EPA Proposes to Lower the PM2.5 NAAQS — Searching For the Goldilocks Level

EPA has finally proposed revisions to the national ambient air quality standard for PM2.5.  The Administrator is proposing to lower the standard from 12.0 ug/m3 to a range of 9.0 to 10.0 ug/m3

Readers of this space will recall that the Clean Air Science Advisory Committee recommended that EPA lower the PM2.5 NAAQS to between 8.0 and 10.0 ug/m3.  Environmentalists aren’t going to be happy with any standard above 8.0 ug/m3 and it’s likely that conservatives aren’t going to be happy with any decrease from the current standard.

In any case, it appears that EPA is not worrying about any stakeholders other than the nine members of the Supreme Court.  Administrator Regan is clearly looking for the Goldilocks NAAQS; neither too lax nor too stringent.  The following or similar language appears repeatedly throughout the proposed reconsideration:

The Administrator recognizes that the final suite of standards will reflect the Administrator’s ultimate judgments in the final rulemaking as to the suite of primary PM2.5 standards that are requisite to protect the public health with an adequate margin of safety from effects associated with PM2.5 exposures. The final judgments to be made by the Administrator will appropriately consider the requirement for standards that are neither more nor less stringent than necessary and will recognize that the CAA does not require that primary standards be set at a zero-risk level, but rather at a level that reduces risk sufficiently so as to protect public health with an adequate margin of safety.

It’s hard to argue with this approach and I expect both that EPA will stick with it in the final decision.  I also expect that the courts will agree that EPA’s decision, whether at 9.0 ug/m3 or 10.0 ug/m3, is neither too hot nor too cold, but is instead just right.

I’d also speculate that the next time EPA reviews the PM NAAQS, the only question will be whether EPA has reduced it enough; it’s not going to be considering whether the then-current NAAQS is too stringent.

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