Short-Term Effects of Gaseous Pollutants on Cause-Specific Mortality in Wuhan, China

摘要

In Asia, limited studies have been published on the association between daily mortality and gaseous pollutants of nitrogen dioxide (NO_2), ozone (O_3), and sulfur dioxide (SO_2). Our previous studies in Wuhan, China, demonstrated long-term air pollution effects. However, no study has been conducted to determine mortality effects of air pollution in this region. This study was to determine the acute mortality effects of the gaseous pollutants in Wuhan, a city with 7.5 million permanent residents during the period from 2000 to 2004. There are approximately 4.5 million residents in Wuhan who live in the city's core area of 201 km~2, where air pollution levels are highest, and pollution ranges are wider than the majority of the cities in the published literature. We used the generalized additive model to analyze pollution, mortality, and co-variate data. We found consistent NO_2 effects on mortality with the strongest effects on the same day. Every 10-μg/m~3 increase in NO_2 daily concentration on the same day was associated with an increase in nonacciden-tal (1.43%; 95% confidence interval [CI]: 0.87-1.99%), cardiovascular (1.65%; 95% CI: 0.87-2.45%), stroke (1.49%; 95% CI: 0.56-2.43%), cardiac (1.77%; 95% CI: 0.44-3.12%), respiratory (2.23%; 95% CI: 0.52-3.96%), and cardiopulmonary mortality (1.60%; 95% CI: 0.85-2.35%). These effects were stronger among the elderly than among the young. Formal examination of exposure-response curves suggests no-threshold linear relationships between daily mortality and NO_2, where the NO_2 concentrations ranged from 19.2 to 127.4 μg/m~3. SO_2 and O_3 were not associated with daily mortality. The exposure-response relationships demonstrated heterogeneity, with some curves showing nonlinear relationships for SO_2 and O_3. We conclude that there is consistent evidence of acute effects of NO_2 on mortality and suggest that a no-threshold linear relationship exists between NO_2 and mortality.