A STUDY OF THE EFFECTS OF WEATHER CONDITIONS ON MORTALITY FROM CIRCULATORY DISEASES

Abstract

Regression analysis was attempted for data on daily mortality from circulatory diseases and daily weather conditions in Tokyo from 1980 to 1981. The relation between the mortality and weather conditions was also examined. For representing the mortality by weather variables, several linear regression models and several autoregression (AR) models including weather variables as common factors were predicted, and applied to the data in 1980. The models identified by the data in 1980 were used for predicting the daily mortality in 1981. Validities of the models were evaluated by this procedure. The latter models generally fit the data better than the former models. Actually, an AR model which included only the daily minimum air temperature as a common factor was selected as the best model among our models. We emphasized that the daily minimum air temperature is closely related to the mortality, although this fact has already been reported in various studies. Further, we found that the variations of air temperature or vapor pressure affected the mortality. This fact was shown by residual analysis. It was also noted that the seasonal features of the residuals decreased in winter and increased in spring because of the difference of weather stability.