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