Detecting spatial heat vulnerability in the city considering spatiotemporal population distribution: A focus on the elderly during daytime

Escalating heatwaves induced by climate change are giving rise to a range of health issues. Traditionally, government policies focus on residential vulnerability, neglecting dynamic population shifts during workday heat peaks away from their residences. This study explores the influence of spatiotemporal population dynamics on the distribution of heatwave damage. Utilizing the data from Seoul, South Korea between 2017 and 2019, we assessed the relative risk of emergency visits for heat-related illnesses during heatwaves across hospital service areas. A multilevel regression approach was employed to examine the contributions of daytime and residential populations of vulnerable groups, while controlling for established heat vulnerability indicators. The results revealed a significant correlation between the relative risk of heat-related emergencies and the proportion of the daytime elderly population. These findings suggest that the daytime population, as compared to the residential population, can better capture vulnerable areas and individuals in the context of an urban heatwave. Consequently, the study proposes that local heat response policies consider the dynamic locations of vulnerable populations.