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2013 National Ambient Air Quality Standard
(NAAQS) for Fine Particulate Matter (PM2.5):
Designating Nonattainment Areas
Robert Esworthy
Specialist in Environmental Policy
March 24, 2015
Congressional Research Service
7-5700
www.crs.gov
R43953
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2013 NAAQS for Fine Particulate Matter (PM2.5): Designating Nonattainment Areas
Summary
On January 15, 2015, the Environmental Protection Agency (EPA) published a final rule
designating areas for compliance with the primary annual National Ambient Air Quality Standard
(NAAQS) for fine particulate matter (PM2.5) as revised in the final rule published January 15,
2013. Revising a NAAQS established under the Clean Air Act (CAA) sets in motion a process
under which the states and EPA identify areas that exceed the standard (“nonattainment areas”)
using multi-year air quality monitoring data and other criteria, requiring states to take steps to
reduce pollutant concentrations in order to meet the standard. Promulgation of the 2013 PM
NAAQS was the subject of considerable congressional oversight. EPA’s implementation of the
standard, beginning with the designation of nonattainment areas, will likewise be an issue of
interest and debate among Members of Congress, states, and other stakeholders.
A summary of the PM NAAQS revisions, published January 2013:
• changed the annual health-based (“primary”) standard for “fine” particulate
matter 2.5 micrometers or less in diameter (or PM2.5) to a limit of 12 micrograms
per cubic meter (µg/m3) from the 15 µg/m3 limit promulgated in 1997 and
retained in 2006;
• retained the existing 24-hour primary standard for PM2.5 of 35 µg/m3 (as
promulgated in 2006) and the existing standard for larger, but still inhalable,
“coarse” particles less than 10 micrometers in diameter, or PM10; and
• set “secondary” standards that provide protection against non-visibility “welfare”
(non-health) effects, such as ecological effects (including impacts on plants and
vegetation, soil and nutrient cycling, wildlife, and water) and material
deterioration, which are identical to the primary standards of 12 µg/m3.
EPA’s January 2015 final rule included 14 areas designated as nonattainment for the revised 2013
primary annual PM2.5 standard. These areas include 38 counties or portions of counties in six
states. Many of the counties within the 14 areas were previously designated as nonattainment for
the 2006 and/or the 1997 PM2.5 NAAQS. Three counties are designated nonattainment for PM
NAAQS for the first time. In accordance with a decision by the U.S. Court of Appeals for the
District of Columbia Circuit on January 4, 2013, EPA classified all 14 areas determined to be in
nonattainment as “moderate” nonattainment areas under the authority of Section 188 of the CAA.
In the January 2015 rulemaking, EPA indicated that it was also deferring initial designation for 10
areas in three states by up to one year due to insufficient data. Included are all of Florida, all of
Tennessee except for three counties, and eight areas in Georgia (including two counties in
Alabama and South Carolina). The EPA also designated three areas (including all of Illinois) as
“unclassifiable.” All remaining state areas and areas in Indian country are designated as
“unclassifiable/attainment” for the annual PM2.5 standard. EPA did not establish new area
designations for the 24-hour PM2.5 standard or for the coarse particles PM10, as these standards
were not changed.
States have 18 months from the April 15, 2015, effective date of EPA’s final designations to
submit State Implementation Plans, which identify specific regulations and emission control
requirements intended to bring an area into compliance or maintain compliance. Section 188 of
the CAA requires that moderate nonattainment areas achieve attainment as expeditiously as
practicable but no later than six years after the effective date of final designation.
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2013 NAAQS for Fine Particulate Matter (PM2.5): Designating Nonattainment Areas
Contents
Introduction ...................................................................................................................................... 1
EPA’s 2013 Changes to the PM NAAQS ......................................................................................... 3
Designation of Geographical Nonattainment Areas ........................................................................ 5
NAAQS Designation Process .................................................................................................... 5
Designations for the 2013 PM2.5 Annual NAAQS ........................................................................... 7
EPA January 2015 Final Designations ....................................................................................... 8
State Recommendations and EPA August 2014 EPA Proposed Designations in
Response ............................................................................................................................... 10
Comparing EPA’s Final Nonattainment Designations for the 2013 PM NAAQS with
the 2006 and 1997 PM2.5 NAAQS Final Designations ......................................................... 11
Demonstrating Attainment with the 2013 PM2.5 NAAQS ............................................................. 16
State Implementation Plans (SIPs) .......................................................................................... 17
EPA NAAQS Implementation Rules/Guidance ................................................................ 18
National Regulations ............................................................................................................... 19
New Source Review ................................................................................................................ 21
Transportation Conformity ...................................................................................................... 21
Conclusion ..................................................................................................................................... 22
Figures
Figure 1. EPA’s Final Designations of Geographical Areas as Nonattainment for the 2013
Annual PM2.5 NAAQS .................................................................................................................. 9
Figure 2. Counties in Nonattainment for the 2006 24-Hour (65 μg/m3) Standards and/or
1997 PM2.5 NAAQS Annual (15 μg/m3): U.S. EPA Final Designations .................................... 13
Figure 3. EPA Final Area Designation: Nonattainment Areas for the 2013 PM2.5 NAAQS
Compared to EPA’s Final Designations for 2006 and 1997 PM2.5 NAAQS ............................... 14
Figure D-1. Counties in Nonattainment for the 1997 PM2.5 NAAQS Annual and/or 24-
Hour Standards: U.S. EPA Final Designations ........................................................................... 31
Tables
Table 1. U.S. EPA Final Nonattainment Designations of Counties Cumulative for the
1997 PM2.5 NAAQS, 2006 PM2.5 NAAQS, and the 2013 PM2.5 NAAQS .................................. 15
Table A-1. History of Particulate Matter (PM) and Total Suspended Particles (TSP)
National Ambient Air Quality Standards (NAAQS) ................................................................... 24
Table B-1. Schedule for Implementation of the 1997, 2006, and 2013 PM2.5 NAAQS................. 26
Table C-1. EPA Final, EPA Proposed, and State Recommended Nonattainment Areas for
the 2013 PM2.5 NAAQS and Final Nonattainment Designations for the 2006 PM2.5 and
1997 PM2.5 NAAQS.................................................................................................................... 28
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Appendixes
Appendix A. Chronology of EPA’s National Ambient Air Quality Standards (NAAQS)
Regulations for Total Suspended Particulates (TSP) and Particulate Matter (PM) 1971-
2013 ............................................................................................................................................ 24
Appendix B. Comparative Timeline for Implementing the 1997, 2006, and 2013 PM2.5
NAAQS ...................................................................................................................................... 26
Appendix C. Comparison of EPA Nonattainment Areas for the 2013 PM2.5 Annual
Standard and Previous PM2.5 Standards ...................................................................................... 28
Appendix D. Counties in Nonattainment for the 1997 PM2.5 NAAQS Annual (15 μg/m3)
and/or 24-Hour (65 μg/m3) Standards: U.S. EPA Final Designations ........................................ 31
Contacts
Author Contact Information........................................................................................................... 32
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Introduction
Under Sections 108-109 of the Clean Air Act (CAA), Congress mandated that the Environmental
Protection Agency (EPA) set national ambient (outdoor) air quality standards (or NAAQS) for
pollutants whose emissions (1) “may reasonably be anticipated to endanger public health or
welfare” and (2) “results from numerous or diverse mobile or stationary sources.” The statute
further requires that EPA review the latest scientific studies and either reaffirm or modify
previously established NAAQS every five years. EPA has identified and promulgated NAAQS for
six principal pollutants commonly referred to as “criteria pollutants”:
1. Particulate matter (PM),
2. Ozone (O3—a key measure of smog),
3. Nitrogen dioxide (NO2, or NOx—inclusively, nitrogen oxides)1,
4. Sulfur oxides (SOx or specifically SO2),
5. Carbon monoxide (CO), and
6. Lead (Pb).
On January 15, 2013, EPA published its revisions to the NAAQS for PM2 to provide protection
against potential health effects associated with short- and long-term exposure to particulates
(including chronic respiratory disease and premature mortality).3 Because the agency finalized its
decision on December 14, 2012, EPA frequently refers to these changes as the “2012 PM
NAAQS.”4 In this report, CRS will refer to the changes as the 2013 PM NAAQS based on the
publication date of the final rule.
The 2013 PM NAAQS primarily tightened the pre-existing (2006 and 1997) standards for “fine”
particulate matter 2.5 micrometers or less in diameter (PM2.5) and affected only the stringency of
the annual PM2.5 standard.5 The 24-hour PM2.5 standard as revised in 2006 was not similarly
1 The NAAQS is for NO2; nitrogen gases that are ozone precursors are referred to as nitrogen oxides or NOx.
2 For background of the process used to establish the 2013 particulates NAAQS and analysis of associated issues, see
CRS Report R42934, Air Quality: EPA’s 2013 Changes to the Particulate Matter (PM) Standard, by Robert Esworthy.
3 U.S. Environmental Protection Agency, “National Ambient Air Quality Standards for Particulate Matter; Final Rule,”
78 Federal Register 3085-3287, January 15, 2013, http://www.gpo.gov/fdsys/pkg/FR-2013-01-15/pdf/2012-30946.pdf.
See also EPA’s PM Regulatory Actions website at http://epa.gov/pm/actions.html.
4 The EPA administrator signed the final PM NAAQS rule on December 14, 2012, as per a June 6, 2012, order issued
by the U.S. Court of Appeals for the District of Columbia Circuit in response to petitions filed by advocacy groups and
11 states (American Lung Association v. EPA, D.D.C., No. 1:12-cv-243, order issued June 6, 2012) and as agreed to in
a September 4, 2012, consent decree (American Lung Association v. EPA, D.D.C., No. 1:12-cv-243, order signed
September 4, 2012). See also EPA, “Proposed Consent Decree,” 77 Federal Register 38060, June 26, 2012,
http://www.gpo.gov/fdsys/search/pagedetails.action?granuleId=2012-15603&packageId=FR-2012-06-26&acCode=FR,
and American Lung Association v. EPA, D.D.C., No. 1:12-cv-243, joint motion filed June 5, 2012.
5 For the 2006 PM NAAQS see EPA, “National Ambient Air Quality Standards for Particulate Matter,” 71 Federal
Register 61144-61233, October 17, 2006, http://www.gpo.gov/fdsys/pkg/FR-2006-10-17/pdf/06-8477.pdf; for the 1997
PM NAAQS, see EPA, “National Ambient Air Quality Standards for Particulate Matter,” Federal Register 38652-
38854, July 18, 1997, http://www.gpo.gov/fdsys/pkg/FR-1997-07-18/pdf/97-18577.pdf, and http://www.gpo.gov/fdsys/
pkg/FR-1997-07-18/pdf/97-18578.pdf. See also EPA’s PM Regulatory Actions website at http://epa.gov/pm/
actions.html, and CRS Report RL33254, Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM) Standards,
by Robert Esworthy and James E. McCarthy, Air Quality: EPA’s 2006 Changes to the Particulate Matter (PM)
(continued...)
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strengthened in the 2013 NAAQS revisions. The standards for slightly larger, but still inhalable,
particles less than or equal to 10 micrometers (PM10) established in 19876 were also not changed
to a more stringent level in the 2013 PM NAAQS revisions.7
Establishing NAAQS does not directly limit emissions or directly compel specific emissions
controls; rather, it represents the EPA administrator’s formal judgment regarding the level of
ambient pollution that will protect public health with an adequate margin of safety. Promulgation
of NAAQS sets in motion a process under which the states and EPA first identify geographic
nonattainment areas (i.e., those areas failing to meet the NAAQS) based on monitoring and
analysis of relevant air quality data. States then submit State Implementation Plans (SIPs), which
identify specific regulations and emission control requirements that will bring areas into
compliance as well as actions for maintaining compliance.
EPA published the final designations for the 2013 PM2.5 NAAQS on January 15, 2015.8 The final
designation rule becomes effective April 15, 2015 (90 days from the date of publication). In part
in response to comments received from states, the final designations reflected some changes to
proposed designations identified by the agency in an August 29, 2014, Federal Register notice.9
In the final rule, EPA designated 38 counties or portions of counties (14 areas) in six states as
nonattainment only for the 2013 revised annual PM2.5 standard. EPA announced that it was also
deferring initial designation for 10 areas in three states by up to one year as a result of insufficient
data. Included are all of Florida, all of Tennessee except for three counties, and eight areas in
Georgia (including two counties in Alabama and South Carolina). The EPA also designated three
areas (including all of Illinois) as “unclassifiable” due to insufficiencies in the available ambient
air quality monitoring data for these areas for the three-year period (2011-2013). All remaining
state areas and areas in Indian country are designated as “unclassifiable/attainment” for the
annual PM2.5 standard, indicating that “the areas either have attaining air quality monitoring data
or that air quality information is not available because the areas are not monitored, and the EPA
has not determined that the areas contribute to a violation in a nearby area.”10
As EPA had specified in its April 2013 area designation guidance to states and tribes,11 the initial
area designations for all 2013 PM2.5 NAAQS nonattainment areas are classified as “moderate” as
(...continued)
Standards, by Robert Esworthy and James E. McCarthy and CRS Report RL32431, Particulate Matter (PM2.5):
Implementation of the 1997 National Ambient Air Quality Standards (NAAQS), by Robert Esworthy.
6 Federal Register 24634-24715, July 1, 1987.
7 EPA announced that it has initiated the next round of review of the PM NAAQS by issuing a call for research
information. U.S. Environmental Protection Agency (EPA), “Notice of Workshop and Call for Information on
Integrated Science Assessment for Particulate Matter,” 79 Federal Register 71764, December 3, 2014,
http://www.gpo.gov/fdsys/pkg/FR-2014-12-03/pdf/2014-28278.pdf.
8 U.S. Environmental Protection Agency, “Air Quality Designations for the 2012 Primary Annual Fine Particle (PM2.5)
National Ambient Air Quality Standards (NAAQS),” 80 Federal Register 2206-2284, January 15, 2015,
http://www.gpo.gov/fdsys/pkg/FR-2015-01-15/pdf/2015-00021.pdf.
9 EPA, “EPA Responses to State and Tribal 2012 Primary Annual Fine Particle Designation Recommendations,” 79
Federal Register 51517-51520, August 29, 2014, http://www.gpo.gov/fdsys/pkg/FR-2014-08-29/pdf/2014-20641.pdf.
See also EPA, “Area Designations for the 2012 Annual Fine Particle (PM2.5) Standard: Regulatory Actions,”
http://www.epa.gov/pmdesignations/2012standards/regs.htm.
10 See footnote 8, p. 2208.
11 See EPA, “April 2013 Guidance for Area Designations for the 2012 Annual PM2.5 NAAQS,” p. 6,
http://www.epa.gov/pmdesignations/2012standards/docs/april2013guidance.pdf.
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provided under Section 188(a) of Subpart 4 of Part D of Title I of the CAA.12 EPA had previously
implemented the PM2.5 NAAQS—including nonattainment determinations for the 1997 and 2006
revisions—only under the general implementation provisions in Subpart 1 (§171-§176) of Part D
in Title I of the CAA (“Subpart 1”). However, in a January 4, 2013, decision,13 the U.S. Court of
Appeals for the District of Columbia Circuit determined that EPA had erred in implementing the
PM2.5 NAAQS under Subpart 1 and required the agency to implement the PM2.5 NAAQS under
Subpart 4 of Part D in Title I of the CAA (“Subpart 4”).14
This CRS report focuses primarily on the NAAQS implementation process for designating
geographical nonattainment areas with respect to the tightening of the PM2.5 annual standard
under the 2013 particulates NAAQS, including comparisons with the final designations under the
2006 and 1997 PM2.5 NAAQS revisions. EPA is not requiring new nonattainment designations for
the PM2.5 24-hour standard or the PM10 standard, as the levels for these standards were unchanged
in the 2013 revisions.
Also included in this CRS report is a brief overview of states’ subsequent obligations for
developing and submitting SIPs for attaining or maintaining compliance with the NAAQS.
Appendix A presents a chronology of PM NAAQS regulations, and Appendix B includes a
comparative table of the implementation timeline for the 1997, 2006, and 2013 PM NAAQS. The
table in Appendix D provides a state and county breakdown of EPA’s final designated
nonattainment areas and areas identified in August 2014 and those proposed by the states for the
2013 PM2.5 NAAQS compared to the final EPA designations for the 2006 and 1997 PM2.5
NAAQS for those states and counties.
EPA’s 2013 Changes to the PM NAAQS
The CAA provides for two types of NAAQS: (1) primary standards, “the attainment and
maintenance of which in the judgment of the [EPA] Administrator ... are requisite to protect the
public health” with “an adequate margin of safety”;15 and (2) secondary standards,16 which are
necessary to protect public welfare17—a broad term that includes visibility impairment as well as
12 Subpart 4 §188(a) includes a two-tier classification (“moderate” and “serious”) requirement for areas designated
nonattainment for PM NAAQS. Sections 188-189 of Subpart 4 contain requirements that EPA had not previously
required states to address, including, in particular, in the event that EPA reclassifies a moderate nonattainment area to a
serious nonattainment area. States must therefore submit plans that reflect the additional requirements.
13 Natural Resources Defense Council and Sierra Club v. EPA, 706 F.3d 428 (D.C. Cir. 2013). See also EPA
“Particulate Matter Regulatory Actions: Summary of January 4, 2013 Court Decision,” http://epa.gov/pm/2013/
20130104dcdecision.pdf.
14 EPA published a final rule reclassifying nonattainment areas as “moderate” for the 1997 and 2006 PM NAAQS and
set a deadline for December 31, 2014, for states to submit outstanding State Implementation Plans (SIPs) requirements.
EPA, “Identification of Nonattainment Classification and Deadlines for Submission of State Implementation Plan (SIP)
Provisions for the 1997 Fine Particle (PM2.5) National Ambient Air Quality Standard (NAAQS) and 2006 PM2.5
NAAQS; Final Rule,” 79 Federal Register 31566, June 2, 2014, http://www.gpo.gov/fdsys/pkg/FR-2014-06-02/pdf/
2014-10395.pdf. See also EPA’s “Fact Sheet” and information regarding the November 15, 2013, proposed rule and the
January 4, 2013, D.C. Circuit Court decision on the agency’s website “Particulate Matter Regulatory Actions” at
http://epa.gov/pm/actions.html.
15 42 U.S.C. 7409(b)(1).
16 42 U.S.C. 7409(b)(2).
17 42 U.S.C. 7602(h).The use of public welfare in the CAA “includes, but is not limited to, effects on soils, water,
crops, vegetation, manmade materials, animals, wildlife, weather, visibility, and climate, damage to and deterioration of
(continued...)
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damage to crops, vegetation, and effects on soil and nutrient cycling, water, wildlife, property,
building materials, etc.
EPA’s 1997 revisions to the PM NAAQS18 revised the standards that focused on particles smaller
than 10 microns (PM10 or coarse particles) established in 198719 and introduced standards for
“fine” particles smaller than 2.5 microns (PM2.5) for the first time. The primary NAAQS as
revised include a daily (24-hour) limit for both PM2.5 and PM10 and an annual limit for PM2.5.
(EPA revoked the previous annual limit for PM10 in 2006.)
Achieving attainment of the annual standard requires that the three-year average of the weighted
annual arithmetic mean PM concentration at each monitor within an area must not exceed the
maximum limit set by the agency. The 24-hour standards are 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 days during the year. For PM2.5 and PM10, EPA set the secondary (welfare)
NAAQS the same as the primary standards, the same correlations as EPA established for the 2006
PM NAAQS.
As modified and published in the January 15, 2013, Federal Register,20 the PM2.5 and PM10
primary (public health) standards as set in the final rule are as follows:
• PM2.5: EPA revised the annual standard of 15 micrograms per cubic meter
(µg/m3) by setting a new limit to 12 µg/m3. (EPA’s proposed rule included an
optional limit of 13 µg/m3 and solicited comment for 11 µg/m3.) Compliance
with the “annual” standard is determined by whether the three-year average of its
annual average PM2.5 concentration (at each monitoring site in the area) is less
than or equal to 12 µg/m3; as proposed, EPA retained the daily (24-hour) standard
at 35 µg/m3 based on the current three-year average of the 98th percentile of 24-
hour PM2.5 concentrations as established in 2006.
• PM10: EPA retained the current daily PM10 standard of no more than one
exceedance of concentrations of 150 µg/m3 per year on average over three years;
there is no current annual standard for PM10. (EPA eliminated21 the previous
annual maximum concentration standard of 50 µg/m3 in 2006.)
(...continued)
property, and hazards to transportation, as well as effects on economic values and on personal comfort and well-being,
whether caused by transformation, conversion, or combination with other air pollutants.”
18 See 62 Federal Register 38652-38896, July 18, 1997.
19 PM10 NAAQS were promulgated in 1987. See 52 Federal Register 24640, July 1, 1987.
20 See footnote 3.
21 This decision was based on the findings in the EPA PM criteria document and staff paper, and the CASAC’s
concurrence, that the studies reviewed did not provide sufficient evidence regarding long-term exposure to warrant
continuation of an annual standard. See EPA, “National Ambient Air Quality Standards,” Section III, 71 Federal
Register 2653, January 17, 2006.
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Designation of Geographical Nonattainment Areas
Designating geographical areas as not achieving the established NAAQS based on monitoring
and analysis of relevant air quality data is a critical step in NAAQS implementation. Section
107(d) of the CAA (42 U.S.C. 7407) establishes the process for designating “attainment” (or
alternatively “unclassifiable”) and “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.
Under Section 107(d)(1) of the CAA, the governor of each state must submit a list identifying
designations for a NAAQS “by such a date as the [EPA] Administrator may reasonably require,
but not later than 1 year after promulgation” of the new or revised NAAQS. EPA must
promulgate final designations “as expeditiously as possible” but no later than two years from the
date of promulgation of the new or revised NAAQS. Section 107(d) of the CAA provides for an
extension of up to one year if the EPA administrator “has insufficient information to promulgate
designations.” The process leading up to final designation determinations has in the past extended
beyond the established deadlines as states have continuously reviewed and analyzed data and
modelling results with EPA.
For the 2013 NAAQS, state submissions were to be submitted by December 13, 2013, and EPA
was to promulgate final designations by December 12, 2014.22
NAAQS Designation Process
The NAAQS designation process is intended as a cooperative federal-state-tribal23 process in
which states and tribes provide initial designation recommendations to EPA for consideration.
Section 107(d)(1)(A) (42 U.S.C. 7407) of the CAA requires the governor of each state to submit a
list to 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). Areas are identified as “attainment/unclassifiable”24 when they meet
the standard or when the data are insufficient for determining compliance with the NAAQS.
Following state and tribal designation submissions, the EPA administrator has discretion to make
modifications, including to the area boundaries. As required by statute (§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.
22 See EPA, “National Ambient Air Quality Standards; Final Rule,” Section IX, 78 Federal Register 3249-3251,
January 15, 2013, http://www.gpo.gov/fdsys/pkg/FR-2013-01-15/pdf/2012-30946.pdf.
23 Tribes have been encouraged to submit recommendations. The area designation requirements under the CAA (§107)
are specific with respect to states but not to tribes. 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 C.F.R. Part 49). For information regarding tribes that have participated in the
PM2.5 designation recommendation process, see EPA, “Fine Particle (PM2.5) Designations,” http://www.epa.gov/
pmdesignations.
24 Section 107(d)(1)(A)(iii) of the CAA provides that any area that EPA cannot designate on the basis of available
information as meeting or not meeting the standards should be designated as unclassifiable.
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Measuring and analyzing air quality to determine where NAAQS are not being met is a key step
in determining an area’s designation. Attainment or nonattainment designations are made
primarily on the basis of three years of federally referenced monitoring data.25 EPA began
developing methods for monitoring fine particles at the time the PM2.5 NAAQS were being
finalized in 1997, and operation of the network of monitors for PM2.5 was phased in from 1999
through 2000. EPA’s final designations for the 2013 particulates NAAQS were based on 2011-
2013 monitoring data.
The network of monitors and their locations has been modified over time. In conjunction with the
October 2006 publication of the revised particulates NAAQS, for example, EPA amended its
national air quality monitoring requirements, including those for monitoring particle pollution.26
The amended monitoring requirements were intended to help federal, state, and local air quality
agencies by adopting improvements in monitoring technology. Additional modifications to the
PM NAAQS monitoring network were included in the final January 2013 rule.27
EPA also considers a number of other relevant factors when designating nonattainment areas28
and recommends that states apply these factors in their determinations in conjunction with other
technical guidance. Examples of these factors include:
• population density and degree of urbanization (including commercial
development);
• location of sources in relation to population;
• existing emission controls;
• traffic and commuting patterns and growth rates;
• weather and transport patterns (meteorology);
• geography/topography; and
• jurisdictional boundaries such as counties (or portions of counties), tribal
reservations, metropolitan planning areas, and air districts.
States and tribes may submit additional information on factors they believe are relevant for EPA
to consider.
Entire metropolitan areas may be designated nonattainment in some cases based on monitoring
data in a single location taking into account other factors. States’ or tribes’ boundary
recommendations for an area are to also show that violations are not occurring in those portions
of the recommended area that have been excluded and that they do not contain emission sources
that contribute to the observed violations.
25 A federally referenced monitor is one that has been accepted for use by EPA for comparison of the NAAQS by
meeting the design specifications and certain precision and bias (performance) specifications (40 C.F.R. Part 58).
26 EPA, “Revisions to Ambient Air Monitoring Regulations; Final Rule,” 71 Federal Register 61235-61328, October
17, 2006, http://www.gpo.gov/fdsys/pkg/FR-2006-10-17/pdf/06-8478.pdf.
27 EPA, “National Ambient Air Quality Standards for Particulate Matter,” Section VIII, 79 Federal Register 3233-
3248, January 15, 2013, http://www.gpo.gov/fdsys/pkg/FR-2013-01-15/pdf/2012-30946.pdf.
28 See EPA, “Area Designations for the 2012 Annual Fine Particle (PM2.5) Standard: Designation Guidance and Data,”
http://www.epa.gov/airquality/particlepollution/designations/2012standards/techinfo.htm.
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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 (§107(d)(4)(A)(iv)). However, unlike the 1997 PM2.5 standards,
Metropolitan Statistical Areas or Consolidated Metropolitan Statistical Areas29 did not generally
serve as the “presumptive boundary” for nonattainment areas under the 2013 PM2.5 standards.
EPA made this change when determining nonattainment for the 2006 PM2.5 standards. Rather than
establish a presumption for the minimum size of an area, in its June 2007 guidance30 EPA
instructed states and tribes to evaluate each area on a case-by-case basis. EPA expected that
nonattainment areas for the 2006 24-hour PM2.5 would include counties with monitors violating
the 24-hour standard and nearby counties that contribute to that violation.
EPA also recommended that states and tribes consider using common boundaries for areas to be
designated as nonattainment for both the annual and 24-hour PM2.5 standards. In April 2013, EPA
provided similar guidance to states and tribes with regard to the 2013 revisions of the annual
PM2.5 standards.31 States used this information, in conjunction with air emission and air quality
data—as well other relevant factors listed above as recommended in EPA’s guidance in
determining the boundaries for the designated areas.
Designations for the 2013 PM2.5 Annual NAAQS32
Section 107(d)(1) of the CAA requires states to submit area designation recommendations no
later than one year following the promulgation of a NAAQS standard.33 During November 2013,
four states—California, Idaho, Ohio, and Pennsylvania—provided EPA with recommended
nonattainment boundaries for the 2013 revised primary annual PM2.5 standard. Remaining states,
the District of Columbia, Puerto Rico, and Guam recommended all areas as attainment or
unclassifiable/attainment.34 EPA also received six tribal recommendations of attainment or
unclassifiable/attainment.35
EPA responded to these recommendations in August 2014, and subsequently promulgated the
final area designations published January 15, 2015. The final EPA designations for the 2013 PM2.5
29 As defined by the Office of Management Budget. For more information on metropolitan areas, see U.S. Census
Bureau, “Metropolitan and Micropolitan Statistical Areas Main,” http://www.census.gov/population/www/estimates/
aboutmetro.html.
30 See EPA’s June 2007 guidance for area designations for the 2006 24-hour PM2.5 NAAQS at http://www.epa.gov/
airquality/particlepollution/designations/2006standards/techinfo/
june_2007_guidance_for_area_designations_for_2006_24-hour_pm2.5.pdf.
31 See EPA’s April 2013 guidance for area designations for the 2012 annual PM2.5 NAAQS at http://www.epa.gov/
pmdesignations/2012standards/docs/april2013guidance.pdf.
32 For detailed PM2.5 state/county geographical designation recommendations by EPA and those from individual states
and tribes for the 1997, 2006, and 2012 PM2.5 NAAQS, see EPA, “Fine Particle (PM2.5) Designations,”
http://www.epa.gov/pmdesignations.
33 For the 2013 PM NAAQS, state recommendations were due by December 13, 2013.
34 See EPA, “Area Designations for the 2012 Annual Fine Particle (PM2.5) Standard: State Recommendations and EPA
Responses for Area Designations,” http://www.epa.gov/pmdesignations/2012standards/state.htm.
35 See EPA, “Area Designations for the 2012 Annual Fine Particle (PM2.5) Standard: Initial Designations for Tribes,”
http://www.epa.gov/pmdesignations/2012standards/tribal.htm.
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NAAQS, published January 15, 2015, reflected some modifications to EPA’s August 2014
proposed designations.36
EPA January 2015 Final Designations
In the January 2015 final rule, EPA designated 14 areas in six states—California, Idaho, Indiana,
Kentucky, Ohio, and Pennsylvania—as nonattainment only for the 2013 revised annual PM2.5
standard, the same as the agency proposed in August 2014 counties (see Table B-1 for state-by-
state county/area nonattainment designations). However, the 14 nonattainment areas included 38
counties or portions of counties, one less than proposed (Lake County, OH).
Comparatively, EPA’s final designations for nonattainment of the 2006 and 1997 PM2.5 NAAQS
(those areas with or contributing to air quality levels exceeding the annual and 24-hour PM2.5
standards or both) included all or part of 242 counties in 28 states and the District of Columbia.37
More than 2,900 counties in 30 states were designated as attainment/unclassifiable for the 2006
24-hour and 1997 annual PM2.5 NAAQS.
As EPA indicated in its April 2013 area designation guidance to states and tribes, the initial area
designations for all 2013 PM2.5 NAAQS nonattainment areas were classified as “Moderate” as
provided under Subpart 4 of Part D of Title I of the CAA (Section 188(a)).38 EPA may reclassify
as “serious” those nonattainment areas that EPA determines cannot practicably attain the PM2.5
NAAQS by the applicable attainment date or has not in fact attained the PM2.5 NAAQS after each
area’s applicable attainment date has passed. Such a determination would trigger additional
implementation requirements on the state that were not previously included in SIPs under Subpart
1 of the CAA.
Counties included in the EPA final nonattainment area designations for the 2013 PM2.5 NAAQS
are indicated in the map in Figure 1. Although EPA’s final designations for the 2013 PM NAAQS
do not identify areas violating the 24-hour PM2.5 standard, as the level is unchanged from the
2006 PM NAAQS, the map distinguishes those proposed counties not previously designated as
nonattainment for the annual or the 24-hour PM2.5 standards.
EPA announced that it was also deferring initial designation for 10 areas in three states by up to
one year as a result of data validity issues. Included are all of Florida, all of Tennessee except for
three counties, and eight areas in Georgia (including two counties in Alabama and South
Carolina). EPA had previously proposed to designate the areas in Tennessee and three of the eight
areas in Georgia as unclassifiable. Florida was added as EPA indicated that it had only recently
identified data quality issues in that state.39
36 See EPA, “Final Area Designations for the 2012 National Air Quality Standard for Fine Particles: Responses to
Significant Comments on the State and Tribal Designation Recommendations for the 2012 Annual PM2.5 National
Ambient Air Quality Standard (NAAQS),” December 17, 2014, Docket Number EPA-HQ-OAR-2012-0918,
http://www.epa.gov/pmdesignations/2012standards/final/20141217rtc.pdf.
37 See EPA’s PM2.5 designations websites at http://www.epa.gov/pmdesignations and http://www.epa.gov/oar/oaqps/
greenbk/qnca.html. See also CRS Report R40096, 2006 National Ambient Air Quality Standards (NAAQS) for Fine
Particulate Matter (PM2.5): Designating Nonattainment Areas, by Robert Esworthy.
38 See EPA, “April 2013 Guidance for Area Designations for the 2012 Annual PM2.5 NAAQS,” p. 6,
http://www.epa.gov/pmdesignations/2012standards/docs/april2013guidance.pdf.
39 See EPA, “Final Area Designations for the 2012 National Air Quality Standard for Fine Particles: Fact Sheet,”
(continued...)
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The EPA also designated three areas as unclassifiable: Puerto Rico, the U.S. Virgin Islands, and
all of Illinois (including two adjacent counties in Indiana as part of the Chicago area and four
counties and one city in Missouri included in the St. Louis area) as “unclassifiable.” All
remaining state areas and areas in Indian country are designated as “unclassifiable/attainment” for
the annual PM2.5 standard.
Figure 1. EPA’s Final Designations of Geographical Areas as Nonattainment for the
2013 Annual PM2.5 NAAQS
(violating the 2013 PM2.5 primary annual standard (12 μg/m3) only)
Source: Prepared by the Congressional Research Service based on EPA’s final designations for the 2013 PM2.5
revised annual NAAQS, with data compiled from EPA’s website for prior PM NAAQS final designations,
http://www.epa.gov/pmdesignations/.
Note: Partial counties are shown on the map as whole counties. EPA’s final designations did not include any
counties or partial counties in Alaska or Hawaii.
While the intended nonattainment areas for the 2013 NAAQS may seem small compared with the
approximately 3,000 counties in the United States, PM NAAQS nonattainment counties tend to
have larger populations than those in attainment. Roughly 28 million people40 reside in the 39
counties EPA designated as nonattainment for the 2013 annual PM2.5 NAAQS. Comparably, at the
(...continued)
http://www.epa.gov/pmdesignations/2012standards/final/20141218fs.pdf.
40 Based on extrapolation of the county population (2010 Census), which EPA identified in its “Book Nonattainment
Areas for Criteria Pollutants” (see http://www.epa.gov/oar/oaqps/greenbk/anayo_pa.html). Estimated total population is
316 million for 2013 based on U.S. Census Bureau, “USA Quick Facts,” http://quickfacts.census.gov/qfd/states/
00000.html.
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time of EPA’s final designation for the 2006 PM NAAQS, more than 70 million people (over 20%
of the U.S. population)41 lived in the 120 counties designated as nonattainment for the 2006 24-
hour PM2.5 NAAQS. For the areas designated for 1997 PM NAAQS, nearly 90 million people
(about 30% of the U.S. population)42 lived in the 205 counties designated as nonattainment.
State Recommendations and EPA August 2014 EPA Proposed
Designations in Response
Four states—California, Idaho, Ohio, and Pennsylvania—identified 12 areas comprising 25
counties, including six partial counties (see Table B-1 for state-by-state county/area
nonattainment designations).43 The recommended designations were primarily based on 2010-
2012 monitoring data, criteria and technical guidance from EPA and assistance from its regional
offices, and states’ own relevant information and criteria. States providing revised determinations
based their area designation recommendations on 2011-2013 monitoring data.
As required by statute, EPA responded to the states with its recommended modifications to the
states’ proposed area designations for the 2013 PM2.5 NAAQS for the annual standard in letters
on or about August 19, 2014.44 As EPA did in implementing the 2006 and 1997 PM2.5 NAAQS,
and as it has done with NAAQS for other criteria pollutants, the agency used its discretion to
identify areas as nonattainment in states that had recommended all areas as attainment or
unclassifiable/attainment, expand the size of nonattainment areas (i.e., added more counties or
portions of counties), or combine areas that states listed as separate areas into a single larger unit.
EPA also combined nonattainment counties across state lines into the same nonattainment areas if
the counties are part of the same metropolitan area.
In its August 2014 response to states, EPA proposed 14 areas comprised of 39 counties—25
whole and 14 partial counties—in six states as nonattainment only for the revised 2013 primary
annual PM2.5 standard. (See table in Appendix C for state-by-state county/area nonattainment
designations.) In addition to the four states that had previously identified counties as
nonattainment for the 2013 PM2.5 NAAQS, EPA added seven counties in Kentucky and Indiana,
four of which are included in the nonattainment area designated as Louisville-KY/IN. The three
additional counties in Kentucky are adjacent to counties in an area previously recommended for
nonattainment designation by Ohio; EPA refers to the area as Cincinnati/Hamilton-OH/KY. EPA
also designated as nonattainment additional counties in Pennsylvania and Ohio that had not been
previously recommended as nonattainment by those states for the 2013 PM2.5 NAAQS. Several of
the 14 nonattainment areas included counties from multiple states.
In the August 29, 2014, Federal Register notice45 announcing the posting of the response letters,
EPA also indicated that due to data validity issues it was extending the designation period by up
41 Based on estimated total population of 314 million for 2012 from the U.S. Census Bureau, 2000 Census data,
http://factfinder.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=PEP_2012_PEPAGESEX&
prodType=table.
42 See footnote 41.
43 See footnote 34.
44 For information regarding EPA’s August 19, 2014, intended designations, see EPA, “Area Designations for the 2012
Annual Fine Particle (PM2.5) Standard,” http://www.epa.gov/airquality/particlepollution/designations/2012standards/
index.htm.
45 EPA, “EPA Responses to Significant Comments on the State and Tribal Designation Recommendations for the 2012
(continued...)
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to one year, to December 2015, for 10 counties in Alabama, Georgia, and South Carolina.46 EPA
determined that the information currently available for these areas was insufficient for making
designations.47 In addition, due to data quality assurance issues at several monitoring sites, EPA
indicated that it intended to designate as “unclassifiable” two territories, one area in Indian
country, three areas in Georgia, all counties in Illinois, two counties in Indiana, four counties and
a city in Missouri, and all counties except three (Chattanooga area) in Tennessee.48 EPA indicated
that it intended to designate all remaining areas throughout the United States, including areas in
Indian country and territories, as unclassifiable/attainment.
Per the CAA, states were provided the opportunity to submit additional relevant information to
demonstrate why EPA’s modifications to the states’ recommendations were inappropriate prior to
the agency’s final designations. Although the CAA provides for up to 120 days, the EPA August
2014 response letters for all states with areas intended to be designated nonattainment urged
states to submit “additional information for the EPA to consider” by October 29, 2014. Several
states, including all those with areas EPA intended to designate nonattainment, submitted their
responses to the EPA’s August 2014 proposed designations by the October 2014 deadline.49 As
with past designations by EPA, a number of states challenged the agency and maintained support
for their original recommendations.
Comparing EPA’s Final Nonattainment Designations for the 2013
PM NAAQS with the 2006 and 1997 PM2.5 NAAQS Final
Designations
EPA’s final designations for nonattainment of the 2006 and 1997 PM2.5 NAAQS (those areas with
or contributing to air quality levels exceeding the annual and 24-hour PM2.5 standards or both)
included all or part of 242 counties in 28 states and the District of Columbia.50 More than 2,900
(...continued)
Annual PM2.5 National Ambient Air Quality Standard (NAAQS),” http://www.epa.gov/pmdesignations/2012standards/
final/20141217rtc.pdf. See additional information at EPA, “Area Designations for the 2012 Annual Fine Particle
(PM2.5) Standard: Regulatory Actions,” http://www.epa.gov/pmdesignations/2012standards/regs.htm.
46 EPA, “Area Designations for the 2012 Annual Fine Particle (PM2.5) Standard Regulatory Actions: Fact Sheet,”
http://www.epa.gov/pmdesignations/2012standards/docs/20140819factsheet.pdf.
47 For a list of the deferred areas, see EPA, “Area Designations for the 2012 Annual Fine Particle (PM2.5) Standard
Regulatory Actions: Deferred Areas,” http://www.epa.gov/pmdesignations/2012standards/docs/
20140819deferredlist.pdf.
48 For a list of the areas EPA proposed to designate as unclassified, see EPA, “Area Designations for the 2012 Annual
PM2.5 Standards,” http://www.epa.gov/pmdesignations/2012standards/docs/20140819unclassifiablelist.pdf. See also
EPA, “Area Designations for the 2012 Annual Fine Particle (PM2.5) Standard Regulatory Actions: Fact Sheet,”
http://www.epa.gov/pmdesignations/2012standards/docs/20140819factsheet.pdf.
49 See communications between states and EPA at EPA, “Recommended Area Designations for the 2012 National Air
Quality Standards for Fine Particles: State Recommendations and EPA Responses for Area Designations,”
http://www.epa.gov/pmdesignations/2012standards/staterec.htm; for tribes see “Recommended Area Designations for
the 2012 National Air Quality Standards for Fine Particles: Tribal Recommendations and EPA Responses for Area
Designations,” http://www.epa.gov/pmdesignations/2012standards/tribalrec.htm.
50 See EPA’s PM2.5 designations websites at http://www.epa.gov/pmdesignations and http://www.epa.gov/oar/oaqps/
greenbk/qnca.html. See also CRS Report R40096, 2006 National Ambient Air Quality Standards (NAAQS) for Fine
Particulate Matter (PM2.5): Designating Nonattainment Areas, by Robert Esworthy.
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counties in 30 states were designated as attainment/unclassifiable for the 2006 24-hour and 1997
annual PM2.5 NAAQS. See the map in Figure 2.
Based on EPA’s January 2015 final designations for the 2013 PM2.5 annual standard, three
counties (or portions) of the 38 counties would be designated nonattainment for PM2.5 for the first
time, but the majority of the counties overlap with EPA’s final nonattainment designations for the
2006 and 1997 PM2.5 annual and/or 24-hour standards. Of the remaining 35 counties designated
as nonattainment for the 2013 annual PM2.5 standard as revised, five have not been previously
designated for the annual standard but were designated as nonattainment for the 24-hour standard,
and the remaining 30 counties have been previously designated as nonattainment only for the
annual standard or for the annual and the 24-hour PM2.5 standards (see Table in Appendix C).
The map in Figure 3 presents the overlap of the January 2015 nonattainment designations for the
2013 PM2.5 annual standard with those areas designated nonattainment for the 2006 and 1997
PM2.5 standards.
EPA final designations published on November 13, 2009, for the 2006 PM NAAQS included 31
areas in 18 states comprising 120 counties (89 counties and portions of 31 additional counties) for
nonattainment of only the revised 2006 24-hour PM2.5 standard.51 EPA’s November 2009 final
designations did not include new counties violating the annual standard, as the level was
unchanged from the 1997 PM2.5 NAAQS. EPA’s designations for the 1997 PM2.5 NAAQS
included all or part of 204 counties in 20 states and the District of Columbia. Most of the counties
were exceeding only the annual standard, only 12 counties were exceeding both the 24-hour and
the annual standards, and no counties were exceeding only the 24-hour standard. (For a historical
presentation of the 1997 NAAQS designations, see Figure D-1 in Appendix D.)52
51 74 Federal Register 58688-58781, November 13, 2009; see also EPA, “Area Designations for 2006 24-Hour Fine
Particulate (PM2.5) Standards—Regulatory Actions,” http://www.epa.gov/pmdesignations/2006standards/regs.htm#4.
52 For a detailed side-by-side presentation of EPA final designations for the 2006 and 1997 PM2.5 see Table B-1 in
Appendix B of CRS Report R40096, 2006 National Ambient Air Quality Standards (NAAQS) for Fine Particulate
Matter (PM2.5): Designating Nonattainment Areas, by Robert Esworthy.
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Figure 2. Counties in Nonattainment for the 2006 24-Hour (65 μg/m3) Standards
and/or 1997 PM2.5 NAAQS Annual (15 μg/m3): U.S. EPA Final Designations
Source: Prepared by the Congressional Research Service based on EPA final designations for the 2006 and 1997
PM2.5 NAAQS. Nonattainment counties for the annual standard are based on the October 2006 final area
designations for the 1997 PM2.5 NAAQS; nonattainment counties for the 24-hour standard are based on EPA’s
November 2009 final designations for the 2006 PM2.5 NAAQS.
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Figure 3. EPA Final Area Designation: Nonattainment Areas for the 2013 PM2.5
NAAQS Compared to EPA’s Final Designations for 2006 and 1997 PM2.5 NAAQS
(violating the 2013 annual [12 μg/m3], compared to 1997 annual standard [15 μg/m3]
and/or the 2006 24-hour [35 μg/m3] standard)
Source: Prepared by the Congressional Research Service with data compiled from EPA’s website for PM
designations, http://www.epa.gov/pmdesignations/. Nonattainment counties for the 2013 annual standard are
based on EPA January 2015 final designations; previously designated nonattainment counties for the annual
standard are based on the October 2006 final area designations for the 1997 PM2.5 NAAQS; previously
designated nonattainment counties for the 24-hour standard are based on EPA’s November 2009 final
designations for the 2006 PM2.5 NAAQS.
Note: Partial counties are shown on the map as whole counties. EPA’s August 14 prosed designations did not
include any counties or partial counties in Alaska or Hawaii.
Table 1 below illustrates the comparative geographic distribution of counties in areas that EPA
designated as nonattainment for the 2013 PM2.5 NAAQS and those counties in EPA’s final area
designations for the 2006 and 1997 PM2.5 NAAQS.
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Table 1. U.S. EPA Final Nonattainment Designations of Counties Cumulative for the
1997 PM2.5 NAAQS, 2006 PM2.5 NAAQS, and the 2013 PM2.5 NAAQS
PM2.5 NAAQS (annual/24-hour μg/m3)
1997 standard
2006 standard
2013 standard
15/65 μg/m3
15/35 μg/m3
12/35 μg/m3
National
West
East
National
West
East
National
West
East
Number of counties (including partial counties and DC)
Total exceeding the
standard
204 13
191 242 43
199 245 45
200
Exceeding the 24-hour and
annual standards
12 12 0
81 11 70
86 13
74
Exceeding the 24-hour
standard only
0 0 0
39 31 8
34 30 4
Exceeding the annual
standard only
192 1
191 122 1
121 125 2
122
Source: Prepared by the Congressional Research Service with data compiled from EPA’s websites for PM
designations at http://www.epa.gov/pmdesignations/ and http://www.epa.gov/oar/oaqps/greenbk/qnca.html.
Nonattainment counties are based on EPA’s final designations for the 2013 PM2.5 NAAQS as published January
15, 2015; final designations for the 2006 PM2.5 NAAQS for the 24-hour standard published November 13, 2009;
and final area designations for the 1997 PM2.5 NAAQS for the 24-hour and annual standards as of July 31, 2009.
Note: The counties in the table for the 2013 standards reflect EPA’s final designation for the revised annual
standards overlaid with the those presented in the previous column for the 2006 standards; the counties in the
table for the 2006 standards reflect EPA’s final designations for nonattainment area boundaries for the 2006 24-
hour only PM2.5 NAAQS based on 2006-2008 air quality monitoring data overlaid with the final designations for
the annual standards (which were unchanged) for the 1997 PM2.5 NAAQS as of July 31, 2009.
It is difficult to anticipate what effect the EPA final area designations for the 2013 PM2.5 NAAQS
may have on current control measures in these areas. In some of these areas, current measures
focused on achieving attainment for the 1997 annual standard and 2006 24-hour PM2.5 standard
may require supplemental or significant modifications to ensure compliance with the stricter
annual standard. The impacts could vary substantially from area to area within a state and from
state to state depending on many factors, including the type and locations of primary emission
sources, current control measures, the extent to which the area is exceeding the standard,
topography, weather, etc. For the most part, these measures will be established by the states in
their SIPs.
Once final designations take effect, they become an important component of state, local, and
tribal governments’ efforts to reduce fine particle pollution. The designations govern what
subsequent regulatory actions states, tribes, and EPA must take in order to improve or preserve air
quality in each area.
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Demonstrating Attainment with the 2013 PM2.5
NAAQS
Under the CAA, EPA sets the nationwide standard for criteria pollutants, and EPA and states are
responsible for placing limits on emissions that contribute to criteria pollution and for regulating
entities that emit criteria pollutants. Areas designated as attainment/unclassifiable will not have to
take steps to improve air quality, but under the statute they must take steps to prevent air quality
from deteriorating to unhealthy levels. For those areas designated as nonattainment, state, local,
and tribal governments must outline detailed control requirements in plans demonstrating how
they will meet and/or maintain compliance with the 2013 PM2.5 annual standard. These plans are
defined as state implementation plans and referred to as SIPs (TIPs for tribal implementation
plans).
As discussed previously in this report, in response to a January 2013 D.C. Circuit Court
decision53 EPA has classified all initial nonattainment area designations for the 2013 PM2.5 annual
standard as moderate. EPA had previously implemented the PM2.5 NAAQS, only under the
general implementation provisions in Subpart 1 of the act. Subpart 4 requires EPA to classify
areas based on the severity of their fine particle pollution problem. Subpart 1 does not include
classification requirements for nonattainment areas but does authorize EPA to establish
classifications if the agency deems it appropriate.
The Subpart 4 requirements for areas classified as moderate are generally comparable to those of
Subpart 1. However, under Subpart 4,54 states have 18 months from the date of EPA’s final
designations to submit SIPs, which identify specific regulations and emission control
requirements that will bring an area into compliance. Implementing the PM2.5 NAAQS under
Subpart 1 required submission of SIPs three years from the date of EPA’s final designations.
Under Subpart 4, EPA may reclassify as “serious” any nonattainment area that the agency
determines cannot practicably attain the PM2.5 NAAQS by the applicable attainment date or those
areas classified as moderate that do not attain the PM2.5 NAAQS after their applicable attainment
date has passed. Subpart 4 introduces additional statutory SIP planning requirements for areas
classified as serious.55 These additional requirements must be reflected in the states’ initial SIP
submissions.
States must achieve attainment for moderate areas as expeditiously as practicable but no later than
six years after designation, and serious areas must achieve attainment no later than 10 years from
designation as nonattainment under Subpart 4. Under the general provisions in Subpart 1, which
53 See footnote 13.
54 Part D of Title I §189(a)(2)(B).
55 EPA references the “General Preamble” of the CAA and “Addendum” as guidance for the specific Subpart 4
statutory requirements: “State Implementation Plans; General Preamble for the Implementation of Title I of the Clean
Air Act Amendments of 1990,” 57 Federal Register 13498, April 16, 1992, and “State Implementation Plans for
Serious PM10 Nonattainment Areas, and Attainment Date Waivers for PM10 Nonattainment Areas Generally;
Addendum to the General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990,” 59
Federal Register 41998, August 16, 1994.
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has no classifications, attainment must be achieved no later than five years from the effective
designation date. Both Subpart 456 and Subpart 157 include provisions for extensions.
Even though EPA has concluded that although in many cases attainment will be reached as the
result of several promulgated federal regulations, states will very likely require some local
controls because of the requirements of the CAA. All areas no matter their classification of
attainment or nonattainment will be required under the CAA58 to conduct emission inventories
which will provide states the basis for states to analyze and estimate the extent to which various
sources are contributing to nonattainment.
To achieve the most expeditious attainment date for an area, EPA has recommended that states
first identify emission reduction programs that have already been adopted and are being
implemented at the federal, state, and local levels. The agency also recommends that states
evaluate additional control measures and control technologies—reasonably available control
measures (RACM) and reasonably available control technology (RACT)—for an area. States are
required under the CAA59 to impose RACM and RACT that can be implemented on sources
located in nonattainment areas and to adopt enforceable regulations to ensure these areas will
attain as expeditiously as practicable.
Some have expressed concern that a nonattainment designation may negatively impact an area’s
economic development, as potential additional requirements associated with achieving
compliance may deter investment. EPA and others contend that the benefits associated with the
CAA exceed the costs and that, while short-term impacts may vary, historical evidence suggests
that impacts on overall economic growth concurrent with environmental (including CAA)
regulations are generally less significant than often anticipated.60
As indicated earlier in this report, based on EPA’s January 2015 final designations for the 2013
PM2.5 annual standard, three counties (or portions) of the 38 counties identified in the rule would
be designated nonattainment for PM2.5 for the first time. Nevertheless, exceeding the 2013 PM2.5
annual standard may have implications with respect to existing SIPs, the extent of which could
vary significantly from area to area based on many factors. In some cases SIPs may require
substantial modifications, while in other cases the current SIP may be sufficient to achieve
compliance with both standards.
State Implementation Plans (SIPs)
Section 110(a)(1) of the CAA requires states to submit new or revised SIPs that provide for
implementation, maintenance, and enforcement of the new or revised NAAQS. All states are
required to submit SIPs that include the basic program requirements for managing air quality
required in Section 110(a)(2) of the CAA showing that they have the capacity to attain, maintain,
56 EPA may grant no more than two one-year extensions of the initial attainment date for moderate designated areas
under Section 188(d) of the CAA and no more than five years for areas designated as serious under Section 188(e).
57 Under Section 172(a)(2)(A) of the CAA, 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).
58 Under 40 C.F.R Part 51, Subpart A, states are required to provide annual statewide inventory data for selected source
categories no matter the area designations determinations.
59 Section 172(c)(1).
60 See EPA, “The Clean Air Act and the Economy,” http://www.epa.gov/air/sect812/economy.html.
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and enforce the revisions associated with the PM2.5 NAAQS. These “infrastructure SIP”
submissions must address a number of basic elements, including:
• Ambient air quality monitoring and data systems,
• Programs for enforcement of control measures,
• Adequate authority and resources to implement the plan, and
• Prohibition of interstate pollution transport.
Section 110(a)(2)(D)(i) of the act contains four elements that revised SIPs must address. The first
two elements of this section require each state in its SIP to demonstrate adequate provisions for
the ability to prohibit air emissions within the state that (1) contribute significantly to another
state’s nonattainment of the NAAQS, or (2) interfere with another state’s maintenance of the
NAAQS.
The specific provisions for requirements for all nonattainment areas designated as moderate under
Subpart 4 of Part D of the CAA include:
• Nonattainment new source review (§172(c)(5)) permit program providing that
permits meet the requirements of Section 173 of the act (§189(a)(1)(A));
• Attainment demonstration or demonstration that attainment by the applicable
attainment date is impracticable (§189(a)(1)(B));
• Assurance of implementation of RACM and RACT (§189(a)(1)(C));
• Quantitative milestones and demonstration of reasonable further progress
(§189(c)); and
• Control requirements applicable to major stationary sources precursors61
(§189(e)).
EPA NAAQS Implementation Rules/Guidance
The EPA typically publishes an “implementation rule” that describes the requirements that states
and tribes must meet in their implementation plans to achieve and maintain attainment. The rule
also provides guidance and procedures for establishing controls to achieve and maintain
attainment. In addition, the implementation rule generally includes guidance for submitting a SIP
when reaching attainment within the five-year requirement is impractical. The implementation
rule takes into account existing (oftentimes pending) federal regulations that contribute to
controlling criteria pollutants and their precursors.
EPA published a proposed implementation rule for the PM2.5 NAAQS on March 23, 2015.62 The
EPA proposal would apply to the 2013 annual PM2.5 NAAQS, the 2006 24-hour PM2.5 NAAQS,
61 The term precursor refers to a directly emitted pollutant that, when released to the atmosphere, forms or contributes
to the formation of a secondary pollutant for which an ambient air quality standard has been adopted.
62 EPA, “Fine Particulate Matter National Ambient Air Quality Standards: State Implementation Plan Requirements;
Proposed Rule,” 73 Federal Register 15340- 15474, March 23, 2015, http://www.gpo.gov/fdsys/pkg/FR-2015-03-23/
pdf/2015-06138.pdf. See also EPA’s PM Regulatory Actions website at http://epa.gov/pm/actions.html for a fact sheet
and prepublication version of the proposed rule as signed by the EPA administrator on March 10, 2015.
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and “any future revisions to the PM2.5 NAAQS.” EPA also proposes revocation of the 1997
primary annual PM2.5 standard because it was revised in the 2013 PM NAAQS. The proposal
details (1) how air agencies are to meet statutory SIP requirements under Subpart 4 for areas
designated nonattainment PM2.5 NAAQS, (2) “specific attainment planning requirements” as they
would pertain to areas based on their classification as moderate or serious, and (3) the process for
reclassifying moderate areas to serious. The proposed PM2.5 NAAQS implementation rule would
replace EPA’s “2007 PM2.5 Implementation Rule’’63 and portions of the ‘‘2008 PM2.5 New Source
Review (NSR) Rule.”64 These rules were remanded to EPA by the U.S. Court of Appeals for the
D.C. Circuit Court in its January 2013 decision.65
In June 2014, EPA published a final rule reclassifying 1997 and 2006 nonattainment as
“moderate” and set a deadline for December 31, 2014, for states to submit outstanding SIP
requirements.66 The basic framework of the implementation rule for the 1997 PM2.5 NAAQS
published in April 2007 included a description of the requirements that states and tribes must
meet in their implementation plans to achieve and maintain attainment of the 2006 standards. The
2007 rule was based on statutory requirements under Subpart 1 of the CAA. In addition to the
2007 implementation rule for the 1997 PM2.5 NAAQS, EPA outlined implementation guidance
regarding the development of SIPs to demonstrate attainment with the 2006 PM2.5 NAAQS in a
March 12, 2012, memorandum to EPA regional air directors.67 The memorandum was withdrawn
on June 6, 2013, following the January 2013 D.C. Circuit Court decision.
National Regulations
EPA expects that in many cases emission reductions from implementing existing national
regulations and strategies will provide a framework for helping states achieve attainment with the
PM2.5 NAAQS. These national actions include:
• Cross-State Air Pollution Rule;68
• Mercury and Air Toxics Standards;69
63 EPA, “Final Clean Air Fine Particle Implementation Rule,” 72 Federal Register 20286-20667, April 25, 2007,
http://www.gpo.gov/fdsys/pkg/FR-2007-04-25/pdf/E7-6347.pdf. The rule addresses attainment demonstration and
modeling, local emission reduction measures (including RACT, RACM, and reasonable further progress), regional
emission reduction strategies, innovative program guidance, emission inventory requirements, transportation
conformity, and stationary source test methods.
64 EPA, “Implementation of the New Source Review (NSR) Program for Particulate Matter Less Than 2.5 Micrometers
(PM2.5); Final Rule,” 73 Federal Register 28321-28350, May 26, 2008, http://www.gpo.gov/fdsys/pkg/FR-2008-05-16/
pdf/E8-10768.pdf.
65 See footnote 13.
66 EPA, “Identification of Nonattainment Classification and Deadlines for Submission of State Implementation Plan
(SIP) Provisions for the 1997 Fine Particle (PM2.5) National Ambient Air Quality Standard (NAAQS) and 2006 PM2.5
NAAQS; Final Rule,” 79 Federal Register 31566, June 2, 2014. See also EPA’s “Fact Sheet” and information
regarding the November 15, 2013, proposed rule and the January 2013 D.C. Circuit Court decision on the agency’s
website at http://epa.gov/pm/actions.html.
67 Memorandum from Stephen D. Page, Director, Office of Air Quality Planning and Standards, to EPA Regional Air
Directors (Regions I-X), “Implementation Guidance for the 2006 24-Hour Fine Particle (PM2.5) National Ambient Air
Quality Standards (NAAQS),” http://www.epa.gov/ttn/naaqs/pm/pdfs/20120302_implement_guidance_24-
hr_pm2.5_naaqs.pdf.
68 See EPA’s website “Interstate Air Pollution Transport” at http://www.epa.gov/airtransport/.
69 See EPA’s website “Mercury and Air Toxics Standards” at http://www.epa.gov/mats/.
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• Light-Duty Vehicle Tier 2 Rule;70
• Motor Vehicle Emission and Fuel Standards Tier 3 Rule;71
• Heavy Duty Diesel Rule;72
• Clean Air Nonroad Diesel Rule;73
• Regional Haze Regulations and Guidelines for Best Available Retrofit
Technology Determinations;74
• NOx Emission Standard for New Commercial Aircraft Engines;75
• Emissions Standards for Locomotives and Marine Compression-Ignition
Engines;76
• Emission Standards for Ignition Engines, Control of Emissions for Nonroad
Spark Ignition Engines and Equipment;77
• Category 3 Oceangoing Vessels;78
• Reciprocating Internal Combustion Engines National Emissions Standards for
Hazardous Air Pollutants;79 and
70 EPA, “Control of Air Pollution from New Motor Vehicles: Tier 2 Motor Vehicle Emissions Standards and Gasoline
Sulfur Control Requirements,” 65 Federal Register 6698-6870, February 10, 2000, http://www.gpo.gov/fdsys/pkg/FR-
2000-02-10/pdf/00-19.pdf.
71 Tier 3 vehicle standards set new limits starting September 2017 for tailpipe and evaporative emissions from
passenger cars, light-duty trucks, medium-duty passenger vehicles, and some heavy-duty vehicles. EPA, “Control of
Air Pollution from Motor Vehicles: Tier 3 Motor Vehicle Emission and Fuel Standards,” 70 Federal Register 23413-
23886, April 28, 2014, http://www.gpo.gov/fdsys/pkg/FR-2014-04-28/pdf/2014-06954.pdf. EPA released amendments
and clarifications to the rule in January of 2015; see EPA’s website “Tier 3 Vehicle Emission and Fuel Standards
Program” at http://www.epa.gov/otaq/tier3.htm.
72 EPA, “Control of Emissions of Air Pollution from 2004 and Later Model Year Heavy-Duty Highway Engines and
Vehicles; Revision of Light-Duty On-Board Diagnostics Requirements,” 65 Federal Register 59896-59978, October 6,
2000, http://www.gpo.gov/fdsys/pkg/FR-2000-10-06/pdf/00-20144.pdf.
73 EPA, “Control of Emissions of Air Pollution from Nonroad Diesel Engines and Fuel,” 69 Federal Register 38958-
39273, June 29, 2004, http://www.gpo.gov/fdsys/pkg/FR-2004-06-29/pdf/04-11293.pdf.
74 EPA, “Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations,”
70 Federal Register 39104-39172, July 6, 2005, http://www.gpo.gov/fdsys/pkg/FR-2005-07-06/pdf/05-12526.pdf.
75 EPA, “Control of Air Pollution from Aircraft and Aircraft Engines; Emission Standards and Test Procedures,” 70
Federal Register 69644-69687, November 17, 2005, http://www.gpo.gov/fdsys/pkg/FR-2005-11-17/pdf/05-22704.pdf.
76 EPA, “Control of Emissions of Air Pollution from Locomotive Engines and Marine Compression-Ignition Engines
Less Than 30 Liters per Cylinder; Republication,” 73 Federal Register 37095-37350, republished June 30, 2008,
http://www.gpo.gov/fdsys/pkg/FR-2008-06-30/pdf/R8-7999.pdf.
77 EPA, “Control of Emissions from Nonroad Spark-Ignition Engines and Equipment,” 73 Federal Register 59034-
59380, October 8, 2008, http://www.gpo.gov/fdsys/pkg/FR-2008-10-08/pdf/E8-21093.pdf.
78 EPA, “Control of Emissions from New Marine Compression-Ignition Engines at or Above 30 Liters per Cylinder,”
75 Federal Register 22895-23065, April 30, 2010, http://www.gpo.gov/fdsys/pkg/FR-2010-04-30/pdf/2010-2534.pdf.
79 EPA, “National Emission Standards for Hazardous Air Pollutants for Reciprocating Internal Combustion Engines,”
75 Federal Register 51569-51608, August 20, 2010, http://www.gpo.gov/fdsys/pkg/FR-2010-08-20/pdf/2010-
20298.pdf; EPA, “National Emission Standards for Hazardous Air Pollutants for Reciprocating Internal Combustion
Engines; New Source Performance Standards for Stationary Internal Combustion Engines; Final Rule,” Final
Amendments, 78 Federal Register 6674-6724, January 30, 2013, http://www.gpo.gov/fdsys/pkg/FR-2013-01-30/pdf/
2013-01288.pdf; see also EPA’s Air Toxics website “Stationary Internal Combustion Engines” at http://www.epa.gov/
ttn/atw/icengines/index.html.
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• New Source Performance Standards and Emissions Guidelines for
Hospital/Medical/Infectious Waste Incinerators Final Rule Amendments.80
New Source Review81
Areas designated nonattainment, as well as those designated unclassifiable or
unclassifiable/attainment for the NAAQS, are also subject to new source review (NSR)
requirements. Enacted as part of the 1977 CAA amendments and modified in the 1990 CAA
amendments, NSR is designed to ensure that newly constructed facilities or substantially
modified existing facilities do not result in violation of applicable air quality standards. NSR
provisions outline permitting requirements both for construction of new major pollution sources
and for modifications to existing major pollution sources. The specific NSR requirements for
affected sources depend on whether the sources are subject to “Prevention of Significant
Deterioration” (PSD) or nonattainment provisions.82
Over time, EPA has promulgated rules83 that contain certain NSR program requirements for
sources that emit PM2.5 and its precursors, including SIP modifications to state NSR programs to
account for emissions of PM2.5. For example, the January 2013 final PM NAAQS includes
revisions to the PSD permitting program (rules) with respect to the revised PM NAAQS so as not
to “unreasonably delay” pending permits and establish a “grandfather” provision for permit
applications if (1) the permitting agency deemed an application complete by December 14, 2012;
or (2) a draft permit or preliminary determination has been issued for public comment by the date
the revised 2013 PM NAAQS went into effect (60 days after January 15, 2013, publication in the
Federal Register).84
Transportation Conformity85
If new or revised SIPs for attainment establish or revise a transportation-related emissions budget
or add or delete transportation control measures, they will trigger “conformity” determinations.
Transportation conformity is required by the CAA, Section 176(c),86 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.
80 EPA, “Standards of Performance for New Stationary Sources and Emissions Guidelines for Existing Sources:
Hospital/Medical/Infectious Waste Incinerators,” 74 Federal Register 51368-51415, October 6, 2009,
http://www.gpo.gov/fdsys/pkg/FR-2009-10-06/pdf/E9-22928.pdf.
81 For an overview, including statutory authority and regulations, see EPA, “New Source Review (NSR),”
http://www.epa.gov/air/nsr/.
82 See CAA, §§171-178, codified at 40 C.F.R. 52.24(f)(10). Section 166 of the CAA authorizes EPA to establish
regulations for PSD of any pollutant for which EPA has issued a national standard.
83 For more information regarding these NSR rules and standards, see EPA, “New Source Review: Regulations and
Standards,” http://www.epa.gov/air/nsr/actions.html.
84 See EPA, EPA’s Revised Air Quality Standards for Particle Pollution: Monitoring, Designations and Permitting
Requirements, fact sheet, http://www.epa.gov/pm/2012/decfsimp.pdf. See also EPA, EPA’s Proposal to Update the Air
Quality Standards for Particle Pollution: Monitoring, Designations and Permitting Requirements, fact sheet,
http://www.epa.gov/airquality/particlepollution/2012/fsimp.pdf.
85 See EPA’s “Transportation Conformity” at http://www.epa.gov/otaq/stateresources/transconf/index.htm.
86 42 U.S.C. 7506(c).
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On March 24, 2010, EPA published a final rule amending the transportation conformity regulation
primarily to incorporate the October 17, 2006, strengthening of the 24-hour PM2.5 air quality
standard and revocation of the annual PM10 standard.87 The final rule, which affects
implementation of conformity in PM2.5 and PM10 nonattainment and maintenance areas, also
addresses a court remand concerning hot-spot88 analyses as they apply to PM2.5 and PM10, as well
as to carbon monoxide and nonattainment and maintenance areas.
On March 14, 2012, EPA published a final rule89 restructuring sections of the conformity rule (40
C.F.R. 93.109 and 93.119) so that existing requirements apply to new or revised NAAQS. EPA
also released associated implementation guidance in July 2012. The rule is intended to remove
the need to amend the transportation conformity rule merely to reference specific new NAAQS.
Conclusion
States will have 18 months from April 15, 2015, the effective date of EPA’s final designations for
the 2013 PM2.5 NAAQS, to submit SIPs, which identify specific regulations and emission control
requirements that will bring an area into compliance. Following EPA approval of SIPs,
implementation through imposition of control measures, where necessary, will occur for several
years. Under CAA, Section 188 of Subpart 4, states must achieve attainment as expeditiously as
practicable but no later than six years after designation:90 April 2021 for the 2013 PM2.5 standard.
(See timeline presented in Appendix B).
Because of health and cost implications, NAAQS decisions have historically been the source of
significant concern to Members of Congress. The evolution and development of the PM NAAQS,
in particular, has been the subject of extensive oversight. (Appendix A presents a chronology of
PM NAAQS regulations.) EPA’s failure to complete timely review and revision of the NAAQS as
required under the CAA has also been an area of concern to some in Congress and others.
Some Members expressed concerns in hearings, letters to the EPA administrator, and proposed
legislation in anticipation of potential changes to the PM NAAQS leading up to the January 2013
final published revisions. Some Members91 and industry stakeholders had urged EPA to delay the
87 EPA, “Guidance for Transportation Conformity Implementation in Multi-Jurisdictional Nonattainment and
Maintenance Areas,” http://www.epa.gov/otaq/stateresources/transconf/regs/420b12046.pdf. See also EPA
Transportation Conformity Rule PM2.5 and PM10 Amendments, 75 Federal Register 14259, March 24, 2010,
http://www.gpo.gov/fdsys/pkg/FR-2010-03-24/pdf/2010-5703.pdf. Prior to the final rule EPA provided interim
guidance for meeting conformity requirements: Interim Transportation Conformity Guidance for 2006 PM2.5 NAAQS
Nonattainment Areas (EPA-420-B-09-036, November 2009). See also EPA’s “Transportation Conformity:
Regulations” at http://www.epa.gov/otaq/stateresources/transconf/conf-regs.htm.
88 Transportation projects that must be analyzed for local air quality impacts.
89 EPA, “Transportation Conformity Rule Restructuring Amendments,” 77 Federal Register 14979, March 14, 2012,
http://www.gpo.gov/fdsys/pkg/FR-2012-03-14/pdf/2012-6207.pdf.
90 Implementing PM NAAQS under Section 176 of Subpart 1 in the CAA requires submission of SIPs three years from
the date of EPA’s final designations and compliance with the new standard no later than five years from the effective
designation date.
91 See letter from Representative Bob Latta et al. to EPA administrator Lisa Jackson, November 21, 2012,
http://latta.house.gov/uploadedfiles/2012_11_29_final_pm2_5_letter_signed_w_attchmt.pdf. See also press release,
“Latta Sends Letter to EPA Expressing Concerns for Proposed Legislation,” Representative Bob Latta,
http://latta.house.gov/news/documentsingle.aspx?DocumentID=314585.
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final rule, while others, including some states92 and various environmental and public health
advocacy groups, urged timely completion of a tighter standard.
Changes to the NAAQS have historically triggered litigation alleging that the standards are too
stringent or not stringent enough and often result in delays in implementation. The agency’s final
designations of nonttainment areas and the implementation of the 2013 PM2.5 NAAQS are
expected to generate further interest and oversight.
92 See December 6, 2012, letter from nine state attorneys general to the acting administrator of the Office of
Information and Regulatory Affairs, White House Office of Management and Budget, http://www.eenews.net/assets/
2012/12/10/document_gw_02.pdf.
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Appendix A. Chronology of EPA’s National
Ambient Air Quality Standards (NAAQS)
Regulations for Total Suspended Particulates (TSP)
and Particulate Matter (PM) 1971-2013
EPA first promulgated annual and 24-hour NAAQS for PM2.5 in July 1997. EPA had previously
addressed particulate matter by regulating “total suspended particles” (TSP) in 1971, followed by
the agency’s regulation of PM10 in 1987.
Table A-1. History of Particulate Matter (PM) and Total Suspended Particles (TSP)
National Ambient Air Quality Standards (NAAQS)
1971-2013
Final
Primary/
Averaging
Year
Rule/Decision
Secondary
Indicator
Time
Levela Form
Not to be exceeded more than
24-hour 260 µg/m3
Primary TSPb
once per year
Annual 75
µg/m3 Annual geometric mean
1971
36 FR 8186
April 30, 1971
24-hour 150 µg/m3 Not to be exceeded more than
Secondary TSP
once per year
Annual 60 µg/m3 Annual geometric mean
Not to be exceeded more than
24-hour 150 µg/m3 once per year on average over a
1987
52 FR 24634
Primary and
PM
3-year period
February 8, 1979
Secondary
10
Annual arithmetic mean,
Annual 50 µg/m3 averaged over 3 years
98th percentile, averaged over 3
24-hour 65 µg/m3 years
PM2.5
Annual arithmetic mean,
Annual 15.0 µg/m3 averaged over 3 yearsc,d
Initially promulgated 99th
percentile, averaged over three
62 FR 38652
Primary and
1997
years; when 1997 standards for
July 18, 1997
Secondary
PM
24-hour 150 µg/m3
10 were vacated, the form of
1987 standards remained in
PM10
place (not to be exceeded more
than once per year on average
over a 3-year period)e
Annual arithmetic mean,
Annual 50 µg/m3 averaged over 3 years
98th percentile, averaged over 3
24-hour 35 µg/m3
73 FR 16483
Primary and
yearsf
2006
March 27, 2008
Secondary
PM2.5
Annual arithmetic mean,
Annual 15.0 µg/m3 averaged over 3 yearsg
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Final
Primary/
Averaging
Year
Rule/Decision
Secondary
Indicator
Time
Levela Form
Not to be exceeded more than
24-hour 150 µg/m3 once per year on average over a
PM
3-year period
10
Annual — EPA revoked the annual PM10
NAAQS
Primary
Annual 12.0 µg/m3 Annual arithmetic mean,
averaged over 3 years
78 FR 3085
Secondary
PM
Annual 15.0 µg/m3 Annual arithmetic mean,
January 15, 2013
2.5
averaged over 3 years
2012/
2013
EPA finalized its
Primary and
decision on
24-hour 35 µg/m3 98th percentile, averaged over 3
Secondary
years
December 14, 2012 Primary and
Not to be exceeded more than
Secondary PM10 24-hour
150 µg/m3 once per year on average over a
3-year period
Source: Congressional Research Service based on data adapted from the U.S. Environmental Protection Agency’s
(EPA’s) “Particulate Matter (PM) Standards-Table of Historical PM NAAQS,” http://epa.gov/ttn/naaqs/standards/
pm/s_pm_history.html.
a. Units of measure are micrograms per cubic meter of air µg/m3.
b. TSP = total suspended particles.
c. The level of the annual standard is defined to one decimal place (i.e., 15.0 µg/m3) as determined by
rounding. For example, a three-year average annual mean of 15.04 µg/m3 would round to 15.0 µg/m3 and,
thus, meet the annual standard, and a three-year average of 15.05 µg/m3 would round to 15.1 µg/m3 and,
hence, violate the annual standard (40 CFR part 50, Appendix N).
d. The level of the standard was to be compared to measurements made at sites that represent “community-
wide air quality” recording the highest level, or, if specific requirements were satisfied, to average
measurements from multiple community-wide air quality monitoring sites (“spatial averaging”).
e. See 69 Federal Register 45592, July 30, 2004.
f.
The level of the 24-hour standard is defined as an integer (zero decimal places) as determined by rounding.
For example, a three-year average 98th percentile concentration of 35.49 µg/m3 would round to 35 µg/m3
and thus meet the 24-hour standard, and a three-year average of 35.50 µg/m3 would round to 36 and,
hence, violate the 24-hour standard (40 CFR part 50, Appendix N).
g. The EPA tightened the constraints on the spatial averaging criteria by further limiting the conditions under
which some areas may average measurements from multiple community-oriented monitors to determine
compliance (see 71 Federal Register 61165-61167).
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Appendix B. Comparative Timeline for
Implementing the 1997, 2006, and 2013 PM2.5
NAAQS
The timeline presented in Table B-1 reflects the most recent key milestone dates for
implementing the 1997 and 2006 NAAQS and estimates for the 2013 PM2.5 NAAQS, including
actual completions. These milestones are driven primarily by statutory requirements. The table
mimics an EPA milestone schedule outlined in an April 1, 2003, memorandum to EPA regional
administrators that also provided the nonbinding guidance for implementation of the 1997 PM2.5
area designations93 and the agency’s projected timeline for the 2006 PM2.5 NAAQS.94
Table B-1. Schedule for Implementation of the 1997, 2006, and 2013 PM2.5 NAAQS
1997 PM2.5
2013 PM2.5
Milestones
NAAQS 2006
PM2.5 NAAQS
NAAQS
Revised standard promulgated (Federal Register notice)
July 18, 1997
October 17, 2006
January 15, 2013
Revised standard effective date
September 1997
December 18, 2006
March 18, 2013
State-tribal area designation recommendations
February 2004
December 18, 2007
December 12, 2013
(based on 2000-
(based on 2004-2006
(based primarily on
2002 monitoring
monitoring data)
2010-2012
data)
monitoring data)
EPA notifies states and tribes regarding modifications to
June-July 2004
August 2008
August 2014
their recommendations
EPA promulgates final area designations and publishes in the
January 5, 2005
November 13, 2009
December 13, 2014
Federal Register (required one year after states and tribes
(based on 2006-2008
(published January
make recommendations)
monitoring data)
15, 2015)
(following delay due to
new Administration’s
review)a
EPA publishes proposed PM2.5 implementation rule/guidance November 1, 2005 March 2, 2012
March 23, 2015
(withdrawn June 6,
2013)
Final area designations effective date (typically not later than April 5, 2005
December 14, 2009
April 15, 2015
90 days after Federal Register publication)
States with new transportation projects submit conformity
April 5, 2006
December 14, 2010
April 15, 2016
determination (required within one year of the effective
date of nonattainment designation)
EPA promulgates final PM2.5 implementation rule
April 25, 2007
March 2, 2012
NA
(withdrawn June 6,
2013)
93 EPA memorandum from the Office of Air and Radiation Assistant administrator Jeffrey R. Holmstead to EPA
Regional Administrators, “Designations for the Fine Particle National Ambient Air Quality Standards,” April 1, 2003,
p. 3, http://www.epa.gov/ttn/oa rpg/t1/memoranda/naqsfp_gda.pdf.
94 See EPA overview for the 2006 review of the PM NAAQS, http://www.epa.gov/airquality/particlepollution/pdfs/
20061013_presentation.pdf, slide #9.
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1997 PM2.5
2013 PM2.5
Milestones
NAAQS 2006
PM2.5 NAAQS
NAAQS
States and tribes submit revised implementation plans (SIPs)
April 2008
December 2012 (some August 2016
(required three years after final area designations effective
(ongoing)
states delayed)
date unless extension granted for 1997 and 2006 PM
NAAQS, 18 months after final designations for 2013 PM
NAAQS)
NAAQS statutory compliance deadline for attainment
April 2010-2015
December 2014-2019
April 2021
(required within five years after final area designations
(projected)
effective date for 1997 and 2006 NAAQS, up to 10 years
with extension, six years after for the 2013 NAAQS)
Source: Prepared by the Congressional Research Service based on U.S. Environmental Protection Agency fact
sheets and guidance documents and relevant Federal Register notices. NA = not available.
a. EPA issued implementation guidance regarding the development of implementation plans in a March 2, 2012,
memorandum to EPA regional directors: http://www.epa.gov/ttn/naaqs/pm/pdfs/
20120302_implement_guidance_24-hr_pm2.5_naaqs.pdf. Subsequently, in a June 6, 2013, memorandum,
EPA withdrew the guidance in response to the January 4, 2013, U.S. Court of Appeals for the District of
Columbia Circuit decision that EPA incorrectly interpreted the CAA with respect to statutory
requirements for the implementation of the 1997 PM2.5: http://www.epa.gov/ttn/naaqs/pm/pdfs/
implementationguidancewithdrawmemo.pdf.
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Appendix C. Comparison of EPA Nonattainment
Areas for the 2013 PM2.5 Annual Standard and
Previous PM2.5 Standards
Table C-1. EPA Final, EPA Proposed, and State Recommended Nonattainment Areas
for the 2013 PM2.5 NAAQS and Final Nonattainment Designations for the 2006
PM2.5 and 1997 PM2.5 NAAQS
2013 PM2.5 NAAQS
2006 and 1997 PM2.5
Designations
NAAQS Designations
EPA Final
Final
(as revised
(Dec. 2014)
EPA Proposed
State
Final
(Aug. 2014)
Recommended 2006)
(1997)
Annual Standard
24-Hour
Annual
Standard
Standard
State/Area Name
Counties and Partial Counties (p)
CALIFORNIA
Imperial County, CA
Imperial (p)
Imperial (p)
Yes
Yes
No
Los Angeles-South
Coast Air Basin, CA
Los Angeles (p)
Los Angeles (p)
Yes
Yes
Yes
Orange
Orange
Yes
Yes
Yes
Riverside (p)
Riverside (p)
Yes
Yes
Yes
San
Bernardino
San Bernardino
(p)
(p) Yes Yes
Yes
Plumas County, CA
Plumas (p)**
Plumas (p)**
Yes
No
No
San Joaquin Valley, CA
Fresno Fresno Yes
Yes Yes
Kern (p)
Kern (p)
Yes
Yes
Yes
Kings
Kings
Yes
Yes
Yes
Madera
Madera
Yes
Yes
Yes
Merced
Merced
Yes
Yes
Yes
San Joaquin
San Joaquin
Yes
Yes
Yes
Stanislaus
Stanislaus
Yes
Yes
Yes
Tulare Tulare Yes
Yes Yes
IDAHO
West Silver Valley, ID
Shoshone (p)**
Shoshone (p)**
Yes
No
No
INDIANA
Louisville, KY-IN
Clark Clark No
No Yes
Floyd
Floyd
No
No
Yes
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2013 NAAQS for Fine Particulate Matter (PM2.5): Designating Nonattainment Areas
2013 PM2.5 NAAQS
2006 and 1997 PM2.5
Designations
NAAQS Designations
EPA Final
Final
(as revised
(Dec. 2014)
EPA Proposed
State
Final
(Aug. 2014)
Recommended 2006)
(1997)
Annual Standard
24-Hour
Annual
Standard
Standard
State/Area Name
Counties and Partial Counties (p)
KENTUCKY
Cincinnati-Hamilton,
Boone (p)
Boone (p)
OH-KY
No No
Yes
Campbell (p)
Campbell (p)
No
No
Yes
Kenton (p)
Kenton (p)
No
No
Yes
Louisville, KY-IN
Bullitt (p)
Bullitt (p)
No
No
Yes
Jefferson
Jefferson
No
No
Yes
OHIO
Canton-Massillon, OH
Stark Stark Yes Yes Yes
Summit Summit No
Yes No
Wayne (p)**
Wayne (p)**
No
No
No
Cincinnati-Hamilton,
Butler Butler
OH-KY
Yes No
Yes
Clermont
Clermont
Yes
No
Yes
Hamilton
Hamilton
Yes
No
Yes
Warren (p)
Warren (p)
No
No
Yes
Cleveland, OH
Cuyahoga Cuyahoga Yes
Yes
Yes
—
Lake
No
Yes
Yes
Lorain
Lorain
No
Yes
Yes
PENNSYLVANIA
Yes
Allegheny, PA
Allegheny (p)
Allegheny (p)
Yes
Yes
Yes
Allentown, PA
Lehigh Lehigh No
Yes No
Northampton
Northampton
Yes
Yes
No
Delaware, PA
Delaware Delaware Yes
Yes
Yes
Lebanon, PA
Lebanon Lebanon Yes
Yes No
Johnstown, PA
Cambria Cambria Yes
Yes Yes
Indiana (p)
Indiana (p)
No
Yes
Yes
TOTALS
6 states
6 states
4 states
3 states
5 states
11 areas
14 areas (39
14 areas (39
13 areas (25
10 areas (25
(31
counties)
counties)
counties)
counties)
counties)
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2013 NAAQS for Fine Particulate Matter (PM2.5): Designating Nonattainment Areas
2013 PM2.5 NAAQS
2006 and 1997 PM2.5
Designations
NAAQS Designations
EPA Final
Final
(as revised
(Dec. 2014)
EPA Proposed
State
Final
(Aug. 2014)
Recommended 2006)
(1997)
Annual Standard
24-Hour
Annual
Standard
Standard
State/Area Name
Counties and Partial Counties (p)
24
whole
25 whole
18 whole
18 whole
20 whole
counties
counties
counties
counties
counties
14
partial
14 partial
7 partial
11 partial
counties
counties
7 partial counties counties
counties
Source: Compiled by CRS using data from EPA PM2.5 NAAQS designations websites.
Notes: ** indicates first time a county has been designated nonattainment for PM NAAQS. “Yes” indicates a
county was designated nonattainment, “No” indicates it was not for the specified PM NAAQS Standard.
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2013 NAAQS for Fine Particulate Matter (PM2.5): Designating Nonattainment Areas
Appendix D. Counties in Nonattainment for the
1997 PM2.5 NAAQS Annual (15 μg/m3) and/or 24-
Hour (65 μg/m3) Standards: U.S. EPA Final
Designations
The figure below provides a historical presentation of counties designated as nonattainment for
the 1997 PM2.5 NAAQS. All counties were designated nonattainment for the PM2.5 annual
standard or both the annual and 24-hour PM2.5 standards. No counties were designated
nonattainment only for the 24-hour PM2.5 standard.
Figure D-1. Counties in Nonattainment for the 1997 PM2.5 NAAQS Annual and/or
24-Hour Standards: U.S. EPA Final Designations
annual (15 μg/m3) and/or 24-hour (65 μg/m3)
Source: Prepared by the Congressional Research Service based on EPA’s final designations for the 1997 PM2.5
NAAQS with data obtained from EPA. There were no PM2.5 nonattainment areas in Hawaii or Alaska.
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Author Contact Information
Robert Esworthy
Specialist in Environmental Policy
resworthy@crs.loc.gov, 7-7236
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