Estimation of Excess Deaths during Hot Summers in Japan

Abstract

Using vital statistics data from 1995 to 2019, the relationships among interannual variations of total mortality, heat-stroke mortality, and temperature in summer were assessed in an attempt to estimate excess deaths in hot summer years in Japan. The number of deaths in July and August increased by 1.1% for each 1°C increment of summer mean temperature over Japan, with an eightfold larger range of interannual variation than the more narrowly defined heat-stroke deaths. This fact implies that excess deaths due to heat are about eight times more prevalent than heat-stroke deaths and can be on the order of 10,000 in a hot summer year. Analyses by age group and cause of death indicated that excess deaths are largely associated with cardiovascular and respiratory diseases among elderly people.