Gao Juan, Wood Dylan, Katsouyanni Klea, Benmarhnia Tarik, Evangelopoulos Dimitris
MRC Centre for Environment and Health, Environmental Research Group, Imperial College, London, W12 0BZ, UK; Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117549, Republic of Singapore; Centre for Sustainable Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119228, Republic of Singapore.
MRC Centre for Environment and Health, Environmental Research Group, Imperial College, London, W12 0BZ, UK; NIHR HPRU in Environmental Exposures and Health, Imperial College, London, UK.
Environ Res. 2025 Jul 15;277:121577. doi: 10.1016/j.envres.2025.121577. Epub 2025 Apr 9.
The health impacts of increasing heat exposure are alarming, especially in a climate change era. The role of ozone in the extreme temperature-mortality association remains unclear. We examined the mechanisms through which ozone influences extreme temperature-mortality association in Greater London, UK, from 2010 to 2018. Employing a time-series analysis with generalized linear quasi-Poisson models, we quantified the effects of daily 8-h maximum ozone concentrations, heatwaves, and extreme temperature on all-cause, respiratory and cardiovascular mortality. Interaction analyses were applied to assess the synergistic effects of ozone and heat-related exposures. A causal mediation analysis was utilised to decompose the total effect of high temperature/heatwave on mortality into direct and indirect effects. The risk of all-cause mortality during the warm season (May to September) increased by 1.3 % (95 % Confidence Interval (CI): 1.1 %, 1.6 %) for each 1 °C increment in daily mean temperature. Heatwave days (two or more days with unusually high temperatures) were associated with an 8.6 % (95 % CI: 6.9 %, 10.4 %) increase in all-cause mortality compared to non-heatwave days. These effects were more pronounced for respiratory mortality, i.e. 1.6 % (95 % CI: 1.0 %, 2.2 %) increase per 1 °C increment in temperature and 9.6 % (95 % CI: 4.6 %, 15.0 %) increase during heatwaves. The risk of heat-related mortality increased on high ozone days, and high temperatures amplified the risk of ozone-related mortality. The proportion of the total effect of extreme temperature and heatwaves on all-cause mortality mediated by ozone was 8.5 % and 8.8 %, respectively. For respiratory mortality and heatwaves, the proportion mediated was 14.9 %. Our findings show synergistic effects of ozone and extreme temperature on mortality, as well as mediating effects of ozone in the heat-mortality associations.
在气候变化的时代，日益增加的高温暴露对健康的影响令人担忧。臭氧在极端温度与死亡率之间的关联中所起的作用仍不清楚。我们研究了2010年至2018年期间，臭氧影响英国大伦敦地区极端温度与死亡率之间关联的机制。通过广义线性拟泊松模型进行时间序列分析，我们量化了每日8小时最高臭氧浓度、热浪和极端温度对全因死亡率、呼吸系统死亡率和心血管死亡率的影响。采用交互分析来评估臭氧与热相关暴露的协同效应。利用因果中介分析将高温/热浪对死亡率的总效应分解为直接效应和间接效应。在温暖季节（5月至9月），日平均温度每升高1°C，全因死亡率风险增加1.3%（95%置信区间（CI）：1.1%，1.6%）。与非热浪日相比，热浪日（连续两天或更多天出现异常高温）全因死亡率增加8.6%（95%CI：6.9%，10.4%）。这些影响在呼吸系统死亡率方面更为明显，即温度每升高1°C，死亡率增加1.6%（95%CI：1.0%，2.2%），在热浪期间增加9.6%（95%CI：4.6%，15.0%）。在高臭氧日，与热相关的死亡率风险增加，高温加剧了与臭氧相关的死亡率风险。极端温度和热浪对全因死亡率的总效应中，由臭氧介导的比例分别为8.5%和8.8%。对于呼吸系统死亡率和热浪，介导比例为14.9%。我们的研究结果表明，臭氧和极端温度对死亡率有协同效应，以及臭氧在热与死亡率关联中的中介作用。
