[Deaths due to heat waves during the summer of 1994 in Osaka Prefecture, Japan]

The summer of 1994 was unusually hot and dry in Japan, setting a record for high temperature and low rainfall in many areas. The daily record of temperature of July and August which were announced by Osaka District Meteorological Observatory exceeded the past ones. The daily recorded temperature of 75 consecutive days in Osaka city was above 30 degrees C with the maximum 39.1 degrees C on 18 August 1994 and 38 degrees C on 16 July 1994. The number of unusual deaths (except traffic accidents) in Osaka Prefecture was 655 and 733 in the month of July and August respectively which exceeded the number of death for the corresponding period of the last 5 consecutive years by 1.5 folds, which was directly proportionate to the change of temperatures. This was due to the illness of the people concerned. We investigated the age, sex and rectal temperature during the inquest and compared them with those of the same period of 1992, which we kept as control. On comparing age and sex of the dead bodies, the cases of 1994 were older than those of 1992, which was due to increased number of death of female aged 70 or more. On comparing the rectal temperatures of those who were found indoors within 8 hours after death, the average temperature of 1994 was also higher than that of 1992. Between the age groups of 75 or more and 74 or younger, the rectal temperature of the former is significantly higher than those of later age group. While regarding the room temperature of the high rectal temperature (39 degrees C < or =) group, no significant difference was observed between the age groups of 75 or more and 74 or younger. In general, the number of unusual deaths in the summer of 1994 in Osaka was more compared to those of previous years. The analysis of the recorded rectal temperatures demonstrated that, 75 or older age group has a tendency to hyperthermia. Since the aging society of Japan is gradually increasing, preventive measures will be necessary when forecasting heat wave to reduce the morbidity and mortality of the aged people.