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 (O₃) needs drastic attention since the levels of O₃ 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 O₃ and mortality. A multicounty time-series study was used to investigate the associations of short-term exposure to PM₁, PM_2.5, PM₁₀, and O₃ 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 O₃ on daily mortality and calculated the mortality fractions attributable to PM and O₃. Our results showed that PM₁ is more strongly associated with daily mortality than PM_2.5, PM₁₀, and O₃, 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 μg/m³ increase in the 2 day average PM₁ concentration. We found multiplicative and additive interactions of short-term co-exposure to PM and O₃ on daily mortality. The risk of mortality was greatest among those with higher levels of exposure to both PM (especially PM₁) and O₃. Moreover, excess total and cardiovascular mortality due to PM₁ exposure is highest in populations with higher O₃ exposure levels. Our results highlight the importance of the collaborative governance of PM and O₃, providing a scientific foundation for pertinent standards and regulatory interventions.