Long-term exposure of PM 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 (PM) is associated with depressive symptoms. However, little is known about the individual effects of PM components, particularly in low-income and middle-income countries. We investigated the association between long-term exposure to major components of PM and worsening depressive symptoms in Chinese adults based on a large, long-term, nationally representative, population-based prospective cohort. Our data were derived from China Family Panel Study (CFPS) wave 2012, 2016 and 2018 and a long-term (2010-2019) high-resolution PM components dataset covering the whole China. We assessed respondents' depressive 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 PM 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 PM components is significantly associated with worsening of depressive symptoms, and that different components may have different toxicity. Reducing PM emissions, especially the major sources of organic matter and ammonium, may reduce the burden of depressive symptoms in Chinese adults.