Order Code RL33254
CRS Report for Congress
Received through the CRS Web
Air Quality: EPA’s 2006 Changes to the
Particulate Matter (PM) Standard
Updated November 13, 2006
Robert Esworthy and James E. McCarthy
Specialists in Environmental Policy
Resources, Science, and Industry Division
Congressional Research Service ˜ The Library of Congress

---

Air Quality: EPA’s 2006 Changes to the
Particulate Matter (PM) Standard
Summary
On October 17, 2006, the EPA published its final revisions to the National
Ambient Air Quality Standards (NAAQS) for particulate matter (PM). The EPA
reviewed more than 2,000 scientific studies and found that the evidence continued
to support associations between exposure to particulates in ambient air and numerous
significant health problems, including aggravated asthma, chronic bronchitis, reduced
lung function, heart attacks, and premature death in people with heart or lung disease.
Based on several analytical approaches, the EPA estimates that compliance with the
new NAAQS will prevent 1,200 to 13,000 premature deaths annually, as well as
substantial numbers of hospital admissions and missed work or school days due to
illness. Although a tightening of the PM standards, the new NAAQS are not as
stringent as recommended by EPA staff or the independent scientific advisory
committee (CASAC) mandated under the Clean Air Act.
The new PM NAAQS strengthen the existing (1997) standard for “fine”
particulate matter 2.5 micrometers or less in diameter (PM ) by lowering the
2.5
allowable daily concentration of PM in the air. The new daily standard averaged
2.5
over 24-hour periods is reduced from 65 micrograms per cubic meter (µg/m3) to 35
µg/m3. However, the annual PM standard, which is set in addition to the daily
2.5
standard to address human health effects from chronic exposures to the pollutants,
is unchanged from the 1997 standard of 15 µg/m3, although the CASAC had
recommended a tighter annual standard in the range of 13 to 14 µg/m3. Eighty-eight
million people live in the 208 counties designated as “nonattainment” areas for the
1997 PM NAAQS.
2.5
The new PM NAAQS also would retain the 24-hour standard and revoke the
annual standard for slightly larger, but still inhalable, particles less than or equal to
10 micrometers (PM ). The EPA abandoned its proposal to replace the particle size
10
indicator of PM with a range of 10 to 2.5 micrometers (PM
), and did not follow
10
10-2.5
through on its proposal to exclude any mix of particles “dominated by rural
windblown dust and soils and PM generated by agricultural and mining sources.”
In addition to the divergence from the CASAC’s recommendation, several
elements of the new PM standard may prove controversial, including the decision not
to exclude rural sources from the coarse particle standard. Some have also
questioned the EPA’s strengthening of the standard for all fine particles, without
distinguishing their source or chemical composition. The establishment of PM
NAAQS in 1997 proved controversial and included extensive congressional
oversight. Congress may conduct oversight of the new PM NAAQS, given their
potential for public health and economic impacts.

---

Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
EPA’s 2006 Changes to the PM NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Potential Impacts of the Revised PM NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
EPA’s Monetized Benefits and Cost Estimates . . . . . . . . . . . . . . . . . . . . . . . 6
Potential Health Impacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Geographical Nonattainment Areas: Potential Impacts . . . . . . . . . . . . . . . . 10
Potential Concerns and Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Fine Particulate (PM ) Primary (Health) Standards . . . . . . . . . . . . . . . . . . 13
2.5
Potential Health Benefits of a More Stringent PM Standard . . . . . . 16
2.5
Coarse Particulate (PM ) Primary Standards . . . . . . . . . . . . . . . . . . . . . . . 18
10
Particle Size Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Rural PM Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
10
Secondary PM and PM Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.5
10
Exclusion of More Recent Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Synopses of Stakeholder Reaction to the New PM NAAQS . . . . . . . . . . . . 21
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
List of Tables
Table 1. Primary (Health) NAAQS for PM and PM : Final Revisions (2006),
2.5
10
and Previously Promulgated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Table 2. EPA’s Estimated Total Annual Monetized Benefits and Costs
of Attaining Alternative PM NAAQS in 2020 . . . . . . . . . . . . . . . . . . . . . . 7
2.5
Table 3. EPA’s Predicted Reductions in Adverse Health Effects Annually
in 2020 Associated with Meeting the New PM NAAQS . . . . . . . . . . . . . . 9
2.5
Table 4. Counties with Monitors Projected by Epa to Be in Nonattainment
of the 1997, New (2006), and Alternative Pm Naaqs . . . . . . . . . . . . . . . . 12
2.5
Table 5. PM Primary (Health) NAAQS: Final (2006), Proposed and
2.5
Alternatives, and as Promulgated in 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 6. EPA’s Predicted Reductions in Adverse Health Effects Annually
in 2020 Associated with Meeting the New PM NAAQS and a More
2.5
Stringent Alternative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

---

Air Quality: EPA’s 2006 Changes to the
Particulate Matter (PM) Standard
Introduction
The EPA has identified and promulgated National Ambient Air Quality
Standards (NAAQS) under the Clean Air Act (CAA)1 for six principal pollutants
classified by the agency as “criteria pollutants”: particulate matter (PM), ozone (O ,
3
a key measure of smog), nitrogen dioxide (NO , or, inclusively, nitrogen oxides,2
2
NOx), sulfur oxides (SOx, or, specifically, SO ), carbon monoxide (CO), and lead
2
(Pb). On September 21, 2006,3 EPA Administrator Stephen Johnson signed revisions
to the NAAQS for particulates to provide protection against potential health effects
associated with short- and long-term exposure to particulate matter (including
chronic respiratory disease and premature mortality).
The EPA’s newly promulgated PM NAAQS modify the standards established
in 19874 that focused on particles smaller than 10 microns (PM , or coarse particles)
10
and standards for “fine” particles smaller than 2.5 microns (PM ) introduced for the
2.5
first time with the promulgation of the 1997 PM NAAQS.5 The revised PM NAAQS
are the culmination of the EPA’s most recent statutorily required periodic review,6
based on its evaluation and analysis of more than 2,000 scientific studies available
between 1997 and 2002, and on determinations made by the Administrator. Prior to
this, the most recent changes to any NAAQS, a strengthening of the particulate
matter and ozone standards, were promulgated jointly in 1997. The EPA’s recently
completed review of the PM NAAQS and of the scientific criteria for setting the
standards was initiated not long after the 1997 promulgation.
While the new PM NAAQS generally tighten the air quality standards for
particulate matter, the action has caused considerable controversy, including concerns
that the standards are outside the range recommended by both EPA staff and by the
1 Sections 108-109 of the Clean Air Act (CAA).
2 The NAAQS is for NO ; nitrogen gases that are ozone precursors are referred to as NOx.
2
3 71 Federal Register 61143-61233, Oct. 17, 2006. Available on EPA’s website at
[http://epa.gov/pm/actions.html].
4 52 Federal Register 24640, July 1, 1987.
5 62 Federal Register 38652-38896, July 18, 1997.
6 Section 109(d)(1) of the CAA. According to the statute, the EPA is required to review the
latest scientific studies and either reaffirm or modify the NAAQS every five years.

---

CRS-2
scientific advisory panel established by the Clean Air Act (CAA).7 Conversely, some
continue to contend that available data do not support the need for stricter standards
or, in some cases, even the standards as promulgated in 1997. The new PM NAAQS
are expected to generate national interest and national debate, and possibly oversight
in Congress, as did the 1997 standard.
In order to better understand EPA’s actions, this report provides an analysis of
the EPA’s final revisions to the PM NAAQS, and the estimated costs and benefits of
the new standard and of a more stringent alternative. The report concludes by
highlighting concerns and issues raised regarding the revisions to the PM standards,
including the response of the science advisory committee (Clean Air Scientific
Advisory Committee, or CASAC), as well as actions by Congress.
EPA’s 2006 Changes to the PM NAAQS
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. Under Sections 108-
109 of the CAA, Congress mandated that the EPA set national ambient (outdoor) air
quality standards for pollutants whose emissions “may reasonably be anticipated to
endanger public health (primary standards) or welfare8 (secondary)” and “the
presence of which in the ambient air results from numerous or diverse mobile or
stationary sources.” The statute further requires that every five years EPA review the
latest scientific studies and either reaffirm or modify previously established NAAQS.
The CAA is quite specific on certain steps of the process for establishing and
reviewing NAAQS,9 particularly in regard to the preparation of a “criteria document”
summarizing the scientific information (the resulting criteria to be used by the EPA
Administrator in deciding on the final standard) and the procedural process for
promulgating the standard. The act also established the Clean Air Scientific
Advisory Committee to review criteria and standards, and to advise the
Administrator. The CASAC augments its own resources by creating a review panel
of scientists with expertise specific to the pollutant in question. The PM review
panel consisted of 22 national experts, primarily academics and independent
researchers.10 In addition to the CAA requirements, the EPA has chosen to add the
7 Section 109(d)(2)of the Clean Air Act.
8 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 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” (42 U.S.C. 7602(h)).
9 42 U.S.C. 7408(a)(1), see CRS Report 97-722, Air Quality Standards: The
Decisionmaking Process, by John E. Blodgett and Larry B. Parker.
1 0 For information regarding the CASAC PM review panel see
[http://www.epa.gov/sab/pdf/casac-ltr-06-002.pdf].

---

CRS-3
preparation of a “staff paper” that summarizes the criteria document and lays out
policy options. The CASAC also formally reviews the EPA staff paper.11
The EPA’s most recent review found that the scientific evidence since 1997
reinforced the associations between exposure to PM and numerous cardiovascular
and respiratory health problems, including aggravated asthma, chronic bronchitis,
reduced lung function, irregular heartbeat, nonfatal heart attacks, and premature
death. The CASAC found that the numerous epidemiological studies that the EPA
reviewed “have shown statistically significant associations between the
concentrations of ambient air PM and PM (including levels that are lower than the
2.5
10
1997 PM NAAQS) and excess mortality and morbidity.”12 Further, the EPA
concluded, and most of the CASAC panel concurred, that the scientific evidence
supported modifying the PM standard.
The primary NAAQS for both PM and PM include an annual and a daily
2.5
10
(24-hour) limit. 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 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.
As modified and published in the October 17, 2006, Federal Register Notice,
the primary PM and PM standards are as follows:
2.5
10
! PM : strengthens the daily (24-hour) standard, which currently
2.5
allows no more than 65 micrograms per cubic meter (µg/m3), by
setting a new limit of 35 µg/m3, based on the three-year average of
the 98th percentile of 24-hour PM concentrations; retains the
2.5
annual standard at 15 µg/m.3
! PM : retains the daily (24-hour) standard at 150 µg/m3 but changes
10
from the 99th percentile to no more than one exceedance per year on
average over three years; eliminates the annual maximum
concentration (50 µg/m3) standard for PM .13
10
11 The EPA October 2004 criteria document and December 2005 staff paper, the CASAC
reviews, and related information supporting the 2006 revisions to the PM NAAQS are
available at [http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html].
12 CASAC Particulate Matter (PM) review of EPA’s Review of the National Ambient Air
Quality Standards for Particulate Matter: Policy Assessment of Scientific and Technical
Information (Second Draft PM Staff Paper, January 2005, EPA-SAB-CASAC-05-007, June
6, 2005), available at [http://www.epa.gov/sab/panels/casacpmpanel.html].
13 Based on the findings in the EPA PM criteria document and staff paper, and the CASAC’s
concurrence, that the studies reviewed do not provide sufficient evidence regarding long-
term exposure to PM to warrant continuation of an annual standard, see 71 Federal
10
Register 2653, Section III. Rationale for Proposed Decision on Primary PM Standards,
10
(continued...)

---

CRS-4
For PM and PM , the secondary (welfare) NAAQS are the same as the primary
2.5
10
standards. Table 1 below provides a comparison of the newly revised primary
NAAQS with those previously promulgated for both PM and PM .
2.5
10
Table 1. Primary (Health) NAAQS for PM and PM : Final
2.5
10
Revisions (2006), and Previously Promulgated
Previous NAAQS
EPA Final Rule (2006)
PM (Fine)
2.5
24-Hour Primary Standard
65 :g/m3
35 :g/m3
Annual Primary Standard
15 :g/m3
15 :g/m3
PM (Coarse)
10
24-Hour Primary Standard
150 :g/m3
150 :g/m3
Annual Primary Standard
50 :g/m3
Revoked
Source: Prepared by the Congressional Research Service (CRS), with information from the EPA’s
final PM NAAQS (71 Federal Register 61143-61233, Oct. 17, 2006), and related technical
documents,14 available at [http://www.epa.gov/air/particles/actions.html].
EPA’s final revisions to the standards for fine particulates (PM ) are the same
2.5
as the agency had proposed in January 2006. However, the final 2006 EPA revisions
to the PM NAAQS, while tightening the standards, are not as stringent as those
2.5
recommended by the CASAC and by the EPA staff. With regard to coarse
particulates, the EPA had proposed replacing the current particle size indicator of
PM with a range of 10 to 2.5 micrometers (PM
), referred to as inhalable (or
10
10-2.5
thoracic) coarse particles, and setting a PM
daily standard of 70 µg/m3 rather than
10-2.5
the current PM daily standard of 150 µg/m3. The proposal also included narrowing
10
the focus of the PM
standard to “urban and industrial” sources and excluding
10-2.5
particles typical to rural areas, including “windblown dust and soils and PM
generated by agricultural and mining sources.” The range of alternative standards
considered and proposed and issues associated with the EPA’s final decisions are
discussed later in this report.
Promulgation of NAAQS sets in motion a process under which the states and
the EPA first identify geographic nonattainment areas, those areas failing to comply
with the NAAQS based on monitoring and analysis of relevant air quality data.
The tightening of the PM standards is expected to increase the number of areas
2.5
(typically defined by counties or portions of counties) in nonattainment. States will
13 (...continued)
Jan. 17, 2006.
14 EPA’s final PM staff paper and the CASAC review of the EPA staff paper
[http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html].

---

CRS-5
not be required to meet the new PM standard until April 2015 (April 2020, if
2.5
qualified for an extension15). The EPA estimates that the effective date for the final
designations will not be before April 2010 for the revised PM NAAQS. Following
2.5
formal designation, the states have three years to submit State Implementation Plans
(SIPs), which identify specific regulations and emission control requirements that
will bring an area into compliance.
The EPA is not requiring new nonattainment designations for PM , and it does
10
not anticipate any significant incremental cost impacts of this action. A discussion
of the potential benefits and cost impacts associated with implementation of the new
PM NAAQS follows.
Potential Impacts of the Revised PM NAAQS
As discussed above, in setting and revising the NAAQS, the CAA directs the
EPA Administrator to protect public health with an adequate margin of safety. This
language has been interpreted, both by the agency and by the courts, as requiring
standards based on a review of the health impacts, without consideration of the costs,
technological feasibility, or other non-health criteria.16 This being the case, costs and
benefits did not play a central role in setting the PM NAAQS. Costs and feasibility
are generally taken into account in NAAQS implementation (a process that is
primarily a state responsibility).
Nevertheless, the EPA released a regulatory impact analysis (RIA) on October
6, 2006, to meet its obligations under Executive Order 12866 and in compliance with
guidance from the White House Office of Management and Budget.17 The RIA only
analyzed the benefits and costs of implementing the PM NAAQS. Citing time,
2.5
data, and modeling limitations, the EPA did not analyze the benefits and costs of
retaining the PM standard. 18
10
15 Under section 172(a)(2)(A) of the CAA, the EPA may grant an area an extension of the
initial attainment date for one to five years (in no case later than 10 years after the
designation date for the area). A state requesting an extension must submit an
implementation plan (SIP) by the required deadline that includes, among other things,
sufficient information demonstrating that attainment by the initial attainment date is
“impracticable.”
16 With regard to the non-relevance of cost considerations, see generally Whitman v.
American Trucking Assns., 531 U.S. 457, 465-472, 475-76 (2001).
17 58 Federal Register 51735, Oct. 4, 1993. See the White House OMB website, Regulatory
Matters at [http://www.whitehouse.gov/omb/inforeg/regpol.html#rr].
18 The EPA did not release an RIA assessing the costs and benefits at the time of its January
17, 2006, proposal, but conducted interim and “provisional” analyses regarding certain
aspects of potential risk reductions in specific locations associated with an array of PM2.5
standards. These analyses did not address national impacts, nor did they address PM10
standards. EPA’s interim and “provisional” analyses focused primarily on comparisons of
potential risk scenarios in specified cities and locales. See EPA’s Particulate Matter
Regulatory Actions website at [http://www.epa.gov/air/particlepollution/actions.html].

---

CRS-6
The EPA emphasized that the October 2006 RIA differs from typical RIAs in
that it does not analyze the regulatory impact of an action and that it is primarily for
illustrative purposes. The basis for the benefits calculations are reductions in
ambient concentrations of PM resulting from a reasonable, but speculative, array
2.5
of cost-effective state implementation strategies selected by the EPA for purposes of
analysis. The analysis does not model the specific actions that each state will
undertake in implementing the new PM NAAQS. The EPA includes a detailed
2.5
discussion of the limitations and uncertainties associated with the analyses.
EPA’s Monetized Benefits and Cost Estimates19
The EPA estimated incremental costs of attaining the new PM standard based
2.5
on a set of assumptions and extrapolations regarding currently designated
nonattainment areas, likely control strategies and technologies and their associated
engineering costs, emissions inventories and sources, and regional variability. The
EPA emphasizes that the technologies and control strategies selected for analysis
only illustrate one way for nonattainment areas to reach attainment, and that states
will compile and evaluate a variety of programs and adopt those attainment strategies
best suited for their specific local conditions. For purposes of comparing costs with
monetized benefits, the EPA estimated that the total annual mean social cost of
attainment of the new PM NAAQS incremental to attainment of the 1997 standards
2.5
would be $5.4 billion in 2020.
EPA’s estimates of the monetized benefits of complying with the new PM2.5
standard reflect the valuation associated with predicted reductions in the incidence
of certain health and social welfare effects. In the RIA, the EPA presents a variety
of benefits estimates based on several published epidemiological studies, including
an American Cancer Society (ACS) Study20 used in previous RIAs, and the Harvard
Six Cities Study,21 as well as an expert elicitation study conducted by the EPA in
2006.22 The EPA estimated the total annual monetized benefits of attaining the new
PM NAAQS would range from $15 billion to $17 billion based on the mortality
2.5
function from the ACS study and morbidity function from the published studies.
Using the mortality function developed using the expert elicitation in conjunction
with the morbidity function from the published studies, the EPA’s total annual
19 EPA’s Regulatory Impact Analysis (RIA) of the 2006 National Ambient Air Quality
Standards for Fine Particle Pollution (PM ), available on EPA’s website at
2.5
[http://www.epa.gov/ttn/ecas/ria.html].
20 Pope, C. Arden, III, et al. “Particulate Air Pollution as a Predictor of Mortality in a
Prospective Study of U.S. Adults.” American Journal of Respiratory and Critical Care
Medicine 151 (1995): 669-674.
21 Dockery, Douglas W. et al. “An Association Between Air Pollution and Mortality in Six
U.S. Cities.” New England Journal of Medicine 329 (1993): 1753-1759. See also the Health
Effects Institute, “Statement: Synopsis of the Particle Epidemiology Reanalysis Project.”
Reanalysis of the Harvard Six Cities Study and the American Cancer Society Study of
Particulate Air Pollution and Mortality, July 2000 (includes Nov. 1, 2001 errata sheet), p.
I. ([http://www.healtheffects.org/Pubs/Rean-ExecSumm.pdf]).
22 See Chapter 5 of the EPA’s October 6, 2006, RIA for more detail [http://www.epa.gov/ttn/
ecas/ria.html].

---

CRS-7
benefits are estimated to range from $8 billion to $76 billion in 2020. The EPA’s
estimated monetized benefits for 2020, like the cost estimates, are based on the
EPA’s projected compliance schedule and are incremental to compliance with the
1997 PM NAAQS by 2015.
2.5
According to the October 6, 2006, RIA, the estimated total annual health and
welfare net benefits (subtracting social costs from the monetized benefits) in 2020
of attaining the new PM NAAQS range from $9 billion to $12 billion, based on
2.5
modeling of morbidity and mortality using published epidemiology studies, and from
$2.4 billion to $70 billion, based on derivation from expert elicitation.
The EPA’s benefits and cost estimates are in terms of 1999 dollars and are
incremental to the agency’s modeled attainment strategy for the 1997 PM NAAQS
2.5
by 2015. The baseline case incorporates expected impacts associated with
implementation of recent national regulations addressing emissions from the power
generation sector (e.g., the Clean Air Interstate Rule [CAIR]), as well as various
mobile sources, that contribute to lowering PM concentrations in future years.
2.5
Table 2 below presents a range of the EPA’s cost and monetized benefits estimates.
Table 2. EPA’s Estimated Total Annual Monetized Benefits and
Costs of Attaining Alternative PM NAAQS in 2020
2.5
(1999 $ billions)
2006 PM NAAQS (15/35 :g/m3)
2.5
Discount Ratea
Benefits
Cost
Net Benefits
Benefits based on American Cancer Society Study Mortality Function and Published
Scientific Literature Morbidity Functions
3%
$17
$5.4
$12
7%
$15
$5.4
$9
Benefits Range based on Expert Elicitation Derived Mortality Function and Published
Scientific Literature Morbidity Functions
Low Mean
High Mean
Low Mean
High Mean
3%
$9
$76
$5.4
$3.5
$70
7%
$8
$54
$5.4
$2.4
$59
Source: Prepared by the Congressional Research Service from the Environmental Protection
Agency’s Regulatory Impact Analysis (RIA) of the 2006 National Ambient Air Quality Standards for
Fine Particle Pollution (PM ), Table ES-1, p. ES-7, available on the EPA’s website at
2.5
[http://www.epa.gov/ttn/ecas/ria.html]. Estimates and results have been rounded.
Note: Estimates (costs and benefits) reflect attainment in 2020, which includes implementation of
several national programs and are incremental to compliance with the 1997 PM NAAQS.
2.5
a. The discount rates are as recommended in the EPA’s Guidelines for Preparing Economic Analyses
(2000) and OMB Circular A-4 (2003).

---

CRS-8
In addition to the monetized health benefits estimates, the EPA estimated the
monetary benefits associated with improvements in visibility in selected Class I
national parks and wilderness areas.23 The EPA primarily used a stated preference
approach which estimates values based on sampling surveys asking people what
amount of compensation would be equivalent to a defined improvement in
environmental quality. Extrapolating the results of a study based on a 1988 survey
on recreational visibility value, the EPA estimated visibility “willingness to pay”
benefits to be $530 million in 2020 with attainment of the new PM NAAQS.24
2.5
EPA estimated the cost and benefits of a more stringent alternative PM for
2.5
purposes of comparative analysis. The comparative results are discussed in the
“Potential Concerns and Issues” section of this report.
Potential Health Impacts
The EPA’s most recent report on air quality trends25 reported that nationally, in
2003, fine particle concentrations were the lowest since monitoring began in 1999,
and coarse particle concentrations were the second lowest since 1988 (concentrations
were lower in 2002). Despite the decline, the EPA reports that there were 62 million
people living in 97 counties with monitors measuring fine and coarse particles above
the current NAAQS in 2003.
For purposes of illustration, Table 3 summarizes the EPA’s predicted
reductions in the incidence of a range of adverse health effects annually in 2020 for
the new PM NAAQS (15/35 µg/m3), as reported in its RIA. The range of the
2.5
estimated mean number of reductions in premature deaths is based on the EPA’s
derivations using the ACS and the Harvard Six-City studies. EPA’s mean estimates
for the remaining adverse health effects are based on various epidemiology studies.
The EPA health effects estimates were a primary component of its derivations of the
monetized benefits discussed above.
23 Defined as areas of the country such as national parks, national wilderness areas, and
national monuments that have been set aside under Section 162(a) of the Clean Air Act to
receive the most stringent degree of air quality protection.
24 See Appendix I Visibility Benefits Methodology of the EPA’s October 6, 2006, RIA
[http://www.epa.gov/ttn/ecas/ria.html].
25 EPA, The Particle Pollution Report: Current Understanding of Air Quality and Emissions
through 2003, EPA 454-R-04-002, December 2004 [http://www.epa.gov/airtrends/aqtrnd04/
pm.html].

---

CRS-9
Table 3. EPA’s Predicted Reductions in Adverse Health Effects
Annually in 2020 Associated with Meeting the New PM NAAQS
2.5
Predicted Reductionsa
Adverse Health Effect
(estimated mean)
Premature deaths in individuals with preexisting
2,500 to 5,700b
cardiovascular and respiratory disease
Cases of chronic bronchitis (age >25)
2,600
Cases of acute bronchitis (age 8-12)
7,300
Nonfatal heart attacks (age >71)
5,000
Hospital admissions for cardiovascular or respiratory
1,630
symptoms (age >17)
Emergency room visits for asthma (age <19)
1,200
Cases of aggravated asthma (asthmatics age 6-18)
51,000
Cases of upper and lower respiratory symptoms (asthmatics
97,000
age 6-18)
Days when individuals miss work (age 18-75)
350,000
Days when individuals must restrict their activities because
2,000,000
of symptoms related to particle pollution (age 18-65)
Source: Prepared by the Congressional Research Service with data based on epidemiology studies
presented in Chapter 5 of the Environmental Protection Agency Regulatory Impact Analysis of the
2006 National Ambient Air Quality Standards for Fine Particle Pollution (PM ) Oct. 6, 2006, and
2.5
available on the EPA’s website at [http://www.epa.gov/ttn/ecas/ria.html]. Estimates are rounded by
EPA to two significant digits.
a. For consistency with the emissions and benefits modeling, the EPA used national population
estimates based on the U.S. Census Bureau projections. U.S. Bureau of Census. 2000.
Population Projections of the United States by Age, Sex, Race, Hispanic Origin and Nativity:
1999 to 2100. Population Projections Program, Population Division, U.S. Census Bureau,
Available at [http://www.census.gov/population/projections/nation/summary/np-t.txt].
b. The range of estimates reflect the mean estimates derived from the American Cancer Society study
and the Harvard Six-City Study, respectively.
In addition to the improved health benefits based on the epidemiology studies,
the EPA estimated reductions in premature mortality based on the expert elicitation
approach discussed above. The estimates were variable from expert to expert,
ranging from a mean of 1,200 to 13,000 avoided premature deaths annually in 2020
resulting from attainment of the new standards (15/35 :g/m3) incremental to the
EPA’s baseline strategy for the 1997 NAAQS (15/65 :g/m3).
When promulgating the 1997 PM NAAQS, the EPA estimated that
2.5
compliance would result in the annual prevention of 15,000 premature deaths, 75,000
cases of chronic bronchitis, and 10,000 hospital admissions for respiratory and
cardiovascular disease, as well as other benefits. These estimates have been the
subject of significant debate and re-analysis. Since 1998, with dedicated funding
from Congress, the EPA accelerated its research and re-analysis on PM to better
2.5

---

CRS-10
understand the potential associated health effects and to develop ways to reduce
risks.26 The funding supported EPA intramural and extramural PM research projects
and the establishment of five university-based PM research centers around the
country. The EPA’s most recent review has increased its confidence in earlier
findings associating exposure to PM with increases in respiratory health problems,
2.5
hospitalizations for heart and lung disease, and premature death, particularly for
children, the elderly, and those with preexisting heart and lung disease.27
Geographical Nonattainment Areas: Potential Impacts
As described earlier, the Clean Air Act has been interpreted to exclude
consideration of the costs, technological feasibility, and other non-health criteria
when setting and revising the NAAQS. Nevertheless, costs and feasibility associated
with the NAAQS implementation (primarily a state responsibility) are key elements
of the debate regarding the new PM NAAQS. The tightening of the PM standards
2.5
is expected to increase the number of areas (typically defined by counties or portions
of counties) in nonattainment, and subsequently result in increased costs to achieve
compliance. The current PM daily (24-hour) standard has been retained at the 1987
10
level and the annual standard revoked. The EPA is not requiring new nonattainment
designations for PM , and it does not anticipate any significant incremental cost
10
impacts of this action.
Designation of geographical areas and the associated impacts on specific areas
would be speculative at best, because implementation of the revised PM NAAQS is
several years off. Initially, areas will be designated nonattainment if they exceed the
standard in 2006-2008. States will not be required to meet the new PM standard
2.5
until April 2015 (April 2020, if qualified for an extension28). With regard to the 1997
PM NAAQS, states are required to submit implementation plans for how they will
2.5
meet the standard by April 2008 and must be in compliance by 2010, unless they are
granted a five-year extension.29
26 Congress increased EPA’s appropriations for particulate matter research from $18.8
million in FY1997 (H.Rept. 104-812) to $49.6 million in FY1998 (H.Rept. 105-297). PM
research appropriations averaged more than $60 million per year from FY1999 through
FY2004, and Congress provided $60.5 million for FY2005. Congress did not identify PM
research funding in EPA’s FY2006 appropriation but included $66.8 million for NAAQS
research (H.Rept. 109-465).
27 EPA criteria and technical documents in support of the Oct. 17, 2006, final PM NAAQS,
the Dec. 20, 2005, proposal, and the 1997 NAAQS, are available at
[http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html].
28 Under section 172(a)(2)(A) of the CAA, the EPA may grant an area an extension of the
initial attainment date for one to five years (in no case later than 10 years after the
designation date for the area). A state requesting an extension must submit an
implementation plan (SIP) by the required deadline that includes, among other things,
sufficient information demonstrating that attainment by the initial attainment date is
“impracticable.”
29 For more information on the implementation of the 1997 PM NAAQS promulgated in
2.5
1997, see CRS Report RL32431, Particulate Matter (PM ): National Ambient Air Quality
2.5
(continued...)

---

CRS-11
Following formal designation (the EPA estimates that the effective date for the
final designations will not be before April 2010 for the revised PM NAAQS), the
2.5
states have three years to submit State Implementation Plans (SIPs), which identify
specific regulations and emission control requirements that will bring an area into
compliance. If new or revised SIPs for attainment establish or revise a
transportation-related emissions allowance (“budget”), or add or delete transportation
control measures (TCMs), they will trigger “conformity” determinations.
Transportation conformity is required by the CAA, Section 176(c),30 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.
Implementation of the 1997 PM standard — delayed several years by litigation,
the lack of monitoring capability, and other factors — is ongoing. The EPA’s recent
final designation of 39 geographical areas, composed of 208 counties in 20 states and
the District of Columbia, in nonattainment with the PM NAAQS (those areas with
2.5
or contributing to air quality levels exceeding the annual and 24-hour standards)
became effective on April 5, 2005. A direct national comparison of nonattainment
areas for the 1997 standard and the newly revised PM NAAQS is not available.
2.5
However, in conjunction with the January 17, 2006, proposal, the EPA projected that
the numbers of counties with monitors that would not attain the new PM NAAQS
2.5
could increase from 116 counties (those with monitors within the total 208 counties),
based on the current standard, to 191, with the proposed PM NAAQS, by 2010.
2.5
Taking into account those areas without monitors but contributing to air quality
levels exceeding the standard, and other factors considered by the agency when
determining the designations, the total number of counties to be in nonattainment
with the new PM NAAQS is likely to be even larger.
2.5
Table 4 summarizes the EPA’s nonattainment designation projections of
counties with monitors for 2010 and 2015, based on the 1997 PM standard, the new
2.5
standard, and other alternative PM standards that the EPA considered at the time
2.5
of its proposal. The EPA notes that its projections are based on 2001-2003
monitoring data, whereas the actual nonattainment designations would be based on
monitoring data from later years.31 The EPA’s projections also take into account
those PM reductions that the agency expects will occur as the result of air quality
29 (...continued)
Standards (NAAQS) Implementation, by Robert Esworthy.
30 42 U.S.C. 7506(c).
31 Revisions to Ambient Air Monitoring Regulations, final rule, 71 Federal Register
61235-61328, Oct. 17, 2006. In a separate but related action, EPA amended its national air
quality monitoring requirements, including those for monitoring particle pollution, to help
federal, state, and local air quality agencies “improve public health protection and inform
the public about air quality in their communities” by taking advantage of improvements in
monitoring technology. Information on the changes are available at
[http://www.epa.gov/air/particlepollution/actions.html].

---

CRS-12
regulations promulgated in 2005,32 including the Clean Air Interstate Rule (CAIR),
the Clean Air Mercury Rule (CAMR), and the Clean Air Visibility Rule (CAVR).
Table 4. Counties with Monitors Projected by Epa to Be in
Nonattainment of the 1997, New (2006), and Alternative Pm2.5
Naaqs
PM NAAQS
2015 with
2.5
2010
Options (24-hour
CAIR/CAVR/CAMR
and annual :g/m3)
National
East
West
National
East
West
15/65 — 1997 PM2.5
116
102
14
32
18
14
NAAQS
15/35 — new (2006)
191
141
50
76
30
46
14/35
235
185
50
96
50
46
15/30
326
264
62
178
116
62
Source: Prepared by the Congressional Research Service with data presented in the EPA White Paper
Preliminary Analyses of Proposed PM NAAQS Alternatives, Office of Air Quality Planning and
2.5
Standards, Office of Air and Radiation, December 21, 2005, available at [http://epa.gov/pm/pdfs/
whitepaper20051220.pdf].
Notes: CAIR = Clean Air Interstate Rule, CAMR= Clean Air Mercury Rule, and CAVR = the Clean
Air Visibility Rule, promulgated in 2005.
Potential Concerns and Issues
Congress and a wide variety of stakeholders have closely followed the
development of the new PM NAAQS. Most recently, during the 109th Congress the
Senate Committee on Environment and Public Works and the committee’s
Subcommittee on Clean Air, Climate Change, and Nuclear Safety have held hearings
regarding implementation and review of the PM NAAQS.33 Well before the EPA
formally proposed revising the NAAQS, stakeholders were providing evidence and
arguments at public hearings and other forums for their preferred recommendations.
In general, business and industry oppose more stringent standards, and public health
and environmental interest groups advocate tighter standards. The EPA received
thousands of comments during various stages of development of the PM criteria
document and in response to drafts of the EPA PM staff paper. The agency reported
32 For more information on these and other recent EPA’s air quality regulations, see
[http://www.epa.gov/cleanair2004/].
33 U.S. Senate Committee on Environment and Public Works, full Committee, The Science
and Risk Assessment Behind the EPA’s Proposed Revisions to the Particulate Matter Air
Quality Standards, July 19, 2006; Subcommittee on Clean Air, Climate Change, and
Nuclear Safety, EPA’s Proposed Revisions to the Particulate Matter Air Quality Standards,
July 13, 2006, and Implementation of the Existing Particulate Matter and Ozone Air Quality
Standards, Nov. 10, 2005.

---

CRS-13
receiving more than 120,000 comments in response to the January 2006 PM NAAQS
proposal.
The Administrator’s proposed and final decisions represent the first time in
CASAC’s nearly 30-year history that the promulgated standards fall outside of the
range of the scientific panel’s recommendations. In letters dated March 21, 2006,
and September 29, 2006, the CASAC raised its concerns and objections regarding
both PM and PM standards. The Administrator is not required by statute to follow
10
2.5
CASAC’s recommendations; the act (in Section 307(d)(3)) requires only that the
Administrator set forth any pertinent findings, recommendations, and comments by
CASAC and the National Academy of Sciences, and, if his proposal differs in an
important respect from any of their recommendations, provide an explanation of the
reasons for such differences. Courts, in reviewing EPA regulations, also generally
defer to the Administrator’s judgment on scientific matters, focusing more on issues
of procedure, jurisdiction, and standing. Nevertheless, CASAC’s detailed objections
to the Administrator’s decisions and its description of the process as having failed to
meet statutory and procedural requirements could play a role if the standards are
challenged in court.
At the time of its January 2006 proposal, the agency solicited comment (90-day
comment period from the date of publication in the Federal Register) regarding its
supporting analysis and a variety of alternative PM NAAQS. In addition to soliciting
written comments, the EPA held public hearings in early March 2006 in Philadelphia,
Chicago, and San Francisco. As presented in its rationale for the final standards
throughout the preamble of the final rule, in some cases the EPA has revised
elements of its proposal based on certain comments; in other cases the EPA lays out
its reasoning for disagreeing. EPA’s final modifications to the existing PM NAAQS
have sparked interest and conflicting concerns among a diverse array of stakeholders
and in Congress. The following sections highlight several areas of interest.
Fine Particulate (PM ) Primary (Health) Standards
2.5
The final revised PM NAAQS, which are the same as proposed, are not as
2.5
stringent as the levels recommended by the independent CASAC and those
recommended by EPA professional staff, as noted above. EPA staff and CASAC
recommendations for PM included a range of levels more stringent than those
2.5
proposed in January and finalized September of 2006. In particular, the majority of
the CASAC panel “did not endorse the option of keeping the annual standard at its
present value.” According to the CASAC:
Of the options presented by EPA staff for lowering the level of the PM standard,
based on the above considerations and the predicted reductions in health impacts
derived from the risk analyses, most Panel members favored the option of setting
a 24-hour PM NAAQS at concentrations in the range of 35 to 30 :g/m3 with
2.5
the 98th percentile form, in concert with an annual NAAQS in the range of 14
to 13 :g/m3. 34
34 CASAC PM Review Panel report, p. 7, June 2005 [http://www.epa.gov/ttn/naaqs/
standards/pm/s_pm_index.html].

---

CRS-14
Table 5 compares the CASAC and EPA staff recommendations for PM primary
2.5
standards, the 1997standards, and 2006 standards as proposed and promulgated.
Table 5. PM Primary (Health) NAAQS: Final (2006), Proposed
2.5
and Alternatives, and as Promulgated in 1997
24-hour Primary
Annual Primary
PM NAAQS Options
2.5
(98th percentile)
(arithmetic mean)
1997 NAAQS
65 :g/m3
15 :g/m3
mid to lower range of
EPA staff paper (December 2005)
35-25 :g/m3
15 :g/m3
or
mid to lower range of
40-30 :g/m3
14-12 :g/m3
CASAC (December 2005)
35-30 :g/m3
14-13 :g/m3
EPA Proposed Rule (January 2006)
35 :g/m3
15 :g/m3
EPA Final Rule (October 2006)
35 :g/m3
15 :g/m3
Source: Prepared by the Congressional Research Service (CRS), with information from the EPA’s
final PM NAAQS (71 Federal Register 61143-61233, Oct. 17, 2006), the EPA’s proposed PM
NAAQS (71 Federal Register 2620, Dec. 20, 2005), and related technical documents,35 available at
[http://www.epa.gov/air/particles/actions.html].
In response to the discrepancies between the proposal and the CASAC
recommendations, EPA Administrator Stephen Johnson indicated that his decision
required consideration of a number of factors and “judgment based upon an
interpretation of the evidence.” The Administrator relied on the evidence of long-
term exposure studies as the principal basis for retaining the annual PM standard.36
2.5
CASAC strongly disagreed with the Administrator’s decision regarding the PM2.5
annual standard and took the unprecedented step of urging reconsideration of the
proposal.37
Many public comments received on the EPA’s proposed revisions to the PM2.5
standards, most frequently from environmental and public health organizations,
medical doctors and researchers, and the association representing state air quality
35 EPA’s final PM staff paper and the CASAC review of the EPA staff paper (see references
earlier in this report).
36 For the EPA Administrator’s rationale for proposing to retain the current level for the
annual PM standard and recognition of the CASAC’s recommendation not endorsing this
2.5
approach, see 71 Federal Register 2650-2653, Jan. 17, 2006.
37 Letter of Dr. Rogene Henderson, Chair, Clean Air Scientific Advisory Committee, to the
Hon. Stephen Johnson, Administrator, U.S. EPA, Mar. 21, 2006, available at
[http://www.epa.gov.sab/pdf/casac-ltr-06.002.pdf], or from the federal docket for the
proposed rule Docket ID No. EPA-HQ-OAR-2001-0017, on the Federal Docket website
[http://www.regulations.gov/fdmspublic/component/main].

---

CRS-15
regulators,38 argue for standards as stringent or more stringent than those
recommended by CASAC. In contrast, another group of commenters, generally
representing industry associations and businesses, opposed revising the 1997 PM2.5
standards, in some cases highlighting different aspects of the same research cited by
the CASAC and others supporting tighter standards.39 Some who opposed more
stringent PM NAAQS called attention to more recent studies of health effects
attributable to PM that demonstrate risk estimates are lower and less statistically
significant than they were in 1997, when the last standard was set.40
In Section II of the preamble of the final October 2006 revisions, “Rationale for
Final Decisions on Primary PM Standards,” the EPA discusses its final decision
2.5
with respect to the CASAC recommendations regarding the PM annual standard.
2.5
The Administrator differs with the CASAC with regard to the level of uncertainty
associated with the agency’s quantitative risk assessment and whether the results
appropriately serve as a primary basis for a decision on the level of the annual PM2.5
standard. The Administrator further stressed the emphasis placed on the long-term
means of the levels associated with mortality effects in the two key long-term
studies41 in determining the level of the annual standard. CASAC considered the
evidence from specific short-term exposure studies as part of the basis for its
recommendation for a lower annual standard level. As noted above, the CASAC
expressed its objections to the EPA’s final PM NAAQS in its September 29, 2006,
letter to Administrator Johnson.42
With regard to PM , the letter stated: “CASAC is concerned that the EPA did
2.5
not accept our finding that the annual PM standard was not protective of human
2.5
health and did not follow our recommendation for a change in that standard.”43 The
letter noted that “there is clear and convincing scientific evidence that significant
adverse human-health effects occur in response to short-term and chronic particulate
matter exposures at and below 15 µ g/m3,” and noted that 20 of the 22 Particulate
Matter Review Panel members, including all seven members of the statutory
committee were in “complete agreement” regarding the recommended reduction. “It
is the CASAC’s consensus scientific opinion that the decision to retain without
38 Personal communication with Mr. William Becker, Executive Director, State and
Territorial Air Pollution Program Administrators/Association of Local Air Pollution Control
Officials (STAPPA/ALAPCO), Jan. 5, 2006.
39 For EPA’s discussion and response to several of these comments, see 71 Federal Register
61143-61233, Oct. 17, 2006, Part II Rationale for Final Decisions on Primary PM2.5
Standards, Sections B and F, on EPA’s website at [http://epa.gov/pm/actions.html].
40 Communication with Mr. Frank Maisano, Media Contact for the Electric Reliability
Coordinating Council, Jan. 17, 2006.
41 71 Federal Register at 2651, Jan. 17, 2006.
42 Letter of Dr. Rogene Henderson, Chair, Clean Air Scientific Advisory Committee, to the
Hon. Stephen Johnson, Administrator, U.S. EPA, Sept. 29, 2006, available at
[http://www.epa.gov/sab/pdf/casac-ltr-06-003.pdf].
43 Letter of Rogene Henderson, Chair of the Clean Air Scientific Advisory Committee, et
al. to Hon. Stephen L. Johnson, EPA Administrator, September 29, 2006, available at
[http://www.epa.gov/sab/pdf/casac-ltr-06-003.pdf].

---

CRS-16
change the annual PM standard does not provide an ‘adequate margin of safety
2.5
... requisite to protect the public health’ (as required by the Clean Air Act) ....”44
Potential Health Benefits of a More Stringent PM Standard. In its
2.5
RIA, the EPA estimated the nationwide monetized human health and welfare benefits
of attaining two suites of PM NAAQS: (1) the newly revised PM NAAQS, which
2.5
2.5
include the new 35 µg/m3 daily (24-hour) standard and the unchanged 15 µg/m3
annual standard, and (2) an alternative standard similar to the least stringent of the
CASAC recommendations that includes a tighter annual standard of 14 µg/m3 and
the same 35 µg/m3 daily (24-hour) standard. As discussed previously, the EPA
presented a variety of benefits estimates based on several epidemiological studies,
the American Cancer Society (ACS) Study45 used in previous RIAs, the Harvard Six-
Cities Study,46 and expert elicitation study conducted by the EPA in 2006.47
The EPA estimated that attainment of the more stringent alternative PM2.5
NAAQS would result in $26 billion to $30 billion of total annual benefits in 2020,
based on the ACS mortality function. This compares to a range of $15 billion to $17
billion estimated for compliance with the newly promulgated PM NAAQS (see
2.5
Table 2 and discussion earlier in this report). EPA’s estimate of annual benefits
derived using the expert elicitation ranged from $15 billion to $140 billion for the
more stringent alternative, compared to the agency’s estimates of $8 billion to $76
billion for compliance with the new standard. EPA also estimated the monetary
benefits (“willingness to pay”) associated with improvements in visibility in selected
Class I national parks and wilderness areas would be $1.2 billion in 2020 with
attainment of the more stringent alternative PM standard analyzed, compared to
2.5
$530 million with attainment of the newly revised PM NAAQS.48 EPA estimated
2.5
the total annual cost associated with attainment of the alternative PM NAAQS
2.5
analyzed would be $7.9 billion in 2020, compared to $5.4 billion.
As discussed previously, a key component of the EPA’s monetized benefits
estimates are the agency’s predicted reductions in the incidence of premature deaths
and a range of adverse health effects annually in 2020 associated with compliance of
PM NAAQS. For example, for the more stringent attainment strategy analyzed
44 Ibid. Italics in original.
45 Pope, C. Arden, III, et al. “Particulate Air Pollution as a Predictor of Mortality in a
Prospective Study of U.S. Adults.” American Journal of Respiratory and Critical Care
Medicine 151 (1995): 669-674.
46 Dockery, Douglas W. et al. “An Association Between Air Pollution and Mortality in Six
U.S. Cities.” New England Journal of Medicine 329 (1993): 1753-1759. See also the Health
Effects Institute, “Statement: Synopsis of the Particle Epidemiology Reanalysis Project.”
Reanalysis of the Harvard Six Cities Study and the American Cancer Society Study of
Particulate Air Pollution and Mortality, July 2000 (includes Nov. 1, 2001 errata sheet), p.
I. ([http://www.healtheffects.org/Pubs/Rean-ExecSumm.pdf]).
47 See Chapter 5 of the EPA’s October 6, 2006, RIA for more detail
[http://www.epa.gov/ttn/ecas/ria.html].
48 See Appendix I Visibility Benefits Methodology of the EPA’s October 6, 2006, RIA
[http://www.epa.gov/ttn/ecas/ria.html].

---

CRS-17
(14/35 µg/m3), the EPA estimated 2,200 to 24,000 fewer premature deaths based on
the expert elicitation. For purposes of illustration, Table 6 provides a comparison
of EPA’s predicted reductions annually for the new PM NAAQS (15/35 µg/m3)
2.5
with a more stringent alternative analyzed (14/35 µg/m3), based on data from the
ACS and Harvard Six-City studies, and various epidemiology studies.
Table 6. EPA’s Predicted Reductions in Adverse Health Effects
Annually in 2020 Associated with Meeting the New PM NAAQS
2.5
and a More Stringent Alternative
Predicted Reductionsa
(estimated mean)
Adverse Health Effect
More Stringent
PM NAAQS
2.5
Alternative
(15/35 µg/m3)
(14/35 µg/m3)
Premature deaths in individuals with preexisting
2,500 to 5,700b
4,000 to 9,000b
cardiovascular and respiratory disease
Cases of chronic bronchitis (age >25)
2,600
4,600
Cases of acute bronchitis (age 8-12)
7,300
13,000
Nonfatal heart attacks (age >71)
5,000
8,700
Hospital admissions for cardiovascular or
1,630
3,080
respiratory symptoms (age >17)
Emergency room visits for asthma (age <19)
1,200
3,200
Cases of aggravated asthma (asthmatics age 6-18)
51,000
79,000
Cases of upper and lower respiratory symptoms
97,000
153,000
(asthmatics age 6-18)
Days when individuals miss work (age 18-75)
350,000
550,000
Days when individuals must restrict their
activities because of symptoms related to particle
2,000,000
3,300,000
pollution (age 18-65)
Source: Prepared by the Congressional Research Service with data based on epidemiology studies
presented in Chapter 5 of the Environmental Protection Agency Regulatory Impact Analysis of the
2006 National Ambient Air Quality Standards for Fine Particle Pollution (PM ) Oct. 6, 2006, and
2.5
available on the EPA’s website at [http://www.epa.gov/ttn/ecas/ria.html]. Estimates are rounded by
EPA to two significant digits.
a. For consistency with the emissions and benefits modeling, the EPA used national population
estimates based on the U.S. Census Bureau projections. U.S. Bureau of Census. 2000.
Population Projections of the United States by Age, Sex, Race, Hispanic Origin and Nativity:
1999 to 2100. Population Projections Program, Population Division, U.S. Census Bureau,
Available at [http://www.census.gov/population/projections/nation/summary/np-t.txt].
b. The range of reductions in premature deaths estimates reflect the mean estimates derived from the
American Cancer Society study and the Harvard Six-City Study, respectively.

---

CRS-18
The estimates EPA derived from an expert elicitation approach were only for
mortality. The results were variable from expert to expert, ranging from a mean of
2,200 to 24,000 avoided premature deaths annually in 2020 resulting from attainment
of the more stringent alternative standard (14/35 µg/m3) incremental to the EPA’s
baseline strategy for the 1997 NAAQS (15/65 µg/m3). For attainment of the new
standards (15/35 µg/m3), EPA estimated 1,200 to 13,000 fewer premature deaths
based on the expert elicitation.
Coarse Particulate (PM ) Primary Standards
10
Particle Size Indicator. The EPA and most of the CASAC panel members
concluded that there was a lack of evidence (often a lack of studies) on long-term
adverse health effects of specific PM measurements to support the annual standard,
10
and that there was a specific need to address particles ranging in size from 2.5 to 10
microns.49 EPA’s January 17, 2006, proposal would have replaced the existing
particle size indicator of 10 micrometers (PM ) with an indicator range of 10 to 2.5
10
micrometers (PM
), referred to as inhalable (or thoracic) coarse particles, and
10-2.5
setting a PM
daily standard of 70 µg/m3 rather than the current PM daily
10-2.5
10
standard of 150 µg/m3. At the time of its proposal, the EPA concluded that the
scientific evidence supported the standard based on short-term exposure to certain
coarse particles, particularly in urban and industrial areas.
In the final PM NAAQS revisions, the EPA decided to maintain the PM , citing
10
the limited body of evidence on health effects associated with thoracic coarse
particles from studies that use PM
measurements. The agency also determined
10-2.5
that the only studies of clear quantitative relevance to health effects most likely
associated with thoracic coarse particles used PM . The new PM NAAQS retain the
10
PM indicator and the daily (24-hour) standard of 150 µg/m3.
10
In its September 29, 2006, letter, the CASAC said it was “completely surprised”
at the decision to revert to the use of PM as the indicator for coarse particles, noting
10
that the option of retaining the existing daily PM standard was not discussed during
10
the advisory process and that CASAC views this decision as “highly-problematic
since PM includes both fine and coarse particulate matter.” The CASAC did agree
10
that having a standard for PM was better than no standard.
10
The EPA indicated that it is promulgating a new federal reference method
(FRM) for measurement of mass concentrations of PM
in the atmosphere as the
10-2.5
standard of reference for measurements of PM
concentrations in ambient air. The
10-2.5
EPA anticipates that the new FRM should provide a basis for gathering scientific
data to support future reviews of the PM NAAQS.50 According to the EPA, these
49 Clean Air Scientific Advisory Committee (CASAC) Review of the EPA Staff
Recommendations Concerning a Potential Thoracic Coarse PM Standard in the Review of
the National Ambient Air Quality Standards for Particulate Matter: Policy Assessment of
Scientific and Technical Information (Final PM OAQPS Staff Paper, EPA-452/R-05-005,
June 2005), Sept.15, 2005, [http://www.epa.gov/sab/panels/casacpmpanel.html].
50 71 Federal Register 61143-61233, Oct. 17, 2006, Section VI. Reference Methods for the
(continued...)

---

CRS-19
monitors will employ the latest in speciation technology to advance the science,
enabling future regulation to provide more targeted protection.
The EPA’s January 17, 2006, proposal to change the indicator of the standard
for coarse particles was in response to a 1999 U.S. Court of Appeals for the DC
Circuit decision51 directing the EPA to ensure that the standard did not duplicate the
regulation of fine particles. The EPA’s standard for PM , as modified by the 1997
10
changes to the PM NAAQS, was challenged shortly after promulgation. Concluding
that PM was a “poorly matched indicator” for thoracic coarse particles because it
10
included the smaller PM category as well as the larger particles, the Court of
2.5
Appeals remanded the standard to the EPA. The agency now contends that it has
addressed the concerns raised by the court regarding PM as an indicator for
10
inhalable coarse particulate matter in its rationale in the final PM NAAQS,
announced September 21, 2006.52 This is an issue that could potentially be
challenged in litigation.
Rural PM Sources. In addition to the changes to the coarse PM indicator,
10
the EPA had proposed narrowing the focus of the PM
standard on “urban and
10-2.5
industrial” sources — particles typical to rural areas including “windblown dust and
soils and PM generated by agricultural and mining sources” would not be subject
to this standard. Additionally, the EPA proposed revoking the current 24-hour PM10
standards, except in areas that have 1) violating monitors, and 2) a population of
100,000 or more. The emphasis on urban and industrial areas in the January 2006
proposal was based on the findings reported in the Criteria Document, the PM staff
paper, and the CASAC conclusion that “the evidence for the toxicity of PM10-2.5
comes from studies conducted primarily in urban areas and is related, in large part,
to the re-entrainment of urban and suburban road dusts, as well as primary
combustion products.”53
The EPA’s proposal to exclude any ambient mix of PM
that is dominated
10-2.5
by rural windblown dust and soils and PM generated by agricultural and mining
sources, and how the EPA would distinguish the sources during its implementation,
raised a number of questions and resulted in numerous comments. In response to the
proposal, in its March 21, 2006, letter to the EPA Administrator, the CASAC stated
that while it had recognized the scarcity of information on the toxicity of rural dust,
it “neither foresaw nor endorsed a standard that specifically exempts all agricultural
and mining sources, and offers no protection against episodes of urban-industrial
PM
in areas of populations less than 100,000.” The committee strongly
10-2.5
50 (...continued)
Determination of Particulate Matter as PM
and PM [http://epa.gov/pm/actions.html].
10-2.5
2.5
51 American Trucking Assns. v. EPA, 175 F.3d 1027, 1054-55 (D.C. Cir. 1999).
52 71 Federal Register 61143-61233, Oct. 17, 2006, Section III.C.3. Decision Not to Revise
PM Indicator, available at [http://epa.gov/pm/actions.html].
10
53 CASAC review. CASAC reviews, the PM criteria document, staff paper, and related
information, are available at [http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html].

---

CRS-20
recommended “expansion of our knowledge of the toxicity of PM
dusts rather
10-2.5
than exempting specific industries (e.g., mining, agriculture).”54
Several Members of the House Committee on Agriculture submitted a letter to
EPA Administrator Stephen Johnson in July 2006 conveying support for the agency
maintaining its provision to exclude agriculture and mining dust and similar sources
of coarse PM in the PM NAAQS, as had been proposed.55 The EPA indicated that
with the exception of representatives of those sources that would have been excluded
under the proposal (e.g., agriculture and mining), most commenters opposed the
exclusion. Those opposed included environmental and public health groups, state
and local agencies, and industries not excluded from the proposed indicator (e.g.,
transportation and construction).
The EPA did not exclude any areas or the types of particle in the final PM
NAAQS revisions, based on further consideration of the data and in response to
comments. In its rationale for the final PM standard, the EPA continued to
10
acknowledge that there is far more evidence concerning health effects associated with
thoracic coarse particles in urban areas than in non-urban areas. However, the EPA
also stated that “the existing evidence is inconclusive with regard to whether or not
community-level exposures to thoracic coarse particles are associated with adverse
health effects in non-urban areas.”56 The EPA indicated that it is expanding its
research and monitoring57 programs to collect additional evidence on the differences
between coarse particles typically found in urban areas and those typically found in
rural areas. The EPA announced the release of a final rule amending its national air
quality monitoring requirements on September 27, 2006.58
In contrast to objections regarding other aspects of EPA’s final PM NAAQS
revisions, the CASAC agreed with the EPA decision against including exemptions
in its September 29, 2006, letter to the EPA Administrator. However, a number of
those representing agriculture interests, including some Members of Congress,
remain concerned that EPA’s decision not to include the exclusions in the final PM
NAAQS will result in unnecessary burdens on the agricultural community. Some
Members of the House Committee on Agriculture expressed their concerns with the
54 Letter of Dr. Rogene Henderson, Chair, Clean Air Scientific Advisory Committee, to the
Hon. Stephen Johnson, Administrator, U.S. EPA, Mar. 21, 2006, available at
[http://www.epa.gov/sab/panels/casacpmpanel.html], or from the federal docket for the
proposed rule Docket ID No. EPA-HQ-OAR-2001-0017, on the Federal Docket website
[http://www.regulations.gov/fdmspublic/component/main].
55 Letter to EPA Administrator Stephen L. Johnson, from the Chairman, the Ranking
Member, and other Members of the House Committee on Agriculture, July 27, 2006.
56 71 Federal Register 61143-61233, Oct. 17, 2006, Section III.C.3, Decision Not to Revise
PM Indicator, available at [http://epa.gov/pm/actions.html].
10
57 71 Federal Register 61236-61328, Oct. 17, 2006.
58 71 Federal Register 61143-61233, Oct. 17, 2006, at [http://epa.gov/pm/actions.html].

---

CRS-21
EPA’s final actions with regard to the exemptions at a September 28, 2006, hearing
regarding the EPA’s pesticide programs.59
Secondary PM and PM Standards
2.5
10
The EPA proposal, and the final PM NAAQS, set the secondary standard for
PM and for PM at the same level as their primary standard. The PM staff paper
10
2.5
and the CASAC both recommended secondary standards at levels different from the
primary in order to be more protective of visibility, and the CASAC reiterated the
recommendations in its March 21, 2006, and September 29, 2006, letters to the EPA
Administrator. For PM , the EPA PM staff paper and most of CASAC panel
2.5
recommended consideration of a sub-daily standard with a level in the range of 20
to 30 :g/m3 for a four- to eight-hour midday time period, with a 92nd to 98th
percentile form, as opposed to the primary daily standard at 35 µg/m3, based on the
current three-year average of the 98th percentile of 24-hour PM concentrations.
2.5
Although the CASAC agreed with setting a secondary standard at the same level as
the primary standard based on the coarse PM indicator PM
, the committee
10-2.5
recommended that the standard not be limited to urban areas, as the EPA had
proposed.
Exclusion of More Recent Research
A number of stakeholders commented that EPA should have considered certain
studies that were published too recently to have been included in the 2004 criteria
document that, they argued, increased the uncertainty about possible health risks
associated with exposure to particulates. Others contend that there are new studies
(some of them the same) in support of their arguments for a lower (more stringent)
level to protect health. Some commenters, opposed to more stringent standards,
argued that the agency should delay its decision regarding the PM NAAQS to take
into consideration several of these studies. At the time of the proposal the EPA
declared its intention to review and evaluate significant new studies developed since
2002, and those published since the close of the criteria document, during the
comment period.60 With the release of its final PM NAAQS revisions, the EPA
acknowledged that these studies provided expansion of the science and some insights
regarding PM exposure and related health effects, but determined that the new data
“do not materially change any of the broad scientific conclusions regarding the health
effects of PM exposure made in the 2004 PM Air Quality Criteria Document.”61
Synopses of Stakeholder Reaction to the New PM NAAQS
Based on the EPA’s references to the comments in the preamble to the final PM
NAAQS revisions published October 17, 2006; a review of several comments in the
59 House Committee on Agriculture, Subcommittee on Conservation, Credit, Rural
Development, and Research, Review of the Environmental Protection Agency’s Pesticide
Program, Sept.28, 2006.
60 71 Federal Register 2625, Jan. 17, 2006 ([http://epa.gov/pm/actions.html]).
61 71 Federal Register 61143-61233, Oct. 17, 2006 ([http://epa.gov/pm/actions.html]).

---

CRS-22
Federal Docket for the January 17, 2006, proposal; and several media articles and
available press releases, views of proponents and critics of stricter standards are
summarized below.
Proponents of more stringent standards generally assert that
! the standards should be at least as stringent as the more stringent
combined daily and annual levels recommended in the EPA PM staff
paper and those recommended by the CASAC, based on its review
of the criteria and the EPA staff analysis;
! scientific evidence of adverse health effects is more compelling than
when the standards were revised in 1997;
! exclusion of rural sources from the coarse particle (PM ) standard
10
would not be sufficiently protective of human health and would be
difficult to distinguish and implement;
! more stringent standards ensure continued progress toward
protection of public health with an adequate margin of safety as
required by the CAA, in addition to avoidance of other adverse
health effects; and
! welfare effects, such as visibility, crop yield, and forest health, will
be enhanced.
Critics of more stringent PM NAAQS contend that
! more stringent standards (and in some cases even the 1997
standards) are not justified by the scientific evidence; the proposal
did not take into account hundreds of studies completed since the
2002 cut-off;
! requiring the same level of stringency for all fine particles without
distinguishing sources is unfounded;
! costs and adverse impacts on regions and sectors of the economy are
excessive; some commenters identified as “urban” sources contend
exemption of rural particles may result in a disproportional
compliance burden;
! those identified as “rural” sources contend exemption of rural
particles is warranted by the lack of evidence regarding adverse
effects associated with emission sources in these areas, and that not
excluding these areas and sources creates an unnecessary burden;
! revising the standards could impede implementation of the existing
PM NAAQS and the process of bringing areas into compliance,
given the current status of this process; revisions could also impede

---

CRS-23
efforts to meet air quality regulations promulgated in 2005, such as
the Clean Air Interstate Rule (CAIR);62 and
! the benefits (and costs) associated with implementation of the 1997
PM standard, as well as compliance with recent EPA air quality
regulations, have not yet been realized.
Conclusions
EPA’s September 21, 2006, announcement of its final modifications to the
existing PM NAAQS following completion of its statutorily required review has
sparked interest and conflicting concerns among a diverse array of stakeholders, and
in Congress.
Tightening the PM NAAQS will result in more areas classified as nonattainment
and needing to implement new controls on particulate matter. States and local
governments will be required to develop and implement new plans for addressing
emissions in those areas that do not meet the new standards. A stricter standard
means increased costs for the transportation and industrial sectors most likely to be
affected by particulate matter controls, including utilities, refineries, and the trucking
industry. In terms of public health, a stricter standard is estimated to result in fewer
adverse health effects for the general population and particularly sensitive
populations, such as children, asthmatics, and the elderly.
Because of health and cost implications, NAAQS decisions have often been the
source of significant concern to many in Congress. The evolution and development
of the PM (and ozone) NAAQS, in particular, have been the subject of extensive
oversight. When the 1997 PM NAAQS were promulgated, Congress held 28 days
of hearings on the EPA rule. Congress enacted legislation specifying deadlines for
implementation of the 1997 standard, funding for monitoring and research of
potential health effects, and the coordination of the PM (and ozone) standard with
other air quality regulations.
The EPA’s previous review and establishment of PM NAAQS were the subject
of litigation and challenges, including a Supreme Court decision in 2001.63 The
EPA’s 1997 promulgation of standards for both coarse and fine particulate matter
prompted critics to charge the EPA with overregulation and spurred environmental
groups to claim that the EPA had not gone far enough. More than 100 plaintiffs
petitioned the court to overturn the standard. Not only was the science behind the
PM NAAQS challenged, but opponents, and the DC Circuit Court panel that
62 EPA, Clean Air Interstate Rule, Clean Air Mercury Rule, and Clean Air Nonroad Diesel
Rule, at [http://www.epa.gov/cleanair2004/].
63 American Trucking Ass’ns v. EPA, 175 F.3d 1027, 1055-56 (D.C. Cir. 1999), rehearing
granted in part and denied in part, 195 F.3d 4 (D.C. Cir. 1999), affirmed in part and reversed
in part, Whitman v. American Trucking Ass’ns, 531 U.S. 457 (2001). In March 2002, the
Court of Appeals rejected all remaining challenges to the standards, American Trucking
Ass’ns v. EPA, 283 F. 3d 355, 369-72 (D.C. Cir. 2002).

---

CRS-24
considered the case prior to the Supreme Court review, maintained that the CAA as
interpreted by the EPA in setting these standards effected “an unconstitutional
delegation of legislative power.”64 In its 1999 decision,65 a three-judge panel of the
U.S. Court of Appeals for the District of Columbia Circuit found “ample support”
for the EPA’s decision to regulate coarse particle pollution, but vacated the 1997
PM standards, including the agency’s change of the indicator to PM
. Although
10
10-2.5
the EPA’s decision to issue the PM standards was upheld in the 1999 and 2001
2.5
decisions, for the most part, stakeholders on both sides of the issue continued to
advocate their predilection for more stringent or less stringent (and in some cases no)
PM standard.
Several elements of the EPA’s most recent action, including the level of
stringency of the new PM NAAQS based on the supporting criteria, the objections
of the CASAC, the agency’s decision not to modify the particle size indicator for
coarse particulates, and not excluding rural sources from the coarse standard as
proposed have already generated debate and controversy. It would not be surprising
if interested parties return to the courts to challenge the EPA’s newly promulgated
final standards. Thus, the final form of the current efforts to revise PM NAAQS may
not be known for some time.
64 Whitman v. American Trucking Ass’ns, 531 U.S. 457 (2001).
65 American Trucking Ass’ns v. EPA, 175 F.3d 1027, 1055-56 (D.C. Cir. 1999).

---