Short-term exposure to ambient air pollution and coronary heart disease mortality in 8 Chinese cities

BackgroundCoronary heart disease (CHD) accounted for a large fraction of death globally. The association between air pollution and CHD has been reported, but evidence from highly-polluted regions was scarce. We aimed to estimate the acute effects of outdoor air pollution on daily CHD mortality in China.MethodsWe collected daily CHD deaths in 8 large Chinese cities from 1996 to 2008. We firstly obtained the city-specific effect estimates of air pollution using generalized additive models with quasi-Poisson regression, controlling for time trends, meteorological indicators and day of the week. The random-effect model in meta-analysis was used to pool the exposure–response relationships.ResultsWe identified a total of 0.13 million CHD deaths. On average, an increase of 10 μg/m3 in 2-day moving average concentrations of particulate matter ≤ 10 μm in aerodynamic diameter (PM10), sulfur dioxide (SO2) and nitrogen dioxide (NO2) was significantly associated with increases of 0.36% [95% confidence intervals (CIs): 0.12%, 0.61%], 0.86% (95% CIs: 0.30%,1.41%) and 1.30% (95% CIs: 0.45%, 2.14%) in daily CHD mortality over the 8 Chinese cities, respectively. The pooled exposure–response curves were almost linear and no apparent thresholds were identified. The effects were more pronounced in cities with lower levels of air pollution. The effects of PM10 and NO2 were more robust than SO2.ConclusionOur findings contributed to the very limited evidence regarding the hazardous effects of ambient air pollution on CHD mortality in highly-polluted regions such as China.