Transition to New or Revised Particulate Matter (PM); National Ambient Air Quality Standards (NAAQS), 6718-6729 [E6-1798]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 71, Number 27 (Thursday, February 9, 2006)]
[Proposed Rules]
[Pages 6718-6729]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E6-1798]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 51

[EPA-HQ-OAR-2005-0175; FRL-8030-6]


Transition to New or Revised Particulate Matter (PM); National 
Ambient Air Quality Standards (NAAQS)

AGENCY: Environmental Protection Agency (EPA).

ACTION: Advance Notice of Proposed Rulemaking (ANPR).

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SUMMARY: The EPA recently issued a notice of proposed revisions to the 
national ambient air quality standards (NAAQS) for particulate matter 
(PM). EPA will take final action on the proposal by September 27, 2006. 
This notice provides advance notice of key issues for consideration in 
the development of potentially new or revised policies and/or 
regulations to implement revisions to the NAAQS for PM recognizing that 
no final decision has been made concerning whether or how to revise the 
PM NAAQS. The EPA is posing a number of questions related to the 
transition from the current to potentially revised PM2.5 
standards, as well as the transition from the current PM10 
standards to potentially new PM10-2.5 standards. In this 
ANPR, EPA is soliciting comment on the Agency's preferred approaches to 
revocation of the 1997 PM2.5 standards once any new 2006 
PM2.5 standards would be in place, and also approaches to 
revocation of the 24-hour PM10 standard in areas where it 
would remain after promulgation of any new PM10-2.5 
standards. The EPA is also highlighting and providing preliminary 
thinking on how to address some of the key New Source Review (NSR) 
issues related to the new PM10-2.5 standards, and the 
transition from PM10 standards to PM10-2.5 
standards. Finally, EPA is requesting comment on potential timeframes 
for designations, attainment demonstrations and State Implementation 
Plan (SIP) submittals and attainment dates for both any new 
PM2.5 and PM10-2.5 standards.

DATES: Comments must be received on or before April 10, 2006.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2005-0175, by one of the following methods:
     https://www.regulations.gov: Follow the on-line 
instructions for submitting comments.
     E-mail: A-and-R-Docket@epa.gov, Attention Docket ID No. 
EPA-HQ-OAR-2005-0175.
     Fax: Fax your comments to (202) 566-1741, Attention Docket 
ID. No. EPA-HQ-OAR-2005-0175.
     Mail: Docket EPA-HQ-OAR-2005-0175 Environmental Protection 
Agency, Mail Code: 6102T, 1200 Pennsylvania Ave., NW., Washington, DC, 
20460. Please include a total of two copies.
     Hand Delivery: Deliver your comments to: Air Docket, 
Environmental Protection Agency, 1301 Constitution Avenue, NW., Room 
B102, Washington, DC 20004, Attention Docket ID No. EPA-HQ-OAR-2005-
0175. Such deliveries are only accepted during the Docket's normal 
hours of operation, and special arrangements should be made for 
deliveries of boxed information.

[[Page 6719]]

    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2005-0175. The EPA's policy is that all comments received will be 
included in the public docket without change and may be made available 
online at https://www.regulations.gov, including any personal 
information provided, unless the comment includes information claimed 
to be Confidential Business Information (CBI) or other information 
whose disclosure is restricted by statute. Do not submit information 
that you consider to be CBI or otherwise protected through https://
www.regulations.gov or e-mail. The https://www.regulations.gov Web site 
is an ``anonymous access'' system, which means EPA will not know your 
identity or contact information unless you provide it in the body of 
your comment. If you send an e-mail comment directly to EPA without 
going through https://www.regulations.gov, your e-mail address will be 
automatically captured and included as part of the comment that is 
placed in the public docket and made available on the Internet. If you 
submit an electronic comment, EPA recommends that you include your name 
and other contact information in the body of your comment with any disk 
or CD-ROM you submit. If EPA cannot read your comment due to technical 
difficulties and cannot contact you for clarification, EPA may not be 
able to consider your comment. Electronic files should avoid the use of 
special characters, any form of encryption, and be free of any defects 
or viruses. For further information about EPA's public docket visit the 
EPA Docket Center homepage at https://www.epa.gov/epahome/dockets.htm. 
For additional instruction on submitting a comment, go to ``What Should 
I Consider as I Prepare My Comments for the EPA?'' of the SUPPLEMENTARY 
INFORMATION section of this document.
    Docket: All documents in the docket are listed in the https://
www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in hard copy. 
Publicly available docket materials are available either electronically 
in https://www.regulations.gov or in hard copy at the EPA Docket Center, 
EPA/DC, EPA West, Room B102, 1301 Constitution Avenue, NW., Washington, 
DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday 
through Friday, excluding legal holidays. A reasonable fee may be 
charged for copying. The telephone number for the Public Reading Room 
is (202) 566-1744, and the telephone number for the Air Docket is (202) 
566-1742.

FOR FURTHER INFORMATION CONTACT: For questions regarding PM 
implementation issues, contact Ms. Barbara Driscoll, U.S. Environmental 
Protection Agency, Office of Air Quality Planning and Standards, Mail 
Code C504-02, Research Triangle Park, NC 27711, phone number (919) 541-
1051 or by e-mail at: driscoll.barbara@epa.gov. Regarding NSR issues, 
contact Raj Rao, U.S. Environmental Protection Agency, Office of Air 
Quality Planning and Standards, Mail Code C339-03, Research Triangle 
Park, NC 27711, phone number (919) 541-5344 or by e-mail at 
rao.raj@epa.gov.

SUPPLEMENTARY INFORMATION:

How Should I Submit CBI to the Agency?

    Do not submit information that you consider to be CBI through 
https://www.regulations.gov or e-mail. Clearly mark the part or all of 
the information that you claim to be CBI.
    For CBI information in a disk or CD-ROM that you mail to EPA, mark 
the outside of the disk or CD-ROM as CBI and then identify 
electronically within the disk or CD-ROM the specific information that 
is claimed as CBI. In addition to one complete version of the comment 
that includes information claimed as CBI, a copy of the comment that 
does not contain the information claimed as CBI must be submitted for 
inclusion in the public docket. Information so marked will not be 
disclosed except in accordance with procedures set forth in 40 CFR part 
2. Send or deliver information identified as CBI only to the following 
address: Roberto Morales, U.S. EPA, Office of Air Quality Planning and 
Standards, Mail Code C404-02, Research Triangle Park, NC 27711, 
telephone (919) 541-0880, e-mail at morales.roberto@epa.gov, Attention 
Docket ID No. EPA-HQ-OAR-2005-0175.

What Should I Consider as I Prepare My Comments for EPA?

    You may find the following suggestions helpful for preparing your 
comments:
    1. Explain your views as clearly as possible.
    2. Describe any assumptions that you used.
    3. Provide any technical information and/or data you used that 
support your views.
    4. If you estimate potential burden or costs, explain how you 
arrived at your estimate.
    5. Provide specific examples to illustrate your concerns.
    6. Offer alternatives.
    7. Make sure to submit your comments by the comment period deadline 
identified.
    8. To ensure proper receipt by EPA, identify the appropriate docket 
identification number in the subject line on the first page of your 
response. It would also be helpful if you provided the name, date, and 
Federal Register citation related to your comments.

Table of Contents

I. What Actions Related to the PM NAAQS Have Recently Been Proposed 
or Will Soon Be Proposed Which Relate to This Notice?
    A. National Ambient Air Quality Standards for Particulate Matter
    B. Revisions to Ambient Air Monitoring Regulations
    C. Treatment of Data Influenced by Exceptional Events
II. What Is EPA'S Strategy for Addressing PM?
    A. The State Implementation Plan (SIP) System
    B. National Rules
III. How Should EPA Implement the Transition From the 1997 
PM2.5 NAAQS to Any New 2006 PM2.5 NAAQS?
    A. What Is the Status of Areas Designated Under the 1997 
PM2.5 NAAQS?
    B. How Might EPA Implement the Transition from the 1997 
PM2.5 NAAQS to Any New 2006 PM2.5 NAAQS?
    1. PM2.5 NAAQS Option 1
    2. PM2.5 NAAQS Option 2
IV. What Are the Potential Timelines for Implementation of Any New 
2006 PM2.5 NAAQS?
    A. How Would the Implementation Schedules of the 1997 
PM2.5 NAAQS and Any New 2006 PM2.5 NAAQS Fit 
Together if the Revised PM2.5 Standards Are More 
Stringent Than the Current Standards?
    B. What Is EPA's Preferred Schedule for Any New 2006 
PM2.5 Designation Process?
    C. What Would the Schedule Be for Attainment Demonstrations and 
SIP Submittals for Any New 2006 PM2.5 Standards?
    D. What Are Attainment Dates for Any New 2006 PM2.5 
Standards?
V. What Are the Potential Timelines for Implementation of Any New 
PM10-2.5 NAAQS?
    A. What Is a Potential Schedule for Any New PM10-2.5 
Designation Process?
    B. What Is EPA's Preferred Schedule for Designations for any New 
PM10-2.5 Standards?
    C. What Is EPA's Preferred Schedule for Attainment 
Demonstrations and SIP Submittals for Any New PM10-2.5 
Standards?
    D. What Is EPA's Preferred Schedule for Attaining Any New 
PM10-2.5 Standards?

[[Page 6720]]

VI. How Should EPA Implement the Transition From the PM10 
Standards to Any New PM10-2.5 Standards?
    A. What Is EPA's Proposal for Revoking the PM10 
Standards?
    B. What Should the Timing Be for Revoking the 24-Hour 
PM10 Standard for Those Areas Where the 24-Hour 
PM10 Standard Is Retained?
    C. What Transition Issues Are Created by Revoking the 24-Hour 
PM10 Standard in Areas Where It is Currently Proposed to 
be Retained and How Might They be Addressed?
    1. Control Measures
    2. Transportation Conformity
    3. General Conformity
    4. New Source Review Program
VII. What Emissions Inventory Requirements Should Apply Under Any 
New PM2.5 and PM10-2.5 NAAQS?
VIII. Statutory and Executive Order Reviews

I. What Actions Related to the PM NAAQS Have Recently Been Proposed or 
Will Soon Be Proposed Which Relate to This Notice?

    This ANPR is intended to solicit input into key issues related to 
the transition to any new or revised NAAQS for PM. The EPA has proposed 
two rulemakings, the NAAQS for Particulate Matter; Proposed Rule (71 FR 
2620, January 17, 2006) and the Revisions to Ambient Air Monitoring 
Regulations (71 FR 2710, January 17, 2006), and will be proposing 
another rulemaking, Treatment of Data Influenced by Exceptional Events 
(anticipated to be published by March 2006). These proposals are 
summarized here to provide background for the issues and questions 
raised in this document. The EPA is not taking comment on these actions 
here. Rather, if you have comments, you should submit them to the 
docket for the proposed rulemaking to which they are applicable, 
following the procedures described in each proposal.

A. National Ambient Air Quality Standards for Particulate Matter

    On December 20, 2005, the Administrator signed a notice proposing 
revisions to the primary and secondary NAAQS for PM, which was 
published on January 17, 2006 (71 FR 2620). The proposal can be found 
at: https://www.epa.gov/oar/particlepollution/actions.html. For the 
primary standards for fine particles (particles generally less than or 
equal to 2.5 micrometers ([mu]m) in diameter, or PM2.5), EPA 
proposed to revise the level of the 24-hour PM2.5 standard 
from 65 micrograms per cubic meter ([mu]mg/m3) to 35 [mu]g/
m3, providing increased protection against health effects 
associated with short-term exposure (including premature mortality and 
increased hospital admissions and emergency room visits) and to retain 
the level of the annual PM2.5 standard at 15 [mu]g/
m3, continuing protection against health effects associated 
with long-term exposure (including premature mortality and development 
of chronic respiratory disease). The EPA is also taking comment on 
alternative NAAQS levels. Additionally, EPA proposed to revise the 
criteria for spatial averaging of monitors for purposes of the annual 
PM2.5 standard.
    In addition, for the primary standards for coarse particles 
generally less than or equal to 10[mu]m in diameter (PM10), 
EPA proposed to revise the 24-hour PM10 standard in part by 
establishing a new indicator for thoracic coarse particles (particles 
generally between 2.5 and 10[mu]m in diameter, PM10-2.5), 
qualified so as to include any ambient mix of PM10-2.5 that 
is dominated by resuspended dust from high-density traffic on paved 
roads and PM generated by industrial sources and construction sources, 
and exclude any ambient mix of PM10-2.5 that is dominated by 
rural windblown dust and soils and PM generated by agricultural and 
mining sources. The EPA also proposed that agricultural sources, mining 
sources and other similar sources of crustal material shall not be 
subject to control in meeting the proposed standard. The EPA proposed 
to set the new PM10-2.5 standard at a level of 70 [mu]g/
m3, continuing to provide a generally equivalent level of 
protection against health effects associated with short-term exposure 
(including hospital admissions for cardiopulmonary diseases, increased 
respiratory symptoms and possibly premature mortality).
    In addition, EPA proposed to revoke the annual PM10 
standard everywhere, and the 24-hour PM10 standard 
everywhere except in areas where there is at least one monitor that is 
located in an urbanized area\1\ with a minimum population of 100,000 
people and that violates the 24-hour PM10 standard based on 
the most recent 3 years of data. This revocation of the PM10 
standards would become effective upon promulgation of the 
PM10-2.5 NAAQS (expected to be December 2006). In the 
January 17, 2006, notice, the Agency provided a specific list of areas 
where the 24-hour PM10 standard would not be revoked under 
the proposal based on the most recent 3 years of data. EPA proposed to 
revoke the 24-hour PM10 standard in all other areas. In 
addition, EPA requested comment on whether the 24-hour PM10 
standard should be retained in additional areas that are either 
urbanized areas with populations less than 100,000 people or non-
urbanized areas (i.e., populations less than 50,000) but where the 
majority of the ambient mix of PM10-2.5 is generated by high 
density traffic on paved roads, industrial sources, and construction 
sources, and which have at least one monitor that violated the 24-hour 
PM10 standard based on the most recent 3 years of data.
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    \1\ As defined by the U.S. Bureau of the Census, an urbanized 
area has ``a minimum residential population of at least 50,000 
people'' and generally includes ``core census block groups or blocks 
that have a population density of at least 1,000 people per square 
mile and surrounding census blocks that have an overall density of 
at least 500 people per square mile.'' The Census Bureau notes that 
``under certain conditions, less densely settled territory may be 
part of each UA.'' See https://www.census.gov/geo/www/ua/ua_2k.html.
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    For the secondary PM standards, EPA proposed to revise the current 
standards by making them identical to the suite of proposed primary 
standards for fine and coarse particles.

B. Revisions to Ambient Air Monitoring Regulations

    At the same time EPA proposed revisions to the PM NAAQS, EPA also 
proposed Revisions to the Ambient Air Monitoring Regulations (71 FR 
2710, January 17, 2006) for criteria pollutants to support the proposed 
revisions to the NAAQS. The proposal can be found at: https://
www.epa.gov/oar/particlepollution/actions.html. Included among the 
proposed PM-related changes are new provisions to be added to 40 CFR 
parts 53 and 58 which address approval of monitoring methods and 
PM10-2.5 monitoring requirements. The added provisions in 
part 53 would address approval of PM10-2.5 filter-based 
Federal Reference Method (FRM) samplers and both filter-based and 
continuous Federal Equivalent Method (FEM) monitors. Provisions in part 
58 would provide the monitoring requirements for a PM10-2.5 
network, including the minimum number of monitors a State must deploy. 
In addition, the proposal adds provisions for the conditions under 
which a PM10-2.5 monitor may be compared to the 
PM10-2.5 NAAQS.
    The proposal also amends a number of existing provisions for 
PM2.5 monitoring, including changing the criteria for FEM 
equivalency determinations for continuous PM2.5 monitors. 
This should allow States to operate continuous monitors at more 
required monitoring sites, thereby providing more robust data for the 
PM2.5 air quality program.

C. Treatment of Data Influenced by Exceptional Events

    The EPA will soon propose a rule to govern the review and handling 
of air

[[Page 6721]]

quality monitoring data influenced by exceptional events. Section 319 
of the Clean Air Act (CAA) defines an event as an exceptional event if 
the event affects air quality; is not reasonably controllable or 
preventable; is a natural event, or an event caused by human activity 
that is unlikely to recur at a particular location; and is determined 
by the Administrator to be an exceptional event. The EPA will be 
proposing procedures and criteria related to the identification, 
evaluation, interpretation and use of air quality monitoring data 
related to the NAAQS where State air quality agencies petition EPA to 
exclude, in whole or in part, air quality data that are directly 
affected by exceptional events. Section 319 of the CAA, as amended by 
section 6013 of the Safe Accountable Flexible Efficient-Transportation 
Equity Act (SAFE-TEA) of 2005, requires EPA to publish a proposed rule 
in the Federal Register, no later than March 1, 2006.

II. What Is EPA's Strategy for Addressing PM?

    Our overall strategy for achieving the PM primary and secondary 
standards is based on the structure outlined in the CAA. The CAA 
outlines important roles for State and Tribal governments and for EPA 
in implementing NAAQS.
    States have primary responsibility for developing and implementing 
SIPs that contain local and in-State measures needed to achieve the air 
quality standards in each area. We assist States and Tribes by 
providing technical tools, assistance and guidance, including 
information on potential control measures. The EPA recently issued a 
Proposed rule to Implement the Fine Particle NAAQS (70 FR 65984) to 
support implementation of the 1997 PM2.5 NAAQS. In addition, 
we set national emissions standards/limits for some sources, such as 
new motor vehicles, certain categories of major new sources, and 
existing stationary sources of toxic air pollutants, all of which may 
obtain reductions in PM. Where upwind sources (such as coal-fired power 
plants) significantly contribute to downwind problems in other States 
or tribal areas, we can issue Federal regulations to ensure that the 
upwind States address these contributing emissions (such as the Clean 
Air Interstate Rule), or we can put in place Federal regulations in 
situations where the upwind States fail to address these sources.

A. The State Implementation Plan (SIP) System

    A SIP is the compilation of regulations and programs that a State 
uses to carry out its responsibilities under the CAA, including the 
attainment, maintenance, and enforcement of the NAAQS. States use the 
SIP process to identify the emissions sources that contribute to the 
nonattainment problem in a particular area, and to select the emissions 
reductions measures most appropriate for that area, considering 
technical and economic feasibility, and a variety of local factors such 
as population exposure, enforceability, and economic impact. Under the 
CAA, SIPs must ensure that areas reach attainment as expeditiously as 
practicable. These plans take into consideration emissions reductions 
resulting from national programs (such as mobile source regulations, 
the acid rain program, or maximum achievable control technology (MACT) 
standards for air toxics), as well as from State or local programs not 
directly mandated under the CAA.

B. National Rules

    As described in a recent EPA report, The Particle Pollution Report: 
Current Understanding of Air Quality and Emissions through 2003,\2\ 
State and Federal programs have made substantial progress in reducing 
ambient concentrations of PM10 and PM2.5. For 
example, PM10 concentrations have decreased 31 percent 
nationally since 1988. Regionally, PM10 concentrations 
decreased most in areas with historically higher concentrations--the 
Northwest (39 percent decline), the Southwest (33 percent decline), and 
southern California (35 percent decline). Direct emissions of 
PM10 have decreased approximately 25 percent nationally 
since 1988.
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    \2\ Environmental Protection Agency (2004). The Particle 
Pollution Report: Current Understanding of Air Quality and Emissions 
through 2003. Office of Air Quality Planning and Standards; 
Emissions, Monitoring, and Analysis Division, Research Triangle 
Park, NC 27711; report no. EPA-454-R-04-002. December 2004.
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    Programs aimed at reducing direct emissions of particles have 
played an important role in reducing PM10 concentrations, 
particularly in western areas. Some examples of PM10 
controls include paving unpaved roads and using best management 
practices for agricultural sources of resuspended soil. Of the 87 areas 
that were designated nonattainment for PM10 in the early 
1990's, 64 now meet those standards. In cities that have not attained 
the PM10 standards, the number of times the standard is 
exceeded is down significantly.
    National programs that affect regional emissions have contributed 
to lower sulfate concentrations and, consequently, to lower 
PM2.5 concentrations, particularly in the Industrial Midwest 
and Southeast. National ozone-reduction programs designed to reduce 
emissions of volatile organic compounds (VOCs) and nitrogen oxides 
(NOX) also have helped reduce carbon and nitrate particles, 
both of which are components of PM2.5. Power plant emissions 
of sulfur dioxide dropped 33% from 1990 to 2003, largely as a result of 
EPA's Acid Rain Program. Nationally, SO2 emissions have 
declined 9 percent, NOX emissions have declined 9 percent, 
and VOC emissions have declined by 12 percent from 1999 to 2003. In 
eastern States affected by the Acid Rain Program, sulfates decreased 7 
percent over the same period.
    Over the next 10 to 20 years, national and regional regulations 
will make major reductions in ambient PM2.5 levels. The 
Clean Air Interstate Rule (CAIR) and the NOX SIP Call will 
reduce SO2 and NOX emissions from electric 
generating units and industrial boilers across the eastern half of the 
U.S., regulations to implement the current ambient air quality 
standards for PM2.5 will likely result in direct 
PM2.5 and PM2.5 precursor controls in 
nonattainment areas, and new national mobile source regulations 
affecting off-highway diesel engines, highway gasoline and diesel 
vehicles, and other mobile sources will reduce emissions of 
NOX, direct PM2.5, SO2, and VOCs. The 
EPA estimates that these Federal regulations for stationary and mobile 
sources will cut SO2 emissions by 6 million tons annually in 
2015 from 2001 levels. Emissions of NOX will be cut by 9 
million tons annually in 2015 from 2001 levels. Emissions of VOCs will 
drop by 3 million tons, and direct PM2.5 emissions will be 
cut by 200,000 tons in 2015, compared to 2001 levels.

III. How Should EPA Implement the Transition From the 1997 PM2.5 NAAQS 
to Any New 2006 PM2.5 NAAQS?

A. What Is the Status of Areas Designated Under the 1997 PM2.5 NAAQS?

    On April 5, 2005, nonattainment designations became final for 39 
nonattainment areas. These areas were designated based on air quality 
data from 2001-2003 and 2002-2004. Nationally, PM2.5 
concentrations have declined by 10 percent from 1999 to 2003. 
Generally, PM2.5 concentrations have also declined the most 
in regions with the highest concentrations--the Southeast (20 percent 
decline), southern California (16 percent decline), and the

[[Page 6722]]

Midwest (9 percent decline)--with the exception of the Northeast, where 
PM2.5 concentrations increased by 1%. Direct emissions of 
PM2.5 have decreased by 5 percent nationally over the past 5 
years.
    Modeling done by EPA indicates that by 2010, 18 of the 39 areas 
currently not attaining the 1997 PM2.5 standards should come 
into attainment of those standards just based on regulatory programs 
already in place, including CAIR, the Clean Diesel Rules, and other 
Federal measures. Four more PM2.5 areas are projected to 
attain the standards by 2015 based on the implementation of these 
programs. All areas in the eastern U.S. will have lower 
PM2.5 concentrations in 2015 relative to present-day 
conditions. In most cases, the predicted improvement in 
PM2.5 ranges from 10 percent to 20 percent.

B. How Might EPA Implement the Transition From the 1997 PM2.5 NAAQS to 
Any New 2006 PM2.5 NAAQS?

    The EPA has evaluated several options for the transition from the 
1997 PM2.5 standards to any new 2006 PM2.5 
standards, and is elaborating on two potential options. Should the 
Agency decide to revise the current PM2.5 standards, then 
either of the following two options would continue the momentum and 
continuity of the existing implementation program as areas look to 
reduce ambient PM2.5 concentrations to meet the current and 
revised PM2.5 NAAQS. Any suggested alternatives to these 
approaches should demonstrate how it will continue the momentum and 
continuity of the implementation program.
1. PM2.5 NAAQS Option 1
    Option 1 recognizes that the only proposed change to the 1997 
annual PM2.5 standard is a change in the application of 
spatial averaging (71 FR 2620). Because the EPA believes that the 
proposed change, if adopted, would not be significant enough to require 
new designations under section 107(d), we are soliciting comment on 
whether it would be appropriate to view this revision as minor, thus 
not requiring a designation process. Even though section 107(d) calls 
for EPA to commence the designation process for ``any new or revised 
NAAQS,'' exceptions could be made for revisions to a NAAQS of a de 
minimis or insignificant nature such that they should not lead to the 
initiation of the designation process and consequent establishment of 
new SIP submission and attainment deadlines. Option 1 would be 
considered only if EPA finalized a revision to the annual 
PM2.5 standard that was of such a minor nature as the 
proposed revision. It would not be available if EPA revised the 
standard more substantially.
    Following this path, EPA would propose not to revoke the 1997 
annual PM2.5 standard, and would propose to revoke the 1997 
24-hour PM2.5 standard 1 year after designations are 
finalized under any new 2006 PM2.5 standard. With the 
exception of 2 areas in California (South Coast Air Quality District 
and San Joaquin Valley) all areas designated as nonattainment for 
PM2.5 were only violating the annual standard. Under this 
path, new nonattainment designations would only be made for the areas 
which do not meet any new 2006 24-hour PM2.5 standard. 
Therefore, areas which are designated nonattainment for the 1997 annual 
PM2.5 standard would continue to develop and implement their 
SIPs based on a final implementation rule for the PM2.5 
NAAQS (proposed on November 1, 2005 at 70 FR 65984). Areas which are 
newly designated nonattainment under any new 24-hour PM2.5 
standard would submit a SIP by April 2013 following the proposed 
schedule in part IV.C below. This approach would maintain the momentum 
in the PM2.5 SIP development and implementation program. It 
would also not require the development and implementation of an anti-
backsliding rule to maintain progress in the program, as no areas are 
in nonattainment based solely on the 24-hour PM2.5 standard. 
Therefore control measures would still be in place under the approved 
PM2.5 SIPs.
2. PM2.5 NAAQS Option 2
    Option 2 varies from Option 1 in that EPA would revoke the 1997 
annual and 24-hour PM2.5 standards 1 year after designations 
under any new 2006 PM2.5 standards. This approach is similar 
to that promulgated under the ozone program (69 FR 23951, April 30, 
2004) for the revocation of the 1-hour ozone standard one year after 
designations under the 8-hour ozone standard. Following this path, EPA 
would develop and implement an ``anti-backsliding'' rule to ensure that 
SIP control measures developed and adopted under the 1997 
PM2.5 NAAQS remained in place until SIPs could be submitted 
and approved to meet any new 2006 PM2.5 standards. In the 
anti-backsliding rule, EPA would address issues similar to those 
addressed in the anti-backsliding rule adopted as part of the 
transition from implementation of the 1-hour ozone standard to the 8-
hour ozone standard including: (1) Which planning and control 
requirements should remain in effect; (2) effect of the revised 
standards on the New Source Review (NSR) program; and (3) how the 
transition would affect general and transportation conformity programs. 
In addressing some of these issues, EPA is inclined to follow the 
precedent set by the ozone program which required areas in 
nonattainment with both the 1-hour and 8-hour ozone NAAQS to maintain 
mandatory control measures already in place, and allowed such areas to 
revise or remove discretionary control measures following a section 
110(l) demonstration. In addition, such areas would implement 
transportation conformity and NSR based on their designations for the 
revised standard only, for the reasons explained in the ozone anti-
backsliding rule (69 FR 23954, April 30, 2004). The EPA invites comment 
on these two options, and solicits comments on any additional options 
which would ensure a smooth transition and continued improvement in air 
quality.

IV. What Are the Potential Timelines for Implementation of Any New 2006 
PM2.5 NAAQS?

A. How Would the Implementation Schedules of the 1997 PM2.5 NAAQS and 
Any New 2006 PM2.5 NAAQS Fit Together if the Revised PM2.5 Standards 
Are More Stringent Than the Current Standards?

    Section 109(d)(1) of the CAA requires a thorough review of the 
NAAQS, and revisions if appropriate, at 5-year intervals. Current 
requirements of the CAA thus anticipate an overlap in review and 
implementation of standards. The EPA believes that for planning 
purposes, when EPA revises a standard as it has proposed to do, it is 
beneficial for States to understand control strategies that may be 
useful in attaining any new 2006 PM2.5 standards when developing 
control strategies for the 1997 PM2.5 standards.

B. What Is EPA's Preferred Schedule for the Any New 2006 PM2.5 
Designation Process?

    Under the terms of the consent decree governing the review of the 
1997 PM NAAQS, EPA agreed that no later than September 27, 2006, it 
would sign for publication a notice of final rulemaking concerning its 
review of the PM NAAQS. The EPA expects that any new 2006 
PM2.5 standards would be published in the Federal Register 
within 4 weeks, and become effective 60 days later probably in December 
2006. Timeframes below are outlined based on this assumption. Section 
107(d)(1) lays out a schedule allowing States up to 1 year in which to 
make recommendations to EPA for areas that

[[Page 6723]]

might be designated as nonattainment for any new PM2.5 
standards. State designation recommendations would then be due by 
December 2007. Tribes would also be encouraged, but not required, to 
submit designation recommendations to EPA for their reservations or 
other areas under their jurisdiction by December 2007.
    These recommendations would be based on 3 years of the most recent 
monitoring data (e.g., 2004-2006). The EPA(s evaluation of the existing 
PM2.5 monitoring network indicates that it is adequate for 
designations under both the proposed revised annual and proposed 
revised 24-hour standards. Depending on which revocation process is 
selected for the 1997 PM2.5 NAAQS, designations may be for 
the revised 24-hour standard alone or both the annual and 24-hour 
standards.
    Following submittal of designation recommendations by the States, 
EPA would evaluate the recommendations and make possible modifications. 
Consistent with section 107, States would be notified of these changes, 
and would be allowed to make additional comments on the proposed 
designations. The EPA would issue final PM2.5 designations 
under any new PM2.5 NAAQS no later than December 2009. These 
designations would be effective by April 2010. The CAA provides EPA 
with up to 3 years to designate nonattainment areas following 
promulgation of a new or revised NAAQS. The EPA anticipates that this 
full time period may be necessary for a variety of reasons as it has 
been in the past, including evaluating more recent data in order to 
determine appropriate designation boundaries. This timeline would allow 
States to look at 2006-2008 monitoring data and update their 
recommendations to EPA if they choose to do so based on the more recent 
data.
    In addition, as was done for the 1997 PM2.5 NAAQS 
designations, we would anticipate allowing a further update based on 
2007-2009 monitoring data, and make designations effective in April 
2010. Table 1 at the end of part IV(D) provides a timeline showing the 
dates that would result from such a designation process. The EPA would 
appreciate comments on this timeline and other potential approaches.

C. What Would the Schedule Be for Attainment Demonstrations and SIP 
Submittals for Any New 2006 PM2.5 Standards?

    Part D of title I of the CAA sets forth the requirements for SIPs 
needed to attain the NAAQS. Part D includes a general subpart 1 which 
applies to all NAAQS for which a specific subpart does not exist. These 
provisions apply to the PM2.5 standards and would apply to 
any revised PM2.5 standards. The EPA has currently proposed 
implementation rules for PM2.5 (70 FR 65984) which, when 
finalized, will govern any revised standards.
    Section 172(b) of the CAA requires that at the time the Agency 
promulgates nonattainment area designations, EPA must also establish a 
schedule for States to submit SIPs meeting the applicable requirements 
of section 172(c) and section 110(a)(2) of the CAA. Section 172(b) 
requires that such schedule allow a State to submit its attainment 
demonstration and SIP revision within no more than 3 years of 
nonattainment designation. Following the above timeline (outlined in 
IV.B), if nonattainment area designations become effective in April 
2010, and EPA allows the maximum time for SIP submissions, then 
attainment demonstrations and SIP revisions would be due by April 2013.

D. What Are Attainment Dates for Any New 2006 PM2.5 Standards?

    Section 172(a)(2)(A) states that the attainment date for a 
nonattainment area must be ``as expeditiously as practicable, but no 
later than 5 years from the date of designation for the area.'' If any 
new 2006 PM2.5 designations are made in December 2009 and 
have an effective date of April 2010, the initial attainment date for 
any new PM2.5 standard would be no later than April 2015. As 
an aside, this attainment date would correspond with the latest date an 
area designated in April 2005 could come into attainment with the 1997 
PM2.5 NAAQS. For an area with a maximum 5-year attainment 
date, EPA would determine whether it had attained the standard by 
evaluating air quality data from the three previous calendar years 
(2012-2014).
    Section 172 also states that if EPA deems it appropriate, the 
Agency may extend the attainment date for an area for a period not 
greater than 10 years from the date of designation as nonattainment, 
taking into account the severity of the nonattainment problem in the 
area, and the availability and feasibility of pollution control 
measures. For any area that is granted the full 5-year attainment date 
extension, the attainment date would be as expeditiously as 
practicable, but no later than April 2020. For such areas, EPA would 
determine whether the area attained the standard by evaluating air 
quality data from 2017, 2018, and 2019. Table 1 is an overview of the 
proposed timeline for implementing any new 2006 PM2.5 
standards.

      Table 1.--Proposed Timeline for Any New 2006 PM2.5 Standards
------------------------------------------------------------------------
     Effective date of standard                 December 2006
------------------------------------------------------------------------
Monitoring data used for State       2005-2007.
 recommendations.
State recommendations to EPA.......  December 2007.
Final designations signature.......  December 2009.
Effective date of designations.....  April 2010.
SIPs due...........................  April 2013.
Attainment date....................  Up to April 2015 (based on 2012-
                                      2014 data).
Attainment date with a 5-year        Up to April 2020 (based on 2017-
 extension.                           2019 data).
------------------------------------------------------------------------

    The EPA is soliciting comments on which relevant factors should 
influence EPA's decision on any potential timeline.

V. What Are the Potential Timelines for Implementation of Any New PM10	
2.5 NAAQS?

A. What Is a Potential Schedule for Any New PM10-2.5 
Designation Process?

    Section 107(d)(1)(B) gives the Agency the authority to promulgate 
designations for all areas as expeditiously as practicable, but no 
later than 3 years from the date of promulgation of the new or revised 
NAAQS.
    Currently, a PM10-2.5 monitoring network does not exist. 
The EPA's proposed monitoring regulations for PM10-2.5 (71 
FR 2710) call for monitors to be deployed by January 2009. If this 
schedule is adopted, the first period

[[Page 6724]]

when 3 years of data would be available for State designation 
recommendations would be mid-2012 based on air quality data for 2009-
2011. As noted above, following the statutory timeline, designations 
for PM10-2.5 would be required to occur no later than late 
2009. Three years of PM10-2.5 monitoring data will not be 
available at that time. For EPA to meet its statutory obligation, EPA 
would need to designate all areas as unclassifiable under section 
107(d)(1)(A)(iii), on the basis that no information is available to 
determine whether an area is meeting any new NAAQS for 
PM10-2.5. From a historical perspective this was the 
situation in 1997 when we established the PM2.5 NAAQS. 
Subsequent, to the establishment of the PM2.5 NAAQS in 1997, 
Congress passed legislation which modified the CAA for the purposes of 
PM2.5 designations. EPA is potentially confronting this 
issue again with respect to any new PM10-2.5 NAAQS. As a 
policy, EPA does not think that designating all areas of the country as 
unclassifiable provides useful information to the public about their 
area meeting new air quality standards. EPA would prefer to not make 
designations until three years of monitoring data is available. EPA is 
soliciting comments on the best way to address this issue.

B. What Is EPA's Preferred Schedule for Designations for Any New PM10	
2.5 Standards?

    The first available 3 years of data from a monitoring network for 
PM10-2.5 will be 2009-2011. If EPA had not previously 
designated areas unclassifiable, EPA could then request recommendations 
from States for areas that might be designated nonattainment for 
PM10-2.5 by July 2012. This is approximately 6 months after 
a full 3 years of data would be available for some areas. EPA believes 
this is adequate time for evaluating and quality assuring data to make 
recommendations on designations. On the other hand, States have until 
May 1 to certify that their monitoring data is correct, and may need 
additional time for designation recommendations. Another option would 
be to allow the States until October 2012 to make recommendations. The 
EPA would like to take comment on this option.
    Following submittal of designation recommendations by the States, 
EPA will evaluate the recommendations and make modifications by 
December 2012. States will be notified of these changes, and given 
another opportunity to comment on the proposed modifications to 
designations. The EPA would then issue final modified 
PM10-2.5 designations by May 2013 which would be effective 
approximately July 2013.
    If EPA had previously designated areas unclassifiable, then, once 
EPA had sufficient monitoring data available, EPA would move forward in 
accordance with the provisions of section 107(d)(3)(A) to notify States 
that it believed designations for areas should be revised. States would 
then have the opportunity to respond in accordance with section 
107(d)(3)(B), and EPA would take action regarding any revisions of the 
designations in accordance with section 107(d)(3)(C).
    Since classifications under Title I are done at the same time as 
designations, EPA is considering the role a classification system could 
play in facilitating the implementation of any new PM2.5 
NAAQS. The EPA prefers not to develop a classification system to use in 
determining the amount of time permitted for attainment, for reasons 
similar to those outlined in the Proposed Rule to Implement the Fine 
Particle National Ambient Air Quality Standards; Proposed Rule (70 FR 
page 66000, November 1, 2005). Developing a classification system is 
only an option, not a requirement under section 172(a)(1), and for the 
reasons noted EPA does not believe it would be preferable to implement 
a classification scheme. The EPA would like comments on this potential 
designation timeline, and on its intentions to not develop a 
classification system.

C. What Is EPA's Preferred Schedule for Attainment Demonstrations and 
SIP Submittals for Any New PM10	2.5 Standards?

    Section 172(b) of the CAA requires EPA to establish a schedule for 
a State to submit its attainment demonstration and SIP revision within 
3 years of nonattainment designation. Following the schedule outlined 
in part V(B) above, if nonattainment designations for any new 
PM10-2.5 standards were effective in July 2013, then 
attainment demonstrations and SIP revisions would be due by July 2016. 
The EPA would like comments on this proposed timeline.

D. What Is EPA's Preferred Schedule for Attaining Any New PM10	2.5 
Standards?

    Section 172(a)(2)(A) states that the attainment date for a 
nonattainment area must be ``as expeditiously as practicable, but no 
later than 5 years from the date of designation for the area.'' If new 
PM10-2.5 designations are made in May 2013 and are effective 
in July 2013, the initial attainment date for PM10-2.5 would 
be as expeditiously as practicable but no later than July 2018. For an 
area with an attainment date of July 2018, EPA would determine whether 
it had attained the PM10-2.5 standards by evaluating air 
quality data from the 3 previous calendar years (i.e., 2015, 2016 and 
2017).
    Section 172 also states that if EPA deems it appropriate, the 
Agency may extend the attainment date for an area for a period not 
greater than 10 years from the date of designation, taking into account 
the severity of the nonattainment problem in the area, and the 
availability and feasibility of pollution control measures. For any 
area that is granted the full 5-year attainment date extension, the 
attainment date would be no later than July 2023. For such areas, EPA 
would determine whether they have attained the standard by evaluating 
air quality data from 2020, 2021 and 2022. Table 2 is an overview of 
this proposed timeline for designation, SIP submittal and attainment 
dates under this proposed schedule.

   Table 2.--Proposed Timeline for a Possible 2006 PM10	2.5 Standards
------------------------------------------------------------------------
     Effective date of standard                 December 2006
------------------------------------------------------------------------
Monitoring data used for State       2009-2011.
 recommendations.
State recommendations to EPA.......  July 2012.
Final designations signature.......  May 2013.
Effective date of designations.....  July 2013.
SIPs due...........................  July 2016.
Attainment date....................  Up to July 2018 (based on 2015-2017
                                      data).
Attainment date with extension.....  Up to July 2023 (based on 2020-2022
                                      data).
------------------------------------------------------------------------


[[Page 6725]]

    The EPA requests comment on this potential timeline for attaining 
any new PM10-2.5 standards.

VI. How Should EPA Implement the Transition From the PM10 
Standards to Any New PM10-2.5 Standards?

A. What Is EPA's Proposal for Revoking the PM10 Standards?

    Before areas are designated under any new PM10-2.5 
standards, we intend to address how to transition from implementation 
of the PM10 standards to any new PM10-2.5 
standards. As part of the NAAQS proposal (71 FR 2620), EPA proposed to 
revoke the annual PM10 standard everywhere, and the 24-hour 
PM10 standard everywhere except in areas where there is at 
least one monitor that is located in an urbanized area with a minimum 
population of 100,000 people and that violates the 24-hour 
PM10 standard based on the most recent 3 years of data. This 
revocation would be effective upon promulgation of the PM NAAQS in 
December 2006. The EPA also provided a list of places where the 24-hour 
PM10 standard would not be revoked under the proposal. In 
addition, EPA requested comment on whether the 24-hour PM10 
standard should be retained in areas that are either urbanized areas 
with populations less than 100,000 people or non-urbanized areas (i.e., 
population less than 50,000) but where the majority of the ambient mix 
of PM10-2.5 is generated by high density traffic on paved 
roads, industrial sources, and construction sources, and which have at 
least one monitor that violated the 24-hour PM10 standard. 
Comments on this revocation plan should be submitted under that notice 
(71 FR 2620).
    This raises a number of issues for those areas where the 24-hour 
PM10 standard would still apply including: When and how 
should the 24-hour PM10 standard be revoked for these areas; 
should anti-backsliding provisions apply; how to address NSR and 
maintenance issues; and other implementation issues. Our principal 
objective for the transition is to ensure that air quality will not 
degrade in areas where the potential new PM10-2.5 NAAQS 
would apply, and that areas continue to make progress toward attainment 
of the PM standards. Subject to requirements under the CAA for revising 
SIPs, EPA expects States would take the opportunity to revise their 
SIPs to reflect the revocation of the PM10 standards.

B. What Should the Timing Be for Revoking the 24-Hour PM10 Standard for 
Those Areas Where the 24-Hour PM10 Standard Is Retained?

    The EPA contemplates that the 24-hour PM10 standard 
would be revoked one year after attainment/nonattainment designations 
are effective for a 24-hour PM10-2.5 standard. Because 
attainment/nonattainment designations would not occur until July 2013, 
it is reasonable to expect that some areas where the 24-hour 
PM10 standard has not been revoked would come into 
attainment with the PM10 standard prior to July 2013. We 
invite comment on how these areas should be treated.

C. What Transition Issues Are Created by Revoking the 24-Hour PM10 
Standard in Areas Where It Is Currently Proposed To Be Retained and How 
Might They Be Addressed?

1. Control Measures
    EPA wants to ensure that air quality is not degraded if we move 
from one version of the NAAQS to another. What protections should 
remain in place to ensure that air quality will not degrade once the 
24-hour PM10 standard is revoked, and that progress will 
continue as areas transition from implementing the 24-hour 
PM10 standard to implementing the 24-hour 
PM10-2.5 standard?
    a. What requirements based on an area's classification for the 
PM10 standard should continue to apply?
    The EPA believes an approach similar to what was done under the 
ozone transition from the 1-hour to the 8-hour standard (69 FR 23951 
page 23969) would be appropriate here in that control measures which 
remain in place were determined by the area's classification. Such an 
approach would mean that moderate PM10 nonattainment areas 
should continue to require reasonably available control measures (RACM) 
(as described in section 189(a)(1)(C) of the CAA). Serious 
PM10 nonattainment areas should also continue to require 
best available control measures (BACM) (section 189(b)(1)(B) of the 
CAA). All nonattainment areas should have an EPA-approved part D SIP in 
place, and continue to implement the nonattainment requirements and 
control measures identified in the SIP. Any effort to change SIP-
approved measures would be subject to a section 110(l) demonstration of 
no interference with applicable requirements.
    The EPA also believes that those areas where the 24-hour 
PM10 standard is being violated and has not been revoked 
should continue to implement the requirements of the CAA until 
nonattainment and attainment designations for PM10-2.5 are 
completed. However, this could represent a significant period of time 
(from 2006-2013). Consequently, EPA is interested in alternative views 
regarding the appropriate implementation pathway for the 
PM10 standard in these areas.
    b. How should EPA address maintenance? Those PM10 
nonattainment areas where the 24-hour PM10 standard has not 
been revoked which come into attainment with the 24-hour 
PM10 NAAQS prior to designations under the 24-hour 
PM10-2.5 standard, may request to be redesignated as 
attainment for PM10 under section 107(d). As such they would 
need to submit a maintenance plan under section 175A. Maintenance areas 
do not have any outstanding obligation to adopt further mandatory 
control obligations. We would anticipate an approach to maintenance 
requirements similar to what was provided in the ozone rule where 
maintenance areas retain the discretion to modify any discretionary 
control measures upon a demonstration under section 110(l) (69 FR 23951 
page 23955). The EPA requests comments on how to address maintenance 
areas.
2. Transportation Conformity
    Transportation conformity is required under section 176(c) of the 
CAA (42 U.S.C. 7506(c)) to ensure that federally supported highway and 
transit project activities are consistent with (conform to) the purpose 
of a SIP. Conformity to the purpose of a SIP means that transportation 
activities will not cause new air quality violations, worsen existing 
violations, or delay timely attainment of the NAAQS. Transportation 
conformity applies in nonattainment areas and maintenance areas. The 
EPA's transportation conformity rule, 40 CFR part 93, establishes the 
criteria and procedures for determining whether transportation 
activities conform to the State air quality plan. It also establishes 
criteria and procedures for determining whether transportation 
activities conform in areas where no SIP containing motor vehicle 
emissions budgets yet exists.
    Transportation conformity rulemakings, as well as other relevant 
conformity materials such as guidance documents, policy memoranda, the 
complete text of the conformity rule, and conformity research can be 
found at EPA's transportation conformity Web site, at https://
www.epa.gov/otaq/transp.htm (once at the site, click on 
``Transportation Conformity.''

[[Page 6726]]

    Until areas are designated nonattainment, transportation conformity 
will not apply for any new PM10-2.5 standard. Based on the 
timeline outlined above, designations for any new PM10-2.5 
NAAQS could be effective in July 2013, and for all nonattainment areas 
transportation conformity would then apply 1 year later. Prior to the 
designation date, EPA would propose to update the transportation 
conformity rule to address any new PM10-2.5 standard.
    The EPA will solicit public comment on these and other issues 
associated with determining transportation conformity in any new 
PM10-2.5 nonattainment areas when it proposes to revise the 
conformity rule to address the new standard. Once we revoke the 
PM10 standard and the associated designations, 
transportation conformity will no longer apply under the terms of the 
statute for that standard.
3. General Conformity
    Section 176(c) of the CAA requires that before a Federal entity 
takes an action, it must make a determination that the proposed action 
will not interfere with the SIP or the State's ability to attain and 
maintain the NAAQS. In November 1993, EPA promulgated two sets of 
regulations to implement section 176(c). One set, known as the general 
conformity regulations, deals with all other Federal activities besides 
funding of highway and mass transit projects. These activities include 
funding and approval of airport projects, expansion of military bases, 
and permitting of projects to deepen waterways.
    Federal agencies take thousands of actions every day and requiring 
determinations on every action would not be possible. Therefore, EPA 
established a number of exemptions to the rule requirements including a 
de minimis emission level generally based upon the size of a major 
stationary source in the nonattainment or maintenance area.
    Following are a series of questions related to implementation of 
general conformity on which EPA is soliciting input:
     What de minimis levels should EPA establish for direct and 
precursor emissions for any new PM10-2.5 standards? The EPA 
currently does not have speciated monitoring data for 
PM10-2.5. Consequently, we do not know if the mass of 
PM10-2.5 contains a significant amount of particulate matter 
formed by atmospheric chemical reactions.
     In transitioning to a new standard, how should EPA treat 
previous conformity evaluations and determinations based on the 
PM10 standard?
     Are there any categories of actions that should be exempt 
from the conformity requirements for any new PM10-2.5 
standards? If so, how could such exemptions be devised?
4. New Source Review Program
    The NSR program is a preconstruction permitting program that 
applies when a new source is constructed or an existing one is 
modified. The major NSR program applies to major stationary sources and 
is comprised of the Prevention of Significant Deterioration (PSD) 
program that applies in attainment areas and a nonattainment NSR 
program that applies to pollutants for which an area is designated 
nonattainment.
    There are many major NSR program implementation issues that EPA 
will address for a new PM10-2.5 NAAQS, including revocation 
of the existing PM10 NAAQS. In this ANPR, EPA is 
highlighting some of the key issues and providing EPA's preliminary 
thinking on approaches for addressing them. We recognize that there may 
be other implementation issues not identified here, and we invite you 
to identify them. When submitting comments, please support your 
comments with adequate data and/or practical scenarios or 
illustrations.
    a. Does PM10 continue to be a regulated NSR pollutant 
for PSD in areas where the 24-hour PM10 NAAQS would be 
revoked?
    The PSD program applies when a major stationary source of any 
``regulated NSR pollutant'', that is located in an area designated as 
attainment or unclassifiable for any criteria pollutant, is constructed 
or undergoes a major modification (40 CFR 52.21(a)(2); 40 CFR 
51.166(a)(7)). EPA defines a ``regulated NSR pollutant'' to include (1) 
any pollutant for which a NAAQS has been promulgated (otherwise known 
as a ``criteria'' pollutant); (2) any pollutant subject to a NewSource 
Performance Standard promulgated under section 111 of the CAA; and (3) 
any pollutant that is otherwise regulated under the Act, except for 
hazardous air pollutants regulated under section 112 of the Act \3\ (40 
CFR 52.21(b)(50); 40 CFR 51.166(b)(49)). Thus, in addition to applying 
to criteria pollutants for which EPA has promulgated a NAAQS, the PSD 
program also applies to any non-criteria pollutant that is covered by 
the additional prongs of the definition of a ``regulated NSR 
pollutant'' described above. However, not all of the PSD program 
requirements outlined below are applicable to non-criteria pollutants 
that are subject to the PSD program.
---------------------------------------------------------------------------

    \3\ This definition also covers any pollutant that is subject to 
any standard promulgated under or established by Title VI of the 
Act, but this is not relevant to particulate matter.
---------------------------------------------------------------------------

    The PSD requirements include but are not limited to:
     Installation of Best Available Control Technology (BACT),
     Air quality monitoring and modeling analyses to ensure 
that a project's emissions will not cause or contribute to a violation 
of any NAAQS or maximum allowable pollutant increase (PSD increment),
     Notification of Federal Land Manager when a proposed 
source or modification may affect nearby Class I areas, and
     Public comment on the permit.
    For any criteria pollutant subject to PSD, all PSD requirements 
including the PSD increments analyses apply. However, since there are 
no NAAQS for non-criteria pollutants, only some requirements, including 
BACT, apply to these pollutants (See 42 U.S.C. 7475(a)(4); 40 CFR 
52.21(j)); 40 CFR 52.166(j)).
    The proposed revocation of the 24-hour PM10 NAAQS in 
certain areas raises issues about whether existing PSD regulations 
would continue to apply to PM10 in any respect after the 
revocation of the NAAQS in these areas. The extent to which all or some 
of the PSD requirements apply depends on whether PM10 
continues to be a regulated NSR pollutant in these areas, either as a 
criteria or a non-criteria pollutant, under EPA's regulations and the 
CAA. We seek comment on the following options to address these issues:
    Option 1. Since the 24-hour PM10 standard would remain 
in effect at least in some areas, we could conclude that 
PM10 continues to be a regulated NSR pollutant for the PSD 
program. Thus, even in those areas in which the 24-hour PM10 
NAAQS is revoked (24-hour revoked areas), PM10 would be 
regarded as a regulated NSR pollutant only by virtue of being otherwise 
subject to regulation under the CAA (40 CFR 52.21(b)(50)(iv)) because a 
24-hour PM10 NAAQS continues to apply in other areas. Under 
this approach, PSD for PM10 would continue to apply in all 
areas. However, as stated earlier, only a few PSD requirements, 
including BACT, would apply in 24-hour revoked areas since 
PM10 would be regarded as a non-criteria pollutant in those 
areas. In those areas where the 24-hour PM10 NAAQS is not 
revoked, all PSD program elements would continue to apply for

[[Page 6727]]

PM10 because it remains a criteria pollutant in these areas.
    Option 2. Alternatively, we could interpret all prongs of the 
``regulated NSR pollutant'' definition to be area-specific. Thus, in 
24-hour revoked areas, PM10 would no longer be a criteria 
pollutant, and none of the other prongs of the definition of 
``regulated NSR pollutant'' would apply to PM10 in these 
areas. Therefore, none of the PSD requirements would apply to 
PM10 in such areas. We request comment on whether there is 
any other basis for retaining PM10 as a regulated NSR 
pollutant, even if it is no longer a criteria pollutant.
    b. Does the CAA require continued obligation for some form of PM 
increment?
    Section 163 of the CAA states that each SIP should contain measures 
assuring that maximum allowable increases over baseline concentration 
(increments) for PM shall not be exceeded in attainment areas. Section 
163 contains specific numerical increments (expressed as [mu]g/m\3\) 
for PM, which EPA initially implemented using the total suspended 
particulate indicator. After EPA transitioned to PM10 as the 
indicator for PM in 1987, the Agency substituted PM10 
increments for the PM increments in section 163 based