Zhonghua Liu Xing Bing Xue Za Zhi. 2026 Sep 10;47(9):1576-1583. doi: 10.3760/cma.j.cn112338-20260118-00051.
ABSTRACT
Objective: To examine the independent and joint effects of short-term exposure to high temperature and ozone (O3) on mortality from circulatory diseases and its subcategories in Beijing-Tianjin-Hebei region and surrounding areas. Methods: Daily mortality data of circulatory diseases, O3 concentrations, and meteorological data were collected from 59 counties in Beijing-Tianjin-Hebei region and surrounding areas during the warm season (May-September) from 2013 to 2018. A two-stage time-series analytic strategy was employed. Independent effects of temperature and ozone were estimated by using Quasi-Poisson generalized linear models and random-effects Meta-analyses with mutual adjustment. Joint effects on circulatory mortality were evaluated through the inclusion of a product term. Results: During the study period, the mean daily maximum 8-hour average ozone concentration was (138.4±57.5) μg/m3, and the daily mean temperature was (24.0±4.1) ℃. The average daily death count of circulatory diseases per county M(Q1,Q3) was 4 (2, 6). Analyses on independent effects indicated that for each 10 μg/m3 increase in ozone concentration, the percentage change in circulatory mortality risk was 0.16% (95%CI: 0.02%-0.31%), with significant risk increases observed for cerebrovascular diseases. An increase in temperature from the P75 to the P99 was associated with a percentage change of 21.43% (95%CI: 16.32%-26.76%) in circulatory mortality risk. A significant synergistic effect between high temperature and ozone was identified. Specifically, as ozone concentrations increased from 65 μg/m3 to 214 μg/m3, the percentage change in circulatory mortality risk associated with high-temperature exposure rose from 9.93% (95%CI: 2.52%-17.89%) to 27.17% (95%CI: 20.48%-34.23%); the strongest modification effect was observed for cerebrovascular diseases. Furthermore, high temperature was found to significantly potentiate the mortality risk associated with ozone. When temperatures reached P91 and P89, the percentage changes in O3-related mortality risk for circulatory and cerebrovascular diseases became statistically significant (0.29% and 0.42%, respectively), and peaked at P99, rising to 0.92% and 1.26%, respectively. A more pronounced association trend with combined exposure was observed among females. Conclusions: Significant synergistic effects of high temperature and ozone on circulatory mortality were observed. Individuals with cerebrovascular disease and women were identified as vulnerable populations. It is suggested to strengthen joint monitoring and early warning systems for compound extreme environmental events and improve the protection of vulnerable populations.
PMID:42763186 | DOI:10.3760/cma.j.cn112338-20260118-00051