Associations of long-term exposure to ambient PM with mortality in Chinese adults: A pooled analysis of cohorts in the China-PAR project.

The concentration-response relationship between mortality and long-term exposure to fine particulate matter (PM) has not been fully elucidated, especially at high levels of PM concentrations.
We aimed to evaluate chronic effects of ambient PM exposure on deaths among Chinese adults in high-exposure settings.
Participants of the Prediction for Atherosclerotic cardiovascular disease Risk in China (China-PAR) project were included from four prospective cohorts among Chinese adults aged ≥18 years old. The overall follow-up rate of the four cohorts was 93.4% until the recent follow-up survey that ended in 2015. The average of satellite-based PM concentrations during 2000-2015 at 1-km spatial resolution was assigned to each participant according to individual residence addresses. Based on the pooled analysis of individual data from the four cohorts, a Cox proportional hazards model was used to estimate the hazard ratio (HR) and corresponding 95% confidence intervals (95% CIs) for the association of PM exposure with mortality after multivariate adjustment.
A total of 116,821 participants were eligible in the final analysis. During a mean of 7.7 years of follow-up, 6,395 non-accidental deaths and 2,507 cardio-metabolic deaths occurred. The mean of PM concentration was 64.9 μg/m ranging from 31.2 μg/m to 97.0 μg/m. For each 10 μg/m increment in PM, the HR was 1.11 (95% CI: 1.08-1.14) for non-accidental mortality and 1.22 (95% CI: 1.16-1.27) for cardio-metabolic mortality. In addition, a weak exponential curve for the concentration-response association between mortality and PM was observed among Chinese adults.
Our study provided important evidence of the long-term effects of PM exposure on deaths among Chinese adults. The findings expand our knowledge on concentration-response relationship in high-exposure environments, which is essential to address the urgent challenge of reducing the disease burden attributable to PM exposure in rapidly industrializing countries such as China.

Copyright © 2020. Published by Elsevier Ltd.