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Quantifying Localized Heatwave Impact on Mortality: A Multi-Country Modeling Study in the Asia-Pacific Region
Background: Heatwave is a global health threat. However, existing heatwave definitions have limitations to account for regional climatic variations and population acclimatization. We aimed to assess the impact of localized heatwave on mortality based on a proposed framework of health-based heatwave definition.
Methods: Based on daily data on death and weather in 25 cities from Australia, China, South Korea, and Thailand, we proposed an excess heat factor (EHF) combined with a tiered health risk-based (THR) approach to defining the localized heatwave (EHFh). THR approach employed the Bayesian hierarchical model to fit the heatwave and mortality association with city-specific temperature threshold. Then the localized threshold was integrated into EHF that considered population acclimatization to high temperatures. Finally, the mortality burden attributable to heatwaves was estimated to compare the performance of distinct heatwave definitions including the EHFh approach, percentile-based definition, and country-specific official definition.
Findings: A total of 2 255 634 deaths from four countries were analyzed. Heatwave of all definitions was associated with an increased mortality risk in four countries. EHFh not only detected a localized and time-varying temperature threshold for the heatwave but also captured a continuous pattern of mortality risk associated with changes in heatwave intensity. Compared with percentile-based and country-specific official definitions, using the health-based heatwave definition framework yielded a larger proportion of deaths attributable to heatwaves, accounting for 8·68% in China, 4·50% in Thailand, 2·99% in Australia, and 1·98% in South Korea. The subtropical zone exhibited a higher attributable fraction (9·18%) than temperate (4·73%) and tropical zones (4·50%).
Interpretation: This multi-country study has developed a generalizable and health-based framework for defining the localized heatwave, assisting in assessing and comparing health impact of heatwaves across regions and climates.
Funding: National Natural Science Foundation of China.
Declaration of Interest: We declare no competing interests.
Tao, Junwen and Xu, Zhiwei and Ho, Hung Chak and Zheng, Hao and Xing, Xiuya and Hu, Jihong and Tong, Shilu and Kim, Ho and Hossain, Mohammad Zahid and Su, Hong and Huang, Cunrui and Cheng, Jian, Quantifying Localized Heatwave Impact on Mortality: A Multi-Country Modeling Study in the Asia-Pacific Region. Available at SSRN: https://ssrn.com/abstract=4922895
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