Order Code RL32431
Particulate Matter (PM ): Implementation of the
2.5
1997 National Ambient Air Quality Standards
(NAAQS)
Updated October 4, 2007
Robert Esworthy
Specialist in Environmental Policy
Resources, Science, and Industry Division

Particulate Matter (PM ): Implementation of the 1997
2.5
National Ambient Air Quality Standards (NAAQS)
Summary
Particulate matter (PM), including fine particulate matter (PM ), is one of the
2.5
six principal pollutants for which the U.S. Environmental Protection Agency (EPA)
has set National Ambient Air Quality Standards (NAAQS) under the Clean Air Act
(CAA). NAAQS are designed to protect human health, with an adequate margin of
safety. After years of litigation and other delays, the EPA is moving to implement
the NAAQS for PM promulgated in 1997. Several key implementation milestones
2.5
are scheduled to be completed during 2007 and 2008. This report provides
information on the designation process for PM “attainment” and “nonattainment”
2.5
areas, and describes the issues that have been raised as the EPA and states develop
implementation strategies.
The EPA’s final designation of 39 areas, consisting of 208 counties in 20 states
and the District of Columbia, as nonattainment areas for the 1997 PM NAAQS
2.5
became effective April 2005. A combined population of almost 90 million resides
in these areas. States with PM nonattainment areas are required to develop
2.5
comprehensive implementation plans, referred to as State Implementation Plans
(SIPs), demonstrating how attainment will be reached by a designated deadline. SIPs
include pollution control measures that rely on models of the impact on air quality
of projected emission reductions to demonstrate attainment. States are required to
submit SIPs for the 1997 PM NAAQS by April 2008 (three years after the effective
2.5
date for the final geographic designations), and states must be in compliance by 2010,
unless they are granted a five-year extension. The EPA published its final “PM2.5
implementation” rule on April 25, 2007, intended to provide guidance and
procedures for establishing controls to achieve and maintain attainment. As of
September 2007, six petitions for legal review of the implementation rule were filed
with the U.S. Court of Appeals for the D.C. Circuit.
A number of issues will continue to be debated as the implementation of the
1997 PM NAAQS progresses. Questions and concerns include the following: what
2.5
criteria were used to determine nonattainment; whether special provisions can be
made for meeting attainment deadlines, particularly for areas affected by upwind
pollution; what grants or other funding might be available to help areas reach
attainment; and how nonattainment designation might affect economic development
and transportation planning in an area.
Other EPA recent rulemakings promulgated and proposed that affect various
aspects of regulating air quality, in particular the Clean Air Interstate Rule (CAIR)
published in May 2005, could influence the PM NAAQS implementation process.
2.5
As part of its periodic review of the particulates NAAQS, as required under the CAA,
on October 17, 2006, the EPA promulgated the final revisions to NAAQS for
particulates, both PM and PM , that included a strengthening of the 1997 PM
2.5
10
2.5
standard. In late December 2006, several states and industry, agriculture, business,
and public advocacy groups petitioned the U.S. Court of Appeals for the D.C. Circuit
to review the new 2006 particulates NAAQS. Actions regarding these new PM
NAAQS could affect implementation of the 1997 PM NAAQS.
2.5

Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
The 1997 PM Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.5
Geographical Area Designation Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1997 PM NAAQS Geographical Area Designations:
2.5
A Chronology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Demonstrating Attainment with the 1997 PM NAAQS . . . . . . . . . . . . . . 12
2.5
The State Implementation Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
EPA’s PM Implementation Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.5
Transportation Conformity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Other National Air Quality Improvement Programs and
Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Continuing Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Defining Nonattainment Boundaries . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Upwind Pollutant Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Economic Impacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Grant Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Identifying Sources and Control Measures . . . . . . . . . . . . . . . . . . . . . 19
Completion of the EPA’s Most Recent Review of
the Particulates NAAQS and the
September 2006 Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Impacts of Actions Regarding the 1997 Ozone NAAQS . . . . . . . . . . . 21
Congressional Action Related to Particulates NAAQS Implementation . . . 22
Implementation of the 1997 PM NAAQS: Timeline and Delays . . . . . . . 23
2.5
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
List of Figures
Figure 1. U.S. Environmental Protection Agency Designations of
Nonattainment Areas for the 1997 PM National
2.5
Ambient Air Quality Standards (NAAQS) . . . . . . . . . . . . . . . . . . . . . . . . . 11
List of Tables
Table 1. Areas Previously Identified as Nonattainment for
1997 PM NAAQS Designated as
2.5
Attaining the Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Table 2. Estimated Schedule for Implementation of
the 1997 PM NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.5

Particulate Matter (PM ): Implementation of
2.5
the 1997 National Ambient Air Quality
Standards (NAAQS)
Introduction
National Ambient Air Quality Standards (NAAQS) are a core component of the
Clean Air Act (CAA).1 NAAQS do not regulate emission sources of pollutants
directly; rather, they define the level of pollution in ambient (outdoor) air above
which health effects occur. The statute requires that, based on a review of the
scientific literature, the Environmental Protection Agency (EPA) set (1) “primary”
standards at a level “requisite to protect the public health” with an “adequate margin
of safety” and (2) “secondary” standards at a level “requisite to protect the public
welfare.”2 NAAQS have been promulgated for six principal pollutants classified by
the EPA as “criteria pollutants”: sulfur dioxide (SO ), nitrogen dioxide (NO ), carbon
2
2
monoxide (CO), ozone, lead, and particulate matter.
This report provides an overview of the NAAQS implementation process in the
context of the 1997 standards for fine particulate matter (PM ), which consists of
2.5
particles less than 2.5 micrometers in diameter. It also discusses issues and concerns
of stakeholders that could potentially alter the PM implementation process. The
2.5
EPA is in the process of implementing the NAAQS for particulates promulgated in
1997,3 delayed because of court challenges and other factors. The EPA’s 1997
revisions to the particulate matter standards (also referred to as the particulates
NAAQS) included separate requirements for PM for the first time. Since they were
2.5
modified, the particulates NAAQS have been the source of significant concern and
national debate, which have delayed their implementation. Congress has been
particularly interested in the EPA’s promulgation and implementation of the CAA
standards and has held numerous hearings on particulate matter (and the ozone
NAAQS established in 1997).
A key component of implementing the 1997 PM NAAQS is the EPA’s
2.5
designations of geographical areas for “attainment” or “nonattainment” of the air
quality standards for PM . The EPA’s final designation of all or part of 208
2.5
1 Sections 108 and 109 of the Clean Air Act (CAA) govern the establishment, review, and
revisions of NAAQS (42 U.S.C. 7408 and 7409). See CRS Report 97-722, Air Quality
Standards: The Decisionmaking Process
, by John Blodgett and Larry Parker.
2 42 U.S.C. 7409(b)(1) for “primary”; 42 U.S.C. 7409(b)(2) and 7602(h) for “secondary.”
3 62 Federal Register 38652-38760, July 18, 1997.

CRS-2
counties4 in 20 states and the District of Columbia for nonattainment of the 1997
PM NAAQS became effective on April 5, 2005.5 A combined population of almost
2.5
90 million lives in these nonattainment areas. The final designations were based, in
part, on the EPA’s consideration of recommendations previously provided by states
and tribes, and supplemental 2004 air monitoring data submitted by some states.
Nonattainment designation begins a process in which states (and tribes) must develop
and adopt emission control programs sufficient to bring air quality into compliance
by a statutorily defined deadline. States are required to submit their “implementation”
plans (referred to as SIPs) for how they will meet the 1997 PM NAAQS by April
2.5
2008, and they must be in compliance by April 5, 2010, unless they are granted a
five-year extension.6
The designation of “nonattainment” areas raised questions and concerns,
particularly for those areas designated as such for the first time. These questions and
concerns include when and why the standards were established, what criteria were
used to determine nonattainment, what measures will be necessary to achieve or
maintain attainment by the scheduled deadlines, whether special provisions can be
made for areas affected by upwind pollution, what flexibility is available for
extending the deadline for reaching attainment, whether grants or other funding are
available to help areas reach attainment, and how designation might affect economic
development and transportation investments in an area.7 Concerns also have been
raised regarding compliance deadlines with respect to the EPA’s timely provision of
implementation procedures and guidance for achieving and maintaining compliance
with the 1997 PM NAAQS. The EPA published its final “PM implementation”
2.5
2.5
rule on April 25, 2007.8 As of September 2007, six petitions for legal review of
EPA’s implementation rule have been filed with the U.S. Court of Appeals for the
4 All designated counties and partial counties, including Indian Country, geographically
located within such areas, except as otherwise indicated by the EPA. See EPA’s PM2.5
Designations website at [http://www.epa.gov/pmdesignations].
5 70 Federal Register 944-1019, January 5, 2005. The EPA published a final supplemental
rule on April 14, 2005 (70 Federal Register 19844), amending the agency’s initial final
designations published in January, re-designating as attainment/unclassifiable 17 counties
previously designated nonattainment. The earlier rule included a provision for the EPA to
withdraw a nonattainment designation prior to the April 5, 2005, effective date if a state
provided 2004 air monitoring data by February 22, 2005, suggesting that a change in
designation would be appropriate. Monitoring data for 2004 was not available in time for
the EPA to meet its statutory deadline for completing its designations.
6 Under section 172(a)(2)(A) of the CAA, the EPA may grant an area an extension of the
initial attainment date for one to five years (in no case later than 10 years after the
designation date for the area). A state requesting an extension must submit an
implementation plan (SIP) by the required deadline that includes, among other things,
sufficient information demonstrating that attainment by the initial attainment date is
“impracticable.”
7 The EPA’s April 15, 2004, designations for the ozone air quality standard (promulgated
the same time as the PM NAAQS in 1997) raised similar concerns. See CRS Report
2.5
RL32345, Implementation of EPA’s 8-Hour Ozone Standard, by James E. McCarthy.
8 72 Federal Register 20586 — 20667, April 25, 2007.

CRS-3
District of Columbia (D.C.) Circuit,9 and one petition for reconsideration has been
filed with EPA.10 Given that states are required to submit their SIPs by April 2008,
state and local air pollution control agencies,11 as well as some Members of
Congress,12 had expressed their concerns about the delays in publishing a final
implementation rule13 and the lack of guidance.
The CAA provisions require the EPA to consider revisions to NAAQS on a
prescribed schedule.14 Based on its finding that a review of the scientific evidence
continued to support associations of exposure to particulates in ambient air with
numerous significant health problems, the EPA promulgated revisions to the NAAQS
for particulate matter on October 17, 2006.15 The new particulates NAAQS tighten
the 1997 standard for PM but do not include several proposed changes to modify
2.5
the standards for inhalable coarse particles smaller than 10 microns but larger than
2.5 microns (PM ). The tightening of the PM standards is expected to increase the
10
2.5
number of areas (typically defined by counties or portions of counties) in
nonattainment. According to the EPA, states will not be required to meet the new
9 The six petitions are: Earthjustice on behalf of American Lung Association (ALA),
National Resources Defense Council (NRDC), Sierra Club and Medical Advocates for
Healthy Air (American Lung Association v. EPA, D.C. Cir., No. 07-1233, June 26, 2007);
National Environmental Development Association’s Clean Air Project (NEDA CAP);
National Petrochemical & Refiners Association; State of New York; State of New Jersey;
National Cattlemen’s Beef Association.
10 Earthjustice, Petition for Reconsideration, Final Clean Air Fine Particle Implementation,
filed before the Administrator of the U.S. Environmental Protection Agency, June 25, 2007,
(RIN 2060-AK, Air Docket #OAR-2003-0062 available at [http://www.regulations.gov/
fdmspublic/component/main].
11 Letter of Shelley Kaderly and Ursula Kramu, Co-Presidents, the National Association of
Clean Air Agencies (NACAA, formerly the State and Territorial Air Pollution Program
Administrators and the Association of Local Air Pollution Control Officials
(STAPPA/ALAPCO)), to Hon. Stephen L. Johnson, EPA Administrator, February 16, 2007,
available at [http://www.4cleanair.org/index.asp].
12 Letter of the Hon. John D. Dingell, Chairman of the House Committee on Energy and
Commerce, to Hon. Stephen L. Johnson, EPA Administrator, January 19, 2007,
[http://energycommerce.house.gov/Press_110/110pr_air_quality.shtml].
13 The EPA had published a proposed rule November 1, 2005 (70 Federal Register 65984).
14 Section 109(d)(1)) of the CAA. According to the statute, the EPA is required to review
the latest scientific studies and either reaffirm or modify the NAAQS every five years, but
reviews have occurred less frequently in practice.
15 71 Federal Register 61143-61233, October 17, 2006. See CRS Report RL33254, Air
Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standard
, by Robert Esworthy
and James E. McCarthy. The schedule for completion of the agency’s review of the
particulates NAAQS is governed by a consent decree resolving a lawsuit filed in March
2003. The EPA was required to finalize its decision regarding the particulates NAAQS by
September 27, 2006 (American Lung Assn. v. Whitman [No. 1:03CV00778, D.D.C. 2003],
as modified by the court).

CRS-4
2006 PM standard until April 2015 (April 2020, if qualified for an extension16).
2.5
The EPA estimates that the effective date for the final designations for the new 2006
PM NAAQS will not be before April 2010.
2.5
It is unclear how the EPA’s new 2006 particulates NAAQS will affect the
ongoing implementation process for the 1997 PM NAAQS. However, the EPA has
2.5
urged states to consider control strategies that may be useful in attaining the new
2006 PM NAAQS when developing control strategies for the 1997 PM
2.5
2.5
standards.17 Several elements of the new 2006 particulates NAAQS have been
controversial, including the decision not to exclude rural sources from the coarse
particle standard that the EPA had initially proposed, and the divergence from
recommendations made by the Clean Air Scientific Advisory Committee (CASAC),18
in particular, with regard the stringency of the PM standard. In late December
2.5
2006, 13 states and the District of Columbia petitioned the court to review the new
2006 particulates NAAQS. In addition, several groups representing various industry
and agriculture interests (including coal, iron, steel, and corn refiners; oilseed
processors; farmers; and cattle and pork producers, as well as a number of public
advocacy groups) also filed petitions to the court challenging the new 2006
NAAQS.19
These and other issues potentially affecting the implementation of the 1997
PM NAAQS are presented in the following sections of this report, beginning with
2.5
an overview of the particulates air quality standards and the geographical designation
process.
The 1997 PM Standards
2.5
Beginning in 1971, regulation and monitoring of particulate matter under the
CAA focused primarily on total suspended particles (TSP) and, eventually, on coarse
16 Under section 172(a)(2)(A) of the CAA, the EPA may grant an area an extension of the
initial attainment date for one to five years (in no case later than 10 years after the
designation date for the area). A state requesting an extension must submit an
implementation plan (SIP) by the required deadline that includes, among other things,
sufficient information demonstrating that attainment by the initial attainment date is
“impracticable.”
17 EPA’s Advanced Notice of Proposed Rulemaking outlining an implementation plan for
the transition to the January 17, 2006, proposed particulates NAAQS (71 Federal Register
6722, February 9, 2006).
18 See the Clean Air Scientific Advisory Committee (CASAC) Particulate Matter Review
Panel website at [http://www.epa.gov/sab/panels/casacpmpanel.html]. For a discussion of
recent issues regarding the CASAC, focusing on the statutory and historical role of CASAC
and various proposals for change, see CRS Report RL33807, Air Quality Standards and
Sound Science: What Role for CASAC?
by James E. McCarthy.
19 The Court has consolidated the cases (American Farm Bureau Federation v. U.S. EPA,
No. 06-1410 (D.C. Cir. 2006)) and ordered submission of briefs from petitioners, EPA, and
supporters for October 2007 through February 2008, with final briefs due by March 2008.
Parties will be notified of the schedule for oral arguments by a separate order.

CRS-5
particles equal to or less than 10 micrometers in diameter (PM ).20 After extensive
10
analysis and review, the EPA revised the particulates standards in 199721 to provide
separate requirements for fine particulate matter (PM ) based on their links to
2.5
several types of cardiovascular and respiratory health problems, including aggravated
asthma and bronchitis, and to premature death.22 In the 1997 promulgation, the EPA
also revised the coarse particles’ designation (PM ) to include particles larger than
10
2.5 but smaller than 10 micrometers (PM
), so as to explicitly exclude fine
10-2.5
particles. As part of the 1997 rule, the EPA also promulgated the eight-hour ozone
standard. The EPA’s standard for PM , as modified by the 1997 changes, was
10
challenged shortly after promulgation. Concluding that PM was a “poorly matched
10
indicator” for thoracic coarse particles because it included the smaller PM category
2.5
as well as the larger particles, the U.S. Court of Appeals for the D.C. Circuit vacated
the 1997 PM standards and remanded them to EPA. The 1999 U.S. Court of
10
Appeals for the D.C. Circuit decision23 directed the EPA to ensure that the standard
did not duplicate the regulation of fine particles. The pre-existing 1987 PM10
standards remained in place.24
The primary (health) PM NAAQS requirements, which became effective on
2.5
September 16, 1997,25 are the same and as the secondary (welfare) requirements. The
1997 PM standards are set at
2.5
! an annual maximum concentration of 15 micrograms per cubic
meter (µg/m3), based on the three-year average of the annual
arithmetic mean PM concentrations from one or more community-
2.5
oriented monitors,26 and
! a 24-hour concentration of 65 µg/m3, based on the three-year average
of the 98th percentile of 24-hour PM concentrations at each
2.5
population-oriented monitor27 within the area.
In requiring both the annual and the 24-hour PM standards in 1997, the EPA
2.5
reportedly considered the “combined effect of the standards rather than an approach
that weighed short- and long-term exposure evidence, analyses, and standards
20 52 Federal Register 24634-24715, July 1, 1987.
21 62 Federal Register 38652-38760, July 18, 1997.
22 For an update of EPA’s health effects and other particulates-related research activities,
see [http://www.epa.gov/pmresearch/].
23 American Trucking Assns. v. EPA, 175 F.3d 1027, 1054-55 (D.C. Cir. 1999).
24 65 Federal Register 80776, December 22, 2000.
25 62 Federal Register 38652-38760, July 18, 1997.
26 Community-oriented monitoring zones are defined as “an optional averaging area with
well established boundaries such as county or census block” (40 CFR Part 58 Subpart A).
27 Population-oriented monitoring (or sites) applies to “residential areas, commercial areas,
recreational areas, industrial areas, and other areas where a substantial number of people
may spend a significant fraction of their day” (40 CFR Part 58 Subpart A).

CRS-6
independently.”28 The EPA considers the annual standard the primary requirement
for reducing total PM risk. The 24-hour standard is intended to provide
2.5
supplemental protection for days with peak PM concentrations, localized “hot
2.5
spots,” and PM risks arising from seasonal emissions.
2.5
In 1997, the EPA changed the “form” of the 24-hour standards to a
concentration-based percentile form, indicating the percentage of the time that a
monitoring station can exceed the standard. For example, a 98th percentile 24-hour
standard indicates that a monitoring station can exceed the standard 2% of the time
during the year. The previous form was known as the “one-expected-exceedance”
form; monitoring stations could exceed the 24-hour particulates NAAQS only once
per year (averaged over three years). Although the limits of PM remained the same,
10
the form of the PM 24-hour standard was changed to be based on a three-year
10
average of the 99th percentile of 24-hour PM concentrations.
10
Geographical Area Designation Process
The designation of geographical areas failing to comply with the NAAQS, based
on monitoring and analysis of relevant air quality data, is a critical step in NAAQS
implementation. The CAA establishes a process for designating nonattainment areas
and setting their boundaries, but it allows the EPA Administrator some discretion in
determining what the final boundaries of the areas will be. Areas are identified as
“nonattainment” when they violate or contribute to the violation of NAAQS. Areas
are identified as “attainment/unclassified”29 when they meet the standard or when the
data are insufficient for determining compliance with the NAAQS.30
The EPA reported 156 areas were designated as nonattainment for at least one
of the six criteria pollutants (including particulate matter) as of March 2007.31 In
addition, estimates from the EPA’s 2006 “trends” data released April 30, 2007,
indicate that approximately 103 million people lived in counties with air quality
concentrations above the NAAQS levels for the six criteria pollutants in 2006.32
The designation process is intended as a cooperative federal-state-tribal process
in which states and tribes provide initial designation recommendations to the EPA
for consideration. Though not required to do so, tribes have been encouraged to
28 U.S. EPA Fact Sheet, EPA’s Revised Particulate Matter Standards, July 17, 1997.
29 Section 107(d)(1)(A)(iii) of the CAA provides that any area that the EPA cannot designate
on the basis of available information as meeting or not meeting the standards should be
designated unclassifiable.
30 The EPA “Greenbook” lists areas of the country where air pollution levels persistently
exceed the national ambient air quality standards and may be designated as nonattainment.
Current information on the location of NAAQS nonattainment areas is available on EPA’s
website at [http://www.epa.gov/oar/oaqps/greenbk/].
31 See, EPA’s Criteria Pollutant Area Summary Report (as of March 30, 2007,the data is
periodically updated) at [http://www.epa.gov/oar/oaqps/greenbk/ancl2.html].
32 U.S. EPA, National Air Quality Trends Data: 2006, preliminary estimates released April
30, 2007, at [http://www.epa.gov/airtrends/econ-emissions.html].

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submit recommendations. The area designation requirements under the CAA (Section
107) are specific with respect to states, but not to tribes. The EPA follows the same
designation process for tribes per Sections 110(o) and 301(d) of the CAA and
pursuant to the 1988 Tribal Authority Rule, which specifies that tribes shall be
treated as states in selected cases (40 CFR Part 49).33 In Section 107(d)(1)(A) (42
U.S.C. 7407), the statute states that the governor of each state shall submit a list to
the EPA of all areas in the state, “designating as ... nonattainment, any area that does
not meet (or that contributes to ambient air quality in a nearby area that does not
meet
) an air quality standard” (emphasis added).
PM attainment or nonattainment designations were made primarily on the
2.5
basis of three-year federally referenced PM monitoring data.34 At the time the
2.5
PM NAAQS were being finalized in 1997, the EPA began developing methods for
2.5
monitoring fine particles. Using funding specifically authorized for this purpose in
FY1998-FY2000 EPA appropriations,35 the agency worked closely with states and
tribes to initiate the deployment of a portion of the network of 1,200 monitors in
January 1999. The majority of the monitors were not in place until January 2000.
States and tribes were expected to rely on data collected during 2000-2002 for their
recommendations. The EPA considered the 2001-2003 data to make the final PM2.5
designations published in January 2005.
In its guidance document,36 the EPA identified several factors that would be
considered in determining attainment with the 1997 PM NAAQS and specified data
2.5
and conditions that would not be acceptable. The EPA’s nonbinding guidance also
included a recommendation that states and tribes consider using the same boundaries
for nonattainment for both the PM and eight-hour ozone standards, to facilitate
2.5
consistency in future implementation plans. The EPA expected that many of the
PM nonattainment areas would overlap with the eight-hour ozone designations.37
2.5
PM designations do not include nonattainment classifications based on
2.5
severity, as is the case with PM and ozone, which have two and seven
10
classifications, respectively. The 1990 CAA Amendments include classifications of
nonattainment, based on the extent to which the NAAQS are exceeded, and establish
specific pollution controls and attainment dates for each classification (Title I Part
D Sections 171-193). Under subpart 4 of the CAA, PM nonattainment designations
10
33 For information regarding tribes that have participated in the PM designation
2.5
recommendation process, see [http://www.epa.gov/pmdesignations].
34 A federally referenced monitor is one that has been accepted for use by the EPA for
comparison of the NAAQS by meeting the design specifications and certain precision and
bias (performance) specifications (40 CFR Part 58).
35 Appropriations for monitoring averaged roughly $50 million per year (P.L. 105-65, P.L.
105-226, P.L. 106-74).
36 Information regarding EPA’s guidance for PM designation is available on EPA’s PM
2.5
2.5
website at [http://www.epa.gov/ttn/naaqs/pm/pm25_index.html] and its Policy and Guidance
website at [http://www.epa.gov/ttn/oarpg].
37 A map showing the final designation areas for PM and for the eight-hour ozone NAAQS
2.5
is available on EPA’s website at [http://www.epa.gov/oar/oaqps/greenbk/mappm25o3.html].

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are either “moderate” or “serious,” and each of these categories is subject to specified
control requirements.38 The EPA interpreted those classification provisions in the act
for particulate matter to apply explicitly to PM , but not PM , NAAQS. Based on
10
2.5
this interpretation, PM implementation is governed by the general nonattainment
2.5
planning requirements of Title I (Part A and Part D, subpart 1) of the act.
The EPA recognized that determining the geographic extent of nearby source
areas that contribute to nonattainment would be complicated. The CAA does not
specifically require combining neighboring counties within the same nonattainment
area, but it does require the use of metropolitan statistical area boundaries in the more
severely polluted areas (Section 107(d)(4)(A)(iv)). Echoing this requirement, and
similar to the eight-hour ozone approach, the EPA recommended that Metropolitan
Statistical Areas or Consolidated Metropolitan Statistical Areas39 serve as the
“presumptive boundary” for nonattainment areas under the 1997 PM standards.
2.5
Metropolitan areas are generally treated as units, even when part of the area lies
in a separate state or does not have readings exceeding the standards. In the latter
case, even though a specific county may not exceed the standards, the pollution
generated there is likely to influence PM levels elsewhere in the metropolitan area.
2.5
In addition, including the entire metropolitan area avoids the creation of additional
incentives for sprawl development on the fringes of urban areas. For rural areas in
violation of the 1997 PM standards, the EPA’s guidance presumed that the full
2.5
county would be designated a nonattainment area.
Following state and tribal designation submissions, the EPA Administrator has
discretion to make modifications, including to the area boundaries. As required by
statute (Section 107[d]1[B][ii]), the agency must notify the states and tribes regarding
any modifications, allowing them sufficient opportunity to demonstrate why a
proposed modification is inappropriate, but the final determination rests with EPA.
1997 PM NAAQS Geographical Area Designations:
2.5
A Chronology
By the end of February 2004, 18 states and the District of Columbia had
recommended 142 counties as potential nonattainment areas for the 1997 PM2.5
NAAQS.40 After reviewing the recommendations, the EPA recommended
38 Moderate areas require permits for new and modified major stationary sources of PM10
and must impose reasonably available control measures (RACM). Serious areas must
impose best available control measures (BACM) and reduce the defined major source of
PM from 100 tons per year to 70 tons per year. The deadline for attainment for moderate
10
areas is six years after designation; for serious areas, the deadline is 10 years after
designation. (Section 188 of Part D subpart 4 of Title I in the CAA; 42 U.S.C. Sec. 7513.)
39 Defined by the Office of Management Budget. For more information on metropolitan
areas, see [http://www.census.gov/population/www/estimates/aboutmetro.html].
40 For the EPA’s final and proposed PM geographical designation recommendations and
2.5
those from individual states and tribes, see [http://www.epa.gov/pmdesignations].

CRS-9
modifications resulting in nonattainment designations for 244 counties41 in 21 states
and the District of Columbia at the end of June 2004. As required by statute, the
EPA notified each of the affected states regarding their specific modifications,
providing them with the opportunity to submit new information and demonstrate why
a proposed modification was inappropriate. Some states responding to the EPA’s
proposal continued to support their original recommendations.
The EPA’s final PM designation rule, published on January 5, 2005 (70
2.5
Federal Register 944-1019), established the boundaries for areas designated as
“nonattainment,” “unclassifiable” (data not sufficient to make a determination
regarding compliance), or “attainment/unclassifiable.”42 The EPA designated 47
areas, composed of 225 counties in 20 states and the District of Columbia, as
nonattainment; 5 areas consisting of 7 counties as unclassifiable;43 and the remaining
counties in the United States as attainment/unclassifiable.
The EPA’s designations reflected minor modifications to its June 2004 proposal.
Primarily, 19 counties were removed from the list of nonattainment areas, and other
counties were redefined by designating only specified locations (“partial”) within the
county as nonattainment. In some cases, when considering factors defined in its
guidance in conjunction with the additional information provided by the states and
tribes, the EPA determined that only those portions of a county that contained the
significant sources of emissions should be considered as contributing to the
violations. In other cases, the agency determined that if emissions from a large
identifiable source in a county contribute to the violations in a nearby area, the
portion of the county where the source is located would be designated nonattainment,
even if it is not contiguous with the remainder of the designated area. The
boundaries for these “noncontiguous” portions are based on legally recognized
government boundaries, such as townships, tax districts, and census blocks.
Some states and stakeholders continued to contend that several counties should
not be designated nonattainment, particularly when taking into account 2004 PM2.5
monitoring data. The EPA’s final designations were based on monitoring data for
the three-year period from 2001-2003. Monitoring data for 2004 were not available
in time for the EPA to meet its statutory deadline for PM geographical area
2.5
designations (see timeline and discussion later in this report). The final PM2.5
41 Included seven cities: Baltimore, MD; St. Louis, MO; Alexandria, VA; Fairfax, VA; Falls
Church, VA; Manassas, VA; and Manassas Park, VA.
42 The EPA designates an area as attainment/unclassifiable if (1) monitored air quality data
show that the area has not violated the standard during a three-year period or(2) there is not
enough information to determine the air quality in the area. Despite the CAA, Section
107(d)(1)(A) definitions for “nonattainment,” “attainment,” and “unclassifiable,” the EPA
does not apply the “attainment” nomenclature. It is generally the case that the agency has
sufficient data to determine that an area is not in nonattainment, but the data are insufficient
or incomplete to fully determine attainment.
43 The EPA concluded that there was insufficient information to designate these areas as
either nonattainment or attainment/unclassifiable. According to the January 2005 Federal
Register Notice (70 Federal Register 65984), these areas had violating monitors for years
2000-2002 but incomplete data or other data issues for years 2001-2003.

CRS-10
designation rule, published on January 5, 2005, included provisions allowing states
to submit no later than February 22, 2005, certified, quality-assured 2004 monitoring
data that suggest a change in designation is appropriate for consideration (70 Federal
Register
948). A nonattainment designation could be withdrawn if the EPA agreed
that the additional data warranted such a change.
On April 14, 2005, the EPA published a final supplemental rule amending the
agency’s initial final designations published in January 2005 (70 Federal Register
19844). After reviewing 2002-2004 air quality monitoring data provided by several
states, the EPA determined that 8 areas comprising 17 counties previously identified
as not meeting the 1997 PM NAAQS should be designated as “in attainment” (see
2.5
Table 1 below). The EPA also changed four of the five areas designated as
“unclassifiable” to “attainment,” based on 2002-2004 data. The EPA did not
consider the modifications for these areas “re-designations” because the changes
were made prior to the April 5, 2005, effective date of the initial designations.
Table 1. Areas Previously Identified as Nonattainment for 1997
PM NAAQS Designated as Attaining the Standards
2.5
State
Area Name
County
Alabama
Columbus, GA-AL
Russell
California
San Diego, CA
San Diego
Georgia
Athens, GA
Clarke
Columbus, GA-AL
Muscogee
Indiana
Elkhart, IN
Elkhart
St. Joseph
Kentucky
Lexington, KY
Fayette
Mercer (partial)
Ohio
Toledo, OH
Lucas
Wood
Youngstown-Warren, OH-PA
Columbiana
Mahoning
Trumbull
Pennsylvania
Youngstown-Warren, OH-PA
Mercer
West Virginia
Marion, WV
Marion
Monongalia (partial)
Harrison (partial)
Source: U.S. Environmental Protection Agency, April 5, 2005, at [http://www.epa.gov/
pmdesignations/documents/Apr05/changes.htm].
As a result of the changes, nonattainment designations are in effect for the
remaining 39 areas, comprising 208 counties within 20 states (and the District of
Columbia) nationwide, with a combined population of almost 90 million. The
designated nonattainment areas are primarily concentrated in the central, mid-
Atlantic, and southeastern states east of the Mississippi River, as well as in
California.44 The EPA map in Figure 1 highlights the PM nonattainment
2.5
44 California has established its own PM standards; for more information, see CRS Report
2.5
RL31531, Particulate Matter Air Quality Standards: Background and Current
(continued...)


CRS-11
designation areas. More than 2,900 counties in 30 states have been designated
attainment/unclassifiable for the 1997 PM NAAQS. Some public interest groups
2.5
maintain that at least 150 additional counties warranted nonattainment designations
on the basis of emission sources in those areas.45 Any area initially designated
attainment/unclassifiable may be subsequently re-designated to nonattainment if
ambient air quality data in future years indicate that such a re-designation is
appropriate.
Figure 1. U.S. Environmental Protection Agency Designations of
Nonattainment Areas for the 1997 PM
2.5
National Ambient Air Quality Standards (NAAQS)
Source: U.S. Environmental Protection Agency, April 5, 2005, at [http://www.epa.gov/
pmdesignations/nonattaingreen.htm]. Based primarily on 2001-2003 monitoring data, and 2002-2004
data for a subset of states.
In letters dated January 20, 2006, the EPA denied six petitions submitted to the
agency requesting reconsideration of the previous designations of one or more full
44 (...continued)
Developments, by Robert Esworthy, or access the California Air Resources Board website
at [http://www.arb.ca.gov/pm/pmmeasures/pmmeasures.htm].
45 American Lung Association, December 17, 2004, press release, “No One Should Have to
Breathe Unsafe Air,” available at [http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E
&b=34841].

CRS-12
or partial counties as nonattainment for the 1997 PM NAAQS. The petitions were
2.5
for counties in Georgia, Illinois, Michigan, Missouri, Ohio, and West Virginia.46
Demonstrating Attainment with the 1997 PM NAAQS
2.5
The State Implementation Plan. Following the designation of an area as
nonattainment, the state where the area is located must develop a State
Implementation Plan (SIP) that demonstrates how attainment with the PM2.5
standards will be achieved. Under Section 110 of the CAA, states must submit their
SIPs to the EPA within three years of designation; PM SIPs are due April 5, 2008.
2.5
To be approved, a SIP must demonstrate that the area will reach attainment of the
standards by a specified deadline — 2010 for PM unless a five-year extension
2.5
allowed under the CAA is granted. SIPs include pollution control measures that will
be implemented by federal, state, and local governments, and rely on models of the
impact on air quality of projected emission reductions to demonstrate attainment.
EPA’s PM Implementation Rule. On April 25, 2007, the EPA published
2.5
its final rule47 that describes the requirements that states and tribes must meet in their
implementation plans to achieve and maintain attainment of the 1997 PM2.5
NAAQS.48 In addition to detailing provisions necessary to demonstrate how the
PM NAAQS will be attained, the implementation rule includes guidance for
2.5
submitting a SIP demonstrating that reaching attainment within the five-year
requirement is impractical. A number of provisions that were of concern to an array
of stakeholders and generated comments during the proposal have been retained in
the final rule,49 and continue to be the topic of continued debate. As noted earlier,
petitions for legal review of EPA’s implementation rule have been filed with the
U.S. Court of Appeals for the D.C. Circuit, and one petition for reconsideration has
been filed with EPA.50
Transportation Conformity. If new or revised SIPs for PM attainment
2.5
establish or revise a transportation-related emissions allowance (“budget”), or add or
delete transportation control measures (TCMs), they will trigger “conformity”
determinations. Transportation conformity is required by the CAA, Section 176(c)
46 See [http://www.epa.gov/pmdesignations/regs.htm#7] for additional information.
47 72 Federal Register 20586-20667, April 25, 2007.
48 The rule addresses attainment demonstration and modeling; local emission reduction
measures, including reasonably available control technology (RACT), reasonably available
control measures (RACM), and reasonable further progress (RFP); regional emission
reduction strategies; innovative program guidance; emission inventory requirements;
transportation conformity; and stationary source test methods.
49 Each section of the final April 25, 2007, PM implementation rule (72 Federal Register
2.5
20586-20667) summarizes relevant policies and options discussed in the proposed rule, and
provides responses to the major comments received on each issue. Comments and other
supporting materials are available the docket established for this rule (ID-HQ-OAR-2003-
0062) electronically at [http://www.regulations.gov] or in hard copy at the EPA Docket
Center.
50 Ibid. footnotes 9 and 10.

CRS-13
(42 U.S.C. 7506(c)), to prohibit federal funding and approval for highway and transit
projects unless they are consistent with (“conform to”) the air quality goals
established by a SIP and will not cause new air quality violations, worsen existing
violations, or delay timely attainment of the national ambient air quality standards.
The initial conformity rule was promulgated by the EPA on November 24, 1993,51
and has subsequently been amended several times. The most comprehensive
amendments, clarifying and streamlining the 1993 rule, were published on August
15, 1997.52 EPA published a proposal in the May 2, 2007, Federal Register to amend
the general transportation conformity rule.53 The proposal would provide more time
and flexibility for state transportation agencies as per the amendments to CAA
section 176(c) in the 2005 Safe Accountable, Flexible, Efficient Transportation
Equity Act: A Legacy for Users (SAFETEA-LU) (P.L. 109-59). Additionally, EPA
included other proposals in the May 2, 2007, Notice not related to SAFETEA-LU,
such as a proposal to allow the Department of Transportation (DOT) to make
categorical hot-spot findings for appropriate projects in carbon monoxide areas.
Transportation conformity, under the EPA’s previous rules, applied to ozone,
PM , CO, and NOx, but did not include PM . On July 1, 2004, the EPA published
10
2.5
a final rule54 making transportation conformity regulations applicable explicitly to
PM nonattainment areas and including criteria and procedures for the new PM
2.5
2.5
and eight-hour ozone NAAQS. Conformity determinations must be submitted to the
EPA within one year of the effective date of designating an area as nonattainment.
Since the conformity requirements could apply in PM nonattainment areas prior to
2.5
the availability of SIP emission budgets, the EPA included provisions in the final rule
for interim emissions tests for conformity determinations. However, the final rule
was challenged by several petitioners, and on October 20, 2006, the interim test
provisions were overturned by the U.S. Court of Appeals for the D.C. Circuit.55 The
Court found that “... petitioners correctly argue, the challenged interim rule, which
purports to create a new standard to which transportation plans must conform,
violates the Act’s requirement that transportation plans conform to an approved SIP,
42 U.S.C. § 7506(c).”56 The court determined that there was no allowance under the
Clean Air Act for interim tests and, as previously determined by the Court, that an
EPA regulation may not allow a conformity provision to supersede an approved SIP.
Given the complexities associated with the final conformity rule, the EPA
provided guidance to accompany the rule. The guidance, entitled Companion
Guidance for the July 1, 2004, Final Transportation Conformity Rule: Conformity

51 58 Federal Register 62188, November 24, 1993.
52 62 Federal Register 43780, August 15, 1997.
53 72 Federal Register 24471-24494, May 2, 2007. See also CRS Report RL33119 Safe,
Accountable, Flexible, Efficient Transportation Equity Act — A Legacy for Users
(SAFETEA-LU or SAFETEA): Selected Major Provisions,
by John W. Fischer.
54 69 Federal Register 40004, July 1, 2004.
55 Environmental Defense v. EPA, No. 04-1291 (D.C. Cir. October 20, 2006), at
[http://pacer.cadc.uscourts.gov/docs/common/opinions/200610/04-1291a.pdf].
56 Ibid.

CRS-14
Implementation in Multi-Jurisdictional Nonattainment and Maintenance Areas for
Existing and New Air Quality Standards
,57 expanded on the final conformity rule by
including additional detailed examples and interpretations for generic scenarios that
are present in the field and are expected to occur under the 1997 standards. The EPA
has provided other fact sheets and summary tables, and has conducted training
sessions for implementers to further assist understanding of the rule.58
On May 6, 2005, the EPA published a final rule59 further amending the
transportation conformity regulations by adding transportation-related PM2.5
“precursors” and specifying when these precursors must be considered in conformity
determinations before and after PM SIPs are submitted.60 Precursors are pollutants
2.5
that react chemically in the atmosphere to form other pollutants. The transportation-
related PM precursors identified in the May 2005 rule are nitrogen oxides (NOx),
2.5
volatile organic compounds (VOCs), sulfur oxides (SO ), and ammonia (NH ).
2
3
The EPA established the criteria for determining which transportation projects
must be analyzed for local particle emissions (referred to as “hot spots”) in PM2.5
nonattainment and maintenance areas, and revised existing requirements for projects
in PM areas, in a final rule published on March 10, 2006.61 The CAA defines
10
“hot-spot analysis” as an estimation of likely future localized pollutant concentrations
resulting from a new transportation project and a comparison of those concentrations
to the relevant air quality standard.62 The March 2006 final rule requires quantitative
PM hot-spot analyses only for projects of air quality concern. These projects are
2.5
further defined in the final rule as highway and transit projects that involve
significant levels of diesel vehicle traffic, or any other project that is identified in the
PM SIP as a localized concern.
2.5
In May of 2006, three environmental organizations filed a complaint challenging
the final rule.63 The petitioners alleged that (1) the regulation does not require that
hot-spot analyses satisfy all of the requirements in Section 176(c) of the act for
demonstrating conformity; (2) the regulation allows EPA to issue quantitative PM
modeling guidance without notice-and-comment rulemaking, in violation of the
Administrative Procedure Act; and (3) EPA had previously approved its current
motor vehicle emissions factor model (MOBILE6.2) for use in PM hot-spot analyses
and improperly withdrew that approval in the 2006 hot-spot rule. EPA published a
57 EPA, July 2004, EPA420-B-04-012, Transportation and Regional Programs Division,
Office of Transportation and Air Quality, available at [http://www.epa.gov/
otaq/stateresources/transconf/policy.htm].
58 For EPA fact sheets, Q&As, and training material regarding conformity, see
[http://www.epa.gov/otaq/stateresources/transconf/index.htm].
59 70 Federal Register 24280, May 6, 2005.
60 See EPA’s website at [http://www.epa.gov/otaq/stateresources/index.htm].
61 71 Federal Register 12468, March 10, 2006.
62 40 CFR 93.101.
63 Natural Resources Defense Council (NRDC), Environmental Defense, and Sierra Club;
Environmental Defense et al. v. EPA
, No. 06-1164 (D.C. Cir.)

CRS-15
proposed settlement agreement addressing the second claim in the June 22, 2007,
Federal Register.64 According to the Notice, EPA and the Petitioners’ negotiated
settlement agreement would require EPA to provide public notice and an opportunity
for public comment on its draft guidance for quantitative hot-spot modeling for PM2.5
and PM . EPA filed a brief in May 2007 in the U.S. Court of Appeals for the D.C.
10
Circuit responding to Petitioners’ allegations on the remaining two issues. At the
time of this CRS report update, the litigation is still pending, and the court has not
yet set a date for oral argument.
Other National Air Quality Improvement Programs and Strategies.
A December 2004 EPA report entitled The Particle Pollution Report: Current
Understanding of Air Quality and Emissions through 2003
, reported that the 2003
monitored national average concentrations of PM decreased 10% and PM
2.5
10
concentrations decreased 7% since 1999, primarily in areas with the highest
concentrations.65 A report released by the American Lung Association (ALA) in
April 2007 indicated higher average concentration levels of year-round PM in
2.5
highly populated areas of the eastern United States during 2003-2005, compared with
2002-2004. The report noted that outside of the eastern United States, particle levels
continued to drop during the same time period, even in areas that the ALA has
historically ranked as high in particle pollution.66 According to EPA, recent estimates
indicate that the 2006 monitored national average concentrations of annual PM2.5
decreased 14% between 2000 and 2006, and the national average PM concentration
10
decreased 30% between 1990 and 2006.67
EPA reports that the areas showing the greatest improvement were the ones that
had the highest concentrations in the earlier years. Decreases in concentrations in
southern California were largely due to decreases in NOx, lowering the amount of
measured nitrate particles and making organic carbon more clearly the major
component of PM in southern California in 2006. The Southeast had little change
2.5
in PM , and decreases in PM concentrations in the industrial Midwest and the
2.5
2.5
Northeast were mostly due to reductions in NOx and SO emissions. The EPA
2
attributes a large portion of the SO decreases to the Acid Rain Program. Despite
2
the decreases in concentrations in 2006, more than 66 million people lived in
counties that exceeded the annual PM national air quality standard.
2.5

64 72 Federal Register 34460
65 U.S. Environmental Protection Agency, EPA 454-R-04-002, December 2004. Revised
report posted on EPA’s website at [http://www.epa.gov/airtrends/pm.html].
66 Estimates are based on air quality data obtained from the U.S. Environmental Protection
Agency’s Air Quality System (AQS), formerly called Aerometric Information Retrieval
System (AIRS). American Lung Association, State of the Air: 2007, released April 2007,
[http://lungaction.org/reports/stateoftheair2007.html].
67 CRS September 12, 2007, personnel communication with EPA’s Office of Air Quality
Planning and Standards. The data are to be included an upcoming agency report entitled
Latest Findings on National Air Quality: 2006 Status and Trends. The report is scheduled
to be released the end of September 2007. Preliminary estimates from the pending report are
presented on EPA’s website at [http://www.epa.gov/airtrends/econ-emissions.html].

CRS-16
The EPA has concluded that in many cases, PM attainment will be reached by
2.5
implementing national strategies developed under the 1999 visibility protection
regulations (Regional Haze Rule);68 voluntary diesel engine retrofit programs; and
federal standards, scheduled to be implemented between 2004 and 2010, on cars,
light trucks, heavy-duty, and nonroad diesel engines. In M a y 2 0 0 5 , t h e E P A
published a final rule, the Rule to Reduce Interstate Transport of Fine Particulate
Matter and Ozone, or Clean Air Interstate Rule (CAIR), to address the interstate
transport of pollutants (SO and NOx) that are hindering downwind states from
2
attaining the eight-hour ozone and 1997 PM NAAQS.69 The final rule covers 28
2.5
states in the eastern United States and the District of Columbia, including 26
jurisdictions in the PM region, and uses a cap-and-trade approach to reduce target
2.5
pollutants by up to 70%.
Based on air quality analyses in support of the CAIR, the EPA predicted that 17
of 36 areas in the eastern United States designated as nonattainment (out of
compliance) with the 1997 PM NAAQS would reach attainment (come into
2.5
compliance) by 2010 as a result of implementing CAIR in conjunction with other
existing national programs.70 On the other hand, the EPA analyses recognized that
as many as 19 of the areas would remain in nonattainment, highlighting the
importance of local and state emission reduction efforts. The extent of pollution
reduction projected as a result of this rule has been the subject of considerable debate
among stakeholders and some Members of Congress.71
Continuing Issues
Defining Nonattainment Boundaries. The EPA has generally used its
discretion to expand the size of nonattainment areas or to combine areas that a state
listed as separate areas into a single larger unit. As it did in implementing other
NAAQS, the EPA also has combined nonattainment counties across state lines into
the same nonattainment area, if the counties are part of the same metropolitan area.
Although, according to EPA, staff in the regions and the agency’s Office of Air
Quality Planning and Standards were available for assistance and consultation
throughout the designation process pursuant to the statutory requirements for
working with states, some states continue to disagree with the EPA’s final
designations relative to the states’ own recommendations.
Upwind Pollutant Contributions. One of the more frequently raised issues
in nonattainment areas is whether any special consideration can be given to areas
whose air quality is adversely affected by pollution from upwind areas. Unlike the
68 64 Federal Register 35714-35774, July 1, 1999. See CRS Report RL32483 Visibility,
Regional Haze, and the Clean Air Act: Status of Implementation
, by Larry Parker.
69 70 Federal Register 25162, May 12, 2005.
70 See page 66006 of 70 Federal Register 65984, November 1, 2005, Proposed Rule To
Implement the Fine Particle National Ambient Air Quality Standards
.
71 For more information on the CAIR, see CRS Report RL32927, Clean Air Interstate Rule:
Review and Analysis
, by Larry B. Parker, and CRS Report RL32273, Air Quality: EPA’s
Proposed Interstate Air Quality Rule
, by Larry Parker and John Blodgett.

CRS-17
larger coarse particles, which generally settle more rapidly and fall near their source
of emission, the smaller PM particles frequently remain in the atmosphere longer
2.5
and can travel significant distances from their original source. The transport of PM2.5
can contribute to, and in some cases can be, the primary cause of nonattainment in
areas downwind of the emission source.
Subpart 1 of the CAA allows the EPA to “classify the area for the purpose of
applying an attainment date” and to consider such factors as “the availability and
feasibility of pollution control measures,” and may provide the agency flexibility.
As referenced in the proposed PM implementation rule, areas also may petition the
2.5
agency under Section 126 of the CAA to impose controls on upwind sources that
significantly contribute to their nonattainment of the standard.72 The agency has
imposed additional controls on sources of nitrogen oxides (which contribute to
particulate and ozone formation downwind) through its “NOx SIP Call” and the
“Regional Haze Rule.”73 In addition, the CAIR, promulgated in May 2005, is
intended to address interstate transport of pollutants that hinder attainment of PM2.5
and eight-hour ozone NAAQS in downwind states.
Economic Impacts. Another concern, particularly of local businesses and
governments in areas with nonattainment designations, is the potential negative
impacts on an area’s economic development. Nonattainment designation does
require new major sources of pollution to offset pollution by equivalent or greater
emission reductions from existing sources, and requires highway and transit planners
to demonstrate that new projects “conform” to the area’s SIP. Although the EPA has
not analyzed the potential economic impact of designating areas as nonattainment for
particulate matter, a 2002 EPA analysis74 found that ozone nonattainment
designations had no net negative impact on those areas. Specifically, 6.5 million jobs
were created in ozone nonattainment areas from 1990 to 1998, and “over 55 percent
of ozone nonattainment areas had average annual employment growth rates greater
than that of their region of the country.” Personal income growth in these
nonattainment areas essentially matched the national average between 1990 and 1998
(38.5% versus 38.9%), according to the EPA.
In contrast to the EPA findings, a study conducted by NERA Economic
Consulting for the American Petroleum Institute (API), found that meeting the 2010
ozone attainment deadline will lead to a $3 billion reduction in economic output in
72 A number of such petitions regarding NAAQS other than PM have been filed with the
2.5
agency. The most well-known are those that were filed in August 1997 by eight
northeastern states, four of which were granted by the agency in January 2000. See CRS
Report 98-236, Air Quality: EPA’s Ozone Transport Rule, OTAG, and Section 126 Petitions
— A Hazy Situation?
by Larry Parker and John Blodgett (available from the authors).
73 The Regional Haze Rule establishes Best Available Retrofit Technology (BART) at
stationary sources in 26 industrial categories; available at [http://www.epa.gov/
visibility/actions.html].
74 U.S. EPA, Office of Air and Radiation, “The Historical Record: Nonattainment Status and
Economic Growth
,” February 26, 2002.

CRS-18
the Philadelphia region in 2011.75 According to the summary of the report, “[t]he
economic impacts would include the cost of local controls of $3.9 billion per year,
the loss of thousands of regional jobs, a reduction of billions of dollars in gross
regional product, and a significant loss of disposable personal income in the area.”
The summary indicates that delaying the eight-hour ozone NAAQS attainment
deadline to 2015 would lower the cost to the local economy to $100 million per year
and lead to 1,000 fewer jobs. Some critics have questioned the analysis supporting
these findings.76
Grant Programs. Although the EPA does not have a grant program
specifically designed to assist nonattainment areas, the agency generally provides
several grants to state air pollution agencies in support of their programs. Other
sources of funding are also available. For example, states may obtain funding for
projects intended to contribute to attainment or maintenance of NAAQS under the
Department of Transportation’s (DOT’s) Congestion Mitigation and Air Quality
Improvement Program (CMAQ). Congress authorized $8.6 billion for the program
for FY2005-FY2009 under the Safe, Accountable, Flexible and Efficient
Transportation Equity Act: A Legacy for Users (SAFETEA-LU) (P.L. 109-59),
signed into law on August 10, 2005.
Authorized initially by Congress under the Intermodal Surface Transportation
Efficiency Act of 1991 (ISTEA, P.L. 102-240) and funded by the Highway Trust
Fund, CMAQ provides funding for surface transportation and other related projects
that contribute to air quality improvements and congestion mitigation. In particular,
the program is authorized to fund projects that contribute to the reduction of carbon
monoxide (CO) and ozone concentrations. CMAQ funds are apportioned to a state
based on its population and pollution reduction needs. The population of each
nonattainment or maintenance area for ozone and/or CO in a state is multiplied by
a weighting factor based on the level of nonattainment (e.g., moderate, serious,
severe). States with no maintenance or nonattainment areas for ozone or CO are
guaranteed a minimum of 0.5% of each fiscal year’s authorized CMAQ funds.
CMAQ was expanded to allow the use of funds for projects intended to reduce
particulates concentrations under the Transportation Equity Act for the 21st Century
(TEA-21, P.L. 105-178). TEA-21 did not, however, change the apportionment
formula that is based on CO and ozone. States with maintenance or nonattainment
areas for only particulates receive the guaranteed minimum.77
75 Economic Impact of 8-Hour Ozone Attainment Deadlines on Philadelphia Region,
September 2005 (released November 7, 2005); conducted by NERA Economic Consulting
for the American Petroleum Institute.
76 Testimony of James Werner, Director, Division of Air and Waste Management, Delaware
Department of Natural Resources and Environmental Control, before the U.S. Senate
Committee on Environment and Public Works, Subcommittee on Clean Air, Climate
Change, and Nuclear Safety, Implementation of the Existing Particulate Matter and Ozone
Air Quality Standards
, November 10, 2005.
77 For a more detailed discussion of CMAQ and relevant legislation, see CRS Report
RL33119, Safe, Accountable, Flexible, Efficient Transportation Equity Act — A Legacy for
(continued...)

CRS-19
Identifying Sources and Control Measures. Determining sources
contributing to emission of fine particles to identify the appropriate actions for
compliance with the PM standards is expected to be complicated. The EPA has
2.5
been conducting several technical studies in an effort to develop extensive guidance
to help states identify appropriate control measures in their SIPs for specific
parameters and conditions. The proposed PM implementation rule provides
2.5
information related to this concern as well.
Completion of the EPA’s Most Recent Review of the Particulates
NAAQS and the September 2006 Changes.78 At the end of 2005, the EPA
completed its statutorily required79 review and assessment of relevant scientific
studies to either reaffirm or modify the particulates NAAQS. Based on the review,
on October 17, 2006, the EPA promulgated revisions to the particulates NAAQS.80
Given the simultaneity of these new 2006 particulates NAAQS and the ongoing
implementation of the 1997 PM
standards, outcomes and challenges associated
2.5
with the review and the EPA’s changes to the existing (1987 and 1997) NAAQS for
PM and PM could affect the current implementation schedule.
10
2.5
Based on its review and analysis of scientific studies available between 1997
and 2002,81 and on determinations made by the Administrator, the EPA’s
modifications to the particulates NAAQS tighten the current NAAQS primarily by
lowering the daily (24-hour) standard for PM . The new 2006 particulates NAAQS
2.5
lower the daily PM standard from 65 micrograms per cubic meter (µg/m3) to 35
2.5
µg/m3 and retain the annual standard at 15 µg/m3. The EPA left the existing (1987)
daily standard for coarse particles (PM ) in place at 150 µg/m3 and relaxed the
10
standard somewhat by revoking the existing annual maximum concentration standard
of 50 µg/m3.
Critics continue to argue that data do not support the stricter PM standards or,
2.5
in some cases, even the 1997 standards. On the other hand, several public interest
groups and scientists, including the Clean Air Scientific Advisory Committee
(CASAC),82 have advocated tightening the standards further than proposed. The
77 (...continued)
Users (SAFETEA-LU or SAFETEA): Selected Major Provisions, by John W. Fischer.
78 For more information regarding of EPA’s changes to the particulates NAAQS, see CRS
Report RL33254, Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM)
Standard
, by Robert Esworthy and James E. McCarthy. Information can also be accessed
on EPA’s website at [http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html].
79 Section 109(d)(1)) of the CAA.
80 71 Federal Register 61143-61233, October 17, 2006.
81 EPA, Air Quality Criteria for Particulate Matter, October 29, 2004. EPA, Review of the
National Ambient Air Quality Standards for Particulate Matter: Policy Assessment of
Scientific and Technical Information, OAQPS Staff Paper
, Office of Air Quality Planning
and Standards, EPA-452/R-05-005, July 2005. The EPA criteria document and staff paper
can are available at [http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_cr_sp.html].
82 The CASAC, mandated under Section 109(d)(2) of the CAA, reviews EPA’s NAAQS
(continued...)

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Administrator’s decisions regarding the particulates NAAQS represent the first time
in CASAC’s nearly 30-year history that the promulgated standards fall outside of the
range of the scientific panel’s recommendations.83 In a letter dated September 29,
2006, the seven members of CASAC objected to the Administrator’s actions, both
as regards PM and PM : “It is the CASAC’s consensus scientific opinion that the
10
2.5
decision to retain without change the annual PM standard does not provide an
2.5
‘adequate margin of safety ... requisite to protect the public health’ (as required by
the Clean Air Act)....”84
Tightening the PM NAAQS is expected to result in more areas classified as
2.5
“nonattainment” and needing to implement new controls on particulate matter. States
and local governments would be required to develop and implement new plans for
addressing emissions in those areas that do not meet any new standards. In a
February 2006 advanced notice of proposed rulemaking (ANPR)85 outlining an
implementation plan for the transition to the January 17, 2006, proposed particulates
standards, the EPA indicated that it would be beneficial for states to consider control
strategies that may be useful in attaining the new 2006 PM NAAQS when
2.5
developing their strategies for the 1997 PM standards.
2.5
A stricter standard may mean more costs for the transportation and industrial
sectors, including utilities, refineries, and the trucking industry, affected by
particulate matter controls. In terms of public health, a stricter standard may mean
fewer health effects for the general population and particularly sensitive populations,
such as children, asthmatics, and the elderly.
The EPA released a regulatory impact analysis (RIA) on October 6, 2006,86 to
meet its obligations under Executive Order 12866 87 and in compliance with guidance
from the White House Office of Management and Budget. The RIA analyzed only
the benefits and costs of implementing the new PM NAAQS. Based on several
2.5
analytical approaches, the EPA estimated that compliance with the new NAAQS
could prevent 1,200 to 13,000 premature deaths annually, as well as substantial
numbers of hospital admissions and missed work or school days due to illness.
82 (...continued)
criteria documents and staff papers as they are prepared, recommends improvements, and,
after further meetings and reviews, signs off only when it is convinced that each accurately
reflects the status of the science ([http://www.epa.gov/sab/panels/casacpmpanel.html]).
83 See CRS Report RL33807, Air Quality Standards and Sound Science: What Role for
CASAC?
, by James E. McCarthy.
84 Letter of Rogene Henderson, Chair of the Clean Air Scientific Advisory Committee, et
al. to Hon. Stephen L. Johnson, EPA Administrator, September 29, 2006, available at
[http://www.epa.gov/sab/pdf/casac-ltr-06-003.pdf].
85 71 Federal Register 6718, February 9, 2006.
86 EPA’s Regulatory Impact Analysis (RIA) of the 2006 National Ambient Air Quality
Standards for Fine Particle Pollution (PM ), available on EPA’s website at
2.5
[http://www.epa.gov/ttn/ecas/ria.html].
87 58 Federal Register 51735, October 4, 1993. See the White House OMB website,
Regulatory Matters, at [http://www.whitehouse.gov/omb/inforeg/regpol.html#rr].

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According to the October 6, 2006, RIA, the estimated total annual health and welfare
net benefits (subtracting social costs from the monetized benefits) in 2020 of
attaining the new PM NAAQS range from $9 billion to $12 billion, based on
2.5
modeling of morbidity and mortality using published epidemiology studies, and from
$2.4 billion to $70 billion, based on derivation from expert elicitation.
Designation of geographical areas and the associated impacts on specific areas
would be speculative at best, because implementation of the new 2006 particulates
NAAQS is several years off. States will not be required to submit SIPs until 2013
and would not have to meet the new PM standard until April 2015 (April 2020, if
2.5
qualified for an extension88). For the 1997 PM NAAQS, states are required to
2.5
submit implementation plans for how they will meet the standard by April 2008 and
must be in compliance by 2010, unless they are granted a five-year extension.89
In late December 2006, 13 states, as well as several industry, agriculture,
business, and public advocacy groups, separately petitioned the court to review new
2006 particulates NAAQS.90 These challenges could affect the current
implementation schedule for the 1997 PM NAAQS. The EPA’s previous review
2.5
and 1997 establishment of particulates (and ozone) standards was the subject of
litigation and challenges, including a Supreme Court decision in 2001.91 (See
discussion below in “Implementation of the 1997 PM NAAQS: Timeline and
2.5
Delays.”) The final form of the new 2006 particulates NAAQS, and therefore the
associated potential impacts of implementation of the 1997 PM standards, may not
2.5
be known for some time.
Impacts of Actions Regarding the 1997 Ozone NAAQS. The final
1997 particulates NAAQS were signed by the EPA Administrator at the same time
as new NAAQS for ground-level ozone. The two NAAQS were jointly published on
July 18, 1997.92 Generally referred to as the “eight-hour ozone standard,” the new
standard for ground-level ozone requires a more stringent concentration limit (0.08
88 Under section 172(a)(2)(A) of the CAA, the EPA may grant an area an extension of the
initial attainment date for one to five years (in no case later than 10 years after the
designation date for the area). A state requesting an extension must submit an
implementation plan (SIP) by the required deadline that includes, among other things,
sufficient information demonstrating that attainment by the initial attainment date is
“impracticable.”
89 Ibid.
90 The Court has consolidated the cases (American Farm Bureau Federation v. U.S. EPA,
No. 06-1410 (D.C. Cir. 2006)) and ordered submission of briefs from petitioners, EPA, and
supporters for October 2007 through February 2008, with final briefs due by March 2008.
Parties will be notified of the schedule for oral arguments by a separate order.
91 American Trucking Ass’ns v. EPA, 175 F.3d 1027, 1055-56 (D.C. Cir. 1999), rehearing
granted in part and denied in part, 195 F.3d 4 (D.C. Cir. 1999), affirmed in part and reversed
in part, Whitman v. American Trucking Ass’ns, 531 U.S. 457 (2001). In March 2002, the
Court of Appeals rejected all remaining challenges to the standards, American Trucking
Ass’ns v. EPA
, 283 F. 3d 355, 369-72 (D.C. Cir. 2002).
92 62 Federal Register 38652-38760, and 38855-38896, July 18, 1997.

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parts per million versus the previous 0.12), but it averages the ozone concentrations
measured over eight hours rather than the previous one hour.
On April 15, 2004, the EPA designated areas in 32 states and the District of
Columbia (474 counties in all) as nonattainment for the new ozone air quality
standard.93 The EPA ozone designations, and the implementation rule94 that
accompanied the designations, have been challenged for being too lenient by several
states and various public interest groups, and too restrictive by industry groups. On
December 22, 2006, the U.S. Court of Appeals for the D.C. Circuit agreed that the
implementation rule was too lenient, vacated it, and remanded the matter to EPA.95
A number of general issues, such as cost and interpretation of boundaries, are
expected to be similar for the eight-hour ozone and PM rules, but the EPA deems
2.5
the CAA requirements regarding PM to be less complicated, relative to ozone
2.5
requirements. The PM implementation rule is new rather than a transformation of
2.5
an existing one, as in the case of eight-hour ozone. In addition, fewer areas have
been designated as nonattainment for PM than were designated under the eight-
2.5
hour ozone NAAQS. Nevertheless, implementation of the eight-hour ozone NAAQS
and associated challenges or other delays, as well as EPA’s June 20, 2007, proposed
changes to the NAAQS for ozone,96 will likely affect the implementation of the 1997
PM NAAQS.
2.5
Congressional Action Related to Particulates
NAAQS Implementation

Concerns regarding the potential impacts of the new ozone and particulate
standards have led to several attempts over the years to modify the implementation
requirements.97 Attempts during the 109th Congress were generally attached to larger
pieces of legislation, such as the energy98 and transportation bills, as well the
proposed multipollutant (Clear Skies) bills to reduce emissions from coal-fired power
plants.99 Although PM was not one of the primary pollutants100 specified in the
2.5
93 69 Federal Register 23857, April 15, 2004.
94 69 Federal Register 23951, April 30, 2004. See 8-hour Ground-Level Ozone
Designations: Regulatory Actions, an EPA website, at [http://www.epa.gov/
ozonedesignations/regs.htm].
95 South Coast Air Quality Management v. EPA, No. 04-1200 (D.C. Cir. December 22,
2006).
96 72 Federal Register 37818 — 37919, and 37682 — 37683, July 11, 2007. See CRS
Report RL34057 Ozone Air Quality Standards: EPA’s 2007 Proposed Changes, by James
E. McCarthy.
97 For a historical perspective, see CRS Issue Brief IB10107, Clean Air Act Issues in the
108th Congress
(available from the author), and CRS Report RL33552, Clean Air Act Issues
in the 109th Congress
, by James E. McCarthy.
98 See CRS Report RL32873, Key Environmental Issues in the Energy Policy Act of 2005
(P.L. 109-58, H.R. 6)
, by Brent D. Yacobucci.
99 See CRS Report RL32782, Clear Skies and the Clean Air Act: What’s the Difference? by
(continued...)

CRS-23
multipollutant legislation considered during the 109th Congress, certain provisions
of some of the bills could have potentially contributed to reducing PM2.5
concentrations. During the first session of the 110th Congress, three multipollutant
bills have been introduced. The proposed bills, S. 1168, S. 1177, and S. 1201, would
establish a regulatory program to reduce the quantities of sulfur dioxide (SO ),
2
nitrogen oxides (NOx), mercury (Hg) emissions, and carbon dioxide (CO ) emissions
2
from the electric generating sector.
Implementation of the 1997 PM NAAQS:
2.5
Timeline and Delays
Because of legal challenges, the lack of a national monitoring network, and
other factors, implementation of the 1997 PM NAAQS has been delayed since it
2.5
was promulgated. The timeline presented in Table 2, driven primarily by statutory
requirements, reflects the most recent key milestone dates for implementing the 1997
PM NAAQS, including actual completions. It follows an EPA milestone schedule
2.5
outlined in an April 21, 2003, memorandum to EPA regional administrators that also
provided the nonbinding guidance for implementation of the PM area
2.5
designations.101 Recognizing potential efficiencies associated with states and tribes
being able to harmonize future control strategies, the initial PM schedule was
2.5
intended to be similar to the eight-hour ozone program.
99 (...continued)
Larry Parker and James E. McCarthy, and CRS Report RL32755, Air Quality:
Multi-Pollutant Legislation in the 109th Congress
, by Larry Parker and John Blodgett.
100 Bills introduced in previous Congresses generally focused on regulating three or four
pollutants; three-pollutant bills addressed sulfur dioxide (SO ), nitrogen oxides (NOx), and
2
mercury (Hg) emissions, and the four-pollutant bills added carbon dioxide (CO )
2
101 EPA memorandum, April 21, 2003, from the Office of Air and Radiation Assistant
Administrator Jeffrey R. Holmstead to EPA Regional Administrators, available at
[http://www.epa.gov/ttn/naaqs/pm/pm25_guide.html].

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Table 2. Estimated Schedule for Implementation of the 1997
PM NAAQS
2.5
Date
1997 PM NAAQS Milestones
2.5
February 2004 (completed)
State-tribal area designation recommendations
(based on 2000-2002 monitoring data)
June-July 2004 (completed)
EPA notifies states and tribes regarding
modifications to their recommendations
January 5, 2005 (completed)
EPA promulgates final area designations
(published in 70 Federal Register
(required one year after states and tribes make
944)
recommendations)
February 2005 (completed November
EPA proposes PM implementation rule
2.5
1, 2005) (published in 70 Federal
Register
65984)
April 5, 2006 (one year after the final
States with new transportation projects submit
designation April 5, 2005 effective
conformity determination within one year of the
date)
effective date of nonattainment designation
Mid-2007 (completed April 25, 2007)
EPA promulgates final PM implementation rule
2.5
April 2008 (3 years after final area
States and tribes submit revised implementation
designations effective date)
plans (SIPs) to achieve PM compliance in
2.5
nonattainment areas
April 2010-2015 (5-10 years after
NAAQS statutory compliance deadline for
final area designations effective date)
attainment
Source: Prepared by the Congressional Research Service based on U.S. Environmental Protection
Agency fact sheets and guidance documents, and relevant Federal Register notices.
The PM NAAQS requirement for three years of monitoring data to determine
2.5
whether areas were meeting the established limits was one factor responsible for
delaying implementation. Comprehensive monitoring data sufficient to make this
determination and the attainment designations were not available in 1997.
Recognizing this dilemma, in the 1998 Transportation Equity Act for the 21st Century
(TEA-21; P.L. 105-178, Title VI), Congress revised the statutory deadline
requirements for the new NAAQS, predicated on a previously released EPA Interim
Implementation Policy. TEA-21 required states to submit designation
recommendations within one year after receipt of three years of data meeting defined
federal protocols, and required the EPA to promulgate designations within one year
after state recommendations are due, but not later than December 31, 2005.
As discussed earlier, operation of the network of monitors was phased in from
1999 through 2000, making three-year monitoring data available at different points,
depending on area location. Rather than a staggered designation schedule, which
would likely result in hampering cross-coordination of implementation plans, the
EPA proposed a single date for state and tribal recommendations and final EPA
designations. The deadlines of February 15, 2004, for governors to submit their

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PM designation recommendations and December 31, 2004, for EPA to promulgate
2.5
designations for each state, were the result of Congress amending the CAA in the
FY2004 omnibus appropriations (P.L.108-199).
In addition to the delay in establishing a monitoring network, the 1997 NAAQS
standards were challenged in District Court by the American Trucking Associations,
the U.S. Chamber of Commerce, and several other state and business groups. An
initial May 1999 opinion by the District Court partially in favor of the plaintiffs was
reversed by the Supreme Court in February 2001.102
Conclusion
Implementation of the 1997 PM NAAQS is affecting a number of areas,
2.5
including some that were not previously designated “nonattainment” for a NAAQS.
Nonattainment designations are in effect for 39 areas, comprising 208 counties within
20 states (and the District of Columbia) nationwide, with a combined population of
almost 90 million. A number of concerns have been raised regarding the potential
impacts, and numerous questions have been triggered regarding the specifics of the
implementation process for the 1997 standards.
According to EPA projections, federal measures, such as recent auto and truck
emission standards and controls on power plants and regional regulations, will be
sufficient to demonstrate attainment in a large portion of monitored nonattainment
counties by 2015, prior to the development and implementation of local measures.
Some Members of Congress and others questioned the EPA’s predictions regarding
the relative magnitude of the emission reductions associated with existing and
proposed air quality controls. Considerable debate also continues regarding the
potential economic consequences associated with nonattainment.
The final form of PM implementation and its effects may not be known for
2.5
some time. Some states and other stakeholders continue to disagree with the EPA’s
PM nonattainment area designations and to suggest that fewer counties should have
2.5
been designated. Other stakeholder groups contend that the EPA should have
included additional counties. The agency’s final PM implementation rule,
2.5
published April 25, 2007, has been formally challenged (like many EPA rules). The
EPA’s first attempt at an implementation plan was among the issues remanded by the
Supreme Court in the 2001 decision that addressed a number of issues related to the
setting of the PM and the eight-hour ozone standard. Delays in publishing the final
2.5
rule and guidance have caused concern among state air pollution control agencies and
some Members of Congress, given that state SIPs are due to EPA by April 2008.
102 United States Court of Appeals for the District of Columbia Circuit, argued December
17, 1998; decided May 14, 1999 (No. 97-1440). American Trucking Associations, Inc., et
al., Petitioners v. United States Environmental Protection Agency
; Whitman v. American
Trucking Associations
, U.S. Supreme Court, No. 99-1257 and No. 99-1426, February 27,
2001 (121 S. Ct. 903). See CRS Report RS20860, The Supreme Court Upholds EPA
Standard Setting Under the Clean Air Act: Whitman v. American Trucking Assn’s
, by Robert
Meltz and James E. McCarthy.

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The EPA’s review and October 2006 revisions of the existing particulates
NAAQS have also been challenged, which could affect implementation of the 1997
PM NAAQS. In addition to the divergence from recommendations of the scientific
2.5
advisory committee (CASAC) mandated under the CAA, several elements of the new
2006 particulates standard have been controversial, including the decision not to
exclude rural sources from the coarse particle standard. Some also questioned the
EPA’s strengthening of the standard for all fine particles, without distinguishing their
source or chemical composition. In late December 2006, several state, industry,
agriculture, business, and public advocacy groups petitioned the court to review new
2006 particulates NAAQS.103 Recommendations to modify the statutory provisions
affecting implementation of the particulates (and the ozone) standards are also likely
to be advocated.
Given that several key implementation milestones are scheduled to be
completed throughout 2007 and 2008, PM will likely remain an area of focus for
2.5
many stakeholders and interest groups, as well as Congress.
103 The Court has consolidated the cases: American Farm Bureau Federation v. U.S. EPA,
No. 06-1410 (D.C. Cir. 2006).