Modification Effect of Ozone on Current and Future Health Burden Associated With Short‐Term Heatwave Exposure in China

Abstract

The co‐occurrence of heatwave (HW) and ozone pollution in China has increased significantly. Epidemiological studies indicate that ozone can modify the association between heatwaves and premature mortalities but quantitative health impacts remain poorly understood. This study evaluates premature cardiovascular mortalities attributable to short‐term heatwave exposure during warm seasons across China during 2013–2022 by integrating a widely‐used health impact assessment model with high‐resolution ERA5 meteorological data and TAP ozone concentrations, and quantitatively assesses the modifying effect of ozone on HW‐related mortality for the first time at the national scale. Future ozone‐modified health burden under different scenarios is also quantified by using multi‐model simulations from CMIP6. Ozone‐modified HW‐related premature deaths increased from 1.8 thousand persons (95% CI: 0.5–3.3 thousand persons) in 2013 to 7.3 thousand persons (95% CI: 1.8–12 thousand persons) in 2022, with the modifying contribution becoming positive since 2017. Age‐specific ozone‐modified effects were negative for individuals aged ≥75 years and positive for those ≤64 years. Traditional exposure‐response analyses ignoring ozone modification will underestimate HW‐related health hazards but overestimate health damage in the elderly. Future HW‐related premature mortalities are projected to decrease by 392 persons (95% CI: 191–610 persons) under SSP1‐2.6 but increase by 1726 persons (95% CI: 912–2528 persons) under SSP3‐7.0 in 2060 compared to 2022. When ozone modification is considered, these changes are amplified by 43.9% and 8.4%, respectively. All results indicate that sustained improvements in ozone air quality can reduce the modifying effect of ozone in the future.