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The Insider

Complicated PM NAAQS Review Highlights Hurdles For Assessing EPA Air Limits

The complicated ongoing review process for EPA’s national ambient air quality standards (NAAQS) for fine particulate matter (PM2.5) is underscoring uncertainty about the future stringency of the standard, and highlighting hurdles for reviewing NAAQS for other pollutants like ozone.

EPA’s seven-member Clean Air Scientific Advisory Committee (CASAC) is currently conducting a mandatory review of the agency’s NAAQS for PM2.5, but the review is highly unusual in that it is pitting various stakeholders against each other: EPA’s staff, its official scientific advisers, a dissident group of expelled advisers, industry and environmental groups.

The multi-faceted battle could foreshadow difficulties for Trump officials as they hope to complete the PM2.5 review by the end of next year, and are publicly stating a similar timeline for a separate review of EPA’s 2015 ozone NAAQS -- even though that review is earlier in the process.

Under the Clean Air Act, NAAQS must be set at a level to protect public health with an adequate margin of safety, and the agency is barred from considering implementation costs when setting the stringency of the standards.

But the standards are highly influential in determining a range of subsequent requirements for states and regulated industry to install pollution controls.

One of the most novel aspects of the current PM2.5 review is the presence of a group of former members of CASAC, who are clashing with the agency’s current advisers and industry-backed scientists:

CASAC Clashes With Former Panel Members Over Particulate Matter Risks
EPA Clean Air Scientific Advisory Committee (CASAC) members are clashing with former panelists over the health risks posed by fine particulate matter (PM2.5) emissions, with committee members and industry-backed scientists suggesting the agency maintain or loosen PM2.5 limits while former members are seeking much stricter standards.

The “shadow” advisers are former members of a specialized CASAC PM NAAQS review panel that the Trump EPA disbanded. The group reconstituted itself as the Independent Particulate Matter Review Panel (IPMRP), urging the agency to tighten both the primary and secondary annual standards for PM2.5, as well as a limit for emissions in any given 24-hour period.

Those calls would go somewhat further than a draft policy assessment (PA), crafted by EPA staff, that calls for tightening the current standard from 12 micrograms per cubic meter (ug/m3) down to a level between 8 ug/m3 and 12 ug/m3. Staff also urge EPA to consider revising the current 24-hour limit of 35 ug/m3.

But current CASAC Chairman Tony Cox, an industry consultant noted for his skeptical view of the health risks of PM2.5, urged the independent panel to justify its decision to use the “weight of evidence” approach to the scientific risks of the pollutant, instead of what he said is a more rigorous approach to establishing causation of health harms.

IPMRP Chairman Chris Frey -- a North Carolina State University professor who earlier chaired both CASAC’s PM panel and CASAC itself -- said on an Oct. 22 call that the weight of evidence approach is “well vetted” and that Cox was “aggressively self-promoting” inappropriate methods of establishing causation between PM exposure and disease by “cherry-picking” studies and “gerrymandering” CASAC’s agenda.

Cox retorted that he “care[s] mainly about empirical evidence.”

In addition to the conflict between IPMRP members and the current CASAC, some industry-funded scientists are seeking to counter EPA staff’s call to tighten the PM standard:

Skeptics of PM2.5 Health Risks Counter Calls For EPA To Tighten NAAQS
Industry-funded scientists and other skeptics of the health risks of fine particulate matter (PM2.5) emissions are warning an EPA advisory panel that studies showing deaths attributable to the pollutant are highly vulnerable to error, providing a counter to calls by agency staff and former panel members for EPA to tighten its PM2.5 air standards.

James Enstrom, of the Scientific Integrity Institute, said the PA “obscures the null relationship” between PM2.5 exposure and increased mortality in the United States, and that EPA used “citation of only positive findings.”

EPA “falsified the research record,” Enstrom said, claiming that all EPA PM standards should be reexamined going back to the early 1990s.

Julie Goodman, a consultant with the firm Gradient, which is funded by the American Petroleum Institute (API) -- said EPA’s risk assessment, included in the PA, is undermined by “compounding levels of conservatism” and not adequate to determine changes in risk between standards differing by only tiny margins such as 1 ug/m3.

As CASAC began its Oct. 24-25 meeting, a majority of the Trump-appointed panel appeared ready to recommend retaining the existing NAAQS:

Divided CASAC Spars On PM Review But Leans Toward Retaining NAAQS
Over the advice of agency staff, a majority of EPA’s Clean Air Scientific Advisory Committee (CASAC) appears ready to recommend that officials retain existing particulate matter (PM) standards, but some members are questioning how to interpret the latest data and whether they can or should complete their review by the agency’s tight deadline.

Four members of the seven-member panel said they supported retaining the current standard, while two backed staff’s recommendation to tighten it.

In addition, a deep divide on procedural issues emerged at the meeting, with those same two panelists urging a halt to CASAC’s review of the PM standards -- which would risk pushing completion of the review past the Trump administration’s goal of finalizing a decision by late 2020 on whether to retain or change the standards.

As such, a consensus recommendation from CASAC to EPA chief Andrew Wheeler on whether the agency should retain, tighten or weaken its PM standards is unlikely.

“I think we need to call a halt to this. We need to stop,” because “the review process is so dysfunctional,” argued Mark Frampton, the committee’s only research scientist, who added that EPA has “enough evidence” to show its current standard is “not protective.”

Meanwhile, EPA’s separate effort to review its 2015 ozone NAAQS is at a much earlier step in the process, with the agency in late September issuing its review of relevant scientific data that will inform the broader review:

Ozone ISA Finds Weaker Health Impacts But Warns Of Environmental Harm
EPA staff’s integrated science assessment (ISA) of the latest data on ozone air pollution finds weaker evidence of a link between ozone exposure and public health harm but sees stronger evidence of the pollutant’s environmental damage, mixed findings that could complicate the agency’s ongoing review of its ozone ambient air standard.

The agency had hoped to release its draft PA for the ozone standard in October, but that had not yet been released by press time. CASAC was slated to review these documents in November or December, with final versions due in “early spring.” EPA hoped to issue a final rule on whether to retain or change the standard by “winter 2020/2021.”

Yet both the procedural and substantive issues that are currently facing EPA on the PM NAAQS review likely will resurface in the ozone review -- raising questions about whether the agency can complete either review by the end of next year.