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Debate Heats Over New Air Quality Standards

New York, Oct 05, 2006

The U.S. Environmental Protection Agency (EPA) recently revised the national air quality standards for particle pollution to levels they say are the most stringent in the nation’s history. But the final standards have sparked sharp criticism from several environmental and public health groups, including the Clean Air Science Advisory Committee (CASAC)—the independent scientific panel that counseled the EPA.

Particle pollution, also known as particulate matter, is made up of tiny solid and liquid particles suspended in the air as dust, smoke, or soot. These particles give smog its color, degrade visibility, and are linked to a variety of serious health problems, including respiratory and heart ailments, and related premature deaths.

The standards are a revision of the previous National Ambient Air Quality Standards (NAAQS) set in 1997 that establish maximum daily and annual levels for fine particles—those 2.5 micrometers in diameter or smaller—and inhalable coarse particles, which range between 2.5 and 10 micrometers in diameter. The revised NAAQS tighten the previous daily fine particle standard by nearly fifty percent. This significantly strengthened standard, EPA says, will reduce premature deaths, heart attacks and hospital admissions for people with heart and lung disease. The agency also estimates that the revision will yield an estimated $9 billion to $75 billion in additional health benefits annually.

The Clean Air Science Advisory Committee (CASAC), which has served as EPA’s advisory panel on air quality issues for decades, has questioned the agency’s decision to maintain the annual fine particle standard at 1997 levels (15 micrograms/cubic meter), despite its science-based recommendations for stricter standards. The CASAC had urged the agency to reduce the annual standard to 13 or 14 micrograms per cubic meter of air, citing research that indicated risk of adverse health effects from even small amounts of exposure over the course of a year.

The panel also raised issue with EPA’s decision not to set new standards for inhalable coarse particles. EPA kept the daily inhalable coarse particle standard at previous levels and revoked the annual coarse particle standard, citing a lack of evidence linking health problems to long-term exposure to coarse particle pollution.

Environmental interest groups have posited that the new standards may draw a legal challenge from public health groups and environmentalists who point to an internal EPA report showing that a one microgram decrease in the annual fine particle standard would save between 17,000 to 30,0000 premature deaths.

“There is clear and convincing evidence that significant adverse human-health effects occur in response to short-term and chronic particulate matter exposures at or below 15 micrograms per cubic meter (of air), the level of the current annual. . . . standard,” the seven permanent members of the CASAC panel wrote in a September 29 letter to EPA administrator Stephen Johnson.

According to EPA, the final standards were selected after reviewing thousands of peer-reviewed scientific studies about the effects of particle pollution on public health and welfare. The agency held three public hearings and considered more than 120,000 written comments.

As they stand now, states are required to meet the revised particulate matter standards by 2015; some states may be granted an extension to 2020, depending on local conditions and the availability of controls.

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