This post was originally published on Legal Planet. Reprinted with permission.
The Biden administration is slowly grinding away at an important regulatory task: reconsidering the air quality standards for particulates and ozone. Setting those standards is an arduous and time-consuming process, requiring consideration of reams of technical data. For instance, a preliminary staff report on fine particulates (PM2.5) is over 600 pages long. When the process is done, the result will not only be better protection of public health. It will also be a reduction in emissions of carbon dioxide and other global warming agents.
Quick legal background: The Clean Air Act requires EPA to set national ambient air quality standards or NAAQS (pronounced "knacks"). They are supposed to be set at a level that, "allowing an adequate margin of safety, are requisite to protect the public health." They're supposed to be revised every five years based on new science, though EPA has tended to fall beyond schedule. The Trump administration decided that the existing standards are just fine, but Biden directed EPA to reconsider.
It seems pretty clear that the current PM2.5 standard is too high. Averaged over a year, the current standard limits emissions to 12.0 μg/m3. Trump fired the panel of scientific experts who are supposed to advise EPA on that standard. After being fired, however, they published their views anyway in the New England Journal of Medicine: "We unequivocally and unanimously concluded that the current PM2.5 standards do not adequately protect public health. An annual standard between 10 μg per cubic meter and 8 μg per cubic meter would protect the general public and at-risk groups." The EPA staff report comes to similar conclusions (see p. 3-156). The Biden administration has also announced that it intends to reconsider standards for ozone pollution.
Revising the standards seems likely to prevent thousands of deaths per year, as well cut other health effects like children's asthma attacks. Revising the standards will also help address air pollution. The reason is that ozone-forming substances come largely from cars, power plants, industrial boilers, refineries, and chemical plants. PM2.5 comes mostly from burning things, notably coal. Changing the standards will require states to tighten their controls on all these sources, making it more expensive to burn fossil fuels. And reducing the use of fossil fuels is crucial for addressing climate change.
Oddly, while many people have written about how climate policy will reduce harmful air pollutants, there isn't much about the converse: the climate co-benefits of air pollution reductions. I couldn't find even rough estimates of how much tightening these standards would impact climate change. Nevertheless, there's every reason to think this climate change "co-benefit" of tougher pollutions standards would be substantial.