Urbanization and Heat-mortality risk in Korea and Japan

Abstract

BACKGROUND AND AIM: The complex role of urbanisation in heat-mortality risk has not been fully studied. Korea and Japan have experienced a rapid population densification in metropolitan areas and the resultant disparities between metropolitan and non-metropolitan areas have intensified. We investigated the multi-dimensional effects urbanization on heat-mortality risk using nationwide data. METHODS: We collected time-series data for mortality and weather variables for all 229 districts in Korea (2011-2017) and 47 prefectures in Japan (1980–2015). We used a distributed lag nonlinear model to calculate the heat-mortality risk. Population density and population size were used as indicators of urbanization level. We also examined neighborhood characteristics that can be related to the spatial heterogeneity in heat-mortality risk. RESULTS:In Korea, we found a U-shaped association between population density and heat-mortality risk with the highest risk for rural populations; in urban areas, risk increases with increasing population density. Higher heat-mortality risk was associated with a lower number of hospital beds per person and higher % people requiring recuperation. In Japan, population growth has intensified in the metropolitan areas since the 2000s, and the highest heat-mortality risk was observed in the metropolitan areas at the same period. Higher apartment % and lower forest area and medical services were associated with higher heat-mortality risk in Japan. CONCLUSIONS:Our findings indicate that the association between urbanization and heat-mortality risk is different in Korea and Japan; however, in both countries, people living in metropolitan areas showed higher vulnerability to heat than people living in non-metropolitan urban areas, and the limited accessibility to medical services was associated with the higher heat risk in metropolitan areas. KEYWORDS: Urbanization, Urban-Rural Disparity, Heat-Mortality Risk, Urban Development, Heat Action Policies