2020 Volume 69 Issue 5 Pages 412-417
The most important direct health risk due to climate change in Japan, one of the developed countries, is heat-related mortality. “Heat-related mortality” is defined in the following manner. There exists a temperature at which the daily mortality risk is at its lowest. This temperature is referred to as the “optimum temperature” or “minimum mortality temperature.” When the daily temperature exceeds the optimum temperature, mortality increases. This added mortality is called heat-related excess mortality, or simply heat-related mortality. In terms of causes of death, heat-related mortality includes circulatory diseases and respiratory diseases, while heatstroke is responsible for less than 1% of heat-related deaths. Heat-related mortality has the following features: 1)the risk in earlier summer is higher than that in later summer; 2) the contribution due to other weather variables, such as humidity and wind speed is small; 3) vulnerable populations include children and the elderly; and, 4) the optimum temperature is lower in colder areas than in warmer areas. For adaptation measures, the appropriate use of air-conditioners and drinking water are the two most important items. Due to both population aging and COVID-19, it is becoming more difficult to adapt to hotter summers, and measures that are tailored for individual municipalities are necessary.
