Revisions to Ambient Air Monitoring Regulations, 61236-61328 [06-8478]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 71, Number 200 (Tuesday, October 17, 2006)]
[Rules and Regulations]
[Pages 61236-61328]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-8478]



[[Page 61235]]

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Part III





Environmental Protection Agency





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40 CFR Parts 53 and 58



Revisions to Ambient Air Monitoring Regulations; Final Rule

Federal Register / Vol. 71, No. 200 / Tuesday, October 17, 2006 / 
Rules and Regulations

[[Page 61236]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 53 and 58

[EPA-HQ-OAR-2004-0018; FRL-8227-2]
RIN 2060-AJ25


Revisions to Ambient Air Monitoring Regulations

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The EPA is issuing final amendments to the ambient air 
monitoring requirements for criteria pollutants. The purpose of the 
amendments is to enhance ambient air quality monitoring to better serve 
current and future air quality management and research needs. The final 
amendments establish limited ambient air monitoring requirements for 
thoracic coarse particles in the size range of PM10-2.5 to 
support continued research into these particles' distribution, sources, 
and health effects. The ambient air monitoring amendments also require 
each State to operate one to three monitoring stations that take an 
integrated, multipollutant approach to ambient air monitoring. In 
addition, the final amendments modify the general monitoring network 
design requirements for minimum numbers of ambient air monitors to 
focus on populated areas with air quality problems and to reduce 
significantly the requirements for criteria pollutant monitors that 
have measured ambient air concentrations well below the applicable 
National Ambient Air Quality Standards. These amendments also revise 
certain provisions regarding monitoring network descriptions and 
periodic assessments, quality assurance, and data certifications. A 
number of the amendments relate specifically to PM2.5, 
revising the requirements for reference and equivalent method 
determinations (including specifications and test procedures) for fine 
particle monitors.

DATES: This final rule is effective on December 18, 2006.

ADDRESSES: The EPA has established a docket for this action under 
Docket ID No. EPA-HQ-OAR-2004-0018. 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., confidential 
business information 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 Revisions to the 
Ambient Air Monitoring Regulations Docket, EPA/DC, EPA West, Room B102, 
1301 Constitution Ave., 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. The telephone number for the Public Reading Room is 
(202) 566-1744, and the telephone number for the Air Docket is (202) 
566-1742.


    Note: The EPA Docket Center suffered damage due to flooding 
during the last week of June 2006. The Docket Center is continuing 
to operate. However, during the cleanup, there will be temporary 
changes to Docket Center telephone numbers, addresses, and hours of 
operation for people who wish to visit the Public Reading Room to 
view documents. Consult EPA's Federal Register notice at 71 FR 38147 
(July 5, 2006) or the EPA Web site at https://www.epa.gov/epahome/
dockets.htm for current information on docket status, locations, and 
telephone numbers.


FOR FURTHER INFORMATION CONTACT: For general questions concerning the 
final amendments, please contact Mr. Lewis Weinstock, U.S. EPA, Office 
of Air Quality Planning and Standards, Air Quality Assessment Division, 
Ambient Air Monitoring Group (C304-06), Research Triangle Park, North 
Carolina 27711; telephone number: (919) 541-3661; fax number: (919) 
541-1903; e-mail address: weinstock.lewis@epa.gov. For technical 
questions, please contact Mr. Tim Hanley, U.S. EPA, Office of Air 
Quality Planning and Standards, Air Quality Assessment Division, 
Ambient Air Monitoring Group (C304-06), Research Triangle Park, North 
Carolina 27711; telephone number: (919) 541-4417; fax number: (919) 
541-1903; e-mail address: hanley.tim@epa.gov.

SUPPLEMENTARY INFORMATION:

I. General Information

A. Does this action apply to me?

    Categories and entities potentially regulated by this action 
include:

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                   Category                     NAICS code \1\            Examples of regulated entities
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Industry.....................................    334513, 541380  Manufacturer, supplier, distributor, or vendor
                                                                  of ambient air monitoring instruments;
                                                                  analytical laboratories or other monitoring
                                                                  organizations that elect to submit an
                                                                  application for a reference or equivalent
                                                                  method determination under 40 CFR part 53.
Federal government...........................            924110  Federal agencies (that conduct ambient air
                                                                  monitoring similar to that conducted by States
                                                                  under 40 CFR part 58 and that wish EPA to use
                                                                  their monitoring data in the same manner as
                                                                  State data) or that elect to submit an
                                                                  application for a reference or equivalent
                                                                  method determination under 40 CFR part 53.
State/territorial/local/tribal government....            924110  State, territorial, and local, air quality
                                                                  management programs that are responsible for
                                                                  ambient air monitoring under 40 CFR part 58 or
                                                                  that elect to submit an application for a
                                                                  reference or equivalent method determination
                                                                  under 40 CFR part 53 or for an approved
                                                                  regional method approved under 40 CFR part 58
                                                                  appendix C. The proposal also may affect
                                                                  Tribes that conduct ambient air monitoring
                                                                  similar to that conducted by States and that
                                                                  wish EPA to use their monitoring data in the
                                                                  same manner as State monitoring data.
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\1\ North American Industry Classification System.

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by this 
action. This table lists the types of entities that EPA is now aware 
could potentially be regulated by this action. Other types of entities 
not listed in the table could also be regulated. To determine whether 
your facility or Federal, State, local, or territorial agency is 
regulated by this action, you should carefully examine the requirements 
for reference or equivalent method determinations in 40 CFR part 53, 
subpart A (General

[[Page 61237]]

Provisions) and the applicability criteria in 40 CFR 51.1 of EPA's 
requirements for State implementation plans. If you have questions 
regarding the applicability of this action to a particular entity, 
consult the person listed in the preceding FOR FURTHER INFORMATION 
CONTACT section.

B. Where can I obtain a copy of this action?

    In addition to being available in the docket, an electronic copy of 
this final action will also be available on the Worldwide Web (WWW) 
through the Technology Transfer Network (TTN). Following the 
Administrator's signature, a copy of the final amendments will be 
placed on the TTN's policy and guidance page for newly proposed or 
promulgated rules at https://www.epa.gov/ttn/oarpg. The TTN provides 
information and technology exchange in various areas of air pollution 
control.

C. Public Comments on Proposed Amendments

    EPA received approximately 20,000 public comments on the proposed 
amendments to the ambient air monitoring regulations during the 90-day 
comment period. These comments were submitted to the rulemaking docket 
and also during public hearings held in Chicago, Illinois; 
Philadelphia, Pennsylvania; and San Francisco, California (71 FR 8228, 
February 16, 2006). Public comments on the proposed amendments were 
submitted by States, local governments, Tribes, and related 
associations; energy, mining, ranching, and agricultural interests and 
related associations; vendors, laboratories, and technical consultants; 
health, environmental, and public interest organizations; and private 
citizens. The EPA has carefully considered these comments in developing 
the final amendments. Summaries of these comments and EPA's detailed 
responses are contained in the Response to Comments document included 
in the docket.

D. Judicial Review

    Under section 307(b)(1) of the Clean Air Act (CAA), judicial review 
of the final amendments is available only by filing a petition for 
review in the U.S. Court of Appeals for the District of Columbia 
Circuit by December 18, 2006. Under section 307(d)(7)(B) of the CAA, 
only an objection to the final amendments that was raised with 
reasonable specificity during the period for public comment can be 
raised during judicial review. Moreover, under section 307(b)(2) of the 
CAA, the requirements established by the final amendments may not be 
challenged separately in any civil or criminal proceedings brought by 
EPA to enforce these requirements.

E. Peer Review

    The EPA sought expert scientific review of the proposed methods, 
technologies, and approach for ambient air monitoring by the Clean Air 
Scientific Advisory Committee (CASAC). The CASAC is a Federal advisory 
committee established to review scientific and technical information 
and make recommendations to the EPA Administrator on issues related to 
the air quality criteria and corresponding NAAQS. CASAC formed a 
National Ambient Air Monitoring Strategy (NAAMS) Subcommittee in 2003 
to provide advice for a strategy for the national ambient air 
monitoring programs. This subcommittee, which operated over a 1-year 
period, and a new subcommittee on Ambient Air Monitoring and Methods 
(AAMM), formed in 2004, provided the input for CASAC on its 
consultations, advisories, and peer-reviewed recommendations to the EPA 
Administrator.
    In July 2003, the CASAC NAAMS Subcommittee held a public meeting to 
review EPA's draft National Ambient Air Monitoring Strategy document 
(dated September 6, 2002), which contained technical information 
underlying planned changes to the ambient air monitoring networks. The 
EPA continued to consult with the CASAC AAMM Subcommittee throughout 
the development of the proposed amendments. Public meetings were held 
in July 2004, December 2004, and September 2005 to discuss the CASAC 
review of nearly 20 documents concerning methods and technology for 
measurement of particulate matter (PM); data quality objectives for PM 
monitoring networks and related performance-based standards for 
approval of equivalent continuous PM monitors; configuration of ambient 
air monitoring stations; \1\ and other technical aspects of the 
proposed amendments. These documents, along with CASAC review comments 
and other information are available at: https://www.epa.gov/ttn/amtic/
casacinf.html.
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    \1\ ``Station'' and ``site'' are used somewhat interchangeably 
in this notice of final rulemaking. When there is a difference 
(which will be apparent from context), ``site'' generally refers to 
the location of a monitor, while ``station'' refers to a suite of 
measurements at a particular site.
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F. How is this document organized?

    The information presented in this preamble is organized as follows:

I. General Information
    A. Does this action apply to me?
    B. Where can I obtain a copy of this action?
    C. Public Comments on Proposed Amendments
    D. Judicial Review
    E. Peer Review
    F. How is this document organized?
II. Authority
III. Overview
    A. Summary of Concurrent Final Action on Revisions to the 
National Ambient Air Quality Standards for Particulate Matter
    B. Summary of Changes to Ambient Air Monitoring Regulations
    C. Significant Dates for States, Local Governments, Tribes, and 
Other Stakeholders
    D. Implementation of the Revised Monitoring Requirements
    E. Federal Funding for Ambient Air Monitoring
IV. Discussion of Regulatory Revisions and Major Comments on 
Proposed Amendments to 40 CFR Part 53
    A. Overview of Part 53 Regulatory Requirements
    B. Requirements for Candidate Reference Methods for 
PM10-2.5
    C. Requirements for Candidate Equivalent Methods 
PM2.5 and PM10-2.5
    D. Other Changes
V. Discussion of Regulatory Revisions and Major Comments on Proposed 
Amendments to 40 CFR Part 58
    A. Overview of Part 58 Regulatory Requirements
    B. General Monitoring Requirements
    1. Definitions and Terminology
    2. Annual Monitoring Network Plan and Periodic Network 
Assessment
    3. Operating Schedules
    4. Monitoring Network Completion for PM10-2.5 and 
NCore Sites
    5. System Modifications
    6. Annual Air Monitoring Data Certification
    7. Data Submittal
    8. Special Purpose Monitors
    9. Special Considerations for Data Comparisons to the National 
Ambient Air Quality Standards
    C. Appendix A--Quality Assurance Requirements for State and 
Local Air Monitoring Stations and Prevention of Significant 
Deterioration Air Monitoring
    1. General Quality Assurance Requirements
    2. Specific Requirements for PM10-2.5, 
PM2.5, PM10, and Total Suspended Particulates
    3. Particulate Matter Performance Evaluation Program and 
National Performance Audit Programs
    4. Revisions to Precision and Bias Statistics
    5. Other Program Updates
    D. Appendix C--Ambient Air Quality Monitoring Methodology
    1. Applicability of Federal Reference Methods and Federal 
Equivalent Methods
    2. Approved Regional Methods for PM2.5
    E. Appendix D--Network Design Criteria for Ambient Air Quality 
Monitoring
    1. Requirements for Operation of Multipollutant NCore Stations

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    2. Requirements for Operation of PM10-2.5 Stations
    3. Requirements for Operation of PM2.5 Stations
    4. Requirements for Operation of PM10 Stations
    5. Requirements for Operation of Carbon Monoxide, Sulfur 
Dioxide, Nitrogen Dioxide, and Lead Monitoring Sites
    6. Requirements for Operation of Ozone Stations
    7. Requirements for Operation of Photochemical Assessment 
Monitoring Stations
    F. Appendix E--Probe and Monitoring Path Siting Criteria for 
Ambient Air Monitoring
    1. Vertical Placement of PM10-2.5 Samplers
    2. Ozone Monitor Setback Requirement from Roads
    G. Sample Retention Requirements
    H. Deletion of Appendices B and F
VI. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health and Safety Risks
    H. Executive Order 12898: Federal Actions to Address 
Environmental Justice in Minority Populations and Low-Income 
Populations
    I. Executive Order 13211: Actions That Significantly Affect 
Energy Supply, Distribution, or Use
    J. National Technology Transfer Advancement Act
    K. Congressional Review Act

II. Authority

    The EPA rules for ambient air monitoring are authorized under 
sections 110, 301(a), and 319 of the Clean Air Act (CAA). Section 
110(a)(2)(B) of the CAA requires that each State implementation plan 
(SIP) provide for the establishment and operation of devices, methods, 
systems, and procedures needed to monitor, compile, and analyze data on 
ambient air quality and for the reporting of air quality data to EPA. 
Section 103 authorizes, among others, research and investigations 
relating to the causes, effects, extent, prevention and control of air 
pollution. Section 301(a) of the CAA authorizes EPA to develop 
regulations needed to carry out EPA's mission and establishes 
rulemaking requirements. Uniform criteria to be followed when measuring 
air quality and provisions for daily air pollution index reporting are 
required by CAA section 319.

III. Overview

A. Summary of Concurrent Final Action on Revisions to the National 
Ambient Air Quality Standards for Particulate Matter

    Elsewhere in this Federal Register, EPA is finalizing revisions to 
the National Ambient Air Quality Standards (NAAQS) for particulate 
matter (PM). These revisions were proposed on January 17, 2006 (71 FR 
2620). For a detailed explanation of these revisions, see that preamble 
elsewhere in this Federal Register.
    The EPA is finalizing the PM2.5 NAAQS revisions as 
proposed. With regard to the primary standards for fine particles 
(generally referring to particles less than or equal to 2.5 micrometers 
([mu]m) in diameter, PM2.5), EPA is revising the level of 
the 24-hour PM2.5 standard to 35 micrograms per cubic meter 
([mu]g/m\3\), providing increased protection against health effects 
associated with short-term exposure (including premature mortality and 
increased hospital admissions and emergency room visits). The EPA is 
retaining the level of the annual PM2.5 standard at 15 
[mu]g/m\3\, continuing protection against health effects associated 
with long-term exposure (including premature mortality and development 
of chronic respiratory disease). The EPA is also finalizing the 
proposed revisions in the conditions under which spatial averaging of 
the annual primary PM2.5 NAAQS is permitted, and placing 
these conditions in appendix N of 40 CFR part 50 rather than in 
appendix D of 40 CFR part 58.
    With regard to secondary PM standards, EPA is revising the current 
24-hour PM2.5 secondary standard by making it identical to 
the revised 24-hour PM2.5 primary standard, retaining the 
annual PM2.5 and 24-hour PM10 secondary 
standards, and revoking the annual PM10 secondary standard. 
This suite of secondary PM standards is intended to provide protection 
against PM-related public welfare effects, including visibility 
impairment, effects on vegetation and ecosystems, and materials damage 
and soiling.
    The EPA is finalizing the proposed Federal reference method (FRM) 
for PM2.5. This action in essence codifies certain desirable 
features that have already been in widespread use as elements of 
approved equivalent methods or national user modifications.
    The EPA is not finalizing the proposed NAAQS for 
PM10-2.5, for reasons explained in the accompanying preamble 
to the revisions to the NAAQS. As a result, EPA is not finalizing a 
number of related provisions (notably those which would have prescribed 
which monitors could have been used for comparison with that proposed 
NAAQS) proposed as amendments to 40 CFR part 58. The EPA is, however, 
finalizing the proposed FRM for PM10-2.5 (see appendix O to 
40 CFR part 50). This FRM is based on paired filter-based samplers for 
PM2.5 and PM10 and it will serve as the standard 
of reference for measurements of PM10-2.5 concentrations in 
ambient air. This should provide a basis for approving Federal 
Equivalent Methods (FEMs) and promote the gathering of scientific data 
to support future reviews of the PM NAAQS. Because it is a filter based 
system, this method can itself be used to provide speciated data. The 
reference measurement from the PM10-2.5 FRM is also 
important in the development of alternative PM10-2.5 
speciation samplers such as dichotomous samplers. The EPA will be 
issuing guidance to ensure the use of a consistent national approach 
for speciated coarse particle monitors as soon as possible.
    In conjunction with the above NAAQS revisions and FRM provisions, 
as part of this final monitoring rule, as described below EPA is 
finalizing certain provisions which support collection of additional 
high quality data on ambient concentrations of PM10-2.5. 
These data should be useful in improving the understanding of 
PM10-2.5 air quality and in conducting future reviews of the 
PM NAAQS.
    As explained in the preamble to the NAAQS revisions, EPA is 
revoking the annual NAAQS for particles generally less than or equal to 
10 [mu]m in diameter (PM10). However, EPA is retaining the 
24-hour PM10 NAAQS as a standard for short-term exposure to 
thoracic coarse particles, rather than revoking that standard in all 
but 15 areas as proposed. This change from the NAAQS revision proposal 
necessitates that the final monitoring rule restore certain 
PM10 monitoring provisions that were proposed for removal.

B. Summary of Changes to Ambient Air Monitoring Regulations

    This rule, in most respects, finalizes the proposals put forth in 
the January 17, 2006, notice of proposed rulemaking (71 FR 2710). This 
final rule will facilitate monitoring program changes envisioned in the 
draft National Ambient Air Monitoring Strategy which was fully 
described in the proposal. These final changes, which apply to the 
monitoring program for all of the criteria pollutants, will reduce the 
required scale of monitoring for pollutants for which most areas have 
reached

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attainment. The changes are intended to better focus monitoring 
resources on current air quality challenges. The changes will also 
allow States and local monitoring agencies more flexibility to design 
their monitoring programs to reflect local conditions.
    In amendments to 40 CFR part 53 (Reference and Equivalent Methods), 
this final rule incorporates the proposed criteria for approval of 
Federal equivalent methods (FEM) for PM2.5, with some 
modifications to the method testing requirements and approval criteria 
in response to persuasive public comments. The modifications will 
require a more robust set of testing conditions and closer performance 
matching of candidate FEMs to FRMs. The EPA is also finalizing the rule 
with some strengthening revisions to the proposed criteria for approved 
regional methods (ARMs) for PM2.5. The new criteria for 
PM2.5 FEMs and ARMs will facilitate the commercialization 
and EPA approval of continuous PM2.5 mass monitors, allowing 
them to be substituted for many of the currently operating filter-based 
FRMs, which will support additional monitoring objectives and reduce 
annual monitoring costs.
    In other amendments to 40 CFR part 53, EPA is adopting FEM approval 
criteria for PM10-2.5, with some revisions from the proposal 
that will provide for approval and use of methods that can meet 
multiple monitoring objectives. The new FEM performance criteria for 
PM10-2.5 will facilitate approval of filter-based methods 
for direct sampling of PM10-2.5 concentrations that can be 
chemically speciated using post-sampling laboratory analysis. The FEM 
criteria are also expected to encourage commercialization of highly 
time-resolved continuous methods. The EPA is hopeful that the 
PM2.5 and PM10-2.5 FEM criteria together will 
result in the approval and commercialization of methods that provide 
equivalent measurements of PM2.5, PM10, and 
PM10-2.5 from a single instrument.
    In amendments to 40 CFR part 58 (Ambient Air Quality Surveillance), 
this final rule, as proposed, requires States to establish and operate 
a network of NCore multipollutant monitoring stations. The EPA intends 
the NCore network to consist of approximately 75 stations, of which the 
rule requires between 62 and 71 such stations. These stations must be 
operational by 2011. Most States, as well as the District of Columbia, 
Puerto Rico, and the Virgin Islands, will be required to operate a 
single station. California, Florida, Illinois, Michigan, New York, 
North Carolina, Ohio, Pennsylvania, and Texas will be required to 
operate two or three NCore stations. For these States, the selection 
between two or three stations will be part of the development and 
approval of the NCore monitoring plan that is due by July 1, 2009. The 
EPA also plans to negotiate with a number of States, local agencies, 
and/or Tribes to operate additional NCore stations on a voluntary 
basis, bringing the total number of stations to about 75. By approving 
some required stations to be in rural areas and by negotiating for 
additional voluntary sites in rural areas, EPA expects that about 55 
NCore sites will be in urbanized areas and about 20 in rural areas. The 
rural sites are intended to be sited away from any large local emission 
sources, so that they represent ambient concentrations over an 
extensive area. The NCore stations must perform the types of pollutant 
measurements that were proposed, with three exceptions. 
PM10-2.5 measurements may be made on a 1-in-3 day schedule 
rather than the proposed every day schedule, NOy \2\ 
measurements may be waived by the EPA Administrator based on certain 
criteria, and as explained later in this section, PM10-2.5 
chemical speciation will be required in addition to PM10-2.5 
mass concentration measurements.
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    \2\ NOy refers to a broad class of nitrogen-
containing reactive compounds in ambient air, explained in more 
detail in sections V.E.1 and V.E.7 of this preamble.
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    The EPA estimated that the proposed rule would have required States 
to operate about 225 PM10-2.5 monitors based on the 
population and estimated PM10-2.5 concentrations of 
metropolitan statistical areas (MSAs) with populations of 100,000 or 
more. In addition, PM10-2.5 monitors were proposed to be 
required at NCore stations; some monitors likely would have satisfied 
both of these requirements. Because EPA is not adopting a NAAQS for 
PM10-2.5, the final monitoring rule does not include the 
proposed requirement for the broad network of PM10-2.5 
monitoring stations in MSAs over 100,000 population. However, the final 
monitoring rule does require PM10-2.5 monitors at the 
required NCore multipollutant monitoring stations. The data gathered 
from these stations should be useful in improving understanding of 
PM10-2.5 air quality and in conducting future reviews of the 
PM NAAQS. The EPA anticipates that due to natural variations among the 
cities and rural areas where the NCore stations will be sited, the 
NCore PM10-2.5 monitors will represent a range of 
concentrations and nearby emission source types, and that many but not 
all will be in well populated locations.
    The EPA is not adopting the proposed population-based and 
population density-based siting requirements for PM10-2.5 
monitors, or any part of the proposed five-part suitability test for 
PM10-2.5 monitoring sites, which as proposed would have 
controlled whether PM10-2.5 data from a monitoring site 
could be compared to the proposed PM10-2.5 NAAQS. These 
proposed requirements were tied to the establishment of a 
PM10-2.5 NAAQS with a qualified PM10-2.5 
indicator based on a determination of whether ambient mixes of coarse 
particles are or are not dominated by coarse particle emissions from 
enumerated types of sources. Since EPA is not adopting this part of the 
proposal, these issues are now moot. In the absence of a 
PM10-2.5 NAAQS, our goal nevertheless will be to locate 
PM10-2.5 monitors in a manner that satisfies an objective of 
the proposed rule, which was to focus most monitoring resources on 
population centers.
    This final rule contains a requirement for PM10-2.5 
speciation to be conducted at NCore multipollutant monitoring stations. 
The EPA had proposed a requirement for PM10-2.5 speciation 
in 25 areas, with the areas required to have this monitoring selected 
based on having a Metropolitan Statistical Area (MSA) population over 
500,000 and having an estimated design value of greater than 80 percent 
of the proposed PM10-2.5 NAAQS. This would have concentrated 
the PM10-2.5 speciation monitoring in areas that have high 
populations and high exposures to PM10-2.5. Since EPA is 
requiring PM10-2.5 monitoring at NCore primarily for 
scientific purposes, it is more appropriate to have monitoring in a 
variety of urban and rural locations to increase the diversity of areas 
for which chemical species data will be available to use in scientific 
studies. The EPA had already proposed to require chemical speciation 
for PM2.5 at NCore stations. The collocation of both 
PM10-2.5 and PM2.5 speciation monitoring at NCore 
stations is consistent with the multipollutant objectives of the NCore 
network and will support further research in understanding the chemical 
composition and sources of PM10, PM10-2.5, and 
PM2.5 at a variety of urban and rural locations. The EPA 
will work with States to ensure that PM10-2.5 speciation 
monitors employ the latest in speciation technology to advance the 
science so that future regulation will provide more targeted protection 
against the effects only of those coarse particles

[[Page 61240]]

and related source emissions that prove to be of concern to public 
health.
    Because the 24-hour PM10 NAAQS is being retained in all 
parts of the country, this final rule retains the existing minimum 
monitoring network design requirements for PM10. These 
longstanding requirements are based on the population of a MSA and its 
historical PM10 air quality. For any given combination of 
these two parameters, a range of required monitors is prescribed, with 
the required number to be determined as part of the annual monitoring 
plan. The EPA estimates that once States and Regional Administrators 
have considered how current population data and recent PM10 
air quality affect the required number of PM10 monitors in 
each area, between 200 and 500 FRM/FEM monitors will be required, 
compared to about 1,200 in operation now. While States may of course 
choose to continue to operate monitors in excess of the minimum 
requirements, EPA notes that many PM10 monitors have been 
recording concentrations well below the PM10 NAAQS and are 
candidates for discontinuation at a State's initiative. States may 
choose to retain PM10 monitors that are recording 
concentrations below the PM10 NAAQS level to support 
monitoring objectives other than attainment/nonattainment 
determinations, such as baseline monitoring for prevention of 
significant deterioration permitting or public information.
    This final rule changes the requirements for the minimum number of 
monitors for PM2.5 and ozone (O3) monitoring 
networks. In response to comments, the final requirements require more 
O3 and PM2.5 monitoring in more polluted areas 
and more monitors in CSAs than was proposed. While this final rule 
requires fewer monitors than are now operating for O3 and 
PM2.5, as did the pre-existing monitoring rule, EPA does not 
intend to encourage net reductions in the number of O3 and 
PM2.5 monitoring sites in the U.S. as a whole. The surplus 
in the existing networks relative to minimum requirements gives States 
more flexibility to choose where to apply monitoring resources for 
O3 and PM2.5. For PM2.5, this final 
rule requires that sampling be conducted on a daily basis for monitors 
that have recently been recording the highest concentrations in their 
area and have been recording concentrations very near the 24-hour 
NAAQS, to avoid a bias in attainment/nonattainment designations that 
can occur with less frequent sampling. Pursuant to this provision, EPA 
estimates that about 50 sites now sampling less frequently will be 
required to change to daily sampling.
    As proposed, minimum monitoring requirements for carbon monoxide 
(CO), sulfur dioxide (SO2), and nitrogen dioxide 
(NO2) are eliminated in this final rule. Minimum 
requirements for lead (Pb) monitoring stations and Photochemical 
Assessment Monitoring Stations (PAMS) are reduced to those that were 
proposed. For all five criteria pollutants, however, existing 
monitoring sites (except those already designated as special purpose 
monitors) cannot be discontinued without EPA Administrator (for PAMS or 
NCore stations) or Regional Administrator (for all other types of 
monitoring) approval. Regional Administrator approval is also required 
for discontinuation of O3, PM2.5, and 
PM10 sites even if they are in excess of minimum network 
design requirements. While the rule requires EPA approval, such 
approvals should be facilitated where appropriate by rule provisions 
which clearly establish certain criteria under which discontinuation 
will be approved. These criteria are the same as those proposed with 
four minor changes explained in detail in section V.B.5, System 
Modifications. These criteria are not exclusive, and monitors not 
meeting any of the listed criteria may still be approved for 
discontinuation on a case-by-case basis if discontinuation does not 
compromise data collection needed for implementation of a NAAQS. 
Specific monitoring for these pollutants may currently be required in 
individual SIPs; this monitoring rule does not affect any SIP 
requirements for such specific monitoring.
    Appendix A to this final rule includes most of the proposed 
revisions to the quality system for ambient air monitoring. In 
particular, the proposed requirement for States to ensure a program of 
adequate and independent audits of their monitoring stations is 
included in this final rule. One way, but not the only way, a State can 
satisfy this requirement is to agree that EPA will conduct these audits 
using funds that otherwise would have been awarded to the State as part 
of its annual air quality management grant. A small number of changes 
to the proposed quality system requirements reflect public comments on 
details of the proposed revisions. Also, because the objective of 
PM10-2.5 monitoring is to better understand 
PM10-2.5 air quality and to support health effects studies, 
rather than to provide data for use in nonattainment designations, and 
because there consequently will be a much smaller network of required 
PM10-2.5 monitors than proposed, the quality system for 
PM10-2.5 in this final rule differs from the proposed system 
in that it aims to quantify data quality at the national level of 
aggregation rather than at the level of individual monitoring 
organizations as had been proposed. Another change from the proposal is 
that a provision has been added allowing the EPA Regional Administrator 
to waive the usual quality system requirements for special purpose 
monitors when those requirements are logistically infeasible due to 
unusual site conditions and are not essential to the monitoring 
objectives.
    The EPA is finalizing the proposed provisions regarding when data 
from special purpose monitors (SPMs) can be compared to a NAAQS, with 
minor clarifications. In summary, the final rule provides that if an 
ozone or PM2.5 SPM operates for only two years or less, EPA 
will not use data from that monitor to make attainment/nonattainment 
determinations. This limitation is inherent in the form of these NAAQS, 
which require three years of data for a determination to be made. For 
the other NAAQS pollutants, as a policy matter, EPA will not use only 
two years of data from a SPM to voluntarily redesignate an area to 
nonattainment. This limitation is possible because as established in 
Section 107(d)(1) of the Act, the only time EPA is obligated to 
redesignate areas as attainment or nonattainment is after it 
promulgates or revises a NAAQS. Under an existing standard, voluntary 
redesignations are at the Administrator's discretion: EPA has no legal 
obligation to redesignate an area even if a monitor should register a 
violation of that standard (see CAA Section 107(d)(3)). In particular, 
in the case of PM10, EPA stated in section VII.B of the 
preamble to the NAAQS rule (printed in today's Federal Register) that 
because EPA is retaining the current 24-hour PM10 standards, 
new nonattainment designations for PM10 will not be required 
under the provisions of the Clean Air Act. The same is true for CO, 
NO2, SO2, and Pb. However, all valid data from a 
SPM will be considered in determining if a previously designated 
nonattainment area has subsequently attained the NAAQS. See also 
section V.B.8 below.
    This final rule advances, to May 1, the date each year by which 
monitoring organizations must certify that their submitted data is 
accurate to the best of their knowledge. However, this requirement will 
take effect one year later than proposed, in 2010 for data collected in 
2009.
    This final rule retains the current requirement for an annual 
monitoring plan and finalizes most of the new

[[Page 61241]]

substantive and procedural requirements that were proposed for these 
plans. One change is that some required new elements proposed for the 
annual plan have instead been shifted to the 5-year network assessment, 
to reduce the annual plan preparation burden and to allow these 
elements to be prepared more carefully. The first 5-year network 
assessment has been postponed by one year, to July 1, 2010.
    The proposed requirements regarding probe heights for 
PM10-2.5 monitors, increased O3 monitor distance 
from roadways (for newly established O3 stations), data 
elements to be reported, and PM filter retention are included in this 
final rule.
    This final rule also removes and reserves the pre-existing appendix 
B, Quality Assurance Requirements for Prevention of Significant 
Deterioration (PSD) Air Monitoring, and appendix F, Annual SLAMS Air 
Quality Information, of 40 CFR part 58 because they are no longer 
needed.

C. Significant Dates for States, Local Governments, Tribes, and Other 
Stakeholders

    Only State governments, and those local governments that have been 
assigned responsibility for ambient air monitoring by their States, are 
subject to the mandatory requirements of 40 CFR part 58.\3\ The 
following summary of applicable requirements is presented in 
chronological order, as an aid for States in planning their activities 
to comply with the rule. States are required to comply with pre-
existing requirements in 40 CFR part 58, until the compliance date for 
each new requirement is reached.
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    \3\ Throughout this preamble, ``States'' is meant to also refer 
to local governments that have been assigned responsibility for 
ambient air monitoring within their respective jurisdiction by their 
States. This preamble also uses ``monitoring organization'' to refer 
to States, local agencies, and/or Tribes conducting monitoring under 
or guided by the provisions of 40 CFR part 58. This final rule 
applies the same requirements to the District of Columbia, Puerto 
Rico, and the Virgin Islands as apply to the 50 States. Other U.S. 
territories are not subject to this final rule.
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    The following provisions in 40 CFR part 53 and part 58 are 
effective on December 18, 2006:
     The criteria and process for EPA Administrator approval of 
FRMs, FEMs, and ARMs or where applicable Regional Administrator 
approval of ARMs. Manufacturers of continuous PM2.5 and 
PM10-2.5 instruments may apply for designation of their 
instruments as FRMs or FEMs starting today. The EPA is eager to receive 
such applications as soon as manufacturers can collect and analyze the 
necessary supporting data. State, local, and Tribal monitoring agencies 
may seek approval of their PM2.5 continuous monitor as ARMs 
beginning today, either independently or in cooperation with instrument 
manufactures.
     The revised quality system requirements, except that full 
quality assurance practices, if not waived, are not required until 
January 1, 2009 for SPMs which use FRM, FEM, or ARM monitors.
     The new minimum requirements (or absence of minimum 
requirements) for the number of monitors for specific NAAQS pollutants 
and for PAMS stations, if the new minimum allows a State to discontinue 
a previously required monitor. See below for the compliance date of the 
new minimum requirements in situations in which the final requirement 
is greater than the currently operating network.
     The criteria for EPA Regional Administrator approval for 
removal of monitors that are in excess of minimum required, if a State 
seeks such removal.
     The criteria for use of data from SPMs in determinations 
of attainment/nonattainment.
     The elimination of the requirement for reporting of 
certain PM2.5 monitor operating parameters.
     The revised requirement for separation between roadways 
and O3 monitors, for new O3 monitors whose 
placement has not already been approved as of December 18, 2006.
     The new specification for probe heights for 
PM10-2.5 monitors.
    The new requirement to archive all PM10c and 
PM10-2.5 filters for 1 year begins with filters collected on 
or after January 1, 2007. However, EPA expects few if any monitoring 
agencies to be operating PM10c or PM10-2.5 
filters this early, so most will be affected later.\4\
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    \4\ As explained in section IV.B of this preamble, the term 
``PM10c'' refers to a PM10 Federal reference 
method (FRM) that is designated as a PM10c FRM under the 
final NAAQS rule appearing elsewhere in today's Federal Register. In 
essence, it would be a PM2.5 FRM with the inertial 
fractionator used to separate out particles larger than 2.5 microns 
removed so that all PM10 is collected. Unlike other 
PM10 instruments, a PM10c instrument must 
control flow to a specified flow rate of 16.67 liters/minute at 
local conditions of temperature and pressure. A PM10-2.5 
FRM consists of a PM2.5 FRM and a PM10c FRM of 
the same model. See also 71 FR 2720.
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    The requirement to submit mass data on blank PM2.5 
filters begins on January 1, 2007.
    The required date to begin daily PM2.5 sampling at 
certain PM2.5 monitoring sites is January 1, 2007. The EPA 
believes this will affect about 50 PM2.5 monitoring sites. 
The EPA will notify the affected States directly.
    This final rule does not change the schedule for reporting ambient 
air quality data to the Administrator, via the Air Quality System 
(AQS). However the rule now explicitly requires that associated quality 
assurance data be submitted along with ambient concentration data. The 
first submission affected will be the one due on June 30, 2007 for data 
collected in January through March of 2007.
    As presently is the case, States must submit an annual network plan 
by July 1 of each year. The next plan is due July 1, 2007.
    States whose PM2.5, PM10, or O3 
networks do not meet the revised requirements of this final rule 
regarding the number of monitors in a given MSA or CSA are required to 
submit a plan for adding the necessary additional monitors by July 1, 
2007 and to begin operating the new monitors by January 1, 2008. The 
EPA believes that this will only affect O3 and 
PM2.5 monitoring in fewer than ten locations each. The EPA 
will notify these States directly.
    A plan for the implementation of the required NCore multipollutant 
monitoring stations, including site selection, is due by July 1, 2009. 
States must implement the required NCore multipollutant stations by 
January 1, 2011, including PM10-2.5 monitoring.
    States will be required to submit earlier certification letters 
regarding the completeness and accuracy of the ambient concentration 
and quality assurance data they have submitted to the Air Quality 
System (AQS) operated by EPA, starting May 1, 2010 for data collected 
during 2009. Until then, States are required to submit these letters by 
July 1 of each year.
    Network assessments are required from States every 5 years starting 
July 1, 2010.
    Under the Tribal Authority Rule (TAR) (40 CFR part 49), which 
implements section 301(d) of the CAA, Tribes may elect to be treated in 
the same manner as a State in implementing sections of the CAA. 
However, EPA determined in the TAR that it was inappropriate to treat 
Tribes in a manner similar to a State with regard to specific plan 
submittal and implementation deadlines for NAAQS-related requirements, 
including, but not limited to, such deadlines in CAA sections 
110(a)(1), 172(a)(2), 182, 187, and 191. See 40 CFR 49.4(a). For 
example, an Indian Tribe may choose, but is not required, to submit 
implementation plans for NAAQS-related requirements, nor is any Tribe 
required to monitor ambient air. If a Tribe elects to do an 
implementation plan, the plan can contain program elements to address 
specific air quality problems in a partial program. The EPA

[[Page 61242]]

will work with the Tribe to develop an appropriate schedule for making 
any appropriate monitoring system changes which meet the needs of each 
Tribe.
    Indian Tribes have the same rights and responsibilities as States 
under the CAA to implement elements of air quality programs as they 
deem necessary. Tribes can choose to engage in ambient air monitoring 
activities. In many cases, Indian Tribes will be required by EPA 
regions to institute quality assurance programs that comply with 40 CFR 
part 58 appendix A, utilize FRM, FEM, or ARM monitors when comparing 
their data to the NAAQS, and to insure that the data collected is 
representative of their respective airsheds. For FRM, FEM, or ARM 
monitors used for NAAQS attainment or nonattainment determinations, 
quality assurance requirements of 40 CFR part 58 must be followed and 
would be viewed by EPA as an indivisible element of a regulatory air 
quality monitoring program.

D. Implementation of the Revised Monitoring Requirements

    After promulgation, EPA will assist States in implementing the 
amended requirements using several mechanisms. The EPA will work with 
each State to develop approvable monitoring plans for its new NCore 
multipollutant monitoring stations, including PM10-2.5 
monitoring. For example, EPA will negotiate the selection of required 
new monitoring sites (or new capabilities at existing sites) and their 
schedules for start up as well as plans to discontinue sites that are 
no longer needed. The EPA will negotiate with each State its annual 
grant for air quality management activities, including ambient 
monitoring work. Once States have established a new monitoring 
infrastructure to meet the new requirements, EPA will review State 
monitoring activities, submitted data, and plans for further changes on 
an annual basis.
    The EPA's support for and participation in enhancing the national 
ambient air monitoring system to serve current and future air quality 
management and research needs will extend beyond ensuring that States 
meet the minimum requirements of this final monitoring rule. The EPA 
will work with each State or local air monitoring agency to determine 
what affordable monitoring activities above minimum requirements would 
best meet the diverse needs of the individual air quality management 
program as well as the needs of other data users. The EPA may also work 
with the States, and possibly with some Tribes, to establish and 
operate PM10-2.5 speciation sites inaddition to those 
required by this final rule. The EPA also plans to work with the 
States, and possibly with some Tribes, to establish and operate sites 
that will measure only PM10-2.5 concentrations in rural and 
less urbanized locations, in addition to the PM10-2.5 
monitors required at NCore sites.
    An important element of implementing the new requirements will be 
EPA's role in encouraging the development and application of FEMs, and 
the development of a sampler or samplers that can provide a direct 
measurement of PM10-2.5 for collection of filters used in 
chemical speciation and for continuous methods that measure both 
PM2.5 and PM10-2.5. The EPA has determined that 
continuous monitoring of PM2.5 has many advantages over the 
filter-based FRM. This final rule makes it more practical for 
manufacturers and users of continuous PM2.5 instruments to 
obtain designation for them as FEMs or ARMs. To ensure objectivity and 
a sound scientific basis for decisions, EPA's Office of Research and 
Development will review applications for FEM and ARM designations based 
on the criteria in this final rule and will recommend approval or 
disapproval to the Administrator. For agencies seeking use of an ARM 
already approved in another monitoring network, the applicable Regional 
Office will conduct a review, most often as part of the EPA approval of 
an annual monitoring plan, based on the criteria in this final 
monitoring rule.
    The EPA will also provide technical guidance documents and training 
opportunities for State, local, and Tribal monitoring staff to help 
them select, operate, and use the data from new types of monitoring 
equipment. The EPA has already distributed a technical assistance 
document on the precursor gas monitors \5\ that will be part of the 
NCore multipollutant sites and EPA has conducted multiple training 
workshops on these monitors. Additional guidance will be developed and 
provided on some other types of monitors with which many State 
monitoring staff are currently unfamiliar, and on network design, site 
selection, discontinuation of sites, quality assurance, network 
assessment, and other topics. While Tribes are not subject to the 
monitoring requirements of this final rule, these technical resources 
will also be available to them directly from EPA and via grantees, such 
as the Institute for Tribal Environmental Professionals and the Tribal 
Air Monitoring Support Center.
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    \5\ Technical Assistance Document (TAD) for Precursor Gas 
Measurments in the NCore Multipollutant Monitoring Network. Version 
4. U.S. Environmental Protection Agency. EPA-454/R-05-003. September 
2005. Available at: https://www.epa.gov/ttn/amtic/pretecdoc.html.
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    The EPA will also continue to support the National Park Service's 
operation of the IMPROVE monitoring network, which provides important 
data for implementing both regional haze and PM2.5 
attainment programs.\6\ The number of sites in the IMPROVE program may 
vary, depending on EPA's enacted budget and the data needs of the 
regional haze and PM2.5 attainment programs.
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    \6\ Additional information on EPA/National Park Service IMPROVE 
(Interagency Monitoring of Protected Visual Environments) Visibility 
Program is available at: https://www.epa.gov/ttn/amtic/visdata.html.
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    The EPA will also continue to operate the Clean Air Status and 
Trends Network (CASTNET), which monitors for O3, PM, and 
chemical components of PM in rural areas across the nation.\7\ EPA is 
in the process of revising CASTNET to upgrade its monitoring 
capabilities to allow it to provide even more useful data to multiple 
data users. The EPA expects that about 20 CASTNET sites will have new 
capabilities similar to some of the capabilities required at NCore 
multipollutant sites.
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    \7\ Additional information on CASTNET is available at: https://
www.epa.gov/castnet/.
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    This final rule includes a requirement that States must ensure a 
program of adequate and independent audits of their monitoring 
stations. One way, but not the only way, a State can satisfy this 
requirement is to agree that EPA will conduct these audits using funds 
that otherwise would have been awarded to the State as part of its 
annual air quality management grant. In anticipation of the possible 
inclusion of this requirement in this final rule, EPA has been working 
with monitoring organizations to determine which of these organizations 
prefer this approach. The EPA expects that, for 2007, nearly all 
monitoring organizations will request that EPA conduct these audits. 
For those that chose another acceptable approach, EPA will conduct 
limited cross-checks of equipment, calibration standards, auditor 
preparation, and audit procedures to ensure that their audit programs 
are adequate.
    The EPA recognizes that characterizing and managing some air 
quality problems requires ambient concentration and deposition data 
that cannot be provided by the types of monitoring required by the 
monitoring activities addressed in today's final rule. These problems 
include near-roadway exposures to emissions from motor

[[Page 61243]]

vehicles and mercury deposition. The EPA is actively researching these 
issues and developing concepts for monitoring programs to address them, 
but these issues are outside the scope of this final rule.
    The Air Quality System (AQS) is the data system EPA uses to receive 
ambient air monitoring data from State, local, Tribal, and other types 
of monitoring organizations and to make those data available to all 
interested users. AQS is based on a particular data structure and uses 
particular data input formats including data elements and defined 
values for categorical data. The existing AQS data structure and input 
formats are for the most part consistent with a number of changes made 
in this final rule to pre-existing terminology and requirements, but 
some changes will be needed in AQS to re-establish full consistency 
with requirements in the monitoring rule. The changes to AQS will 
likely, in turn, require some modifications to data preparation tools 
and practices at monitoring agencies. The EPA will prepare and 
implement a plan for making these changes, and will advise AQS users of 
the ramifications while doing so. Generally, the compliance deadlines 
in the rule are such that monitoring agencies are not required to 
immediately comply with any changes in rule provisions that would 
affect data transfer formats and procedures. Monitoring agencies, for 
the present, should continue to follow pre-existing AQS formats and 
procedures until notified.

E. Federal Funding for Ambient Air Monitoring

    EPA has historically funded part of the cost to State, local, and 
Tribal governments of installation and operation of monitors to meet 
Federal monitoring requirements. Sections 105 and 103 of the CAA allow 
EPA to provide grant funding for programs for preventing and 
controlling air pollution and for some research and development efforts 
respectively. Eligible entities must apply for section 103 grants. 
Eligible entities must provide nonfederal matching funds for section 
105 grants. The EPA's enacted budget specifies overall how much State 
and Tribal Air Grant (STAG) funding is available for these grants.
    In recent years, EPA has received special authority through 
appropriations acts to use section 103 grant funding for establishing 
and operating PM2.5-related monitoring stations. Funding for 
other types of monitoring has been included in the grants awarded under 
section 105. Grants to Tribes for air quality management work, 
including ambient monitoring, have been awarded under section 103 with 
the overall amount for these funds established by the enacted budget.
    During the public comment period for this rulemaking EPA received a 
large number of comments addressing funding issues. Most of these 
comments expressed opposition to the Administration's proposed EPA 
budget for fiscal year 2007, which included a proposal to provide 
PM2.5 monitoring support through section 105 grant funding, 
as is done for all other criteria pollutants. (As of today, the 
Congress has not enacted a 2007 budget for EPA.) Commenters stated that 
if funding for monitoring were reduced as proposed, State and local 
agencies would have less flexibility than desired in designing and 
operating their monitoring programs, and that the proposed requirements 
for new PM10-2.5 and NCore networks and for adequate and 
independent audits of monitoring stations would be burdensome. Some 
commenters requested that the proposed new requirements not be included 
in this final rule for this reason.
    The EPA understands these concerns. However, the CAA requirements 
from which this final rule derives \8\ are not contingent on EPA 
providing funding to States to assist in meeting those requirements. 
Accordingly, the comments regarding funding are not directly relevant 
to the content of this final rule. Nevertheless, EPA recognizes that 
resources always have been and will remain a practical consideration 
for establishing and operating monitoring programs. The EPA will 
continue to work with States in this regard, in particular as EPA 
determines how to allocate enacted funding among States and among types 
of monitoring so as to achieve the best possible environmental 
outcomes. Several provisions of this final rule reduce minimum 
requirements, which will provide flexibility for States to reduce some 
of their pre-existing costs.
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    \8\ Section 103(c)(2) of the Clean Air Act [42 U.S.C.A. 7403(c)] 
provides that the Administrator shall conduct a program for sampling 
air pollution that includes the establishment of a national network 
to monitor air quality and to ensure the comparability of air 
quality data collected in different states. Section 110(a)(2)(B) [42 
U.S.C.A 7410(a)] provides that each State implementation plan shall 
provide for establishment and operation of appropriate devices, 
methods, systems, and procedures necessary to monitor, compile, and 
analyze data on ambient air quality and upon request make such data 
available to the Administrator. Section 182(c)(1) [42 U.S.C.A. 
7511a(c)(1)] states that the Administrator will promulgate rules for 
enhanced monitoring for ozone, oxides of nitrogen, and volatile 
organic compounds in serious ozone areas.
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    Several commenters stated that EPA should not use STAG funds for 
the improvement or operation of Federal monitoring networks such as 
CASTNET. The EPA does not intend to use STAG funds from fiscal year 
2007 or beyond in this way.

IV. Discussion of Regulatory Revisions and Major Comments on Proposed 
Amendments to 40 CFR Part 53

A. Overview of Part 53 Regulatory Requirements

    Various appendices to 40 CFR part 50 define certain ambient air 
monitoring methods as Federal reference methods which may be used to 
determine attainment of the National Ambient Air Quality Standards 
(NAAQS), and which form the benchmark for determining equivalency of 
other methods which may also be used to determine attainment. Under 40 
CFR part 53, EPA designates specific commercial instruments or other 
versions of methods as Federal reference methods (FRMs). To be so 
designated, a particular FRM must be shown, according to the procedures 
and requirements of part 53, to meet all specifications of both the 
applicable appendix of part 50 as well as applicable specifications and 
requirements of part 53.
    To foster development of improved alternative air monitoring 
methods, EPA also designates--as Federal equivalent methods (FEMs)--
alternative methods that are shown to have measurement performance 
comparable to the corresponding FRM. Part 53 contains explicit 
performance tests, performance standards, and other requirements for 
designation of both FRMs and FEMs for each of the criteria pollutants. 
In addition, States' air surveillance monitoring networks are required, 
under 40 CFR part 58, appendix C, to use only EPA-designated FRMs, 
FEMs, or ARMs at SLAMS sites. A list of all methods that EPA has 
designated as either FRMs or FEMs for all criteria pollutants is 
available at https://www.epa.gov/ttn/amtic/criteria.html.
    Elsewhere in today's Federal Register, EPA is promulgating a new 
Federal reference method for measurement of mass concentrations of 
thoracic coarse particles (PM10-2.5) in the atmosphere, to 
be codified as appendix O to 40 CFR part 50. Although, as explained 
earlier, EPA is not at this time adopting any NAAQS for 
PM10-2.5, EPA believes an FRM for PM10-2.5 is 
still highly desirable to aid in a variety of needed

[[Page 61244]]

research studies.\9\ This new FRM is