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, finding the link between PM2.5 exposure and COVID-19 mortality to be even stronger than they initially thought.
We found that higher historical PM2.5 exposures are positively associated with higher county-level COVID-19 mortality rates after accounting for many area-level confounders. The results were statistically significant and robust to secondary and sensitivity analyses.
I may be a cockeyed optimist, but I continue to believe that, over time, this will become (to the extent it is not already) the scientific consensus, and that the PM2.5 NAAQS will be reduced, as the science so clearly indicates that it should be.