Differential association between ambient PM2.5 constituents and depression and anxiety among Indian adults.

Ambient fine particulate matter (PM2.5) exposure influences mental disorders, yet the differential effects of its chemical constituents remain poorly understood in low-and middle-income countries. We examined associations between PM2.5 components with depression and anxiety among 34,802 Indian adults from the National Mental Health Survey (2015-16). We integrated satellite data and chemical transport modeling at 1-km resolution to assign one-year PM2.5 component exposures to participants' residential addresses. Mental disorders were assessed using standardized diagnostic interviews. Using logistic mixed-effect regression, we found that an interquartile range increase in PM2.5 raised the odds of depression and anxiety by 8% (7-9) and 2% (1-3), respectively. Secondary inorganic aerosols and carbonaceous aerosols showed stronger associations than other constituents. The cumulative effect of PM2.5 components exceeded that of total mass, indicating that relying solely on PM2.5 mass underestimates mental health effects. Our findings support targeted emission controls that focus on sectors producing the most toxic species, resulting in greater health benefits.