Based on these assumptions, here we examine, in a mouse model, the effects of PM2.5 exposures on ACE, ACE2, COX-2, HO-1, and iNOS in the main organs involved in COVID-19 pathology (lung, heart, liver, and brain), to test the potential close relationship between PM2.5 exposure and disease severity. Here, PTGS2 is linked to COVID-19.