Long-term PM2.5 exposure and depressive symptoms in China: A quasi-experimental study

Tao Xue; Tianjia Guan; Yixuan Zheng; Guannan Geng; Qiang Zhang; Yao Yao; Tong Zhu

doi:10.1016/j.lanwpc.2020.100079

Long-term PM_2.5 exposure and depressive symptoms in China: A quasi-experimental study

Lancet Reg Health West Pac. 2020 Dec 13:6:100079. doi: 10.1016/j.lanwpc.2020.100079. eCollection 2021 Jan.

Authors

Tao Xue¹, Tianjia Guan², Yixuan Zheng³, Guannan Geng⁴, Qiang Zhang⁵, Yao Yao⁶, Tong Zhu⁷

Affiliations

¹ Institute of Reproductive and Child Health, Ministry of Health Key Laboratory of Reproductive Health and Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China.
² School of Health Policy and Management, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.
³ Center of Air Quality Simulation and System Analysis, Chinese Academy for Environmental Planning, Beijing 100012, China.
⁴ School of Environment, Tsinghua University, Beijing 100086, China.
⁵ Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing 100086, China.
⁶ Center for Healthy Aging and Development Studies, Raissun Institute for Advanced Studies, National School of Development, Peking University, Beijing, China.
⁷ BIC-ESAT and SKL-ESPC, College of Environmental Science and Engineering, Peking University, Beijing 100871, China.

Abstract

Background: Air pollutants, particularly fine particulate matters (PM_2.5) have been associated with mental disorder such as depression. Clean air policy (CAP, i.e., a series of emission-control actions) has been shown to reduce the public health burden of air pollutions. There were few studies on the health effects of CAP on mental health, particularly, in low-income and middle-income countries (LMICs). We investigated the association between a stringent CAP and depressive symptoms among general adults in China.

Methods: We used three waves (2011, 2013 and 2015) of the China Health and Retirement Longitudinal Study (CHARLS), a prospective nationwide cohort of the middle-aged and older population in China. We assessed exposure to PM_2.5 through a satellite-retrieved dataset. We implemented a difference-in-differences (DID) approach, under the quasi-experimental framework of the temporal contrast between 2011 (before the CAP) and 2015 (after the CAP), to evaluate the effect of CAP on depressive symptoms. The association was further explored using a mixed-effects model of the three waves. To increase the interpretability, the estimated impact of PM_2.5 was compared to that of aging, an established risk factor for depression.

Findings: Our analysis included 15,954 participants. In the DID model, we found a 10-µg/m³ reduction of PM_2.5 concentration was associated with a 4.14% (95% CI: 0.41-8.00%) decrement in the depressive score. The estimate was similar to that from the mixed-effects model (3.63% [95% CI, 2.00-5.27%]). We also found improved air quality during 2011-2015 offset the negative impact from 5-years' aging.

Interpretation: The findings suggest that implementing CAP may improve mental wellbeing of adults in China and other LMICs.

Keywords: Air pollution; China; Clean air policy; Depressive symptoms; Mental health.