Heat-Related Mortality In Urban And Non-Urban Counties Of China

Abstract

Introduction: Few multi-location studies of heat-related mortality have been conducted in developing countries, especially China. Moreover, the vast majority of previous multi-location studies only focused on urban areas; little is known of the health effect of high temperature in non-urban areas. This study explored the heat-related mortality risk in 102 urban and non-urban counties in one province, China. Methods: A distributed lag non-linear model was first applied to evaluate the heat-mortality relationship in 102 counties during 2009 to 2013. Then, a Bayesian hierarchical model was used to pool the estimates across all counties. Effect modification by individual characteristics such as sex, age, and education were also examined by stratified analysis. Finally, county-level characteristics such as percentage of urban population and air conditioning were analyzed to explain the variation in heat-related mortality risks by county. Results: The overall cumulative relative risk at the 99th vs. 75th percentiles (32.47°C vs. 24.23°C) in 102 counties was 1.35(95%CI, 1.30-1.39) for total mortality and 1.56(95%CI, 1.49-1.64) for cardiorespiratory mortality. The heat effects on cardiorespiratory and total mortality were both stronger in non-urban counties than those in urban counties. Female, elderly people, and people with low educational level were found to be more vulnerable. County characteristics such as percentage of urban population, education, and air conditioning were all significantly associated with decreased risk estimates, while percentage of elderly people(≥ 65 years old) was significantly associated with increased risk estimates. Conclusions: Our findings reveal that non-urban areas in China have significantly high heat-related mortality risks. This evidence has important implications for adaptation planning in Chinese rural areas under a changing climate.