Association of Short-Term Co-Exposure to Particulate Matter and Ozone with Mortality Risk

A complex regional air pollution problem dominated by particulate matter (PM) and ozone (O-3) needs drastic attention since the levels of O-3 and PM are not decreasing in many parts of the world. Limited evidence is currently available regarding the association between co-exposure to PM and O-3 and mortality. A multicounty time-series study was used to investigate the associations of short-term exposure to PM1, PM2.5, PM10, and O-3 with daily mortality from different causes, which was based on data obtained from the Mortality Surveillance System managed by the Jiangsu Province Center for Disease Control and Prevention of China and analyzed via overdispersed generalized additive models with random-effects meta-analysis. We investigated the interactions of PM and O-3 on daily mortality and calculated the mortality fractions attributable to PM and O-3. Our results showed that PM1 is more strongly associated with daily mortality than PM2.5, PM10, and O-3, and percent increases in daily all-cause nonaccidental, cardiovascular, and respiratory mortality were 1.37% (95% confidence interval (CI), 1.22-1.52%), 1.44% (95% CI, 1.25-1.63%), and 1.63% (95% CI, 1.25-2.01%), respectively, for a 10 mu g/m3 increase in the 2 day average PM1 concentration. We found multiplicative and additive interactions of short-term co-exposure to PM and O-3 on daily mortality. The risk of mortality was greatest among those with higher levels of exposure to both PM (especially PM1) and O-3. Moreover, excess total and cardiovascular mortality due to PM1 exposure is highest in populations with higher O-3 exposure levels. Our results highlight the importance of the collaborative governance of P-M and O-3, providing a scientific foundation for pertinent standards and regulatory interventions.