The U.S. Environmental Protection Agency should consider strengthening its current standard for deadly fine particulate matter pollution, an independent panel of scientific experts recommended Oct. 11.
The experts were previously tasked with aiding the EPA's seven-member Clean Air Scientific Advisory Committee, or CASAC, in reviewing the latest science on the tiny airborne pollutant. The panel arrived at the conclusion a year after EPA Administrator Andrew Wheeler abruptly dismissed it along with a similar expert panel for ground-level ozone pollution.
Wheeler claimed the move was necessary to adhere to the Clean Air Act's five-year review timelines for the National Ambient Air Quality Standards, or NAAQS, but former EPA staff have argued dismissing the panels has thrown the review process into disarray.
In defiance of Wheeler's dismissal, 20 of the disbanded particulate matter experts sought to bring more scientific clarity to the process by reconvening outside of Washington, D.C., for a two-day meeting organized by the Union of Concerned Scientists. "This holds the EPA and CASAC's feet to the fire," Gretchen Goldman, research director for the Center for Science and Democracy at the Union of Concerned Scientists, said in an interview following the Oct. 11 meeting.
While the self-organized panel is no longer formally advising CASAC, its recommendations could carry significant weight in a legal challenge to the EPA's determination — expected early next year — as to whether the NAAQS, for fine particulate matter, or PM 2.5, should be maintained or strengthened. The EPA aims to complete reviews for both PM 2.5 and ozone by late 2020 under a streamlined "back-to-basics" approach outlined by former EPA Administrator Scott Pruitt.
'The courts may have the last say'
Based on a lengthy scientific review, the EPA in 2012 strengthened the primary standard for PM 2.5 to 12 micrograms per cubic meter, down from the previous standard of 15 micrograms per cubic meter. That decision ultimately withstood a legal challenge from a coalition of electric utilities at the U.S. Court of Appeals for the District of Columbia Circuit.
Without the benefit of the auxiliary panel's expertise, the seven-member CASAC — comprised primarily of state air regulators — told Wheeler in April that it lacked the depth and breadth of experience needed to review a 1,000-page Integrated Science Assessment on the health effects of exposure to PM 2.5. In doing so, the CASAC asked Wheeler to reinstate the disbanded panel, a request Wheeler rejected in July by instead appointing a different pool of subject matter experts.
The disbanded panel is now poised to submit a public letter to the CASAC recommending that the EPA lower the primary standard for PM 2.5 to between 8 to 10 micrograms per cubic meter and the secondary standard to between 25 to 30 micrograms per cubic meter. Calculated on an annual basis, the primary standard is designed to protect human health with an adequate margin of safety, while the secondary standard, measured over a 24-hour period, is aimed at visibility.
The letter will follow a draft policy assessment released by EPA staff in September estimating that approximately 50,000 PM 2.5-linked deaths occur annually under the current standards.
Noting a recent ozone ruling by the D.C. Circuit that referred to the CASAC nearly 100 times, former CASAC Chairman Chris Frey said the group plans to craft its letter with an eye toward judicial review.
"I think the courts have shown they do care about the science, and we're writing our letter keeping in mind that this will become part of the public record upon judicial review and the courts may have the last say," Frey, an environmental engineering professor at North Carolina State University, said in an Oct. 11 interview.
Frey's view was echoed during the meeting by Steven Silverman, a former EPA lawyer who served as counsel on the last two NAAQS reviews for PM 2.5. "These are legally uncharted grounds," Silverman said in an interview on the sidelines of the meeting. "To me, the target audience is not Andrew Wheeler. It's the D.C. Circuit."
An EPA spokesperson said in an Oct. 11 email that the agency is committed to scientific integrity and transparency. "EPA has the utmost confidence in its career scientist and the members on its science advisory boards and panels," the spokesperson said. "EPA routinely takes comments from the public and outside organizations, including those not employed or associated with EPA, and will continue to take into consideration those comments that meet our scientific standards."
The CASAC will convene again via public teleconference on Oct. 22 to peer review the draft policy assessment EPA staff released in early September. Following the teleconference, the committee will hold a two-day face-to-face meeting starting on Oct. 24 in Research Triangle Park, N.C.