Clean Air, Clean Mind: Study Ties Air Pollution To Depression, Suicide Risk:

The study used data from 16 countries in what authors say is the first systematic review and meta-analysis of links between fine particulate matter — small airborne particles including dust and soot — and various mental health problems. By the researchers’ calculations, if the relationship between depression, suicide, and air pollution is causal, then lessening the world-wide average exposure to fine particulate matter from 44 micrograms per meter cubed (μg/m3) to 25 μg/m3 would cause a 15% reduction in the global risk of depression.