Relationship between air temperature and death in all 47 prefectures of Japan

Y. Owari, N. Miyatake, Y. Yamamoto, H. Kataoka, K. D. Mochimasu

Abstract: Objective. The aim was to investigate the link between air temperature and number of deaths in all 47 prefectures of Japan.
Method. The parameters of air temperature from January 2005 to December 2014 were obtained from the Japan Meteorological Agency, Japan. We also obtained the number of deaths and population data for the study period from each prefectural government. The effect of air temperature on the number of deaths was evaluated by ecological analysis.
Results. The number of deaths were 2.4 ± 0.4 per hundred thousand people and the mean air temperature was 15.5 ± 2.3 ¯C. The number of deaths was highest in January in most prefectures. However, the lowest numbers were in June (24 prefectures), July (18 prefectures), August (2 prefectures), September (2 prefectures) and April (1 prefecture). By using nonlinear (second-order polynomial) regression analysis, the number of deaths was significantly correlated with mean air temperature in all 47 prefectures of Japan. (r = 0.3463 to 0.8243).
Conclusion. U-shaped relationships between the parameters of mean air temperature and number of deaths were found in all 47 prefectures of Japan by second-order polynomial regression analysis.
Keywords: death, air temperature, second-order polynomial regression analysis.