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Soot FAQ
WHY DID EPA ISSUE NEW SOOT STANDARDS?
Our nation's Clean Air Act requires the EPA to protect the health of the American people and our environment from air pollution. Using the best available scientific evidence, EPA is required to set limits for pollutant levels in our air low enough and with "a margin of safety" sufficient to protect everyone including the people most sensitive to air pollution. These protective standards are called the "national ambient air quality standards" (NAAQS) and they are vital to the health of the American people. The Clean Air Act requires the EPA to review the adequacy of clean air standards every five years so that the standards are based on the most recent scientific information.
WHAT ARE THE SOURCES OF SOOT POLLUTION?
Soot is produced by coal combustion, coal and coal ash handling, high-temperature industrial process like smelters and steel mills, rock crushing, agricultural operations including concentrated animal feeding operations, roadway dust and vehicle fumes, cement and steel plants, mining operations, farming, tire and brake wear, and fires. Soot, or particulate matter, includes both solid material and liquid droplets. It can be formed by chemical reactions of gaseous pollutants released into the atmosphere.
WHAT ARE THE HEALTH EFFECTS OF EXPOSURE TO SOOT?
Since 1997, when the EPA first set particle standards, more than 2,000 scientific studies have shown links between particulate matter and a host of illnesses. In California, the California Air Resources Board has found that premature deaths linked to particulate matter are now at levels comparable to deaths from traffic accidents and second-hand smoke.
Exposure to elevated levels of soot results in reduced lung function and, in people afflicted with heart and lung diseases, an increased incidence of premature death. Short-term exposure to high levels of soot causes increased respiratory disease and cardiovascular disease as indicated by higher hospital admissions and emergency room visits. Damage to the circulatory system is evidenced by increased incidence of non-fatal heart attacks, arrhythmia, and physiological changes. Damage to the respiratory system is indicated by increased coughing, wheezing, and shortness of breath as well as reduced lung function.
About 90% of the lung's alveoli, the tiny sacs where oxygen enters the body, are formed after birth. Damage done to a child's developing lungs by soot is irreversible. Long-term exposure to soot pollution may also result in the development of chronic respiratory disease in children. Short-term exposure to elevated levels of coarse particulate pollution results in increased hospital admissions for respiratory symptoms and heart disease, reduced lung function, and premature deaths.
WHAT ARE THE ENVIRONMENTAL IMPACTS OF SOOT POLLUTION?
Soot pollution plays a major role in the formation of haze, which obscures our ability to enjoy vistas in parks, skylines in cities, and the stars at night.
WHAT STANDARD SHOULD BE APPLIED TO SOOT POLLUTION?
Because soot can be dangerous whether inhaled over a short-term (measured daily) or over a long-term at lower levels (averaged annually), the standard has two parts. In this latest round, EPA lowered the daily limit from 63 to 35 micrograms per cubic meter of air and kept the same annual standard of 15 micrograms per cubic meter of air. Recent rigorous scientific studies have demonstrated the occurrence of severe health effects at lower levels, and EPA considered those lower levels in its own analysis. In deciding what standard would be protective of the most vulnerable populations, the Sierra Club looked to the recommendations of public health and medical groups like the American Academy of Pediatrics which recommended lowering the annual standard to 12 µg/m3 and the daily standard to 25 µg/m3. These levels are consistent with the most recent, comprehensive, and reliable scientific evidence and provides some margin of safety for children, the elderly, and other sensitive people. Unfortunately, in announcing the new standards, the EPA maintained the annual average standard at 15 micrograms per cubic meter and only slightly revised the daily average standard to 35 µg/m3. The Sierra Club opposes the new standards.
WILL THIS STANDARD PROTECT VISIBILITY IN OUR PARKS, AND URBAN AND RURAL AREAS?
EPA staff papers included stunning photographs which depict the impact of poor air quality in and around our major cities, and EPA set a separate soot standard (called a secondary standard because it is intended to protect aesthetics rather than health) to address visibility problems in urban areas. However, the EPA merely adopted the primary standard for the secondary standard, and did not go as low as had been recommended by the Clean Air Scientific Advisory Committee.
WHAT STANDARD SHOULD BE APPLIED TO COARSE PARTICULATES?
Although the EPA proposed reducing the daily standard for coarse particulates, in the end it decided to keep the old standard. Dr. Bart Ostro, Chief of the Air Pollution Epidemiology Unit in California EPA's Office of Environmental Health Hazard Assessment and world-renowned scientist on the health effects of soot pollution, found that EPA's proposed lower standard would still not be protective of human health. His review of the scientific literature detailing coarse particle pollution levels and associated hospital admissions led to a recommendation of a more stringent regulation between 36-45 µg/m3.
The American Lung Association favored a broader margin of safety and supports a more stringent 25-30 µg/m3 standard. The Sierra Club urged the adoption of a 24-hour standard for coarse particulate matter set well below that which has been scientifically demonstrated to harm human health. In addition to abandoning their proposal to strengthen the daily standard, the EPA also decided to eliminate the annual standard. Sierra Club is opposed to these standards.
ARE THERE LOOPHOLES IN THE RULE?
The EPA's proposed rule included several loopholes which would have undermined the annual particulate soot standard. One example is the "98th percentile," which would allow a certain number of high pollution days to be excluded from the calculation of the annual average. In practice, this meant that air quality is permitted to exceed health-based standards for two weeks every year! Other loopholes included a proposed mining and agriculture exemptions from the national ambient air quality standards as well as an attempt to limit the coarse particulate matter standard only to urban areas.
Fortunately, in the final rule announced September 21, 2006, the EPA backed off these poorly planned exemptions and did not include the loopholes in the new standards. Sierra Club advocated for removing statistical tricks, exemptions for polluting industries, and protecting all communities equally, and supports a national ambient air quality standard that protects all Americans and requires every day to be good air day.
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