Particulate Matter Experts Still Think that the PM2.5 NAAQS Should Be Lowered. Will The Courts Defer to Them Or to EPA?

Last week, the New England Journal of Medicine published The Need for a Tighter Particulate-Matter Air-Quality Standard, written by the Independent Particulate Matter Review Panel.  For those who don’t remember, the Review Panel used to be a sub-committee of EPA’s Clean Air Science Advisory Committee, until EPA Administrator Wheeler decided that CASAC did not need the specific advice that the Review Panel had to offer.

The review panel was not deterred.  The NEJM article largely mirrors the report they issued last October, which concluded that the current PM2.5 annual standard is not sufficiently protective.  The authors state that:

The estimated all-cause mortality from long-term exposure to PM2.5, calculated on the basis of the 2015 air quality adjusted to just meet the existing standards, ranges from 13,500 to 52,100 deaths annually.

Their recommendation remains that EPA should lower the standard to between 8 and 10 ug/m3, although they note that risks remain even at the low end of that range.

As I’ve noted previously, the relevant statutory provision is that the NAAQS must be requisite to protect public health “with an adequate margin of safety.”  I still don’t understand how EPA can conclude that the current PM2.5 NAAQS complies with the statute, even if there is uncertainty surrounding these mainstream conclusions.  What does “adequate margin of safety” mean other than that EPA must resolve uncertainties in favor of protection of public health?

The article poses this question about judicial review of EPA’s decision to leave the PM2.5 standard unchanged:

Federal courts have in the past given considerable deference to the Clean Air Scientific Advisory Committee regarding its scientific advice. Will the courts defer to a committee that has been arbitrarily and capriciously deprived of a particulate matter–specific expert panel? Or will the courts look elsewhere, such as to public comments from experts and input from the dismissed panel?

I asked the nearly identical question last April, when EPA’s proposal was released.  It remains the question of the day.  How much deference does EPA get when it ignores the recommendation of the overwhelming weight of mainstream science?

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