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'CURRENT standards leave far too many Americans at risk, particularly children." That's EPA Administrator Carol Browner defending what will probably be the costliest regulatory action of the decade. The EPA wants to tighten air-quality standards for ozone, a/k/a smog, by one-third. It also proposes prohibiting tiny airborne particles, or soot, that are 1/28th of a human hair in width -- 75 times smaller than the particles currently regulated under the Clean Air Act.

Stricter standards will supposedly reduce by 250,000 the number of severe asthma attacks and prevent 15,000 of the 64,000 deaths linked to particulate matter each year. Yet the scientific "evidence" behind these claims is, at best, dubious. While deaths and hospitalizations increase on days when particle pollution rises, so do levels of pollutants such as sulfur dioxide and carbon monoxide. An EPA staff paper acknowledges the impossibility of assigning blame to a particular pollutant when so many different pollutants rise and fall together. Moreover, although reported cases of asthma increased 45 per cent over the past decade, ozone and particulate levels are sig- nificantly lower. Could something else be to blame?

EPA ignores its own findings on the benefits of ozone. Recall a few years ago the agency touted ozone's screening effect on harmful ultraviolet-B radiation. Chlorofluorocarbons (CFCs) used in aerosol sprays and air conditioners were banned to protect the public from a decline in ozone. Although concerns about the "ozone hole" focused on the stratosphere, studies show that ground-level ozone also significantly screens UV-B rays. In fact, one internal EPA study estimates that the proposed new ozone regulations will result in 3,000 to 4,000 additional cases of non-melanoma skin cancer annually.

Tighter standards would put hundreds of counties out of compliance with the Clean Air Act. Administrator Browner acknowledges that California will probably have to abandon diesel fuel, which powers everything from generators to trucks, trains, and ships. Midwestern states dependent on coal-powered electric plants would also be hit hard. EPA puts national compliance costs at just $6 billion a year, starting in 2007. This is an egregious understatement; it ignores the fact that many states haven't even met the existing standards. An analysis by the George Mason University's Center for Study of Public Choice estimates the annual cost at $54 to $328 billion for the ozone rule and $55 billion for the particulate matter rule --orders of magnitude above EPA's num- bers. Similarly, benefit calculations are distorted by EPA's choice of $4.8 million as the value of each life saved. (By comparison, the Department of Transportation uses a $2.7 million figure.) Benefits are also inflated by EPA's failure to calculate the number of years of life its new regulations would save. Individuals who die from higher smog concentrations are likely to have had pre-existing heart or respiratory conditions. Put simply, a regula- tion that adds a few years to a sick person's life should not be valued as highly as one that saves people in their prime.

Regulatory costs themselves affect public health. It is well established, for example, that mortality rises as income falls. OMB has estimated the trade-off as one statistical death per every $9 to $12 million decline in aggregate per- sonal income. Using this relationship, the EPA's partial cost figure implies from 50 to 700 deaths each year.

Good news: states will have until 2002 to craft strategies, and 8 to 10 years more to implement them. By then the links, if any, between air quality and health will be better understood.