2006 National Ambient Air Quality Standard for Fine Particulate Matter (PM25): Designating Nonattainment Areas)

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The Environmental Protection Agency (EPA) published its final revisions to the National
Ambient Air Quality Standards (NAAQS) for particulate matter (particulates, or PM) on October
17, 2006. EPA’s actions leading up to and following promulgation of the 2006 standard has been
the subject of considerable Congressional oversight. EPA’s implementation of the standard,
beginning with the designation of those geographical areas not in compliance, will likewise be an
area of concern and debate among many Members of Congress, states, and other stakeholders for
some time.
Promulgation of NAAQS sets in motion a process under which the states and the 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
achieve it. As an initial phase of this process, in its August 2008 letters responding to
recommendations received from States, EPA proposed area boundaries (typically defined by
counties or portions of counties) for consideration as nonattainment for the 2006 NAAQS. EPA
expects to finalize these nonattainment designations by the end of 2008, with an effective date of
April 2009. Following formal designation, the states have three years to submit State
Implementation Plans (SIPs), which identify specific regulations and emission control
requirements that would bring an area into compliance.
The 2006 NAAQS strengthened the pre-existing (1997) standard for “fine” particulate matter 2.5
micrometers or less in diameter (PM^2.⁵) by lowering the allowable daily concentration of PM^2.⁵ in
the air. The daily standard averaged over 24-hour periods is reduced from 65 micrograms per ³³
cubic meter (µg/m) to 35 µg/m. However, the annual PM^2.⁵ standard, which addresses human
health effects from chronic exposures to the pollutants, is unchanged from the 1997 standard of ³

15 µg/m. The 2006 NAAQS did not substantially modify the daily standard for slightly larger,

but still inhalable, particles less than or equal to 10 micrometers (PM¹⁰), retaining the 24-hour
standard, but revoked the annual standard for PM¹⁰.
The EPA is not requiring new nonattainment designations for PM¹⁰. The 2006 tightening of the
PM^2.⁵ standards is expected to affect areas currently designated nonattainment for the 1997 PM^2.⁵
NAAQS; a number of areas would be designated nonattainment for the PM^2.⁵ NAAQS for the
first time. In its August 2008 letter to states, EPA identified 215 counties and portions of counties
in 25 states for designation as nonattainment only for the revised 2006 24-hour PM^2.⁵ standard.
EPA’s final designations for nonattainment of the 1997 PM^2.⁵ NAAQS included all or part of 205
counties in 20 states and the District of Columbia, the majority of which did not meet the annual
PM^2.⁵ standard. Overall, the total number of counties or portions of counties throughout the
United States that will be designated “nonattainment,” will increase as a result of the 2006
NAAQS.

Introduc tion ..................................................................................................................................... 1
EPA’s 2006 Changes to the Particulates NAAQS............................................................................2
Designation of Geographical Nonattainment Areas........................................................................3
NAAQS Designation Process....................................................................................................3
PM^2.⁵ NAAQS Designations.....................................................................................................4
Comparing the 2006 and 1997 PM^2.⁵ NAAQS Designations....................................................7
Demonstrating Attainment with the 2006 PM^2.⁵ NAAQS............................................................10
State Implementation Plans (SIPs)..........................................................................................10
EPA NAAQS Implementation Rules.................................................................................11
National Regulations..........................................................................................................11
New Source Review..........................................................................................................12
Transportation Conformity...............................................................................................12
Conclusions ................................................................................................................................... 13
Figure 1. Counties in Nonattainment for the 2006 PM^2.⁵ NAAQS—EPA’s August 2008
Response to States’ Recommendations........................................................................................6
Figure 2. Currently Designated Nonattainment Areas 1997 PM^2.⁵ Standards.................................7
Figure 3. Counties Projected to be Designated Nonattainment for the 2006 PM^2.⁵ NAAQS..........9
Table 1. Counties Designated Nonattainment for the 1997 PM^2.⁵ NAAQS and Projected
to be Nonattainment for the 2006 PM^2.⁵ NAAQS........................................................................8
Table A-1. Schedule for Implementation of the 1997 and the 2006 PM^2.⁵ NAAQS.....................15
Table B-1. Recommended Nonattainment Areas for the 2006 PM^2.⁵ NAAQS and Final
Nonattainment Designations for the 1997 PM^2.⁵ NAAQS.........................................................16
Appendix A. Comparative Timeline for Implementing the 1997 and 2006 PM^2.⁵ NAAQS..........15
Appendix B. Comparison of Recommended Nonattainment Areas for the 2006 PM^2.⁵
NAAQS and the Final Nonattainment Designations for the 1997 PM^2.⁵NAAQS....................16
Author Contact Information..........................................................................................................27

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) “the presence of which in the ambient air 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. The EPA
has identified and promulgated NAAQS for six principal pollutants commonly referred to as
“criteria pollutants”: particulate matter (PM), ozone (O³, a key measure of smog), nitrogen ¹
dioxide (NO², or, inclusively, nitrogen oxides, NOx), sulfur oxides (SOx, or, specifically, SO²),
carbon monoxide (CO), and lead (Pb).
On October 17, 2006, the EPA published its revisions to the NAAQS for particulate matter (PM)
to provide protection against potential health effects associated with short- and long-term ²
exposure to particulates (including chronic respiratory disease and premature mortality). The

2006 particulates NAAQS primarily tightened the pre-existing (1997) standard for “fine” ³

particulate matter 2.5 micrometers or less in diameter (PM^2.⁵). The standard for slightly larger, ⁴
but still inhalable, particles less than or equal to 10 micrometers (PM¹⁰) established in 1987 was
not similarly strengthened.
Establishing NAAQS does not directly limit emissions; 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 the EPA first identify geographic nonattainment areas, those areas
failing to meet the NAAQS based on monitoring and analysis of relevant air quality data. States
have three years from the date of EPA’s final designations to submit State Implementation Plans
(SIPs), which identify specific regulations and emission control requirements that will bring an
area into compliance. EPA expects to finalize the nonattainment designations for the 2006 PM ⁵
NAAQs by the end of 2008 with an effective date of April 2009.
This report focuses primarily on the NAAQS implementation process for designating
geographical nonattainment areas with respect to the tightening of the PM^2.⁵ standards under the
2006 particulates NAAQS, including comparisons with the final designations under the 1997
PM^2.⁵ NAAQS. The EPA is not requiring new nonattainment designations for PM¹⁰. Also included
is a brief overview of states’ subsequent obligations for developing and submitting
implementation plans (SIPs) for attaining or maintaining compliance with the NAAQS.
Appendix A includes a table displaying a state and county breakdown of designated nonttainment

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areas proposed by the states and by EPA for the 2006 PM^2.⁵ NAAQS, as well as the final EPA
designations table for the 1997 PM^2.⁵ NAAQS.
For background of the process used to establish the 2006 particulates NAAQS and analysis of
associated issues see CRS Report RL34762, The National Ambient Air Quality Standard for
Particulate Matter (PM): EPA’s 2006 Revisions and Associated Issues, by Robert Esworthy and
James E. McCarthy.

The Clean Air Act provides for two types of NAAQS: 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”; and secondary standards, necessary to
protect public welfare, a broad term that includes damage to crops, vegetation, property, building ⁶
materials, etc.
The primary NAAQS include a daily (24-hour) limit for both PM^2.⁵ and PM¹⁰, and an annual
limit for PM^2.⁵ (the previous annual limit for PM¹⁰ was revoked). To attain the annual standard,
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 ^th
station can exceed the standard. For example, a 98 percentile 24-hour standard indicates that a
monitoring station can exceed the standard 2% of the days during the year. For PM^2.⁵ and PM¹⁰,
the secondary (welfare) NAAQS are the same as the primary standards.
As modified and published in the October 17, 2006 Federal Register Notice, the primary PM^2.⁵
and PM¹⁰ standards are as follows:
• PM^2.⁵: strengthens the daily (24-hour) standard, which currently allows no more ³
than 65 micrograms per cubic meter (µg/m) under the 1997 PM^2.⁵ NAAQS, by ³^th
setting a new limit of 35 µg/m, based on the three-year average of the 98
percentile of 24-hour PM^2.⁵ concentrations; retains the annual standard at 15 ³
µg/m.
• PM¹⁰: retains the daily (24-hour) standard at 150 µg/m³ set in 1987 but changes ^th
from the 99 percentile to no more than one exceedance per year on average over ³
three years; eliminates the annual maximum concentration (50 µg/m) standard ⁷
for PM¹⁰.
• As will be shown in more detail in the following section, strengthening the daily
standard for PM^2.⁵ will have implications for those counties and partial counties

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designated nonattainment for the 1997 PM^2.⁵ NAAQS. With only a few
exceptions, most of the designated nonattainment areas for the 1997 PM^2.⁵
NAAQS were not meeting the annual standard, but were meeting the daily (24-
hour) standard. Since the PM¹⁰ standard was not strengthened, no new areas will
be designated as nonattainment for PM¹⁰^.To the contrary, a few counties
previously designated nonattainment have been determined by EPA to be in ⁸
attainment since the 2006 revisions to the particulates NAAQS.

Designating geographical areas 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 and
nonattainment areas and setting their boundaries, but 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.
The NAAQS designation process is intended as a cooperative federal-state-tribal⁹ process in
which states and tribes provide initial designation recommendations to EPA for consideration. In
Section 107(d)(1)(A) (42 U.S.C. 7407), the statute states that the governor of each state shall
submit a list to 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 ¹⁰
quality standard” (emphasis added). Areas are identified as “attainment/unclassified” 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 (Section 107(d)1(B)(ii)),
the agency must notify the states and tribes regarding any modifications, allowing them sufficient
opportunity to demonstrate why a proposed modification is inappropriate, but the final
determination rests with EPA.
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 ¹¹
primarily on the basis of three-years of federally referenced monitoring data. EPA began

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developing methods for monitoring fine particles at the time the PM^2.⁵ NAAQS were being
finalized in 1997, and operation of the network of monitors for PM^2.⁵ was phased in from 1999
through 2000.
The network of monitors and their locations have been modified over time. Most recently, in a
separate action in conjunction with the October 2006 publication of the revised particulates
NAAQS, EPA amended its national air quality monitoring requirements, including those for ¹²
monitoring particle pollution. The amended monitoring requirements were intended to help
federal, state, and local air quality agencies by adopting improvements in monitoring technology.
EPA’s final designations for the 2006 particulates NAAQS are to be based on 2003-2007
monitoring data.
In addition to air emission and air quality data, EPA considers a number of other relevant ¹³
factors, 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), growth rates, traffic and commuting patterns,
weather and transport patterns, and geography/topography. States and Tribes may submit
additional information on factors they believe are relevant for EPA to consider.
Nonattainment areas include those counties where pollutant concentrations exceed the standard as
well as those that contribute to exceedance of the standard in adjoining counties. Entire
metropolitan areas tend to be designated nonattainment, even if only one county in the area has
readings worse than the standard. In addition to identifying whether monitored violations are
occurring, 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.

In December 2007, 20 states provided EPA with recommended nonattainment boundaries for the
2006 revised particulates NAAQS based on 2004 to 2006 monitoring data. The states identified
46 areas comprising 116 counties, including 31 partial counties (see Table A-1 for state by state
county/area nonattainment designations). The recommended designations are primarily based on
2004-2006 monitoring data, criteria and technical guidance from EPA and assistance from its
regional offices, and states’ own relevant information and criteria.
The CAA does not specifically require combining neighboring counties within the same
nonattainment area, but it does require the use of metropolitan statistical area boundaries in the
more severely polluted areas (Section 107(d)(4)(A)(iv)). However, unlike the 1997 PM^2.⁵

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standards, Metropolitan Statistical Areas or Consolidated Metropolitan Statistical Areas¹⁵ did not
generally serve as the “presumptive boundary” for nonattainment areas under the 2006 PM^2.⁵
standards. Rather than establish a presumption for the minimum size of an area, in its June 2007 ¹⁶
guidance 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 PM^2.⁵would 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 PM^2.⁵standards. This information in
conjunction with air emission and air quality data, as well other relevant factors as recommended
in EPA’s guidance, such as population density, growth rates, traffic and commuting patterns,
weather and transport patterns, and geography/topography, were used by states in determining the
boundaries for the designated areas.
As required by statute, EPA responded to the states with its modifications to the area designation
recommendations for the 2006 PM^2.⁵ NAAQS for the 24-hour standard in letters dated August 19,

2008. The EPA solicited the states’ comments and additional information for consideration in ¹⁷

determining the final designations. As it did in implementing the 1997 PM^2.⁵ NAAQS and has
done with other NAAQS, EPA used its discretion to expand the size of nonattainment areas
(added more counties or portions of counties) or to combine areas that a state listed as separate
areas into a single larger unit, EPA also combined nonattainment counties across state lines into
the same nonattainment area, if the counties are part of the same metropolitan area.
The counties that EPA has identified as nonattainment for the 2006 PM^2.⁵ NAAQS are indicated
in the map in Figure 1 on the next page. While the identified areas can seem small compared with
the approximately 3,000 counties in the United States, nonattainment counties tend to have larger
populations than those in attainment: for example, nearly 90 million people (about 30% of the
U.S. population) live in the 205 counties designated nonattainment for the current 1997 PM^2.⁵
NAAQS. The map distinguishes those counties not previously designated nonattainment for the
PM^2.⁵ NAAQS and those areas that are being designated for the 2006 PM^2.⁵ 24-hour standard, that
were previously designated nonattainment for the 1997 PM^2.⁵ NAAQS.
The agency identified 57 areas in 26 states, comprising 215 counties (169 counties and portions
of 46 additional counties) for designation as nonattainment for the revised 2006 24-hour PM^2.⁵
standard (see table in Appendix A for state by state county/area nonattainment designations). The
EPA’s designations do not identify counties violating the annual standard, as the level is
unchanged from the 1997 PM^2.⁵ NAAQS. Areas include whole and partial counties and, as with
the designations for the 1997 PM^2.⁵ and other criteria pollutant NAAQS standards, several areas
include counties from multiple states.

¹⁵^A^s^defⁱ^ne^{d by}^the^O^f^fⁱ^c^e^of^Maⁿ^a^g^e^m^e^{nt B}^udg^e^t^{. F}^o^r^m^o^r^e^inf^o^r^m^a^{tion o}ⁿ^m^e^tr^opol^ita^{n a}^r^e^a^s^{, s}^e^e
^h^ttp^:^//www^.^cen^su^s.^go^v/^p^o^p^u^lation^/^www/^estim^at^es/^a^b^o^u^t^m^e^tro^.^h^t^ml.
¹⁶^S^{ee E}^P^A^’^{s gu}ⁱ^d^an^{ce o}ⁿⁱ^t^s^w^e^b^sⁱ^t^e^“A^r^{ea Desi}^gn^atⁱ^oⁿ^s^f^o^{r 20}⁰⁶²⁴^-Ho^u^r^P^M^2.⁵^NAA^QS^—T^echⁿⁱ^cal^In^f^o^rm^atⁱ^oⁿ^,^”
^http:^//w^w^w^.e^pa^.g^ov^/^ttn/ⁿ^a^a^q^s^/^pm^/pm^25_2⁰⁰^6_te^c^h^inf^o^.htm^l.
¹⁷^Forⁱⁿ^f^o^r^m^a^{tion r}^e^g^a^r^d^ing^E^P^A^’^{s A}^u^g^u^s^t^19,²⁰⁰⁸^de^sⁱ^gⁿ^a^tio^ns^{, s}^e^e^http:^//w^w^w^.e^pa^.g^ov^/^p^m^d^e^s^ig^na^tions^/
²⁰⁰^6s^taⁿ^d^a^r^ds^/^r^e^g^s^.^ht^m^#2.

Figure 1. Counties in Nonattainment for the 2006 PM^2.5 NAAQS—EPA’s August

2008 Response to States’ Recommendations

^(viol^a^{ting the 24-hour standard (35}^µ^g/m³^{) onl}^y⁾
^Source:^Prepa^{red by t}^{he Congr}^{essional Research Service ba}^sed^{on EPA’s Responses to State}^{Nonattainment}
^{Recommendations, August}^{19, 2}⁰^{08, with data compiled from EPA’}^{s website for PM}^{designations. Partial counties}
^{are shown o}ⁿ^the^{map as}^whole^{counties. http://www.epa.gov/pm}^{designations/.}
States (and tribal groups) had 120 days to respond to EPA’s recommendations, and the agency ¹⁸
also issued a notice for a 30-day public comment period. EPA expects to finalize these ¹⁹
nonattainment designations (based on 2005-2007 monitoring data) by December 18, 2008, with
an effective date of April 2009. The date of final designations may be extended up to one year,
but no later than December 18, 2009, if the Administrator determines that the agency has
insufficient information to promulgate the designations.
In responding to EPA’s proposal for Nonattainment designations for the 1997 PM^2.⁵ NAAQS, a
number of states challenged the agency and maintained support for their original
recommendations. The final EPA designations for the 1997 PM^2.⁵ NAAQS reflected minor
modifications to its proposal; primarily, 19 counties were removed from the list of nonattainment
areas, and other counties were redefined by designating only specified locations (“partial”) within
the county as nonattainment. EPA also subsequently denied six petitions submitted to the agency
requesting reconsideration of the previous designations of one or more full or partial counties as ²⁰
nonattainment for the 1997 PM^2.⁵ NAAQS.

¹⁸⁷³^Fe^de^{ral Re}^giste^r⁵¹²^57,^Se^pt^em^be^r^{2, 2}⁰⁰⁸^.
¹⁹^R^e^vⁱ^sⁱ^ons^to^A^m^bieⁿ^{t A}ⁱ^r^Monit^o^rⁱ^ng^R^e^g^u^la^tio^ns^{, f}ⁱ^na^{l r}^u^le^{, 7}¹^F^e^de^r^a^{l Re}^gis^t^e^r⁶¹²^35-⁶¹³²^{8, O}^c^tobe^r^17,²⁰⁰⁶
^http:^//www^.e^pa^.g^ov^/^a^ir/pa^r^tic^le^p^o^lluti^on/^a^c^tions.^h^tm^l.
²⁰^T^h^e^pe^titio^ns^w^e^re^f^o^{r c}^ount^ie^sⁱⁿ^G^e^orgⁱ^a^,^Illinois^,^Mic^h^ig^aⁿ^,^Mi^s^s^{ouri, O}^h^io^{, a}ⁿ^d^W^e^s^t^Vⁱ^rg^inia^{; s}^e^e
^http:^//w^w^w^.e^pa^.g^ov^/^p^m^d^e^s^ig^na^tions^/19^97s^ta^nda^r^d^s^/^r^e^g^s^.htm^.

As of August 2008, EPA’s final designations for nonattainment of the 1997 PM^2.⁵ NAAQS (those
areas with or contributing to air quality levels exceeding the annual and 24-hour standards) ²¹
included all or part of 205 counties in 20 states and the District of Columbia. As indicated in the
map in Figure 2 the designated nonattainment areas for the 1997 PM^2.⁵ NAAQS are primarily
concentrated in the central, mid-Atlantic, and southeastern states east of the Mississippi River, as
well as in California. More than 2,900 counties in 30 states have been designated
attainment/unclassifiable for the 1997 PM^2.⁵ NAAQS.
Figure 2. Currently Designated Nonattainment Areas 1997 PM^2.5 Standards
^(viol^a^{ting the annual (15}^µ^g/^m³^{) and/or 24-hour (65}^µ^g/m³^{) standar}^d⁾
^Sources:^{U.S. EPA, PM Standards Revision - 200}^{6 G}^rap^{hs and}^Ma^{ps, Oct. 25,}²⁰⁰⁶^{http://www.epa}^.gov/^oar/
^{particlepollution/}^naaq^srev²⁰^06.ht^{ml#maps. The ma}^{p includes t}^{he 3}^{-county nonattai}^{nment a}^{rea in Pe}^nnsylvania
^{determined by}^{EPA to be in attai}^{nment in}^Aug^{ust 2}⁰⁰^{8; the}^{re are}^{no PM}^2.5^nonattain^{ment a}^{reas in}^{Hawaii or}
^{Alaska, which were}^{not included on the}^{EPA map.}

²¹^S^{ee E}^P^A^’^{s P}^M^2.⁵^D^e^sⁱ^gⁿ^a^tions^w^e^bs^ite^a^t^htt^p^://w^w^w^.e^pa^.g^ov^/^p^m^d^e^s^ig^na^tions^{. Se}^e^a^l^s^o^CR^{S Re}^p^o^rt^RL³²⁴³^1,
^Partic^ul^ate^M^a^tte^{r (}^P^M^2.⁵⁾^:^I^m^ple^m^eⁿ^tati^on^{of t}^h^e¹⁹⁹⁷^N^a^tio^nal^A^m^bieⁿ^{t Air}^Q^ual^ity^St^an^dar^ds⁽^N^AAQ^S)^{, by}^R^obe^r^t
^Esw^o^rthy^.

Based on EPA’s recommendations for the 2006 PM^2.⁵ NAAQS, a few counties would be
designated nonattainment for PM^2.⁵ for the first time but the majority of the counties identified
overlap with EPA’s final nonattainment designations for the 1997 PM^2.⁵ NAAQS. Most of the
1997 PM^2.⁵ nonattainment areas were only exceeding the annual standard; only 12 counties were
exceeding both the 24-hour and the annual standards. Thus, tightening the 24-hour standard will
result in an increased number of areas being designated nonttainment based on exceedances of
both the 24-hour and the annual standard.
Table 1 below illustrates the comparative geographic distribution of counties projected to be in
nonattainment with the 2006 PM^2.⁵NAAQS (based on EPA’s August 2008 letters to states and
tribes), and those counties in EPA’s final area designations for the 1997 PM^2.⁵ NAAQS. The map
in Figure 3 below, overlaps the final nonattainment designations for the annual and 24-hour
standard under the 1997 PM^2.⁵ NAAQS, with the nonattainment areas for the 24-hour standard as
modified under the 2006 PM^2.⁵ NAAQS, identified by EPA in its August 2008 letters to states.
Table 1. Counties Designated Nonattainment for the 1997 PM^2.5 NAAQS and
Projected to be Nonattainment for the 2006 PM^2.5 NAAQS
^PM^2.5^NAA^{QS (ann}^ual/24-ho^ur^µ^g/m³⁾
¹⁹⁹^{7 Standard}²⁰⁰^{6 Standard}
^15/6⁵^µ^g/m³^15/3⁵^µ^g/m³
^National^{West East}^National^{West East}
^Num^{ber of cou}^{nties (including pa}^{rtial counties and D.C.)}
^{Total exceeding the standard}²⁰⁵¹³¹⁹²²⁶⁵⁴⁵²²⁰
^{Exceeding t}^he^24-hou^{r and a}ⁿⁿ^u^a^l¹²¹²^{0 156}^{13 143}
^standards
^{Exceeding t}^he^24-hou^{r standa}^{rd only}⁰⁰⁰⁵⁸³²²⁶
^{Exceeding t}^{he an}^{nual sta}^{ndard on}^ly¹⁹³¹¹⁹²⁵¹⁰⁵¹
^Source:^Prepa^{red by t}^{he Congr}^{essional Research Service with da}^{ta compiled from EPA’s website f}^{or PM}
^{designations http://www.epa.gov/pmdesignations/. Nonattainme}^nt^{counties for t}^{he 2}^4-hour^standar^{d are based}
^{on those recomme}^{nded by}^{EPA in their A}^ugust²⁰⁰⁸^{letters to sta}^{tes; Nonattainme}^{nt cou}^{nties for t}^{he an}^nual
^{standard are}^{based on t}^{he Octob}^{er 2}⁰⁰⁶^{final area designations fo}^{r the}¹⁹^{97 P}^M^2.5^NAAQS.
^Note:^{The counties in the ta}^{ble f}^{or the 2}⁰⁰⁶^sta^{ndards reflect t}^{hose designated for the}^24-^{hour onl}^{y by}^EPA
^August²⁰^{08 in}^res^{ponse to State}^{s’ recommendations for no}^{nattainment a}^{rea bo}^{undaries for t}^he²⁰⁰⁶^PM^2.5
^{NAAQS based on}²⁰^04-²⁰^{06 mo}^{nitoring data, combined with the}^{final annual sta}^{ndards for t}^he¹⁹⁹⁷^PM^2.5
^NAAQS.

Figure 3. Counties Projected to be Designated Nonattainment for the 2006 PM^2.5 NAAQS
^(viol^a^{ting the annual (15}^µ^g/^m³^{) and/or 24-hour (65}^µ^g/m³^{) standar}^d⁾
ⁱ^{ki/CRS-R40096}
^g/w
^s^.or
^le^ak
^://wiki
^h^ttp
^Source:^Prepa^{red by t}^{he Congr}^{essional Research Service with da}^{ta compiled from EPA’s website f}^{or PM designations http://www.e}^pa.gov/pmd^{esignations/. Nonattainment}
^{counties for t}^{he 2}^4-hour^standar^{d are based on t}^{hose recomme}ⁿ^{ded by EPA in t}^{heir Aug}^ust²⁰⁰⁸^{letters to states; nonattainme}^{nt c}^{ounties for the}^an^{nual standa}^{rd are}

^{based on the}^Octobe^{r 2}⁰⁰⁶^final^{area designations for the}¹⁹⁹⁷^P^M^2.5^{NAAQS. Partial counties are}^{shown on t}^{he ma}^{p as w}^{hole counties.}

It is difficult to anticipate what effect this may have on current control measures in these areas. In
some areas, current measures focused on achieving attainment for the annual standard may be
sufficient to attain the 24-hour standard as well. Other areas may require supplementing current
measures or significant modifications to ensure compliance over a shorter averaging period. 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.
Once 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.

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 emitting criteria pollutants. Areas designated 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 nonattainment, state, local and
tribal governments must outline detailed control requirements in plans demonstrating how they
will meet the 2006 PM^2.⁵ NAAQS. These plans, defined as state implementation plans and
referred to as SIPs (TIPs for tribal implementation plans), must be submitted to EPA three years
after the effective date of Agency’s final designations. If states fail to develop an adequate
implementation plan, EPA can impose one.
SIPs include pollution control measures that will be implemented by federal, state, and local
governments, and rely on models of the impact on air quality of projected emission reductions to
demonstrate attainment. SIPs must identify, among other items, specific regulations, emissions
limitations, and monitoring provisions that will bring an area into compliance. Under the CAA,
states are required to meet the 2006 PM^2.⁵standard “as expeditiously as practicable,” but no later
than five years from the date of designation—April 2014—unless an extension allowed under the ²²
CAA is granted.
States and local governments are required to develop and implement new or revised plans (SIPs)
for addressing emissions in those areas that do not meet the 2006 revised PM^2.⁵NAAQS. Several
counties identified by EPA in its August 2008 letters to states would be designated as
nonattainment for the PM^2.⁵ NAAQS for the first time. As noted earlier, a large portion of the

²²^Unde^{r se}^c^tio^{n 1}^72(a⁾⁽²^)(A^{) of}^the^CAA^,^EP^A^m^a^y^g^r^aⁿ^{t a}ⁿ^a^r^e^a^aⁿ^e^x^te^nsion^of^theⁱⁿ^itia^{l a}^ttaⁱⁿ^m^e^{nt da}^te^f^o^r^one^t^o
^fⁱ^v^e^y^ear^{s (i}ⁿ^no^{case l}^a^t^e^{r t}^h^an¹⁰^y^ear^{s a}^f^t^e^{r t}^h^{e d}^e^si^gn^atⁱ^o^{n d}^a^t^e^f^o^{r t}^h^{e area).}^A^st^at^{e req}^u^e^stⁱⁿ^{g a}ⁿ^ext^eⁿ^sⁱ^o^{n m}^u^st
^s^ubm^{it a}ⁿ^im^plem^eⁿ^ta^{tion p}^l^aⁿ⁽^S^I^P⁾^by^the^r^e^quir^e^{d de}^a^d^lⁱ^ne^t^h^a^tⁱⁿ^c^l^ude^s^,^a^m^ong^ot^he^r^thiⁿ^g^s^{, s}^u^f^fⁱ^cⁱ^eⁿ^{t inf}^o^r^m^a^tion
^de^m^onstra^ting^tha^t^a^tta^inm^e^{nt by}^theⁱⁿⁱ^tia^{l a}^tta^inm^e^{nt da}^te^{is “}ⁱ^m^p^ra^c^tic^a^b^le^.”

nonattainment areas for the 2006 PM^2.⁵ NAAQS identified by EPA in August 2008 overlap with
those areas designated nonattainment for 1997 PM^2.⁵ NAAQS. However, as discussed in the
previous section, these counties are unable to meet the 24-hour standard, whereas previously they
were designated nonattainment based on their inability to meet the annual standard. Exceeding
both an annual and 24-hour 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.
In a February 2006 advance notice of proposed rulemaking (ANPR)²³ outlining an
implementation plan for the transition to the 2006 particulates standards, EPA indicated that it
would be beneficial for states to consider control strategies that may be useful in attaining the

2006 revised PM^2.⁵ NAAQS when developing their strategies for the 1997 PM^2.⁵ standards.

The EPA typically publishes an “implementation rule” which describes the requirements that ²⁴
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 to detailing provisions necessary to demonstrate how the 2006 PM^2.⁵
NAAQS will be attained, 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 (oft times pending) federal regulations that ²⁵
contribute to controlling criteria pollutants and their precursors.
The EPA expects that in many cases implementing national strategies—including the 1999 ²⁶
visibility protection regulations (Regional Haze Rule); voluntary diesel engine retrofit
programs; and federal standards scheduled to be implemented between 2004 and 2010 on cars,
light trucks, heavy-duty, and nonroad diesel engines—would provide a framework for achieving
attainment with the PM^2.⁵ NAAQS. However, one of the key federal regulations, EPA’s May 2005 ²⁷
Clean Air Interstate Rule (CAIR), was vacated in a July 11, 2008, decision (North Carolina v. ²⁸
EPA), by the U.S. Court of Appeals for the D.C. Circuit. CAIR was expected to serve as the

²³⁷¹^Fe^de^r^a^{l R}^e^gⁱ^s^t^e^r⁶⁷^18,^Fe^br^ua^r^y^{9, 200}^6.
²⁴^E^P^A^publ^is^he^d^its^fⁱ^na^{l im}^plem^enta^tio^{n r}^u^le^f^o^r^the¹⁹⁹⁷^PM^2.⁵^NAAQS^On^A^p^{ril 25}^,²⁰⁰⁷^.^T^h^{e rule ad}^d^r^esses
^a^tta^inm^e^{nt de}^m^ons^tr^a^{tion a}ⁿ^d^m^ode^ling^;^l^o^c^a^l^e^m^is^sⁱ^{on r}^e^duc^tioⁿ^m^e^a^s^ur^e^s^{, inc}^l^udi^ng^r^e^a^s^ona^bly^av^a^ila^ble^c^ontr^o^l
^te^c^hnol^og^y⁽^R^A^C^T⁾^{, r}^e^a^s^ona^bly^av^a^ila^ble^c^ontr^o^l^m^e^a^s^ur^e^s⁽^R^A^C^M)^{, a}ⁿ^{d r}^e^a^s^ona^ble^f^u^r^t^he^r^pr^og^r^e^s^s⁽^R^FP⁾^;^r^e^gⁱ^ona^l
^em^is^sⁱ^{on r}^e^duc^ti^on^s^t^r^a^te^gⁱ^e^s^{; inn}^o^v^a^tiv^e^pr^og^r^a^m^g^u^idaⁿ^c^e^;^e^m^issⁱ^{on i}ⁿ^v^e^ntor^y^r^e^quir^e^m^e^nts^;^tr^aⁿ^s^p^or^ta^tioⁿ
^c^onf^or^mⁱ^t^y^{; a}^{nd s}^t^a^tiona^r^y^s^our^c^e^te^s^t^m^e^thods⁽⁷²^Fe^de^r^a^{l R}^e^gⁱ^s^t^e^r²⁰⁵⁸^6-²⁰⁶⁶⁷^,^A^p^r^{il 2}⁵^,²⁰⁰⁷⁾^.
²⁵^T^h^e^te^r^m^pre^c^u^{rsor re}^f^e^{rs to a}^dir^e^c^t^l^y^e^m^itte^{d poll}^u^ta^nt^th^a^t^{, w}^h^eⁿ^re^le^a^s^e^d^{to the}^a^t^m^o^sphe^re^{, f}^o^rm^{s, or c}^o^ntri^bute^s
^{to t}^h^e^f^o^rm^a^{tion of}^a^s^e^c^onda^ry^polluta^{nt f}^o^{r w}^h^ic^{h a}ⁿ^a^m^bieⁿ^{t a}ⁱ^r^qua^lity^s^t^a^nda^rd^ha^s^be^eⁿ^a^d^opte^d^.
²⁶⁶⁴^Fe^de^r^a^{l R}^e^gⁱ^s^t^e^r³⁵⁷¹^4-³⁵⁷⁷⁴^{, J}^u^ly^1,¹⁹^99.^Se^e^C^R^S^R^e^p^o^r^t^R^L³²⁴⁸^3,^Visⁱ^bili^ty^{, Re}^gi^on^{al H}^a^z^e^{, an}^{d the}^C^l^e^an
^Air^Ac^t:^St^at^us^of^I^m^ple^m^eⁿ^ta^tioⁿ^{, by}^L^a^r^r^y^P^a^r^k^e^r^a^{nd J}^o^{hn B}^l^o^d^g^e^{tt, a}^l^s^o^C^R^S^R^e^por^t^R^L³²⁹^27,^C^l^e^{an Air}^Iⁿ^te^r^s^t^ate
^R^u^l^e^{: R}^evi^{ew an}^d^Aⁿ^al^ysi^s^{, by}^L^a^rry^P^a^rk^e^r^.
²⁷^P^r^om^ulg^a^te^{d un}^de^r^the^C^A^A^,⁴²^U^.^S.C^.⁷⁴^{01 e}^t^s^e^q^.,⁷⁰^Fe^de^r^a^{l R}^e^gⁱ^s^t^e^r²⁵¹⁶^2,^Ma^y^{12, 2}⁰⁰⁵^.
²⁸⁵³^{1 F}^.³^d⁸⁹⁶⁽^D^.C^{. C}ⁱ^r^.²⁰⁰⁸⁾^.^F^o^r^a^m^o^r^e^de^ta^ile^{d dis}^c^us^sⁱ^on^of^the^c^our^t’^s^de^cⁱ^sⁱ^on^aⁿ^d^its^im^plic^a^tions^{, s}^e^e^C^R^S
^R^e^por^{t R}^L³⁴⁵⁸^9,^Cl^e^aⁿ^Aⁱ^{r A}^f^t^e^r^t^h^{e CA}^IR^Deci^si^on^{: B}^a^{ck t}^o^S^q^u^a^{re On}^e?^{, by}^J^a^m^e^s^{E. Mc}^Ca^rthy^,^L^a^rr^y^P^a^rk^e^r^{, a}^nd
^R^obe^r^t^Me^ltz^.

primary tool to assist downwind states in meeting the PM^2.⁵ (and 8-hour ozone) NAAQS by
mitigating interstate transport of sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions from ²⁹
electric generating units that contribute to the formation of PM^2.⁵.
The D.C. Circuit Court’s decision to vacate CAIR puts the focus back on § 126 petitions as the
available means to address interstate transport of air pollutants in the immediate future. Under §
126 of the CAA, areas may petition EPA to impose controls on upwind sources that significantly
contribute to their nonattainment of the standard. EPA has never granted a § 126 petition in the
manner outlined by the statute. The D.C. Circuit’s decision regarding the CAIR could result in ³⁰
significant delays, and has garnered attention in Congress.
Designated nonattainment areas also are 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 ³¹
(PSD) or nonattainment provisions.
If new or revised SIPs for attainment establish or revise a transportation-related emissions budget,
or add or delete transportation control measures (TCMs), they will trigger “conformity” ³²
determinations. Transportation conformity is required by the CAA, Section 176(c), to prohibit
federal funding and approval for highway and transit projects unless they are consistent with
(“conform to”) the air quality goals established by a SIP, and will not cause new air quality
violations, worsen existing violations, or delay timely attainment of the national ambient air
quality standards.
EPA promulgated several transportation conformity rules and rule amendments since the statute ³³
was strengthened as part of the 1990 CAA. The rules generally establish the criteria and

²⁹^Sulf^ur^dioxⁱ^d^e⁽^S^O²^{) i}^s^a^p^r^ecu^rso^r^co^nt^ri^bu^tⁱⁿ^g^t^o^t^h^{e f}^o^rm^atⁱ^oⁿ^of^P^M^2.⁵^coⁿ^cen^t^r^atⁱ^oⁿ^s^,^an^{d NOx i}^s^{a p}^r^ecu^rso^r^(a
^poll^u^ta^nt^tha^t^is^tr^aⁿ^s^f^or^m^e^{d in a}ⁱ^r^{to f}^o^r^m^a^nothe^r^aⁱ^r^poll^u^ta^nt)^c^oⁿ^t^rⁱ^but^ing^t^o^the^f^o^r^m^a^{tion of}^b^o^th^oz^one^aⁿ^d^PM^2.⁵
^c^onc^eⁿ^tr^a^tio^ns^{. E}^P^A^ha^s^c^o^nc^lu^d^e^{d tha}^t^SO²^aⁿ^d^N^O^x^em^is^sⁱ^ons^{, t}^h^r^o^ug^{h the}^phe^nom^e^non^of^aⁱ^r^pol^lutio^{n tr}^aⁿ^s^por^t,
^c^ontrⁱ^bute^sⁱ^gⁿ^if^ic^aⁿ^tly^{to dow}^nw^ind^no^na^tta^inm^e^{nt, or}^inte^r^f^e^r^e^wⁱ^{th m}^a^inte^na^nc^e^,^of^the^P^M^2.⁵^aⁿ^{d 8-}^h^our^oz^one
^NAAQS⁽⁷⁰^F^e^d^e^{ral Register 2}⁵¹⁶²^,^M^a^y¹²^,²⁰⁰⁵^).
³⁰^For^a^m^o^r^e^de^ta^ile^d^dis^c^us^sⁱ^oⁿ^of^the^c^o^ur^t’^s^de^cⁱ^sⁱ^oⁿ^aⁿ^{d its}^im^plic^a^tions^{, s}^e^e^C^R^S^R^e^p^o^r^t^R^L³⁴⁵⁸^9,^Clean^Air^After
^t^h^{e CA}^IR^Deci^si^on^{: B}^a^{ck t}^o^S^q^u^a^{re On}^e?^{, by}^J^a^m^e^s^{E. Mc}^C^a^r^t^hy^,^L^a^r^r^y^P^a^r^k^e^r^{, a}^{nd R}^obe^r^t^Me^ltz^{, a}^l^s^o^s^e^e^r^e^la^te^d
^dis^c^us^sⁱ^onⁱⁿ^C^R^S^R^e^p^o^r^t^R^L³²⁴^31,^Par^tic^ulate^M^a^t^t^e^r⁽^P^M^2.⁵⁾^:^I^m^ple^m^eⁿ^tati^on^of^the¹⁹⁹⁷^N^a^ti^o^nal^Am^bieⁿ^t^Air
^Quality^Staⁿ^d^a^rds⁽^N^AAQS)^,^by^R^obe^r^t^Es^w^o^r^t^hy^.
³¹^Se^e^C^l^e^aⁿ^Aⁱ^r^A^c^{t, P}^a^r^t^D^—^Plaⁿ^R^e^quir^e^m^e^nts^f^o^r^N^ona^tta^inm^e^{nt A}^r^e^a^s^,^s^e^c^tions¹⁷^1-¹⁷⁸^,^c^o^difⁱ^e^d^a^t⁴⁰^C^F^R
^52.²⁴⁽^f⁾⁽¹⁰⁾^.
³²⁴²^U^.^S^.^C^.⁷⁵⁰⁶⁽^c⁾^.
³³^E^P^A^c^onf^or^mⁱ^t^y^r^u^le^pr^om^ulg^a^{ted o}ⁿ^N^o^v^e^m^b^e^r^24,¹⁹^{93 (}⁵⁸^Fe^d^e^r^a^{l R}^e^gⁱ^s^t^e^r⁶²¹⁸⁸⁾^{, a}ⁿ^{d s}^u^bs^e^q^u^e^ntly^am^e^nde^d;
^s^e^e^EP^A^’^s^“^C^hr^on^olog^ic^a^l^Lⁱ^s^t^of^T^r^aⁿ^s^por^ta^tio^{n C}^o^nf^or^mⁱ^t^y^R^u^lem^a^kⁱ^ng^s^”^a^t^http:^//w^w^w^.e^pa^.g^ov^/^o^ta^q/^s^t^a^t^e^r^e^s^our^c^e^s^/
^tr^aⁿ^s^c^onf^/c^onf^-^r^e^g^s^-^c^.ht^m^{, a}^{nd “}^T^r^a^ns^por^ta^ti^{on C}^onf^or^mⁱ^t^y^R^e^g^u^la^tⁱ^ons^C^u^r^r^e^{nt a}^s^of^J^a^nua^r^y^2008,”^E^P^A^420-^B^-^08-
⁽^c^onti^nue^d.^..)

procedures for determining whether transportation plans, transportation improvement programs
(TIPs), or projects conform to a state’s SIP.

The designation of geographical areas unable to meet the NAAQS is a critical step in NAAQS
implementation, and historically has been an issue of concern and debate among EPA, states and
tribes, various stakeholders, and many Members of Congress. The EPA’s 2006 tightening of the
PM^2.⁵ standards will increase the number of areas (typically defined by counties or portions of
counties) in nonattainment, and subsequently potentially result in an encumbrance on states to
achieve compliance.
In August 2008 letters to states, EPA provided its proposed modifications to nonattainment
designation recommendations submitted by states for the 2006 PM^2.⁵ NAAQS. EPA intends to
finalize the designations for the 2006 PM^2.⁵ NAAQS by December 18, 2008, although this
determination could be delayed up to a year if the Administrator determines that the agency has
insufficient information. Historically, there have been disagreements between EPA and states, and
other stakeholders, with regard to final NAAQS nonattainment designations.
Following the final nonattainment determination, State, local and tribal governments are to
outline detailed control requirements in plans (or SIPs) demonstrating how areas designated
nonattainment will meet the 2006 PM^2.⁵ NAAQS. Although a large portion of the nonattainment
areas for the 2006 PM^2.⁵ NAAQS identified by EPA in August 2008 overlap with those areas
designated nonattainment for 1997 PM^2.⁵ NAAQS, these new designations are based on the 24-
hour standard, whereas the previous designations were based on the annual standard. The
implications of this with regard to SIPs could vary significantly from area to area based on
numerous factors.
States would not be required to submit SIPs until 2012, and would not have to meet the PM^2.⁵ ³⁴
standard until 2014 (or April 2019, if qualified for an extension). The EPA is not requiring new
nonattainment designations for PM¹⁰, and it does not anticipate any significant incremental cost
impacts associated with the change in the PM¹⁰ standard. The associated impacts on specific
geographical nonattainment areas would be speculative at best, because compliance with the 2006
revised particulates NAAQS is several years off.
With regard to the 1997 PM^2.⁵ NAAQS, states with nonattainment areas must be in compliance
with the 1997 PM^2.⁵ NAAQS by April 5, 2010, unless they are granted an extension.
Implementation of the 1997 PM^2.⁵ NAAQS, already delayed considerably, is threatened with
further delay as a result of the U.S. Court of Appeals for the D.C. Circuit’s July 11, 2008, decision ³⁵
(North Carolina v. EPA) that would vacate the Clean Air Interstate Rule (CAIR). Further delays

^(...c^on^tin^ue^d)
⁰⁰¹^{, J}^aⁿ^u^a^r^y^2008,^htt^p^://w^w^w^.e^p^a^.g^ov^/ota^q/^s^t^a^t^e^r^e^s^ourc^e^s^/^t^ra^ns^c^o^nf^/re^g^s^/⁴²⁰^b0⁸⁰⁰¹^.p^df^.
³⁴^Unde^r^§¹⁷^2(a^)(2)(A^{) of}^the^CAA^,^EP^A^m^a^y^g^r^aⁿ^{t a}ⁿ^a^r^e^a^aⁿ^e^x^te^nsion^of^theⁱⁿ^itia^{l a}^ttaⁱⁿ^m^e^{nt da}^te^f^o^{r one}^to^fⁱ^v^e
^{years (n}^o^t^l^a^t^e^{r t}^h^{an 10}^y^ears^af^t^e^{r t}^h^{e d}^e^si^gn^atⁱ^oⁿ^d^a^t^e^f^o^{r t}^h^{e area).}^A^st^at^{e req}^u^e^stⁱⁿ^{g an}^ext^eⁿ^sⁱ^oⁿ^m^u^st^su^b^mⁱ^t^an
^im^plem^eⁿ^ta^{tion pla}ⁿ⁽^S^I^P⁾^by^the^r^e^quir^e^d^de^a^d^li^ne^tha^tⁱⁿ^c^l^u^d^e^s^{, a}^m^ong^othe^r^thiⁿ^g^s^{, s}^u^f^fⁱ^cⁱ^eⁿ^{t inf}^o^r^m^a^tion
^de^m^onstra^ting^tha^t^a^tta^inm^e^{nt by}^theⁱⁿⁱ^tia^{l a}^tta^inm^e^{nt da}^te^{is “}ⁱ^m^p^ra^c^tic^a^b^le^.”
³⁵^{42 U}^.^S.C^.⁷⁴⁰¹^e^t^s^e^q.

in implementing 1997 PM^2.⁵ NAAQS would have direct implications for implementing the 2006
PM^2.⁵ NAAQS.
Concerns regarding looming key implementation milestones and attainment deadlines for the

2006 PM^2.⁵ NAAQS, and associated delays effecting implementation of the current 1997 PM^2.⁵

NAAQS, will remain an issue of considerable debate for many stakeholders and interest groups,
as well as Congress.

Table A-1. Schedule for Implementation of the 1997 and the 2006 PM^2.5 NAAQS
¹⁹⁹^{7 PM}^2.5
^Miles^tones^{NAAQS 200}⁶^PM^2.5^NAAQS
^{Revised standard promulgated}^{July 1}^{8, 19}⁹⁷^October^{10, 2}⁰⁰⁶
^{Revised standard effective date}^September¹⁹⁹⁷^December^{18, 2}⁰⁰⁶
^{State-tribal area designation recommendations}^Februar^{y 2}⁰⁰⁴^December^{18, 2}⁰⁰⁷^(bas^ed
^{(based on 2}⁰⁰⁰^-^{on 20}^04-²⁰^{06 monitoring}
²⁰⁰^{2 monitoring}^data)
^data)
^{EPA notifies states and t}^{ribes reg}^{arding modifications to their}^June-J^{uly 2}⁰⁰⁴^August²⁰⁰⁸
^{recommendations}
^{EPA promulgates}^{final area design}^{ations (required one y}^{ear afte}^r^Janua^{ry 5,}²⁰⁰⁵^December^{18, 2}⁰⁰⁸
^{states and tribe}^{s make r}^ecomme^ndations)
^{EPA proposes P}^M^2.5^implementati^{on rule}^November^{1, 2}⁰⁰⁵^NA
^{Final Area designations effective}^{date (typically not later than}⁹⁰^{April 5, 20}⁰⁵^{April 20}⁰⁹
^{days after}^{Federal Register}^p^ublication)
^{States with new tra}^ns^{portation p}^{rojects submit con}^formity^{April 5, 20}⁰⁶^December^{18, 2}⁰⁰⁹
^{determination (required within}^{one year of t}^{he ef}^{fective date of}^(projected)
^{nonattainment}^designation)
^{EPA promulgates}^{final PM}^2.5^impl^{ementation rule}^{April 25, 2}⁰⁰⁷^NA
^{States and tribes s}^u^b^{mit revised implementation plan}^{s (SIPs)}^{April 20}⁰⁸^{April 20}¹²
^{(required th}^{ree yea}^{rs afte}^{r final a}^{rea designations effective date}^(ongoing)
^{unless e}^{xtension gra}^nted)
^{NAAQS statutory}^{compliance de}^{adline for attainment (re}^quired^{April 20}^10-2⁰¹⁵^{April 20}^14-2⁰¹⁹
^{within five years a}^{fter final area}^{designations effective date; u}^p^to
^{ten years}^{with ext}^ension)
^Source:^Prepa^{red by t}^{he Congr}^{essional Research Service ba}^sed^{on U.S. Environmental Protection Agency fa}^ct
^{sheets a}^{nd guidance docume}^nts,^{and relevant}^{Federal Register}^notic^es.
The timeline presented in Table A-1 above reflects the most recent key milestone dates for
implementing the 1997 and the 2006 PM^2.⁵ NAAQS, including actual completions. These
milestones are driven primarily by statutory requirements. The table follows an EPA milestone
schedule outlined in an April 21, 2003, memorandum to EPA regional administrators that also ³⁶
provided the nonbinding guidance for implementation of the 1997 PM^2.⁵ area designations, and ³⁷
the agency’s projected timeline for the 2006 PM^2.⁵ NAAQS.

³⁶^E^P^A^m^e^m^o^r^a^ndum^{, A}^p^r^{il 21,}²⁰^{03, f}^r^om^the^O^f^fⁱ^c^e^of^Aⁱ^r^a^{nd R}^a^dia^tio^{n A}^s^sⁱ^s^t^aⁿ^{t A}^d^mⁱ^nis^t^r^a^tor^J^e^f^f^r^e^y^R^.
^H^o^lm^s^t^e^a^d^{to E}^P^A^Re^gⁱ^ona^{l A}^d^mⁱ^nis^t^ra^tors^,^a^v^a^ila^ble^a^t^[htt^p://w^w^w^.e^pa^.g^ov^/ttn/na^a^q^s^/^pm^/pm^25_g^uide^.htm^l]^.
³⁷^Se^e^[htt^p://w^w^w^.e^pa^.g^ov^/oa^r^/pa^r^tic^le^poll^u^tio^n/^na^a^q^s^r^e^v²⁰⁰⁶^.htm^l]^.

Table B-1. Recommended Nonattainment Areas for the 2006 PM^2.5 NAAQS and
Final Nonattainment Designations for the 1997 PM^2.5 NAAQS
²⁰⁰^{6 PM}^2.5^NAAQS¹⁹⁹^{7 PM}^2.5^NAAQS
^EPA^State^Final
^Recommended^{Recommended Final}^Designations^Designations
^24-Hour^24-Hour^24-Hour^Annual
^Standard^Standard^Standard^Standard
^{State/Area Name}^{Counties and Partial Co}^{unties (p)}
^ALABAMA
^{Birmingham, AL}^{Jefferson Jefferson}^Jefferson
^Shelby^Shelby
^{Walker (p)}^{Walker (p)}
^{Chattanooga, AL-TN-}^Jackson^(p)
^GA
^ALASKA
^Fairba^{nks, AK}^{Fairbanks N. Star (}^p)^{Fairbanks N. Star (}^p)
^{Juneau, AK}^Junea^{u (p)}
^ARIZONA
^{Nogales, A}^Z^{Santa Cruz}^{Santa Cruz (p)}
^CALIFORNIA
^{Chico, CA}^{Butte Butte}^(p)
^{Imperial County, CA}^{Imperial Imperial}^(p)
^{Los Angeles, CA}^{Los Angeles (p)}^{Los Angeles (p)}^{Los Angeles (p)}
^Orange^Orange^Orange
^{Riverside (p)}^{Riverside (p)}^{Riverside (p)}
^{San Bernardino (p)}^{San Bernardino (p)}^{San Bernardino}
^(p)
^{Sacramento, CA}^{El Dorado (p)}
^Placer^(p)
^Sacramento^Sacramento
^Solano^(p)
^Yol^o

²⁰⁰^{6 PM}^2.5^NAAQS¹⁹⁹^{7 PM}^2.5^NAAQS
^EPA^State^Final
^Recommended^{Recommended Final}^Designations^Designations
^24-Hour^24-Hour^24-Hour^Annual
^Standard^Standard^Standard^Standard
^{State/Area Name}^{Counties and Partial Co}^{unties (p)}
^{San Fr}^{ancisco Bay}^{Alameda Alameda}
^{Area, CA}
^{Contra Costa}^{Contra Costa}
^Marin^Marin
^Napa^Napa
^{San Francisco}^{San Francisco}
^{San Mateo}^{San Mateo}
^{Santa Clara}^{Santa Clara}
^{Solano (p)}^{Solano (p)}
^{Sonoma (p)}^{Sonoma (p)}
^{San Joaquin Val}^{ley, CA}^{Fresno Fresno}^Fresno^Fresno
^{Kern (p)}^{Kern (p)}^{Kern (p)}^{Kern (p)}
^Kings^Kings^Kings^Kings
^Madera^Madera^Madera^Madera
^Merced^Merced^Merced^Merced
^{San Joaquin}^{San Joaquin}^{San Joaquin}^San
^Joaquin
^Stanislaus^Stanislaus^Stanislaus^Stanislaus
^Tulare^Tulare^Tulare^Tulare
^{Yuba City-Marysville,}^{Sutter Sutter}^(p)
^CA
^Yuba^Yuba(p)
^CONNECTICUT
^{New York, NY}^-NJ-CT^{Fairfield Fairfield}^Fairfield
^{New Have}ⁿ^{New Have}ⁿ^New
^Haven
^DELAWA^RE
^{Philadelphia-}^{New Castle}^{New Castle}^New
^{Wilmington, PA-}^NJ-DE^Castle
^{DISTRICT OF COLUMBIA}
^{Washington, DC-MD-}^{Entire District}

^VA

²⁰⁰^{6 PM}^2.5^NAAQS¹⁹⁹^{7 PM}^2.5^NAAQS
^EPA^State^Final
^Recommended^{Recommended Final}^Designations^Designations
^24-Hour^24-Hour^24-Hour^Annual
^Standard^Standard^Standard^Standard
^{State/Area Name}^{Counties and Partial Co}^{unties (p)}
^ILLINOIS
^{Chicago-Gary-La}^ke^{Cook Cook}^Cook
^{County, IL-IN}
^DuPage^DuPage^DuPage
^Gru^{ndy (p)}^Gru^{ndy (p)}^Gru^{ndy (p)}
^Kane^Kane^Kane
^{Kendall (p)}^{Kendall (p)}^{Kendall (p)}
^Lake^Lake^Lake
^McHen^ry^McHen^ry^McHen^ry
^Will^Will^Will
^{Davenport-Moline-}^{Rock Island}
^{Rock Island, IA-IL}
^{Paducah-Mayfield, KY-}^Massac
^IL
^{St. Louis, MO-IL}^{Madison Madison}^Madison
^Monroe^Monroe^Monroe
^{Randolph (p)}^{Randolph (p)}^{Randolph (p)}
^{St. Cla}^ir^{St. Cla}^ir^{St. Cla}^ir
^INDIANA
^{Chicago-Gary-La}^ke^{Lake Lake}
^{County, IL-IN}
^Porter
^Cincinnati-^Hamilton,^{Dearborn (p)}^{Dearborn (p)}
^OH-KY-IN
^{Evansville, IN}^Dubois^Dubois
^{Gibson (p)}^{Gibson (p)}
^{Pike (p)}^{Pike (p)}
^{Spencer (}^p)^{Spencer (}^p)
^Vanderbu^rgh^Vanderbu^rgh^Vanderbu^rgh
^Warrick^Warrick
^{Indianapolis, IN}^Hamilton^Hamilton
^Hendricks^Hendricks
^Johnson^Johnson
^Marion^Marion^Marion

²⁰⁰^{6 PM}^2.5^NAAQS¹⁹⁹^{7 PM}^2.5^NAAQS
^EPA^State^Final
^Recommended^{Recommended Final}^Designations^Designations
^24-Hour^24-Hour^24-Hour^Annual
^Standard^Standard^Standard^Standard
^{State/Area Name}^{Counties and Partial Co}^{unties (p)}
^Morgan^Morgan
^Lafayette-Fr^ank^{fort, IN}^{Tippecanoe Tippecanoe}
^{Louisville, KY-IN}^Clark^Clark
^Floyd^Floyd
^Jefferson^(p)^Jefferson^(p)
^{Vincennes, IN}^{Knox Knox}
^IOWA
^{Davenport-Moline-}^{Scott Scott}^(p)
^{Rock Island, IA-IL}
^{Muscatine, IA}^{Muscatine Muscatine}^(p)
^KENTUCKY
^Cincinnati-^Hamilton,^{Boone Boone}^Boone
^OH-KY-IN
^Campbell^Campbell^Campbell
^Kenton^Kenton^Kenton
^Clar^{ksville, TN-KY}^Muhle^nberg
^{Huntington-Ashland,}^Boyd^Boyd
^WV-KY-OH
^Lawrence^(p)^Lawrence^(p)
^{Louisville, KY-IN}^Bullitt^Bullitt
^Jefferson^Jefferson
^{Paducah-Mayfield, KY-}^McCrackeⁿ
^IL
^MARYLAND
^{Baltimore, MD}^{Anne Ar}^undel^{Anne Ar}^undel^{Anne Ar}^undel
^{Baltimore City}^{Baltimore City}^{Baltimore City}
^Baltimore^Baltimore^Baltimore
^Carroll^Carroll^Carroll
^Harford^Harford^Harford
^Howard^Howard^Howard

²⁰⁰^{6 PM}^2.5^NAAQS¹⁹⁹^{7 PM}^2.5^NAAQS
^EPA^State^Final
^Recommended^{Recommended Final}^Designations^Designations
^24-Hour^24-Hour^24-Hour^Annual
^Standard^Standard^Standard^Standard
^{State/Area Name}^{Counties and Partial Co}^{unties (p)}
^{Washington, DC-MD-}^Charles
^VA
^Frederick
^Montgomery
^{Prince George’s}
^{Martinsburg, WV-}^Washington
^{Hagerstown, MD}
^MICHIGAN
^Detroit-^{Ann Arbor, MI}^{Livingston Livingston}^Livingston
^Macomb^Macomb^Macomb
^Monroe^Monroe^Monroe
^Oakland^Oakland^Oakland
^{St. Cla}^ir^{St. Cla}^ir^{St. Cla}^ir
^Washtenaw^Washtenaw^Washtenaw
^Wayne^Wayne^Wayne
^{Grand Rapids, MI}^{Kent Kent}
^Ottawa
^MISSOURI
^{St. Louis, MO-IL}^Franklin^Franklin
^Jefferson^Jefferson
^{St. Charles}^{St. Charles}
^{St. Louis}^{St. Louis}
^{St. Louis City}^{St. Louis City}
^MONTANA
^{Libby, MT}^{Lincoln (p)}^{Lincoln (p)}
^{NEW JERSEY}
^{Allentown, PA}^{Warren (p)}
^{New York, NY}^-NJ-CT^{Bergen Bergen}^Bergen
^Essex^Essex^Essex
^Hudson^Hudson^Hudson
^Mercer^Mercer^Mercer
^Middlesex^Middlesex^Middlesex
^Monmouth^Monmouth^Monmouth

²⁰⁰^{6 PM}^2.5^NAAQS¹⁹⁹^{7 PM}^2.5^NAAQS
^EPA^State^Final
^Recommended^{Recommended Final}^Designations^Designations
^24-Hour^24-Hour^24-Hour^Annual
^Standard^Standard^Standard^Standard
^{State/Area Name}^{Counties and Partial Co}^{unties (p)}
^{Morris Morris}^Morris
^Passaic^Passaic^Passaic
^{New York, NY}^-NJ-CT^{Somerset Somerset}^Somerset
^(cont.)
^Union^Union^Union
^{Philadelphia-}^{Burlington Burlington}^Burlington
^{Wilmington, PA-}^NJ-DE
^Camden^Camden^Camden
^Gloucester^Gloucester^Gloucester
^{NEW YORK}
^{New York, NY}^-NJ-CT^{Bronx Bronx}^Bronx
^Kings^Kings^Kings
^Nassau^Nassau^Nassau
^{New York}^{New York}^{New York}
^Orange^Orange^Orange
^Queen^s^Queen^s^Queen^s
^Richmond^Richmond^Richmond
^Rockland^Rockland^Rockland
^Suffolk^Suffolk^Suffolk
^Westchester^Westchester^Westchester
^{NORTH CAROLINA}
^{Hickory, NC}^Catawba
^{Greensboro- Winston}^Davidson
^{Salem-High Point, NC}
^Guilford
^OHIO
^{Canton-Massillon, OH}^{Stark Stark}^Stark
^Cincinnati-^Hamilton,^{Butler Butler}^Butler
^OH-KY-^IN
^Clermont^Clermont^Clermont
^Hamilton^Hamilton^Hamilton
^Warren^Warren^Warren

²⁰⁰^{6 PM}^2.5^NAAQS¹⁹⁹^{7 PM}^2.5^NAAQS
^EPA^State^Final
^Recommended^{Recommended Final}^Designations^Designations
^24-Hour^24-Hour^24-Hour^Annual
^Standard^Standard^Standard^Standard
^{State/Area Name}^{Counties and Partial Co}^{unties (p)}
^Cleveland-Ak^ron-^Ashtab^{ula (p)}^Ashtab^{ula (p)}
^{Lorain, OH}
^Cuyahoga^Cuyahoga^Cuyahoga
^Lake^Lake^Lake
^Lorain^Lorain^Lorain
^Medina^Medina^Medina
^Portage^Portage^Portage
^Summit^Summit^Summit
^{Columbus, OH}^{Coshocton (p)}^{Coshocton (p)}
^Delaware^Delaware^Delaware
^Fairfield^Fairfield^Fairfield
^Franklin^Franklin^Franklin
^Licking^Licking^Licking
^{Dayton-Springfiel}^{d, OH}^Clark^Clark
^Greene^Greene^Greene
^Montgomery^Montgomery^Montgomery
^{Huntington-Ashland,}^{Adams (p)}^{Adams (p)}
^WV-^KY-OH
^{Gallia (p)}^{Gallia (p)}
^Lawrence^Lawrence
^Scioto^Scioto
^{Parkersburg- Ma}^rietta,^{Washington Washington}^Washington
^WV-OH
^{Steubenville- Weirton,}^{Jefferson Jefferson}^Jefferson
^OH-WV
^{Wheeling, WV-OH}^Belmont
^{Youngstown, OH}^{Mahoning Mahoning}
^Trumb^ull^Trumb^ull
^OREGON
^{Klamath Falls, OR}^{Klamath (p)}^{Klamath (p)}
^Oakri^{dge, OR}^{Lane (p)}^{Lane (p)}

²⁰⁰^{6 PM}^2.5^NAAQS¹⁹⁹^{7 PM}^2.5^NAAQS
^EPA^State^Final
^Recommended^{Recommended Final}^Designations^Designations
^24-Hour^24-Hour^24-Hour^Annual
^Standard^Standard^Standard^Standard
^{State/Area Name}^{Counties and Partial Co}^{unties (p)}
^PENNSYLVANIA
^{Allentown, PA}^{Lehigh Lehigh}
^Northam^pton^Northam^pton
^Har^risburg-Leba^non-^{Cumberland Cumberland}^Cumberland
^{Carlisle, PA}
^Dauphin^Dauphin^Dauphin
^Lebanon^Lebanon^Lebanon
^{Johnstown, PA}^{Cambria Cambria}^Cambria
^{Indiana (p)}^{Indiana (p)}^{Indiana (p)}
^{Lancaster, PA}^{Lancaster Lancaster}^Lancaster
^Liberty-Cl^{airton, PA}^{Allegheny (p)}^{Allegheny (p)}^{Allegheny (p)}
^{Philadelphia-}^{Bucks Bucks}^Bucks
^{Wilmington, PA-}^NJ-DE
^Chester^Chester^Chester
^Delaware^Delaware^Delaware
^Montgomery^Montgomery^Montgomery
^Philadelphia^Philadelphia^Philadelphia
^Pittsburgh-^Beaver^{Allegheny (p)}^{Allegheny (p)}^{Allegheny (p)}
^{Valley, PA}
^{Armstrong (p)}^{Armstrong (p)}^{Armstrong (p)}
^Beaver^Beaver^Beaver
^Butler^Butler^Butler
^Greene^(p)^Greene^(p)
^Lawrence^(p)^Lawrence^(p)^Lawrence^(p)
^Washington^Washington^Washington
^Westmoreland^Westmoreland^Westmoreland
^{Reading, PA}^{Berks Berks}^Berks
^{York, PA}^{York York}^York

²⁰⁰^{6 PM}^2.5^NAAQS¹⁹⁹^{7 PM}^2.5^NAAQS
^EPA^State^Final
^Recommended^{Recommended Final}^Designations^Designations
^24-Hour^24-Hour^24-Hour^Annual
^Standard^Standard^Standard^Standard
^{State/Area Name}^{Counties and Partial Co}^{unties (p)}
^WASHINGTON
^{Seattle-Tacoma}^{, WA}^{Pierce (p)}^{Pierce (p)}
^{WEST VIRGINIA}
^{Charleston, WV}^{Kanawha Kanawha}^Kanawha
^Putnam^Putnam^Putnam
^{Huntington-Ashland,}^Cabell^Cabell
^WV-KY-OH
^{Mason (p)}^{Mason (p)}
^Wayne^Wayne
^{Martinsburg, WV-}^Berkeley
^{Hagerstown, MD}
^{Morgantown, WV}^Monongalia
^{Parkersburg- Ma}^rietta,^{Pleasants (p)}^{Pleasants (p)}
^WV-OH
^Wood^Wood
^{Steubenville- Weirton,}^{Brooke Brooke}^Brooke
^OH-WV
^Hancock^Hancock^Hancock
^{Wheeling, WV-OH}^Marshall
^Ohio
^WISCONSIN
^{Green Bay, WI}^Brown
^{Madison-Baraboo, WI}^Columbia
^Dane
^{Milwaukee-Racine, WI}^Milwaukee
^Racine
^Waukesha
^TOTALS
^{25 state}^s^{20 state}^s^{1 state}^{20 state}^{s and D.C.}
^{57 ar}^eas^{46 ar}^eas^{2 areas}^{39 ar}^eas
¹⁶⁹^{whole counties}¹¹⁶^{whole counties}^{9 whole counties}¹⁷⁶^{whole counties}
⁴⁶^{partial counties}³¹^{partial counties}^{3 partial coun}^ties³²^{partial counties}
^Source:^{Compiled by CRS using}^{data from EPA PM designations}^websites.

^R^obert^Esw^o^rt^hy
^Sp^{ecialist i}ⁿ^En^vⁱ^r^oⁿ^m^eⁿ^{tal P}^o^lic^y
^resw^ort^h^y^@^crs^.^l^o^c.g^o^v^,^7-⁷²³⁶