Long-term exposure of PM2.5 components on the adults' depressive symptoms in China - Evidence from a representative longitudinal nationwide cohort

In recent years, there is growing evidence that long-term exposure to fine particulate matter (PM2.5) is associated with depressive symptoms. However, little is known about the individual effects of PM2.5 components, particularly in low-income and middle-income countries.We investigated the association between long-term exposure to major components of PM2.5 and worsening depressive symptoms in Chinese adults based on a large, long-term, nationally representative, population-based prospective co-hort. Our data were derived from China Family Panel Study (CFPS) wave 2012, 2016 and 2018 and a long-term (2010-2019) high-resolution PM2.5 components dataset covering the whole China. We assessed respondents' depres-sive symptoms using standardized scales and applied advanced Fixed-effect ordered logit model (FE-ologit) to capture the ordinal nature of respondents' depressive symptoms and control for individual-specific and time-invariant effects to investigate their associations with PM2.5 components.We included 9503 respondents and the FE-ologit model results indicated that the odds ratio of increase per standard unit was 1.118 (95 % CI: 1.020, 1.225) for black carbon, 1.134 (95 % CI: 1.028, 1.252) for organic matter, 1.127 for ammonium (95 % CI: 1.011, 1.255), 1.107 for nitrate (95 % CI: 0.981, 1.248), and 1.117 for sulfate (95 % CI: 1.020, 1.224). Our study suggests that long-term exposure to PM2.5 components is significantly associated with worsening of depressive symptoms, and that different components may have different toxicity. Reducing PM2.5 emissions, especially the major sources of organic matter and ammonium, may reduce the burden of depressive symptoms in Chinese adults.