In Japan the summer of 2007 was very hot and national new record for maximum temperature (40.9℃) were observed. According to the emergency transportation records 5,102 patients suffering from heat disorders were reported from 18 major cities all around Japan. From the results in 6 cities, where the data from 2000 to 2007 are available, the number of the patients in 2007 was the highest.

Two thirds of the patients were male. For male the patients in 19-39 years, 40-64 years and 65 years and over were 25, 28 and 30%, respectively, but for female 65 years and over occupied 54%. Concerning the place of the events occurred, the patients in 19-39 years and 40-64 years occurred at many places, such as on the works, outdoors, on the sports and at the public places. For school children (7-18 years) 51% and 17% occurred on the sports and at school, respectively. For elderly (65 years and over) 54% happened in the home (living room).

In all cities daily numbers of the patients well correlated to the daily maximum temperature and they exponentially increased according to the daily maximum temperature. But the magnitudes of the increase of patients differed between cities and years.