The Clear Skies Initiative is Hazy

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Proponents of the Clear Skies Initiative claim that it will avert thousands of deaths annually by reducing emissions from coal-fired power plants. Environmental activist groups counter that Clear Skies will kill tens of thousands annually because it does not go far enough to curb emissions. This paper counsels skepticism on the root epidemiological premise behind the claims of both proponents and opponents of Clear Skies—the assumption that fine particulate (PM2.5) pollution kills people at any level of exposure.

The paper makes four main points.  First, it is unlikely that PM2.5 at current levels is causing any mortality. EPA based its PM2.5 standard largely on the American Cancer Society (Pope et al.) study. The odd variations that study found in the association between PM2.5 and mortality defies biological explanation. For example, Pope et al. found no association between PM2.5 levels and mortality for women, for persons with more than a high school education, and for persons between the ages of 60 and 69.

Second, Clear Skies (like its more aggressive alternative, Sen. James Jeffords’ (I-VT) Clean Power Act) assumes without evidence that there is no threshold below which PM2.5 poses no health risks. This unsupported assumption leads to greatly exaggerated estimates of the mortality effects of current PM2.5 levels.

Third, if PM2.5 were the dire threat that Clear Skies advocates assume, then Clear Skies would do little to combat it. Clear Skies does not target resources at areas with the highest PM2.5 levels. Rather, it seeks to save lives by achieving small incremental reductions in PM2.5 levels everywhere. This makes about as much sense as establishing a national anti-obesity program designed to help every overweight person lose one pound rather than to help the most dangerously obese individuals lose tens of pounds. 

Fourth, when the Clear Skies benefits model is run retrospectively, i.e., backward from 2000 to 1980, it fails to show any benefits corresponding to the known decreased trend in PM2.5 exposures. Significant reductions in PM2.5 over the past two decades did not reduce cardiopulmonary mortality risk at all.