The Impacts of Atmospheric PM_2.5 Components on Depression in Middle-Aged and Elderly People

Previous research has found association between PM_2.5 exposure and the worsening of depression. Nevertheless, studies specifically examining the harmful effect of components of PM_2.5 were relatively limited.A national survey enrolled individuals aged 45 and older, gathering personal data and assessing depression in mainland China. Monthly exposure to PM_2.5 and its seven components, black carbon (BC), organic matter (OM), nitrate (NO^3-), sulfate (SO₄^2-), ammonium (NH⁴⁺), soil particles (SOIL) and sea salt (SS) were matched via each participant's residence. Linear mixed effect models (LME) to assess the association between single pollutants with depression score, and weighted quantile sum (WQS) regression was used to investigate the effect of mixed exposure and identify contribution of each component. The modified effects of social activity and green space were evaluated. 9,725 participants for depression were included in this analysis, respectively. In single exposure model, per interquartile range (IQR) rise in PM_2.5 (29.18μg/m³), BC (2.25μg/m³), OM (7.18μg/m³), SOIL (6.04μg/m³) and SS (0.14μg/m³) were significantly associated with increase of 0.90 (95%CI: 0.59, 1.20), 0.71[0.42, 1.09], 0.94[0.61, 1.26]), 0.51[0.38, 0.63]), 0.53[0.33, 0.73] point in depression score. In mixed exposure models, for each IQR increase in the mixture of all components, depression score increased by 1.104 (95%CI: 0.901, 1.307), and BC held the largest index weight (33.6%), followed by SOIL (28.59%) and SS (25.05%). The harmful effect of PM_2.5 and specific components on depression were lower in those participating in social activity or in higher level green space (p< 0.05).The harmful effects of PM_2.5 on depression may be influenced by its components. Social activity and green space could reduce the risk of depression related to PM_2.5 and its components.