Acute Mortality Effects of Ambient Particle Air Pollution, Air Pollution-By-Hot Weather Interaction in Wuhan, China

Abstract

P-054 Abstract: Our previous studies in Wuhan, China have demonstrated significant effects of long-term ambient air pollution on respiratory health among children and adults. However, no study has been carried out in Wuhan to determine the acute effects of ambient particulate matter (PM) air pollution on mortality. This study, funded by the Health Effects Institute as part of the Public Health and Air Pollution in Asia Project (PAPA) is intended to determine the acute effects of ambient PM pollution on mortality, and to investigate the effect modification of the extreme hot weather on the pollution mortality effects in Wuhan, China. Wuhan is a large city with 4.3 million permanent residents living in its nine urban core districts. Historically, Wuhan has been called “a stove city” in China because of its hot summer. We retrieved city-wide daily air pollution data, meteorological data, and mortality data for the four years from July 1, 2000 to June 30, 2004. Under the assumption that daily death counts follow a Poisson variate with constant over- or underdispersion, we used quasi-likelihood estimation within the context of the Generalized Additive Models (natural spline models in R) to model the natural logarithm of the expected daily death counts as a function of the predictor variables. We performed time-series analysis to associate daily nonaccidental mortality with daily mean PM10 concentrations, controlling for important covariates including gaseous pollutants SO2, NO2, or O3. We also examined the interaction between extreme hot weather and PM10. For a 10 μg/m3 increase in PM10 at lag 0, we observed an elevated risk of total nonaccidental cause mortality (0.28%; 95% CI 0.09%–0.46%), total nonaccidental mortality with age over 65 (0.32%; 95% CI 0.11%– 0.54%), cardiovascular mortality (0.42%; 95% CI 0.17%–0.66%), and respiratory mortality (0.73%; 95% CI 0.15%–1.32%). We also observed significant interactions between PM10 and extreme hot weather, in the direction that the presence of extreme hot weather enhanced the effects of PM10 on the above mortality. These results confirmed that ambient PM pollution has a significant effect on mortality in Wuhan China, which is consistent with the finding from other studies. Furthermore, our findings suggest that the PM10 mortality effects were enhanced by the presence of extreme hot weather. Future studies will be conducted to determine whether the results reported above would be modified by important factors, such as socioeconomic position.