exposure to DPM. This discussion
evaluates the extent to which literature added to the record changes
the conclusions of the 2001 risk assessment. Section IV.D, Significance
of Risk, supplements Section 2 of the 2001 risk assessment (66 FR 5764-
5822) by addressing comments related to the risk assessment.
We reviewed comments on the potential health effects of
substituting EC for TC as a surrogate measure of DPM. We believe that
the issue of an appropriate surrogate for a measure of DPM is separate
from the issue of determining whether adverse health effects are caused
by whole DPM or a specific component of DPM. The 2001 risk assessment
is definitive in explaining relevant adverse health effects caused by
exposure to DPM. The risk assessment accurately portrays adverse health
effects ranging from sensory irritation to lung cancer caused by
exposure to DPM. The method by which exposures are measured does not
affect the conclusion that exposure to DPM produces serious adverse
health effects. Comments concerning the analytical method are addressed
in part VIII.A. Section 57.5060(b), addressing the final limits.
B. Exposures to DPM in Underground Metal and Nonmetal Mines
The 2001 risk assessment and the update presented in 2005 used the
best available data on exposure to DPM at underground M/NM mines to
quantify excess lung cancer risk. ``Excess risk'' refers to the
lifetime probability of dying from lung cancer during or after a 45-
year occupational DPM exposure. All of the exposure-response models for
lung cancer are monotonic (i.e., increased exposure yields increased
excess risk).
We evaluated exposures based on 355 samples collected at 27
underground U.S. M/NM mines prior to promulgating the 2001 rule. Mean
DPM concentrations found in the production areas and haulageways at
those mines ranged from about 285 [mu]g/m\3\ to about 2000 [mu]g/m\3\,
with some individual measurements exceeding 3500 [mu]g/m\3\. The
overall mean DPM concentration was 808 [mu]g/m\3\. All of the samples
considered in the 2001 risk assessment were collected prior to 1999.
Two sets of DPM exposure data, collected after promulgation of the
2001 final rule, were compiled for underground M/NM mines: (1) data
collected in 2001 and 2002 from 31 mines for purposes of the 31-Mine
Study (Table IV-1) and (2) data collected between 10/30/2002 and 10/29/
2003 from 183 mines to establish a baseline for future sample
comparisons (Table IV-2). The mean whole DPM concentration across all
358 valid samples in the 31-Mine Study was 432DPM [mu]g/
m\3\. The mean concentration across all valid 1,194 baseline samples
was 318DPM [mu]g/m\3\.\1\
---------------------------------------------------------------------------
\1\ The relationship DPM [ap] TC/0.8 is the same as that assumed
in the 2001 risk assessment. The relationship TC [ap] 1.3 x EC was
formulated under the Second Partial Settlement Agreement, based on
TC:EC ratios observed in the joint 31-Mine Study.
Table IV-1.--DPM Concentrations ([mu]g/m\3\) by Mine Category for Samples Collected for the 31-Mine Study (2001-
2002)
[DPM is estimated by TC / 0.8]
----------------------------------------------------------------------------------------------------------------
Estimated 8-hour Full Shift Equivalent DPM
Concentration ([mu]g/m\3\)
-----------------------------------------------
Metal Stone Trona Other
----------------------------------------------------------------------------------------------------------------
No. of samples.................................................. 116 105 54 83
Minimum......................................................... 46 16 20 27
Maximum......................................................... 2,581 1,845 331 1,210
Median.......................................................... 491 331 82 341
Mean............................................................ 610 465 94 359
Std. Error.................................................. 45 36 9 27
95% UCL..................................................... 699 537 113 412
95% LCL..................................................... 522 394 75 306
----------------------------------------------------------------------------------------------------------------
[[Page 28928]]
Table IV-2.--DPM Concentrations by Mine Category for Samples Collected During the Baseline Sampling Period (10/
30/2002-10/29/2003)
[DPM is estimated by (1.3 x EC) / 0.8.]
----------------------------------------------------------------------------------------------------------------
Estimated 8-hour Full Shift Equivalent DPM Concentration ( [mu]g/m\3\)
-----------------------------------------------------------------------
Total
Metal Stone Other N/M Trona Total excluding
Trona
----------------------------------------------------------------------------------------------------------------
No. of Samples.......................... 284 689 196 25 1,194 1,169
Maximum................................. 2,532 3,724 1,200 509 3,724 3,724
Median.................................. 339 186 185 102 218 223
Mean.................................... 444 295 243 132 318 322
Std. Error.......................... 23 13 15 20 10 10
95% UCL............................. 490 320 272 173 338 342
95% LCL............................. 399 270 214 91 299 303
----------------------------------------------------------------------------------------------------------------
Thus, despite substantial improvements attained since the 1989-1999
sampling period addressed by the 2001 risk assessment, underground M/NM
miners are still faced with an unacceptable risk of lung cancer due to
their occupational exposure to DPM. The reader is referred to part D of
this section, Significance of Risk, for further discussion of excess
risk.
Personal exposure samples taken after October 2003 are collected
according to our enforcement sampling policy. These enforcement samples
collected after the end of the Baseline Sampling period are not
representative of the average M/NM miner's exposure to DPM because we
collect samples to target the highest risk miner, not the average
miner. Therefore, this exposure information is not used to characterize
the average miner's exposure to DPM. See section V.B, Economic
Feasibility, for a summary of enforcement sampling results. However,
our enforcement activities from November 1, 2003 through January 31,
2006 continue to show some miners have experienced exposures
substantially greater than 308EC [mu]g/m\3\. During the time
period from November 1, 2003 to January 31, 2006, 1,798 valid personal
compliance samples from all mines covered by the regulation were
collected. From these samples collected, 18% (324) of samples exceeded
308EC [mu]g/m\3\, 22% (396) exceeded 350TC [mu]g/
m\3\, and 64% (1,151) exceeded 160TC [mu]g/m\3\. These
percentages show that miners are still being exposed to high levels of
DPM.
C. Health Effects
A key conclusion of the 2001 risk assessment was:
Exposure to DPM can materially impair miner health or functional
capacity. These material impairments include acute sensory
irritations and respiratory symptoms (including allergenic
responses); premature death from cardiovascular, cardiopulmonary, or
respiratory causes; and lung cancer. [66 FR 5854-5855]
We have reviewed scientific literature pertaining to health effects
of fine particulates in general and DPM in particular published later
than what was considered in the 2001 risk assessment. This scientific
evidence supports the 2001 risk assessment, and nothing in our review
suggests that it should be altered.
A number of commenters endorsed the 2001 risk assessment, and
suggested that the latest evidence strengthens its conclusions. Some
other commenters responding to our 2003 NPRM jointly stated that
``[t]he scientific evidence for the [adverse] health effects of DPM is
overwhelming'' and that ``evidence for the carcinogenicity and non-
cancer health effects of DPM has grown since 1998.''
A number of commenters contended that all of the evidence to date
is insufficient to support limitation of occupational exposure to DPM.
We believe that these commenters did not appreciate evidence presented
in the 2001 risk assessment and/or mischaracterized its conclusions.
For example, a few commenters erroneously stated that promulgation of
the 2001 rule was based on only ``two principal health concerns: (1)
The transitory, reversible health effects of exposure to DPM; and, (2)
the long-term impacts that may result in an excess risk of lung cancer
for exposed workers.'' Actually, as shown in the conclusion cited
above, the 2001 risk assessment identified three different kinds of
material health impairment associated with DPM exposure: (1) Acute
sensory irritations and respiratory symptoms (including allergenic
responses); (2) premature death from cardiovascular, cardiopulmonary,
or respiratory causes; and (3) lung cancer. Although the
cardiovascular, cardiopulmonary, and respiratory effects were
associated with acute exposure to DPM, commenters presented no evidence
that any such effects were ``transitory'' or ``reversible.'' Nor did
commenters present evidence that immunological responses associated
with either short-term or long-term DPM exposure were ``transitory'' or
``reversible.''
In addition, some commenters erroneously stated that ``no
[quantitative] dose/response relationship related to the PELs could be
demonstrated by MSHA.'' These commenters apparently did not appreciate
the discussion of exposure-response relationships in the 2001 risk
assessment (66 FR 5847-54) and failed, specifically, to note the
quantitative exposure-response relationships shown for lung cancer in
the two tables provided (66 FR 5852-53). Relevant exposure-response
relationships were also demonstrated in articles by Pope et al. cited
in the 2003 NPRM, which will be discussed further below.
Some commenters objected that the exposure-response relationships
presented in the 2001 risk assessment did not justify adoption of the
specific DPM exposure limits promulgated. These commenters mistakenly
assume the limits set forth in the 2001 final rule were derived from an
exposure-response relationship. As explained in 66 FR at 5710-14, the
choice of exposure limits, while justified by quantifiable adverse
health effects, was actually driven by feasibility concerns. The
exposure-response relationships provided clear evidence of significant
adverse human health effects (both cancer and non-cancer) at exposure
levels far below those determined to be feasible for mining.
The additional scientific literature cited in the 2003 NPRM, the
2005 final rule and this 2006 final rule is meant only to update and
supplement the evidence of health effects cited in the 2001 risk
assessment. Although the
[[Page 28929]]
2001 risk assessment presented ample evidence to justify its
conclusions, additional supplemental DPM health effects literature is
reviewed in this document that became available after the 2001 risk
assessment was published.
The following section summarizes additional studies submitted to
the record. Our review focuses on the implications of these study
results for the characterization of risk presented in MSHA's 2001
assessment. These study summaries are presented in three tables that
correspond to the material health impairments identified in the 2001
risk assessment: (1) Respiratory and immunological effects, including
asthma, (2) cardiovascular and cardiopulmonary effects, and (3) cancer.
A fourth table focuses on a recent study about potential mechanisms of
action for DPM. These tables describe the studies that some commenters
and the agency felt were representative of the type of new information
available since the completion of the 2001 assessment and the updated
2001 risk assessment, however, these tables are not to represent a
comprehensive review of all information published about particulate
matter.
(1) Respiratory and Immunological Effects, Including Allergenic
Responses
In the 2001 risk assessment, acute sensory irritations with
respiratory symptoms, including immunological or allergenic effects
such as asthmatic responses, were grouped together. Similar material
health impairments likely to be caused or exacerbated by excessive
exposures to DPM were identified. This finding was based on human
experimental and epidemiological studies and was supported by
experimental toxicology. (For an explanation of what type of health
effects are considered by us to be material impairments of health, the
reader is referred to the 2001 risk assessment (See 66 FR 5766.)
Table IV-3 summarizes five studies dealing with respiratory and
immunological effects of DPM and/or fine particulates in general that
have been submitted to the record since the 2005 literature update to
the 2001 risk assessment. The epidemiological studies by Hoppin (2004)
and Pourazar (2004) provide additional support for the association
between diesel exhaust exposure and development of asthma. Three of the
studies, Gluck (2003), Stenfors (2004), and Behndig (2006), have also
shown that exposures of human volunteers to diesel exhaust at levels
below 160TC [mu]g/m\3\ cause inflammation of the human
respiratory tract.
Table IV-3.--Studies of Human Respiratory and Immunological Effects
----------------------------------------------------------------------------------------------------------------
Authors, year Description Key results
----------------------------------------------------------------------------------------------------------------
Behndig et al., 2006......................... 15 healthy volunteers exposed to Exposure to diesel exhaust at
diesel exhaust or air (2 hours, this concentration is
diesel concentration measured sufficient to cause airway
as PM10: 100 [mu]g/m\3\) inflammation.
Eighteen hours after exposure,
the volunteers were assessed
using bronchoscopy with
bronchoalveolar lavage and
endobronchial mucosal biopsy.
Gluck et al., 2003........................... Comparison of nasal cytological The exposed group was found to
examinations of 136 customs have chronic inflammatory
officers involved solely in changes of the nasal mucosa,
clearance of heavy-goods including goblet cell
vehicles using diesel engines hyperplasia, increased
with examinations of 58 metaplastic and dysplastic
officers working only in epithelia, and increased
offices. Examinations were leukocytes while the unexposed
performed twice a year over a group did not.
period of 5 years. Measured
diesel engine emission
concentrations for the exposed
group varied between 31 and 60
[mu]g/m\3\.
Hoppin et al., 2004.......................... An association between diesel Driving diesel tractors was
exhaust exposure and significantly associated with
development of asthma is elevated odds of wheeze (odds
explored. The study evaluated ratio = 1.31; 95% confidence
the odds of wheeze associated interval = 1.13, 1.52). The
with nonpesticide occupational odds ratio for driving
exposures in a cohort of gasoline tractors was lower
approximately 21,000 farmers in but significant at 1.11 (95%
Iowa and North Carolina. confidence interval = 1.02,
Logistic regression models 1.21). A duration-response
controlling for age, state, relationship was observed for
smoking, and history of asthma driving diesel tractors but
or atopy were applied to not for driving gasoline
evaluate odds of wheeze in the tractors.
past year.
Pourazar et al., 2004........................ 15 healthy volunteers were This level of diesel exposure
exposed to diesel exhaust or caused a significant increase
air for 1 hour. Diesel in expression of the cytokine
concentration was measured as interleukin-13 in the airways
PM10 at 300 [mu]g/m\3\). of these volunteers.
Interleukin-13 is known to
play a key role in the
pathogenesis of asthma.
Stenfors et al., 2004........................ 25 healthy volunteers and 15 Diesel exhaust exposure was
mild asthmatics were exposed to documented to cause airways
diesel exhaust or air alone for inflammation in healthy
two hours (diesel concentration volunteers. Diesel exhaust
measured as PM10 at 108 [mu]g/ exposure did not significantly
m\3\). At six hours after worsen existing airways
exposure, subjects underwent inflammation in the
bronchoscopy with asthmatics, but did
bronchoalveolar lavage and significantly increase airways
mucosal biopsies. expression of the important
allergy-associated cytokine,
interleukin-10.
----------------------------------------------------------------------------------------------------------------
Review Article on Respiratory and Immunological Effects Considered
after the 2005 Final Rule
There is a progressive accumulation of evidence showing the
inflammatory and immunologic effects of diesel exhaust particulate
exposure plays a role in the development of allergies and asthma. The
2001 risk assessment and the update to the risk assessment describe in
detail review articles addressing these effects. The most recent review
by Riedl and Diaz-Sanchez (2005), summarized in Table IV-4, provides an
overview of observational and experimental studies that link DPM and
asthma.
[[Page 28930]]
Table IV-4.--Review Articles on Respiratory and Immunological Effects
----------------------------------------------------------------------------------------------------------------
Authors, year Description Key results
----------------------------------------------------------------------------------------------------------------
Riedl and Diaz-Sanchez, 2005................. Review of evidence-based studies Intact DEP and extracts of DEP
of the health effects of air induce reactive oxygen species
pollutants on asthma, focusing production. DEP and
on diesel exhaust particles particulate matter induce
(DEP). release of Granulocyte
Macrophage-Colony Stimulating
Factor and increase
intracellular peroxide
production.
The ultrafine particle fraction
of diesel exhaust might also
exert biologic effects
independent of chemical
composition through
penetration of cellular
components, such as
mitochondria.
----------------------------------------------------------------------------------------------------------------
In its 2002 ``Health Assessment Document for Diesel Engine
Exhaust,'' the Environmental Protection Agency (EPA) reached the
following conclusion with respect to immunological effects of diesel
exhaust:
Recent human and animal studies show that acute DE [diesel
exhaust] exposure episodes can exacerbate immunological reactions to
other allergens or initiate a DE-specific allergenic reaction. The
effects seem to be associated with both the organic and carbon core
fraction of DPM. In human subjects, intranasal administration of DPM
has resulted in measurable increases of IgE antibody production and
increased nasal mRNA for some proinflammatory cytokines. These types
of responses also are markers typical of asthma, though for DE,
evidence has not been produced in humans that DE exposure results in
asthma. The ability of DPM to act as an adjuvant to other allergens
also has been demonstrated in human subjects. (EPA, 2002)
Submissions to the rulemaking record since the 2005 final rule
support our previous position that exposure to DPM is associated with
the development of adverse respiratory and immunological effects.
(2) Cardiovascular and Cardiopulmonary Effects
In the 2001 risk assessment, the evidence presented for DPM's
adverse cardiovascular and cardiopulmonary effects relied on data from
air pollution studies in the ambient air. This evidence identifies
premature death from cardiovascular, cardiopulmonary, or respiratory
causes as an endpoint significantly associated with exposures to fine
particulates. The 2001 risk assessment found that ``[t]he mortality
effects of acute exposures appear to be primarily attributable to
combustion-related particles in PM2.5 [i.e., fine
Particulate Matter] (such as DPM) * * *.''
There are difficulties involved in utilizing the evidence from such
studies in assessing risks to miners from occupational exposure to DPM.
As noted in the 2001 risk assessment,
First, although DPM is a fine particulate, ambient air also
contains fine particulates other than DPM. Therefore, health effects
associated with exposures to fine particulate matter in air
pollution studies are not associated specifically with exposures to
DPM or any other one kind of fine particulate matter. Second,
observations of adverse health effects in segments of the general
population do not necessarily apply to the population of miners.
Since, due to age and selection factors, the health of miners
differs from that of the public as a whole, it is possible that fine
particles might not affect miners, as a group, to the same degree as
the general population (66 FR 5767).
However,
Since DPM is a type of respirable particle, information about
health effects associated with exposures to respirable particles,
and especially to fine particulate matter, is certainly relevant,
even if difficult to apply directly to DPM exposures (66 FR 5767).
One new study on cardiovascular and cardiopulmonary effects was
added to the record. See Toxicological Effects in this section for a
summary of this article.
The EPA concluded in its 2002 Health Assessment Document for Diesel
Engine Exhaust that diesel exhaust (as measured by DPM) is ``likely to
be a human carcinogen.'' Furthermore, the assessment concluded that
``[s]trong evidence exists for a causal relationship between risk for
lung cancer and occupational exposure to D[iesel]E[xhaust] in certain
occupational workers'' (Health Assessment Document for Diesel Engine
Exhaust, EPA, 2002, Sec. 9, p. 20). The EPA's 2004 Air Quality Criteria
Document for particulate matter (EPA, 2004b) describes a number of
additional studies related to the cardiopulmonary and cardiovascular
effects of PM2.5, including work published later than that
cited in MSHA's 2003 NPRM (68 FR 48668). One of the summary conclusions
presented in that document is:
Overall, there is strong epidemiological evidence linking (a)
short-term (hours, days) exposures to PM2.5 with
cardiovascular and respiratory mortality and morbidity, and (b)
long-term (years, decades) PM2.5 exposure with
cardiovascular and lung cancer mortality and respiratory morbidity.
The associations between PM2.5 and these various health
endpoints are positive and often statistically significant. [EPA,
2004b, Sec. 9 p. 46]
Submissions to the rulemaking record since the 2001 final rule
support our previous position that exposure to DPM is associated with
the development of adverse cardiovascular and cardiopulmonary effects.
(3) Cancer Effects
The 2001 risk assessment concluded that DPM exposure, at
occupational levels encountered in mining, was likely to increase the
risk of lung cancer. The assessment also found that there was
insufficient evidence to establish a causal relationship between DPM
and other forms of cancer. This update contains a description of three
human research studies and a literature review relating DPM and/or
other fine particulate exposures to lung cancer.
Lung Cancer
Table IV-5 presents three human studies pertaining to the
association between lung cancer and exposures to DPM or fine
particulates submitted to the record after the 2005 update of the 2001
risk assessment was done.
[[Page 28931]]
Table IV-5.--Studies on Lung Cancer Effects
----------------------------------------------------------------------------------------------------------------
Authors, year Description Key results
----------------------------------------------------------------------------------------------------------------
Garshick et al., 2004........................ An evaluation of lung cancer Railroad workers in jobs
mortality in 54,793 railroad associated with operating
workers ages 40-64 with 10-20 trains had a relative risk of
years of service in 1959. Based lung cancer mortality of 1.4
on evaluation of death (95% confidence limits = 1.30-
certificates, subsequent 1.51). The authors did not
mortality was assessed through think this association was due
1996. Diesel-exposed workers to uncontrolled confounding.
such as engineers and No relationship was found
conductors were compared to a between years of exposure and
referent group of less exposed lung cancer risk. The authors
workers such as ticket agents, discussed the potential for
station agents, signal- this to be due to factors such
maintainers, and clerks. as a healthy worker survivor
effect, lack of information on
historical changes in
exposure, and the potential
contribution of coal
combustion product before the
transition to diesel
locomotives.
Guo et al., 2004............................. Evaluation of lung cancer After controlling for other
mortality in all working Finns exposures such as asbestos and
born between 1906 and 1945 and quartz dust, only a slight
participating in the national excess of lung cancer was
census of December 1970. Based found in men aged 20-59
on the reported occupation held associated with diesel exhaust
for longest time and a national exposure. A parallel, but
database of exposures for weaker, association was
various occupations, a variety documented in women. The
of exposures including diesel authors concluded that risk
exhaust were estimated. associated with diesel exhaust
Information about subsequent ``was not consistently
diagnosis of lung cancer during elevated'' and speculated that
the period 1971 to 1995 was this was the result of factors
obtained from the Finnish such as low exposures or
Cancer Registry. confounding from unmeasured
non occupational exposures.
Jarvholm et al., 2003........................ Mortality study of Swedish Truck drivers had significantly
construction workers. increased risk for cancer of
Information about occupation the lung, while heavy
and smoking was taken from construction vehicle operators
computerized health records did not. In heavy construction
available for the period 1971- operators, a significant trend
1992. Workers in two of decreased risk for lung
occupations exposed to diesel cancer was associated with
exhaust, 6,364 truck drivers increasing use of vehicle
and 14,364 drivers of heavy cabins. The authors explained
construction vehicles were that there was a difference
compared to a reference group between truck and heavy
of 119,984 carpenters and equipment operators, but no
electricians. conclusion could be reached
without more detailed
information about the duration
and concentration of diesel
exhaust exposures and smoking
habits.
----------------------------------------------------------------------------------------------------------------
A Cohort Mortality Study With a Nested Case-Control Study of Lung
Cancer and Diesel Exhaust Among Nonmetal Miners [NIOSH/NCI 1997]
A number of commenters expressed opinions on the unpublished
document authored by Dr. Gerald Chase (2004) entitled Characterizations
of Lung Cancer in Cohort Studies and a NIOSH Study on Health Effects of
Diesel Exhaust in Miners. This document presents an analysis of some
very preliminary data provided by NIOSH and the National Cancer
Institute at a public stakeholder meeting held on Nov. 5, 2003. These
data were taken from unpublished charts that NIOSH and NCI used to
inform the public of the status and progress of their ongoing project,
A Cohort Mortality Study with a Nested Case-Control Study of Lung
Cancer and Diesel Exhaust Among Nonmetal Miners (NIOSH/NCI Study 1997).
We previously addressed Dr. Chase's analysis in our 2005 final rule (70
FR 32906). NIOSH and NCI researchers involved in that project have not
yet published their analyses or conclusions based on these data. When
the study is concluded, we will assess the results and their
association to our updated 2001 risk assessment findings. Therefore,
the Agency believes that the opinions expressed by commenters on Dr.
Chase's unpublished analysis of preliminary data are inappropriate for
identifying or assessing the relationship between occupational DPM
exposure and excess lung cancer mortality in that data set.
Bladder Cancer and Pancreatic Cancer
No additional information was submitted to the rulemaking record
that would change our position that bladder cancer is associated with
exposure to DPM. The Agency has not received additional information
that would change our position that there is insufficient evidence to
support a link between exposure to DPM and pancreatic cancer.
(4) Toxicological Effects of DPM Exposure
Table IV-6 presents one new particulate matter toxicity study (Sun
et al., 2005) obtained since the 2005 final rule. The table identifies
the agent(s) of toxicity investigated and indicates how the results
support the risk assessment by categorizing the toxic effects and/or
markers of toxicity found in each study.
[[Page 28932]]
Table IV-6.--Study On Toxicological Effects of DPM Exposure
--------------------------------------------------------------------------------------------------------------------------------------------------------
Authors, year Description Key results Agent(s) of toxicity Toxic effect(s)*
