Fine particulate air pollution and daily mortality in Shenyang, China

Fine particulate matter (PM2.5) is not a criteria pollutant in China, and few studies were conducted in the country to investigate the health impact of PM2.5. In this study, we did a time-stratified case-crossover analysis to examine the association between PM2.5 and daily mortality in Shenyang, an industrial center in northeast China. Daily mortality, air pollution and weather data from August 1, 2006 to December 31, 2008 in Shenyang were collected. A time-stratified case-crossover approach was used to estimate the association of PM2.5 with both total and cause-specific mortality. Controls were selected as matched days of the week in the same month. Potential effect modifiers, such as age, gender, and season, were also examined. We found significant associations between PM2.5 and daily mortality in Shenyang. A 10 μg/m3 increment in the 2-day moving average (lag 01) concentrations of PM2.5 corresponded to 0.49% (95% CI: 0.19%, 0.79%), 0.53% (95% CI: 0.09%, 0.97%), and 0.97% (95% CI: 0.01%, 1.94%) increase of total, cardiovascular, and respiratory mortality, respectively. The associations appeared to be stronger in older people (aged ≥ 75 years), in females and during the warm season. To our knowledge, this is the longest PM2.5 health study in time duration in China. Our findings provide new information on the adverse health effects of PM2.5, and may have implications for environmental policy making and standard setting in China.

Research highlights
► Exposure to PM2.5 was associated with increased mortality risk in Shenyang.
► The associations were stronger in older people, in females and during the warm season.
► Lower exposure-response functions may exist in Chinese air pollution studies.