Multiple recent studies have looked at whether air pollution increases the risk of developing or dying from COVID-19. 1,2,3,4,5,6 Ambient air pollution is known or suspected to cause or worsen conditions associated with SARS-CoV-2 infection, 7 including cardiorespiratory disease, respiratory disease, obesity, and type 2 diabetes. 8,9,10,11 So it is plausible that air pollution exposures could also be risk factors for not only SARS-CoV-2 infection but also worse disease severity and heightened mortality risk. However, a recent commentary in Environmental Health Perspectives warns that multiple studies on the topic-some of them not yet peer reviewed before being picked up by the media-are so flawed as to be invalid. 12