Long-Term Exposure to Fine Particulate Matter and Cardiovascular Disease in China

Background: Evidence of the effects of long-term fine particulate matter (PM_2.5) exposure on cardiovascular diseases (CVDs) is rare for populations exposed to high levels of PM_2.5 in China and in other countries with similarly high levels.

Objectives: The aim of this study was to assess the CVD risks associated with long-term exposure to PM_2.5 in China.

Methods: A nationwide cohort study, China-PAR (Prediction for Atherosclerotic Cardiovascular Disease Risk in China), was used, with 116,972 adults without CVD in 2000 being included. Participants were followed until 2015. Satellite-based PM_2.5 concentrations at 1-km spatial resolution during the study period were used for exposure assessment. A Cox proportional hazards model with time-varying exposures was used to estimate the CVD risks associated with PM_2.5 exposure, adjusting for individual risk factors.

Results: Annual mean concentrations of PM_2.5 at the China-PAR sites ranged from 25.5 to 114.0 μg/m³. For each 10 μg/m³ increase in PM_2.5 exposures, the multivariate-adjusted hazard ratio was 1.251 (95% confidence interval: 1.220 to 1.283) for CVD incidence and 1.164 (95% confidence interval: 1.117 to 1.213) for CVD mortality. The slopes of concentration-response functions of PM_2.5 exposure and CVD risks were steeper at high PM_2.5 levels. In addition, older residents, rural residents, and never smokers were more prone to adverse effects of PM_2.5 exposure.

Conclusions: This study provides evidence that elevated long-term PM_2.5 exposures lead to increased CVD risk in China. The effects are more pronounced at higher PM_2.5 levels. These findings expand the current knowledge on adverse health effects of severe air pollution and highlight the potential cardiovascular benefits of air quality improvement in China and other low- and middle-income countries.