Short-term exposures to PM2.5 and cause-specific mortality of cardiovascular health in China

Background: Many multi-center epidemiological studies have robustly examined the acute health effects of exposure to low concentrations of fine particulate matter (PM2.5) on cardiovascular mortality in developed counties. However, data limitations have resulted in few related studies being conducted in developing counties with high levels of PM2.5 exposure. In recent years, people in China with a heavy cardiovascular disease burden have been exposed to particularly high levels of PM2.5. Objective: We conducted a multi-county time series study investigating the acute effects of PM2.5 on the increased risk of cardiovascular death across China, and explored subpopulations susceptible to PM2.5 exposure. Methods: Appling a county-specific Poisson regression in 30 Chinese counties, we estimated PM2.5 effects on all cause mortality and cause-specific mortality of cardiovascular health for 2013-2015. We also considered PM2.5 effects on several subpopulations, including males, females, and three age groups (< 65, 65-74 and > 74 years old). We pooled the county-specific results across China using a random effects meta-analysis by cause and by subpopulation. Results: We found a 0.13% (95% confidence interval (CI), 0.04-0.22) increase in all-cause mortality, a 0.12% increase (95% CI, 0.001-0.25) increase in cardiovascular disease (CVD), a 0.42% (95% CI, 0.03-0.81) increase in AMI, a 0.17% (95% CI,- 0.04-0.40) increase in coronary heart disease, and a 0.13% (95% CI,- 0.12-0.33) increase in stroke in association with a 10-mu g/m(3) increase in PM2.5 concentrations on the same day. The magnitudes of the associations were less than those reported in developed counties with lower PM2.5 levels. A vulnerable effect on all-cause mortality was observed in the elderly population (older than 65 years) and on CVD in males. Conclusions: This study showed the positive magnitude of PM2.5 effects with high exposure on all natural, CVD, and cause-specific mortality and on the susceptible populations in China. The findings complemented evidence related to exposure-mortality relationships at the higher end of short-term exposure to PM2.5 on a global scale.