Inverse reports:

You may be breathing dirty air right now. Nine out of ten people in the world live in areas with high levels of air pollutants, according to the World Health Organization.

This is a problem for physical and mental health. In addition to its well-established relationships to cancer and respiratory and heart diseases, a growing trove of scientific evidence links air pollution with depression and other mental health disorders.

A study published Monday in the Proceedings of the National Academies of Sciences adds to our understanding of this relationship, revealing one mechanism by which air pollution may trigger depression.

Researchers at the Lieber Institute for Brain Development and Peking University in Beijing studied the genetic makeup of 352 healthy residents of Beijing for markers that show a predisposition to depression. High exposure to air pollution, in turn, was correlated to poor performance on mental exercises used to measure depression-related cognitive difficulties.

The people who struggled the most were both getting doused with pollutants and had the genetic markers for depression.

“It’s a multiplicative effect,” lead author Hao Yang Tan, an investigator at the Lieber Institute, tells Inverse. “It’s genetic risk combined with air pollution that dramatically increases the impact of air pollution on the brain.” [Continue reading…]