COVID-19 and air pollution

A persistent characteristic of the COVID-19 pandemic is the large range of effects over time and among locations, often exceeding an order of magnitude. We analyzed cumulative effects over 15 months, and focused on variability among 100 urban counties concerning selected plausible risk factors. We developed linear regression models and found highly significant risk factors. These models explained up to half of the observed variance, much more than typical epidemiology studies.   
A study early in the COVID-19 pandemic linked air pollution, especially smaller particles, to COVID-19's mortality. As it turns out, and as ACSH scientific advisor Dr. Fred Lipfert points out, the linkage is weak -- at best.