A panel of independent experts has published a paper in a leading peer-reviewed medical journal that calls into question the U.S. Environmental Protection Agency's proposal to leave in place air pollution standards that allow tens of thousands of avoidable soot-linked premature deaths every year.

The paper was published June 10 in the New England Journal of Medicine by former members of an independent review panel previously tasked with aiding the EPA's seven-member Clean Air Scientific Advisory Committee, or CASAC. The review panel was disbanded by EPA Administrator Andrew Wheeler in October 2018 under the disputed justification that it was preventing the agency from meeting its five-year statutory deadline to review the National Ambient Air Quality Standards, or NAAQS.

The firing came after Wheeler's predecessor, Scott Pruitt, imposed a new scientific integrity policy — since ruled arbitrary and capricious by multiple federal appeals courts — that barred EPA grant recipients from serving on advisory panels.

Tasked with assessing the latest science on soot-forming fine particulate matter, or PM 2.5, members of a reconstituted CASAC told Wheeler in March 2019 that they lacked the breadth and depth of experience needed to perform an adequate review.

Meanwhile, the disbanded panel of PM 2.5 experts self-organized to perform their own review. In October 2019 they recommended tightening the primary NAAQS for PM 2.5 to between 8 micrograms and 10 micrograms per cubic meter, down from the current standard of 12 micrograms set in 2012.

Wheeler ignored that advice by proposing to leave the current PM 2.5 standards in place, citing the recommendation of a divided CASAC that was unable to reach a consensus. The proposal is now up for public comment with a deadline that ends June 29.

The proposal was delivered as the EPA advanced a separate rulemaking that would limit the agency's ability to consider health studies that rely on private medical information linking PM 2.5 to respiratory conditions and premature death. The EPA has also proposed to heavily discount the public health co-benefits associated with PM 2.5 reductions in Clean Air Act rulemakings.

Most of the cost savings in energy- and climate-related EPA regulations, such as the Obama-era Clean Power Plan, have been attributed to public health benefits tied to the retirement of coal-burning power plants, the largest emitters of PM 2.5.

Chris Frey, a former CASAC chair and co-author of the June 10 journal article, said the independent panel decided to publish its findings in the New England Journal of Medicine in order to deliver a succinct message. The main takeaway is that tens of thousands of avoidable premature deaths will occur every year if the PM 2.5 standard is not tightened, he said.

EPA staff's own policy assessment found that approximately 50,000 PM 2.5-linked deaths occur annually at the agency's current standard, and they estimated that between 21% and 27% of those deaths could be avoided by tightening the standard to 9 micrograms per cubic meter.

"At the current standard, tens of thousands of people are dying prematurely, and if you lower the ambient concentration that will lower the extent of adverse effects," Frey, an environmental engineering professor at North Carolina State University, said in an interview.

An EPA spokesperson said in a June 11 email that the current CASAC was selected through a public process that included appropriate ethics evaluations. She added that most of the committee members found the latest PM 2.5 review documents do not provide "a sufficiently comprehensive, systematic assessment of the available science relevant to understanding the health impacts of exposure." Average annual PM 2.5 concentrations in the U.S. fell by 39% between 2000 and 2018, she noted.

In the past, federal courts have afforded the agency considerable deference in legal challenges to its NAAQS rulemakings. However, the U.S. Court of Appeals for the District of Columbia Circuit has also indicated that it highly values the CASAC's expertise. For example, the D.C. Circuit in August 2019 partially remanded the EPA's 2015 NAAQS standard for ozone in an opinion that referred to the committee 98 times.

A court challenge to a final rule that maintains the current PM 2.5 standards could raise novel legal questions. For instance, Frey noted that the independent panel's article disputes the legitimacy of the current CASAC, a committee convened under a policy that has now been struck down by the courts.

"Based on the public record, as we've pointed out numerous times as a group and individuals, the CASAC has been modified such that personally I don't think it's a credible source of advice on the air quality standards," Frey said. "And I think that's going to be a tough issue for the courts to grapple with."