Did you know that pollution is associated with mental health issues? Cognitive functioning? Murder rates? I could definitely see the first, and maybe the second, but third.... To be clear these results are not from studies that employ full-on causal analysis, but this is interesting nonetheless.
A more straightforward but still chilling conclusion from a different study: one of the largest causes of infant mortality in Europe is air pollution. https://www.mdpi.com/1660-4601/16/6/1084
"Worldwide, outdoor air pollution reduces the average life expectancy at birth
by one year. The effect is much more pronounced in some countries: It
cuts the average Egyptian’s life span by 1.9 years and the average
Indian’s by 1.5 years. In Russia, it’s around nine months." https://www.nytimes.com/2018/08/22/climate/air-pollution-deaths.html
"[W]e find significant positive effects of air pollution ... on body mass index (BMI)" http://ftp.iza.org/dp12296.pdf
“Air pollution can harm acutely, as well as chronically, potentially
affecting every organ in the body,” conclude the scientists from the Forum of International Respiratory Societies in the two review papers, published in the journal Chest.
“Ultrafine particles pass through the [lungs], are readily picked up by
cells, and carried via the bloodstream to expose virtually all cells in
the body.” https://www.theguardian.com/environment/ng-interactive/2019/may/17/air-pollution-may-be-damaging-every-organ-and-cell-in-the-body-finds-global-review
This NYT summary talks about the effects of air pollution on mental health while this research article shows that "PM2.5 reduces hedonic happiness and increases the rate of depressive symptoms" http://ftp.iza.org/dp12313.pdf
Historical studies of for example the four day London smog of 1952 increased mortality rates by 2%, and caused long-term damage to human development, ability to work, and increased cancer risk for decades.
Update July 2019: "New study links air pollution with over 30,000 deaths and reduced life expectancy in the United States" PLoS article
Also, dust from the Sahara desert increases infant mortality NBER paper
