UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON D.C. 20460
OFFICE OF THE ADMINISTRATOR
SCIENCE ADVISORY BOARD
March 2 1,2006
EPA-CASAC-LTR-06-002
Honorable Stephen L. Johnson
Administrator
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Subject: Clean Air Scientific Advisory Committee Recommendations Concerning the
Proposed National Ambient Air Quality Standards for Particulate Matter
Dear Administrator Johnson:
EPA's Clean Air Scientific Advisory Committee (CASAC), supplemented by subject-
matter-expert panelists — collectively referred to as the CASAC Particulate Matter (PM) Review
Panel ("PM Panel") — held a public teleconference meeting on February 3, 2006 to consider
whether to provide the Agency with additional advice and recommendations concerning EPA's
proposed revisions to the PM National Ambient Air Quality Standards (NAAQS).
The PM Panel agrees that this letter adequately represents their views. The chartered
CASAC — whose seven members are also members of the PM Panel — fully endorses the PM
Panel's letter and hereby forwards it to you as the CASAC's consensus letter on this subject.
The current Clean Air Scientific Advisory Committee roster is found in Appendix A of this
letter, and the PM Panel roster is attached as Appendix B.
This meeting continued the PM Panel's review and recommendations on the Agency's
revision to PM NAAQS. The most recent reports to you on this topic — i.e., the PM Panel's
final report from its peer-review of the 2nd draft PM Staff Paper (EPA-SAB-CASAC-05-007,
dated June 6, 2005); and the CASAC's final report (EPA-SAB-CASAC-05-012, dated
September 15, 2005) concerning the PM Panel's August 11, 2005 teleconference to review EPA
Staff recommendations concerning a potential thoracic coarse PM standard in the final PM Staff
Paper — are found at URLs: http://www.epa.gov/sab/pdf/casac-05-007.pdf and
http://www.epa.gov/sab/pdf/sab-casac-05-012.pdf respectively.
The CASAC requests reconsideration of the proposed ruling for the level of the annual
PM2.5 NAAQS so that the standard is set within the range previously recommended by the PM
Panel, i.e., 13 to 14 |ig/m3. The CASAC also recommends that the proposed 24-hour PMio-2.5
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primary standard be accompanied by a national monitoring program for PMio-2.5 in both urban
and rural areas to aid in informing future health and welfare effects studies on rural dusts.
Moreover, the CAS AC strongly recommends expansion of our knowledge of the toxicity of
PMio-2.5 dusts rather than exempting specific industries (e.g., mining, agriculture). Finally, the
CASAC requests that the sub-daily secondary standard to protect visibility, as recommended
both in the PM Staff Paper and by the CASAC, be favorably reconsidered. The scientific
rationale for the CASAC's recommendations is given in the remainder of this letter.
1. Background
The CASAC, comprised of seven members appointed by the EPA Administrator, was
established under section 109(d)(2) of the Clean Air Act (CAA or "Act") (42 U.S.C. § 7409) as
an independent scientific advisory committee, in part to provide advice, information and
recommendations on the scientific and technical aspects of issues related to air quality criteria
and NAAQS under sections 108 and 109 of the Act. The PM Panel is comprised of the seven
members of the chartered (statutory) Clean Air Scientific Advisory Committee, supplemented by
fifteen technical experts.
EPA announced its proposal to revise the NAAQS for particulate matter on December 20,
2005. This proposal was published in the Federal Register in a January 17, 2006 (71 FR 2620-
2708) notice entitled, "National Ambient Air Quality Standards for Particulate Matter; Proposed
Rule." As announced in that notice, the Agency will accept comments on the proposed rule for
PM NAAQS for 90 days after its publication in the Federal Register.
2. CASAC Recommendations Concerning the Agency's Proposal to Revise the PM
NAAQS
In August 2005, the CASAC, through its PM Panel, completed an extensive review of the
PM air quality criteria document and the PM staff paper, making its recommendations to the
Agency based on the current science. The CASAC acknowledged and was pleased that the EPA
has chosen to accept its advice on some revisions of the PM NAAQS. However, the PM Panel
noted that some of the scientific recommendations were not accepted. The CASAC recognizes
that the EPA Administrator must include policy judgments as well as scientific information in
making his decisions. That is one reason that the CASAC's recommendations for levels of the
NAAQS are given in ranges, rather than as a single level. The value that the Administrator
chooses within that range is clearly a policy judgment. The CASAC and the PM Panel have held
in-depth discussions and deliberations, as described in previous reports, on the scientific data
underpinning the basis for the recommended ranges. To underscore its previous
recommendation, the CASAC would like to reiterate and expand the scientific rationale behind
its advice, to better inform the Administrator on the scientific basis of its recommendations.
Proposed 24-hour PMi.5 standard level: Generally, members of the PM Panel were
pleased to see that the recommended revision of the 24-hour PM2.5 level of the standard was
within the range of that recommended by most members of the PM Panel. The PM Panel
recognizes that, as a policy judgment, the high end of the suggested range was chosen.
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Proposed annual PMi* standard level: For this NAAQS level, the Agency has chosen
to propose going outside the range of the CASAC-recommended levels and to retain the annual
standard level at its current level of 15 |ig/m3. Our report to you dated June 6, 2005 stated,
"There was a consensus among the [PM] Panel members in agreement with the EPA
staff recommendations that focused on decreasing PM2 5 concentrations through lowering
of the 24-hour PM standard, but the [PM] Panel did not endorse the option of keeping the
annual standard at its present level. It was appreciated that some cities have relatively
high annual PM concentrations, but without much variation in concentrations from day-
to-day. Such cities would only rarely exceed a 24-hour PM2 5 standard, even if set at
levels below the current standard. This observation indicates the desirability of lowering
the level of the annual PM2 5 standard as well.
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 [PM] Panel members favored the option of setting a 24-hour
PM2.s NAAQS at concentrations in the range of 35 to 30 |ig/m3 with the 98th percentile
form, in concert with an annual NAAQS in the range of 14 to 13 |ig/m3."
The CASAC would like to reiterate and elaborate on the scientific basis for the PM
Panel's earlier recommendation, as follows:
First, the Agency's risk assessment indicating reduced health risks at annual PM2.5 levels
below the current standard was a key component in the PM Panel's recommendation to lower the
current annual level. While the risk assessment is subject to uncertainties, most of the PM Panel
found EPA's risk assessment to be of sufficient quality to inform its recommendations. The
authors of the Agency's risk assessment followed CASAC's advice in conducting extensive
sensitivity analyses and in revising the threshold assumptions as published in the final PM Staff
Paper. The risk analyses indicated that the uncertainties would increase rapidly below an annual
level of 13 |ig/m3 — and that was the basis for the PI
the lower bound for the annual PM2.5 standard level.
level of 13 |ig/m3 — and that was the basis for the PM Panel's recommendation of 13 |ig/m3 as
In our June 6, 2005 report, the PM Panel noted that "some cities have relatively high
annual PM2 5 concentrations, but without much variation in concentrations from day-to-day."
Dependence on a lower daily PM2.5 concentration limit alone cannot be relied on to provide
protection against the adverse effects of higher annual average concentrations The changes
suggested in the 24-hour standard will have significant impact when done "in concert" with a
change in the annual standard. The effect of changing the short-term (98th percentile) and long-
term standard levels in concert can be seen in Figures 5-1 and 5-2 of the Agency's staff paper.
The cities of St. Louis and Detroit are examples of cities where the estimated reduction in PM2.5-
related short-term and long-term mortality risk with a daily standard of 35 |ig/m3 would be
enhanced by a concerted reduction in the annual standard below the current level of 15 |ig/m3.
While the risk analysis is the primary means of determining the effects on risk of changes
in the 24-hour and annual PM2.s standards in concert, there is evidence that effects of long-term
PM2.s concentrations occur at or below the current annual standard level of 15 |ig/m3. Studies
described in the PM Staff Paper indicate that short-term effects of PM2.5 persist in cities with
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annual PM2.5 concentrations below the current standard. In a Canadian study (Burnett et a/.,
2000; and Burnett and Goldberg, 2003), significant associations with total and cardiovascular
mortality were present at a long-term mean PM2.5 concentration of 13.3 |ig/m3. There were also
positive findings in studies in Phoenix, AZ (Mar etal., 1999, 2003) and in Santa Clara County,
CA (Lipsett et a/., 1997) in which long-term mean concentrations of PM2.5 were approximately
13 |ig/m3.
In summary, the epidemiologic evidence, supported by emerging mechanistic
understanding, indicates adverse effects of PM2.5 at current annual average levels below 15
|ig/m3. The PM Panel realized the uncertainties involved in setting an appropriate, health-
protective level for the annual standard, but noted that the uncertainties would increase rapidly
below the level of 13 |ig/m3. That is the basis for the PM Panel recommendation of a level at 13-
14 |ig/m3.
Therefore, the CASAC requests reconsideration of the proposed ruling for the level of the
annual PM2.5 NAAQS so that the standard is set within the range previously recommended by the
PM Panel, i.e., 13 to 14 fj,g/m3.
Proposed 24-hour PMm-i.s Standards: The PM Panel was pleased to see that the
indicator for coarse thoracic particles of concern to public health took into account some of the
various approaches that the PM Panel identified for consideration. However, the PM Panel is
concerned that some of the advice provided may have been misunderstood, as follows:
1. Monitoring: Our report of September 15, 2005 indicated that it was essential to monitor
coarse thoracic particle concentrations in both rural and urban areas. As stated therein,
"It is essential to have data collected on the wide range of both urban and rural areas in
order to determine whether or not the proposed UPMio-2.5 standard should be modified at
the time of future reviews."
2. Source of toxic components in coarse thoracic particles: The preamble to the proposed
rule on PM NAAQS cites "specific initial advice from CASAC (Henderson, 2005),"
which was "most [PM] Panel members concurred that the current scarcity of information
on the toxicity of rural dusts makes it necessary for the Agency to base its regulations on
the known toxicity of urban-derived coarse particles." However, that same report also
underscored the associated "need for monitoring thoracic coarse particle levels [in rural
areas] and for population-based health-effects studies in those rural areas where it is
feasible to conduct such studies." The CASAC neither foresaw nor endorsed a standard
that specifically exempts all agricultural and mining sources, and offers no protection
against episodes of urban-industrial PMio-2.5 in areas of populations less than 100,000.
3. Secondary PMui-2^ Standards: As stated in the CAS AC's report of September 15, 2005,
the CASAC recommends that a secondary PMio-2.5 standard be set at the same level as the
primary PMio-2.5 standard to protect against the various irritant, soiling and nuisance
welfare or environmental effects of coarse particles. Since these effects are not uniquely
related to urban sources or receptors, the standard should not be limited to urban areas.
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Accordingly, the CASAC recommends that the proposed 24-hour PM'10-2.5 primary
standard be accompanied by monitoring of particles in both urban and rural areas to aid in
informing future health effects studies on rural dusts. Moreover, the CASAC strongly
recommends expansion of our knowledge of the toxicity of rural dusts rather than exempting
specific industries (e.g., mining, agriculture). Serious consideration should also be given to a
secondary PM/0-2.5 at a level similar to the proposed primary standard, but without the "urban "
geographical constraint.
Proposed Secondary PMi.g Standard to Protect Visibility: To protect visibility, the
EPA staff paper, with concurrence of most CASAC members, recommended a sub-daily
standard for PM2.5 with a level in the 20 to 30 |ig/m3 range for a four- to eight-hour (4-8 hr) mid-
day time period with a 92nd to 98th percentile form. The upper end of this range (25-30 |ig/m3
and a 92% to 95% form) was considered to be "lenient" in terms of protecting visibility,
permitting a relatively high number of days with relatively poor visual air quality. It was
suggested as a starting point for a national secondary standard given the uncertainties in both the
current science of what is adverse to the public and in the mechanics of setting and operating a
new sub-daily standard to protect visibility.
The proposed rule recommended relying on the proposed 24-hour primary standard of 35
|ig/m3 as a surrogate for visibility protection, noting through analysis that a percentage of
counties with monitors (and the corresponding percentages of populations) not likely to meet the
sub-daily secondary standard with a lenient level and form is comparable to those not likely to
meet a 24-hour primary standard set at the proposed 35 |ig/m3level. EPA's proposal to revise the
NAAQS for PM also cited limitations in the science and in the available hourly air quality data
required for a sub-daily standard.
CASAC members note three cautions to the Agency's proposed visibility standard, which
was outside the range recommended in the EPA staff paper and by most of the PM Panel:
1. As both the Staff Paper and the preamble to the proposed rule on PM NAAQS note, the
PM2.5 mass measurement is a better indicator of visibility impairment during daylight
hours when humidities are low. Moreover, the sub-daily standard more clearly matches
the nature of visibility impairment, whose adverse effects are most evident during
daylight hours. Using the 24-hour primary standard as a proxy introduces error and
uncertainty in protecting visibility Sub-daily secondary standards are used elsewhere
(e.g., a three-hour secondary standard for 862 and an eight-hour secondary standard for
ozone), and should be the focus for visibility.
2. CASAC and its monitoring subcommittees have repeatedly commended EPA's initiatives
promoting the introduction of continuous and near-continuous PM measurements in
various aspects of its monitoring strategy (e.g., Hopke, March 1, 2002; Henderson, April
20, 2005). The PM Panel notes that expanded deployment of continuous PM2.5 monitors
is consistent with setting a sub-daily standard to protect visibility, especially given that
compliance time frames for secondary standards are less rigid than for primary standards.
3. The cited comparability between percentages of counties not likely to meet a lenient sub-
daily secondary standard and the proposed 24-hour primary standard is a numerical
coincidence, and is not indicative of any fundamental relationship between visibility and
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health. Visual air quality is substantially impaired at PM2.5 concentrations of 35 |ig/m3.
However, peak short-term concentrations during daylight hours can be substantially
higher than 24-hour average values, and the Agency is specifically seeking comments on
whether the 24-hour primary standard should be set at an even higher level. It is not
reasonable to have the visibility standard tied to the health standard, which may change
in ways that make it even less appropriate for visibility concerns.
Thus, the CASAC requests that the sub-daily secondary standard to protect visibility, as
recommended both in the PM Staff Paper and by most of the PM Panel, be favorably
reconsidered.
Consideration of More Recent Scientific Information: The Agency has agreed to
consider more recent publications if they are critical to the setting of new standards. Whether a
new study is critical to the setting of new standards is difficult to determine. The CASAC is
concerned that the newer literature suggested by either CASAC or by the general public will not
have had a chance to undergo thorough EPA staff and CASAC review in a public setting. Such
an approach would set a bad precedent for future reviews and weaken the role of the independent
scientific review process. The PM Panel arrived at its recommendations based on the literature
presented in the PM Air Quality Criteria Document and in the PM Staff Paper (publications
through 2004). Scientific literature published since that time appears to support the findings of
the PM Panel, but is not needed to support the original conclusions of the PM Panel. Individual
members of the PM Panel, in response to the Administrator's request, have suggested new
articles to consider, which are listed in Appendix C. These articles have not been reviewed
either by EPA staff or by the CASAC in a public setting.
Views of PM Panel Members Not in Agreement with Majority Opinion: Finally, it
should be noted that two of the 22 members of the PM Panel do not agree with the majority
opinion of the PM Panel. These two PM Panel members expressed the view that the PM Staff
Paper provided an adequate scientific basis for the EPA Administrator to propose an annual
PM2.5 standard from within the range of 12 to 15 |ig/m3 and a 24 hour PM2.5 standard from
within the range of 30 to 40 |ig/m3. It was their opinion that the choice of specific numerical
levels from within the ranges was a policy decision. They also expressed the view that the
Administrator, as well as individual scientists, might have different preferences from among the
various policy options. Thus, these two PM Panel members felt that the choices made by the
Administrator in the Proposed PM Rule are scientifically acceptable. One of these two PM Panel
members also felt that the Administrator's decision to propose the use of the primary 24-hour
PM2.5 NAAQS as a secondary standard for visibility was an appropriate policy decision. He
expressed the view that the science reviewed by and commented on by the PM Panel should
inform the policy decision; however, the policy decision as to the level of visibility to accept is a
responsibility of the Administrator outside the purview of the PM Panel.
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Concluding Remarks: In conclusion, the members of the CASAC PM Review Panel
have carefully reviewed this letter, and all seven members of the statutory CASAC and a
substantial majority of PM Panel members are in agreement that this letter, with the exception of
the preceding paragraph immediately above, represents their views as expressed during the PM
Panel's February 3, 2006 teleconference and subsequent e-mail correspondence to me.
The CASAC is pleased to provide scientific advice to the Administrator concerning the
proposed new standards for airborne particulate matter. We recognize that the setting of a
NAAQS goes beyond the scientific data base into the realm of pubic policy. However, the
efforts of the Agency's scientific staff as well as the CASAC in providing a sound scientific
basis must, fundamentally, be the foundation of these standard-setting decisions. The members
of the CASAC hope that we can continue to work with EPA both to provide the best scientific
advice available and to aid the Agency in protecting the public health and the environment in an
effective and efficient manner.
Sincerely,
/Signed/
Dr. Rogene Henderson, Chair
Clean Air Scientific Advisory Committee
Appendix A - Roster of the Clean Air Scientific Advisory Committee
Appendix B - Roster of the CASAC Parti culate Matter Review Panel
Appendix C - Newer Literature Suggested by Individual PM Panel Members
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Appendix A - Roster of the Clean Air Scientific Advisory Committee
U.S. Environmental Protection Agency
Science Advisory Board (SAB) Staff Office
Clean Air Scientific Advisory Committee (CASAC)
CHAIR
Dr. Rogene Henderson, Scientist Emeritus, Lovelace Respiratory Research Institute,
Albuquerque, NM
MEMBERS
Dr. Ellis Cowling, University Distinguished Professor-at-Large, North Carolina State
University, Colleges of Natural Resources and Agriculture and Life Sciences, North Carolina
State University, Raleigh, NC
Dr. James D. Crapo, Professor, Department of Medicine, National Jewish Medical and
Research Center, Denver, CO
Dr. Frederick J. Miller, Consultant, Cary, NC
Mr. Richard L. Poirot, Environmental Analyst, Air Pollution Control Division, Department of
Environmental Conservation, Vermont Agency of Natural Resources, Waterbury, VT
Dr. Frank Speizer, Edward Kass Professor of Medicine, Channing Laboratory, Harvard
Medical School, Boston, MA
Dr. Barbara Zielinska, Research Professor, Division of Atmospheric Science, Desert Research
Institute, Reno, NV
SCIENCE ADVISORY BOARD STAFF
Mr. Fred Butterfield, CASAC Designated Federal Officer, 1200 Pennsylvania Avenue, N.W.,
Washington, DC, 20460, Phone: 202-343-9994, Fax: 202-233-0643 (butterfield.fred@epa.gov)
(Physical/Courier/FedEx Address: Fred A. Butterfield, III, EPA Science Advisory Board Staff
Office (Mail Code 1400F), Woodies Building, 1025 F Street, N.W., Room 3604, Washington,
DC 20004, Telephone: 202-343-9994)
A-l
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Appendix B - Roster of the CASAC Participate Matter Review Panel
U.S. Environmental Protection Agency
Science Advisory Board (SAB) Staff Office
Clean Air Scientific Advisory Committee (CASAC)
CASAC Particulate Matter Review Panel
CHAIR
Dr. Rogene Henderson*, Scientist Emeritus, Lovelace Respiratory Research Institute,
Albuquerque, NM
MEMBERS
Dr. Ellis Cowling*, University Distinguished Professor-at-Large, North Carolina State
University, Colleges of Natural Resources and Agriculture and Life Sciences, North Carolina
State University, Raleigh, NC
Dr. James D. Crapo*, Professor, Department of Medicine, National Jewish Medical and
Research Center, Denver, CO
Dr. Philip Hopke, Bayard D. Clarkson Distinguished Professor, Department of Chemical
Engineering, Clarkson University, Potsdam, NY
Dr. Jane Q. Koenig, Professor, Department of Environmental Health, School of Public Health
and Community Medicine, University of Washington, Seattle, WA
Dr. Petros Koutrakis, Professor of Environmental Science, Environmental Health , School of
Public Health, Harvard University (HSPH), Boston, MA
Dr. Allan Legge, President, Biosphere Solutions, Calgary, Alberta
Dr. Paul J. Lioy, Associate Director and Professor, Environmental and Occupational Health
Sciences Institute, UMDNJ - Robert Wood Johnson Medical School, NJ
Dr. Morton Lippmann, Professor, Nelson Institute of Environmental Medicine, New York
University School of Medicine, Tuxedo, NY
Dr. Joe Mauderly, Vice President, Senior Scientist, and Director, National Environmental
Respiratory Center, Lovelace Respiratory Research Institute, Albuquerque, NM
Dr. Roger O. McClellan, Consultant, Albuquerque, NM
Dr. Frederick J. Miller*, Consultant, Cary, NC
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Dr. Gunter Oberdorster, Professor of Toxicology, Department of Environmental Medicine,
School of Medicine and Dentistry, University of Rochester, Rochester, NY
Mr. Richard L. Poirot*, Environmental Analyst, Air Pollution Control Division, Department of
Environmental Conservation, Vermont Agency of Natural Resources, Waterbury, VT
Dr. Robert D. Rowe, President, Stratus Consulting, Inc., Boulder, CO
Dr. Jonathan M. Samet, Professor and Chair, Department of Epidemiology, Bloomberg School
of Public Health, Johns Hopkins University, Baltimore, MD
Dr. Frank Speizer*, Edward Kass Professor of Medicine, Channing Laboratory, Harvard
Medical School, Boston, MA
Dr. Sverre Vedal, Professor, Department of Environmental and Occupational Health Sciences,
School of Public Health and Community Medicine, University of Washington, Seattle, WA
Mr. Ronald White, Research Scientist, Epidemiology, Bloomberg School of Public Health,
Johns Hopkins University, Baltimore, MD
Dr. Warren H. White, Visiting Professor, Crocker Nuclear Laboratory, University of California
- Davis, Davis, CA
Dr. George T. Wolff, Principal Scientist, General Motors Corporation, Detroit, MI
Dr. Barbara Zielinska*, Research Professor, Division of Atmospheric Science, Desert Research
Institute, Reno, NV
SCIENCE ADVISORY BOARD STAFF
Mr. Fred Butterfield, CASAC Designated Federal Officer, 1200 Pennsylvania Avenue, N.W.,
Washington, DC, 20460, Phone: 202-343-9994, Fax: 202-233-0643 (butterfield.fred@epa.gov)
(Physical/Courier/FedEx Address: Fred A. Butterfield, III, EPA Science Advisory Board Staff
Office (Mail Code 1400F), Woodies Building, 1025 F Street, N.W., Room 3604, Washington,
DC 20004, Telephone: 202-343-9994)
* Members of the statutory Clean Air Scientific Advisory Committee (CASAC) appointed by the EPA
Administrator
B-2
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Appendix C - Newer Literature Suggested by Individual PM Panel Members
• Sun et al (2005): Long-term air pollution exposure and acceleration of atherosclerosis
and vascular inflammation in an animal model, JAMA 294, 3003-3010. Suggested by Dr.
Morton Lippmaim. Cardiovascular effects were observed in animals chronically-exposed to
PM2.s: The animal inhalation studies reported in Sun et al. (2005) used an atherosclerosis-prone
mouse model in demonstrating that exposure of these mice to concentrated PM2.5 ambient air
particles for six months resulted in altered vasomotor tone, induced vascular inflammation and
acceleration of atherosclerosis.
• Laden et al. (2006): Reduction in fine particulate air pollution and mortality: extended
follow-up of the Harvard Six Cities Study, Am J. Respir. Crit. Care Med. 173:667-672.
Suggested by Dr. Frank Speizer. Reduction in annual ambient PM2.5 levels lead to a reduction in
human health effects: The paper of reports that cardiovascular and lung cancer mortality were
each positively-associated with ambient PM2.5 concentrations and that a reduction in PM2.5
concentrations was associated with reduced mortality risk. The study was an extended follow-up
of the Harvard Six Cities Study and found improved overall mortality was associated with
decreased mean PM2.5 levels between Period 1 (1980-1985) and Period 2 (1990-1998).
• Dominici et al. (2006): Fine Particles and Hospital Admission for Cardiovascular and
Respiratory Diseases: Results for 204 US Counties, 1999-2002, JAMA 295(10): 1127-1134.
Suggested by Mr. Ron White. This study involving 204 urban counties and 11.5 million
Medicare enrollees was just published in JAMA in March 2006, and found statistically-
significant relationships between a 10 |ig/m3 increase in PM2.5 and hospitalization for
cerebrovascular, peripheral, and ischemic heart diseases, heart rhythm, heart failure, chronic
obstructive pulmonary disease, and respiratory infection. No association was found between
PM2.5 levels and hospital admissions for injury, which served as the control. The average of
county mean PM2.5 concentrations for the 1999-2002 study period was 13.4 |ig/m3.
• Bayer-Oglesby et al. (2005): Decline of ambient air pollution levels and improved
respiratory health in Swiss children, Environ. Health Perspec. 113, 1632-1637. Suggested by
Dr. Rogene Henderson. This paper reported reductions in morbidity in children in nine cities in
Switzerland during a time of reduced PMio (which would include PM2.5). Various indicators of
respiratory problems were compared for Period 1 (1993) and Period 2 (1997-2000). Beneficial
effects from the reduction in particles were observed, with no threshold. Significant reductions
in morbidity indicators were associated with reductions in particles — even below 15 |ig/m3.
• Pope et al (2004): Cardiovascular mortality and long-term exposure to particulate air
pollution: Epidemiological evidence of general pathophysiological pathways of disease.
Circulation 109:71-77. Suggested by Dr. Morton Lippmann. The report on the ACS cohort
indicated that long-term PM2 5 exposures were most strongly associated with mortality
attributable to ischemic heart disease, dysrhythmias, heart failure and cardiac arrest.
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• Krewski et al. (2005): Mortality and long-term exposure to ambient air pollution:
ongoing analyses based on the American Cancer Society cohort. J. Toxicol. Environ. Health
68:1093-1109. Suggested by Dr. Frank Speizer. Ongoing analyses based on the ACS cohort in
many cities across the country reported robust associations between ambient fine particulate air
pollution and elevated risks of cardiopulmonary and lung cancer mortality
• Kunzli et al (2005): Ambient air pollution and atherosclerosis in Los Angeles.
Environ. Health Perspect. 113:201-206. Suggested by Dr. Frank Speizer. In an additional study
in humans an association was found between estimated long-term exposure to PM2.5 and carotid
artery intimal medial layer thickening.
• Jerrett et al. (2005): Spatial analysis of air pollution and mortality in Los Angeles.
Epidemiology 16:727-736. Suggested by Dr. Frank Speizer. Health risk estimates were larger
using smaller spatial scale exposure estimates. The association between air pollution and
mortality using small-area exposure measures within Los Angeles indicated relative risk ratios
for mortality resulting from ischemic heart disease and lung cancer in the range of 1.24-1.6.
• Enstrom (2005): Fine particulate air pollution and total mortality among elderly
Californians, 1973-2002. Inhalation Toxicology 17:803-816. Suggested by Dr. Roger
McClellan. The epidemiologic results of the study do not support a current relationship between
fine particulate pollution and total mortality in elderly Californians, but they do not rule out a
small effect, particularly before 1983.
• Moolgavkar (2005): A review and critique of the EPA's rationale for a fine particle
standard. Regulatory Toxicology & Pharmacology 42:123-144. Suggested by Dr. George Wolff.
The author of the review concludes that a particle mass standard is not defensible on the basis of
a causal association between ambient particle mass and adverse effects on human health.
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NOTICE
This report has been written as part of the activities of the U.S. Environmental
Protection Agency's (EPA) Clean Air Scientific Advisory Committee (CASAC), a
Federal advisory committee administratively located under the EPA Science Advisory
Board (SAB) Staff Office that is chartered to provide extramural scientific information
and advice to the Administrator and other officials of the EPA. The CAS AC is
structured to provide balanced, expert assessment of scientific matters related to issue
and problems facing the Agency. This report has not been reviewed for approval by the
Agency and, hence, the contents of this report do not necessarily represent the views and
policies of the EPA, nor of other agencies in the Executive Branch of the Federal
government, nor does mention of trade names or commercial products constitute a
recommendation for use. CASAC reports are posted on the SAB Web site at:
http ://www. epa.gov/sab.
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