The short-term effect of ambient ozone on mortality is modified by temperature in Guangzhou, China

Effects of ozone on mortality have been widely assessed in developed countries but rarely in developing countries, and the effects of season and temperature on these associations remain unclear. The present study aimed to explore the modifying effects of temperature on the association of ozone with mortality, and to examine the lag effect structure in Guangzhou, China. Daily non-accidental mortality, air pollution and meteorological data from January 1st 2006 to December 31st 2008 in Guangzhou were collected. Generalized additive models (GAM) and distributed lag models (DLM) were used to estimate the excess risk (ER) of ozone on daily mortality and capture the lag effect structure. Results revealed that, in cold season, an increment in the ozone concentration of 10 μg m−3 was associated with a 0.87% (95% CI: −0.06 to 2.29%) and 3.34% (95%CI: 1.36–5.35%) increase of mortality for lag0 and lag0–6, respectively. However, no significant effects were observed in the warm season. Daily average temperature and ozone concentration had interactive negative effects on non-accidental mortality in the cold season and at daily average temperatures in the 0–25th percentile, and mortality displacement was also found in these conditions. Therefore, the short-term effect of ambient ozone on mortality is modified by temperature in Guangzhou, China.

► Ambient ozone had independent effects on non-accidental mortality in cold season. ► The effects of ozone lasted longer in cold season and low temperature days. ► Mortality displacement was observed in days with low temperature. ► The risk assessment might be underestimated by using single-day exposure model.