Short-term exposure to sulfur dioxide and daily mortality in 17 Chinese cities: The China air pollution and health effects study (CAPES)

摘要

Sulfur dioxide (SO_2) is a major air pollutant and has significant impacts upon human health. Few multi-city studies in Asia have examined the acute health effects of SO_2. As part of the China Air Pollution and Health Effects Study (CAPES), this study aimed at investigating the short-term association between SO_2 and daily mortality in 17 Chinese cities. We applied two-stage Bayesian hierarchical models to obtain city-specific and national average estimates for SO_2. In each city, we used Poisson regression models incorporating natural spline smoothing functions to adjust for long-term and seasonal trend of mortality, as well as other time-varying covariates. We examined the associations by age, gender and education status. As a result, the combined analysis showed that an increase of 10 μg/m~3 of two-day moving averaged SO_2 was associated with 0.75% [95% posterior interval (PI), 0.47 to 1.02], 0.83% (0.95% PI, 0.47 to 1.19) and 1.25% (95% PI, 0.78 to 1.73) increase of total, cardiovascular and respiratory mortality, respectively. The effects of SO_2 appeared more evident among the elderly. These associations were generally independent of particles with aerodynamic diameter <10 μm (PM_(10)) but did not persist after adjustment for nitrogen dioxide (NO_2). In conclusions, this largest epidemiologic study of air pollution in China to date suggests that short-term exposure to SO_2 is associated with increased mortality risk; however, these associations may be attributable to SO_2 serving as a surrogate of other substances. Further studies are needed to tackle the independent health effect of SO_2.