EPA announced yesterday that it will “reconsider” the Trump EPA’s decision not to change the PM_2.5 National Ambient Air Quality Standard.  I’ve blogged numerous times about the growing body of evidence that exposure to concentrations of PM_2.5 below the current NAAQS causes significant additional mortality and morbidity.  The evidence is clear.

I certainly agree that climate change is an existential threat and that’s where our emphasis needs to be.  At the same time, it’s human nature to focus on the here and now.  Here and now, people are dying or becoming ill because of exposure to PM_2.5.  Many of them of children or elderly.  Many of them are in environmental justice communities.  Tightening the PM_2.5 should be a priority for EPA.

Fortunately, many of the measures that should be implemented to address climate change would also reduce PM_2.5 exposures.  Let’s hear it for co-benefits.  And I don’t care which way the co-benefits run.  We can reduce PM_2.5 exposure through our climate change regulation.  Or, if there is concern about existing legal authority to reduce GHG emissions, we can reduce emissions to reduce PM_2.5 concentrations – and address climate at the same time.

Either way, the requirement to set NAAQS remains at the core of the Clean Air Act.  If EPA is to protect public health with “an adequate margin of safety”, it should be undeniable that the PM2.5 NAAQS needs to be more stringent.

I will agree with the Trump administration on one point – the NAAQS development process takes way too long.  EPA’s timeline for reconsidering the Trump decision provides that a proposed rule will be issued in the summer of 2022 and a final rule will be issued in the Spring of 2023.  By the time state implementation plans are revised to include measures to attain the new NAAQS, it will be sometime in 2025 or 2026.

There really should be a better way.  I know that EPA wants to bulletproof the new NAAQS, but it should not take this long.