Differentiating the effects of fine and coarse particles on daily mortality in Shanghai, China

The findings on health effects of ambient fine particles (PM 2.5) and coarse particles (PM 10-2.5) remain inconsistent. In China, PM 2.5 and PM 10-2.5 are not the criteria air pollutants, and their monitoring data are scarce. There have been no epidemiological studies of health effects of PM 2.5 and PM 10-2.5 simultaneously in China. We conducted a time series study to examine the acute effects of PM 2.5 and PM 10-2.5 on daily mortality in Shanghai, China from Mar. 4, 2004 to Dec. 31, 2005. We used the generalized additive model (GAM) with penalized splines to analyze the mortality, air pollution and covariate data. The average concentrations of PM 2.5 and PM 10-2.5 were 56.4 μg/m 3 and 52.3 μg/m 3 in our study period, and PM 2.5 constituted around 53.0% of the PM 10 mass. Compared with the Global Air Quality Guidelines set by World Health Organization (10 μg/m 3 for annual mean) and U.S. National Ambient Air Quality Standards (15 μg/m 3 for annual mean), the PM 2.5 level in Shanghai was much higher. We found that PM 2.5 was associated with the death rates from all causes and from cardiorespiratory diseases in Shanghai. We did not find a significant effect of PM 10-2.5 on mortality outcomes. A10 μg/m 3 increase in the 2-day moving average (lag01) concentration of PM 2.5 corresponded to 0.36% (95% CI 0.11%, 0.61%), 0.41% (95% CI 0.01%, 0.82%) and 0.95% (95% CI 0.16%, 1.73%) increase of total, cardiovascular and respiratory mortality. For PM 10-2.5, the effects were attenuated and less precise. Our analyses provide the first statistically significant evidence in China that PM 2.5 has an adverse effect on population health and strengthen the rationale for further limiting levels of PM 2.5 in outdoor air in Shanghai.