Does temperature enhance acute mortality effects of ambient particle pollution in Tianjin City, China

Only a few epidemiological studies have explored whether there were interactive effects between temperature and particulate matter < 10 μm in aerodynamic diameter (PM10) on mortality, especially in Asian countries. The present study used time-series analysis to explore the modification effects of temperature on the association between PM10 and the cause-specific mortality for cardiovascular, respiratory, cardiopulmonary, stroke and ischemic heart diseases (IHD), as well as non-accidental mortality in Tianjin between 2007 and 2009. Results showed that the PM10 effects were stronger on high temperature level days than that on low temperature level days. The interactions between PM10 and temperature were statistically significant on cardiovascular, cardiopulmonary, and IHD mortalities. The effect estimates per 10-μg/m3 increase in PM10 concentrations at the moving average of lags 0 and 1 day in high temperature level were 0.62% (95% confidence interval (CI): 0.27, 0.97) for non-accidental, 0.92% (0.47, 1.36) for cardiovascular, 0.74% (− 0.33, 1.82) for respiratory, 0.89% (0.47, 1.32) for cardiopulmonary, 0.65% (0.00, 1.31) for stroke and 1.20% (0.63, 1.78) for IHD mortalities. In addition, the PM10 effects on high temperature level days were stronger on older (≥ 65 years) compared with younger subjects (< 65 years). This suggests that the modifying effects of the temperature should be considered when analyzing health impacts of ambient PM10.