Acute Effects Of Fine Particulate Matter And Ozone On Daily Mortality In China

Objectives Few studies in China investigate the health impact of fine particulate matter (PM2.5) and ozone (O3) due to lack of monitoring data and the findings are inconsistent. Furthermore, controversy remains regarding the relationship between various metrics of O3and mortality. The objectives of this study are to examine the short-association between PM2.5and daily mortality in Guangzhou, and to investigate the relationship between various metrics of O3and daily mortality in Suzhou.Methods In Guangzhou, we conducted a time-stratified case-crossover analysis to explore the association between PM2.5and daily mortality between2007and2008, and examined potential effect modifiers including age, sex,and education. In Suzhou, we used three exposure metrics of O3(1-hour maximum, maximum8-hour average and24-hour average) to examine its short-term association with daily mortality. We used a generalized additive model (GAM), with penalized splines, to analyze the mortality, O3, and covariate data. We examined the association by season, age group, sex and educational level.Results In Guangzhou, the averaged PM2.5concentration was70.1μg/m3during2007-2008, which was much higher than the WHO Air Quality Guidelines for PM2.5(annual average:10μg/m3). Regression analysis showed that ambient PM2.5was associated with mortality from all non-accidental causes and cardiorespiratory diseases. An increase of10μg/m3in2-day moving average (lag01) concentration of PM2.5corresponded to0.90%[95%confidence interval (CI):0.55%,1.26%] increase of total mortality,1.22%(95%CI:0.63%,1.68%) increase of cardiovascular mortality, and0.97%(95%CI:0.16%,1.79%) increase of respiratory mortality. The associations were stronger in the elderly (aged65years or more), in females and in those with low education level, but the differences within groups were statistically insignificant. When NO2or both NO2and SO2were added in the regression models, the effects of PM2.5decreased and became statistically insignificant. In Suzhou, we found that O3was associated with daily mortality from all non-accidental causes and cardiovascular diseases. Among various metrics of O3, maximum8-hour average and1-hour maximum concentrations seemed to be more strongly associated with increased mortality rate compared to24-hour average concentrations. Using maximum8-hour average, an inter-quartile range increase of2-day average O3(lag01) corresponded to2.15%(95%CI:0.36%,3.93%),4.47%(95%CI:1.43%,7.51%),-1.85%(95%CI:-6.91%,3.22%) increase in all-cause, cardiovascular, and respiratory mortality, respectively. The associations between O3and daily mortality appeared to be more evident in the cool season than in the warm seasonConclusions Our findings provided new information for the adverse health effects of PM2.5and O3in China. Maximum8-hour average and1-hour maximum concentrations of O3were more closely associated with daily mortality than24-hour average concentrations in Suzhou. Our analyses may have some implications for environmental policy making and standard setting in China.