I’ve written a lot about how the developing science around particulate exposure supports making the PM2.5 NAAQS more stringent. So it won’t come as a surprise that a new study published in the Proceedings of the National Academy of Sciences indicates that the benefits of on-road emissions reductions from 2008 to 2017 could be measured in the hundreds of billions of dollars and almost 10,000 fewer deaths. … More
Category Archives: NOx
EPA Will Reconsider the Ozone NAAQS — What Is An Adequate Margin of Safety, Anyway?
On Friday, EPA announced that it was reconsidering its 2020 decision to leave the National Ambient Air Quality Standards for ozone unchanged. 
The reconsideration will be based on the existing record. The notice does not identify any specific perceived flaws in the 2020 decision. However, EPA stated that it:
will reconsider the decision to retain the ozone NAAQS in a manner that adheres to rigorous standards of scientific integrity.… More
EPA’s Ozone NAAQS Decision — Perhaps the Statute Itself Deserves Some of the Blame
Yesterday, EPA formalized its decision to leave the ozone NAAQS unchanged, at 70 ppb. I don’t think that this decision is in the same category of egregiousness as EPA’s recent decision not to reduce the PM2.5 NAAQS. After all, only one decision can be the single worst environmental policy of an entire administration.
I’m not that close to the science on the ozone NAAQS,… More
COVID-19 and PM2.5 Are Still Not a Healthy Mix
In April, I noted that researchers at the T.H. Chan Harvard School of Public Health had identified a relationship between PM-2.5 exposure and mortality from COVID-19. 
That study received some criticism, and it certainly did not move the Clean Air Science Advisory Committee to alter its recommendation to keep the PM2.5 NAAQS unchanged at 12 ug/m3.
Earlier this month, the same researchers updated the study,… More