Plain language summary:

This study found that long-term exposure to air pollution may increase the risk of developing depression and anxiety. The study looked at nearly 400,000 people in the U.K. and found that exposure to PM2.5, NO2, and NO was associated with higher risk for depression and anxiety. Even at relatively low levels of exposure, all three pollutants were linked to depression and anxiety. The risks for depression and anxiety were higher in the second, third, and fourth quartiles of exposure compared to the lowest quartile. The authors suggest that air pollution may increase mental health issues by causing inflammation and oxidative stress in the central nervous system.