Urbanization and Vulnerability to Heat-Mortality: Different Roles of Urbanization between Urban and Rural Districts in South Korea; A Nationwide Time-series Study.

Abstract

Background/Aim: Although urbanization has been an important topic in heat vulnerability studies, the complex role of urbanization, which can be different in urban and rural regions, has rarely been studied. We investigated the disparate roles of urbanization between urban and rural areas. Methods: We collected nationwide daily data for all 229 local authority districts in South Korea during 2011-2017. The districts were classified into urban (147 districts) and rural (82 districts) areas, based on the administrative districts. We applied three demographic variables (percentage of the urban population, population number, and population density) as urbanization indicators and also used medical-social environment indices to explain the role of urbanization. Results: There was no evident difference in the heat-mortality risk between urban and rural areas, and the role of urbanization was different in urban and rural areas; the higher urbanization level was associated with lower heat-mortality risk in rural areas, however, with lower heat-mortality risk in urban areas (i.e. the U-shaped relationship). The number of beds in hospital per person was associated with this U-shaped relationship, and the linkage was more evident in urban areas than in rural areas, and in the highest urbanized areas within urban areas. Meanwhile, the lower quality of health-related life and lower social gatherings were related to higher heat-mortality risk in rural areas. Conclusions: We found the urbanization level was linked in the opposite direction to the heat vulnerability in urban and rural areas, and the lower accessibility to hospital beds observed in rural and the highest urbanized areas was associated with higher heat vulnerability. Furthermore, regional indicators related to heat vulnerability were also heterogeneous between urban and rural areas. These results can contribute to understanding the complex role of urbanization in heat vulnerability and to establish evidence-based region-specific policies.