EPA’s Particulate Matter Standard Challenged

Published July 1, 2003

A recent study by Competitive Enterprise Institute Adjunct Scholar Joel Schwartz challenges the scientific basis of the Bush administration’s Clear Skies Initiative and Senator Jim Jeffords’ (I-Vermont) Clean Power Act.

The analysis, released April 21, has implications for climate policy. Jeffords’ legislation includes regulation of carbon dioxide emissions, and Bush’s plan could serve as a proxy climate policy by forcing utilities to close coal-fired power plants in order to achieve mandated limits on mercury emissions.

Clear Skies and Clean Power would impose tough new controls on power plants to reduce levels of fine particle (PM2.5) pollution, alleged to kill tens of thousands of people every year. Supporters of these bills promise substantial benefits from additional PM reductions. [2.5 refers to particle size of 2.5 microns or smaller.]

Weak Science Foundation

Schwartz’s new study concludes that Clear Skies and Clean Power rest on a weak scientific foundation. The U.S. Environmental Protection Agency (EPA) based its PM2.5 standard on an American Cancer Society (ACS) study of PM and mortality, which evaluated the association between PM2.5 levels in dozens of American cities and the risk of death between 1982 and 1998.

Although the ACS study reported an association between PM and mortality, some odd features of the results suggest PM is not the culprit. For example, higher PM levels increased mortality in men, but not women; in those with no more than a high school degree, but not those with at least some college; in former smokers, but not those who currently smoke or never did; and in those who said they were moderately active, but not those who said they were very active or sedentary.

Such variations in the relationship between PM2.5 and mortality seem biologically implausible. Moreover, the ACS study reported that higher PM2.5 levels were not associated with an increased risk of mortality due to respiratory disease–a surprising finding, given that particulate matter would be expected to exert its effects through the respiratory system.

In setting its new PM2.5 standard, EPA ignored the results of another epidemiological study that found no effect of PM2.5 on mortality in a cohort of veterans with high blood pressure, even though this relatively unhealthy cohort should have been more susceptible to the effects of pollution than the general population.

The evidence suggests EPA’s annual standard for PM2.5 is unnecessarily stringent. Attaining the standard will be expensive but is unlikely to improve public health.

Air pollution has declined dramatically over the past 30 years, and it will continue to decline. More recent vehicle models start out cleaner than earlier ones and stay cleaner as they age, and already-adopted standards for new vehicles and existing power plants will come into effect in the next few years.

If policymakers feel they must do something to speed up PM reductions, Schwartz advises they offer people tax incentives to scrap high-polluting older vehicles that account for a substantial portion of ambient PM levels in metropolitan areas. This flexible, cost-effective approach is more likely to result in net public health benefits than either Clear Skies or Clean Power.

S. Fred Singer is professor emeritus of environmental sciences at the University of Virginia and president of the non-profit Science & Environmental Policy Project in Arlington, Virginia. http://www.sepp.org

For more information …

Joel Schwartz’s 45-page study for the Competitive Enterprise Institute, “Particulate Air Pollution: Weighing the Risks,” is available through PolicyBot. Point your Web browser to http://www.heartland.org, click on the PolicyBot icon, and search for document #12327.