Spatio-temporal assessment of heat health risk in Chinese metropolitan cities based on the modified multi-indicators coupled risk framework

Extreme heat events are the leading cause of climate-related disease and death globally. Heat health risk assessment is an effective tool to understand and reduce heat-related morbidity and mortality. However, the indicators of previous studies made it difficult to characterize risk accurately, especially the most important hazard. Besides, studies prefer to focus on spatial variation and ignore the temporal variation. Based on these challenges, this study constructed a modified framework from three components including heat hazard, human exposure, and social vulnerability to propose an assessment of heat health risk in Chinese metropolitan cities from 2000 to 2020. The results indicated that (1) Compared to the traditional framework using a single indicator, the R² has been improved 0.16. (2) Spatially, in the large city, the city with a larger size has a higher risk index except supercity. And more open space has the ability to reduce the damage caused by heat. (3) Temporally, the average heat health risk index of cities increased gradually about 24.72% from 2020 to 2000. This framework can help to improve the accuracy and flexibility of heat health risk assessment and provide support for sustainable urban development.