We are writing to express our grave concern that the proposed revisions to the National Ambient Air Quality Standards for fine and coarse particulate matter (PM) are insufficient to protect public health and welfare as required by the Clean Air Act. Under the Clean Air Act, primary standards must protect public health, including the health of sensitive populations, with an adequate margin of safety. Secondary standards must protect public welfare, including important adverse effects such as visibility impairment and damage to materials and crops. The proposed standards fail on both counts.
The adverse health effects of particulate matter are serious and have been well documented in EPA’s Criteria Document and Staff Paper. The thousands of studies published over the last nine years make a much stronger case for the regulation of fine particles than in 1997, and indicate that the current standards must be lowered to protect public health. Community health studies have consistently demonstrated associations between daily increases in fine particles and decreased lung function, exacerbation of asthma, more frequent emergency department visits, increased risk of heart attacks and strokes, additional hospital admissions , and increased number of daily deaths. These effects have been demonstrated in cities where the daily concentrations of PM2.5 are well below the current standard and rarely reach the level of the proposed 24-hour standard. Furthermore, the form of the proposed standard excludes too many of the most polluted days from compliance determinations.
Long term exposures to fine particles are implicated in premature death from heart disease, lung disease, and lung cancer. Lives may be shortened by one to three years. EPA’s risk assessment demonstrates that thousands of premature deaths attributable to particulate air pollution are occurring each year under the current standard, and that the proposed standards would do little to reduce this toll. Building on earlier work, the largest ever epidemiological study of the effects of PM2.5 in 204 U.S. counties was published in the Journal of the American Medical Association in March 2006.1 This study showed clearly that the proposed standards for PM2.5 fail to protect public health as required by the Clean Air Act. In this study, the average of the county mean annual values was 13.4 µg/m3—well below the proposed standard of 15 µg/m3. At levels below what EPA proposes as an annual standard, the findings showed cardiovascular and respiratory hospital admissions for the elderly increasing as concentrations PM2.5 increased. Significant associations with excess cardiac and respiratory admissions persisted even after excluding all days above 35 µg/m3 (the level of the proposed daily standard) from the study.2
Even where PM2.5 concentrations met both the proposed annual and 24-hour standards, serious health effects occurred. Furthermore, a follow-up to the Harvard Six Cities Study published in March 2006 documented the life-saving benefits from reduced particulate levels. That study found that an average of three percent fewer people died for every reduction of one µg/m3 in the annual average levels of PM2.5.3 According to EPA’s Children’s Health Protection Advisory Committee, the proposed annual PM2.5 standard does not provide the required adequate margin of safety to protect infants and children. The Committee concluded that the proposed daily PM2.5 standard must also be revised downward to protect public health.4 The Clean Air Scientific Advisory Committee to the EPA has indicated that PM2.5 causes adverse health effects including premature death at annual concentrations below the current standard, and has reiterated its recommendations for lowering the annual standard. 5
Coarse particles are associated with increased hospitalization for respiratory infections in children, decreased lung function, increased hospital admissions for heart disease, increased hospital admissions for respiratory disease in the elderly and increased risk of premature death. EPA proposes a daily coarse particle standard that would be higher than levels where serious health effects have been reported in the studies EPA reviewed.
EPA would enforce the standard only in urban areas with populations above 100,000, and exempt mining and agricultural sources of particles. EPA must set a coarse particle standard that applies nationally and without exemptions, to protect the health of all Americans as the Clean Air Act requires. Furthermore, EPA must not revoke the PM10 standard in any area of the country without providing protection against backsliding.
The Children’s Health Protection Advisory Committee has recommended that the level of the coarse particle standard be lowered, that standards apply nationwide, with monitoring in both urban and rural areas, and that the exemption for agriculture and mining be withdrawn. The Clean Air Scientific Advisory Committee has also opposed exempting specific industries and recommended establishment of a national coarse particle monitoring program in urban and rural areas.
Our organizations strongly support lowering both the annual average and the 24-hour fine particle standard, while tightening the way compliance with the standards is measured. We urge you to adopt protective coarse particle standards that will apply nationwide, with monitoring in both urban and rural areas. We oppose the special exemptions for agribusiness and mining. In addition, we believe that EPA must establish secondary standards for fine particles that protect against deterioration of visibility caused by fine particle pollution, as recommended by the Clean Air Scientific Advisory Committee, and set secondary standards for coarse particles that apply nationwide to protect against the ecosystem damage and visibility degradation they cause.
Specifically, we favor:
. an annual average PM2.5 standard of 12 µg/m3 or below, with elimination of the spatial averaging loophole;
. a 24-hour PM2.5 standard of 25 µg/m3, 99th percentile;
. a 24-hour PM10-2.5 standard of 25-30 µg/m3, 99th percentile, to apply nationally.
. Application of the course particle standard across the country, with monitoring in rural areas and elimination of the special exemption for the mining and agriculture industries; . a PM2.5 secondary standard of 20 µg/m3 or below, based upon a rolling 4-hour average; and
. a secondary standard for coarse PM that protects ecosystems and scenic vistas across the country.
The decision over the air quality standards for fine and coarse particulate matter is the most far-reaching environmental health decision you will make this year. We urge you to strengthen the proposed standards, consistent with the law and the science.
1 Dominici F, Peng RD, Bell ML, Pham L, McDermott A, Zeger SL, Samet JM. Fine Particulate Air Pollution and Hospital Admission for Cardiovascular and Respiratory Diseases. JAMA 2006; 10:1127- 1134.
2 Letter from Francesca Dominici to U.S. EPA, March 23, 2006. Docket ID No. EPA-HQ-OAR-2001-0017-0988.
3 Laden F, Schwartz J, Speizer FE, Dockery DW. Reduction in Fine Particulate Air Pollution and Mortality: Extended Follow-up of the Harvard Six Cities Study. Am J Respir Crit Care Med 2006; 173: 667-672.
4 Letter from Melanie A. Marty, Ph.D., Chair, EPA Children’s Health Protection Advisory Committee, to Stephen L. Johnson, Administrator, U.S. Environmental Protection Agency, RE: Proposed NAAQS for Particulate Matter, March 3, 2006.
5 Dr. Rogene Henderson, Chair, Clean Air Scientific Advisory Committee letter to Stephen L. Johnson, Administrator, U.S. Environmental Protection Agency, March 21, 2006, Subject: Clean Air Scientific Advisory Committee Recommendations Concerning the Proposed National Ambient Air Quality Standards for Particulate Matter, EPA-CASAC-LTR-06-002.