Synergistic air pollution exposure elevates depression risk: A cohort study.

Depression is a leading mental health disorder worldwide, contributing substantially to the global disease burden. While emerging evidence suggests links between specific air pollutants and depression, the potential interactions among multiple pollutants remain underexplored. Here we show the influence of six common air pollutants on depressive symptoms among middle-aged and older Chinese adults. In single-pollutant models, a 10 μg m increase in SO, CO, PM, and PM is associated with increased risks of depressive symptoms, with odds ratios (95% confidence intervals) of 1.276 (1.238-1.315), 1.007 (1.006-1.008), 1.066 (1.055-1.078), and 1.130 (1.108-1.153), respectively. In two-pollutant models, SO remains significantly associated with depressive symptoms after adjusting for other pollutants. Multi-pollutant models uncover synergistic effects, with SO, CO, NO, PM, and PM exhibiting significant interactions, identifying SO as the primary driver of these associations. Mediation analyses further indicate that cognitive and physical impairments partially mediate the relationship between air pollution and depressive symptoms. These findings underscore the critical mental health impacts of air pollution and highlight the need for integrated air quality management strategies. Targeted mitigation of specific pollutants, particularly SO, is expected to significantly enhance public mental health outcomes.