In an essay in the London Review of Books, David Wallace-Wells contrasted the 5.5 million annual global deaths from COVID  with the 7 million deaths attributed to air pollution (AP) projected by the World Health Organization ; he bemoaned the lack of attention being given to the latter.  He noted that other AP mortality estimates run as high as 8.7 million and 10 million if indoor air pollution were included. This is getting downright scary.
pm2.5 health consequences
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.
There are any number of papers supporting the idea that higher levels of air pollution are inversely correlated with poorer health outcomes. These studies all suffer from the fellow travelers of air pollution, traffic density, poverty, and lesser education which confound a clear linkage between air pollution and health. A new study offers a possibility.