Trends in ambulance dispatches related to heat illness from 2010 to 2019: An ecological study

• Published in: PloS one Vol. 17; no. 11; p. e0275641
• Main Authors: Nakamura, Daisuke, Kinoshita, Hiroki, Asada, Kazuo, Arimitsu, Takuma, Yasumatsu, Mikinobu, Ishiwata, Takayuki
• Format: Journal Article
• Language: English
• Published: San Francisco Public Library of Science 07.11.2022; Public Library of Science (PLoS)
• Subjects: Age differences; Air conditioning; Ambulances; Analysis; Biology and Life Sciences; Classification; Computer and Information Sciences; Datasets; Earth Sciences; Ecological studies; Engineering and Technology; Environmental aspects; Health hazards; Health risks; Heat; Heat stroke; Heatstroke; Hydration; Illnesses; Medicine and Health Sciences; Meteorological conditions; Morbidity; Mortality; People and Places; Population; Prevention; Regions; Regression analysis; Risk assessment; Risk factors; Social Sciences; Statistics; Thermoregulation; Time trends (Statistics); Weather; Weather forecasting; Websites; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0275641

Heatstroke is a serious heat-related illness that can even cause death. Heat alert systems play an important role in reducing the number of patients experiencing heat illness, as they encourage preventive actions such as the use of air conditioning, hydration, or other strategies. However, to date, the Japanese hazard classification has not considered seasonal and regional variations, despite clear differences in meteorological conditions across different regions in Japan. Moreover, several studies have reported a difference in thermoregulation between older and younger adults, implying that the hazard classification should also consider age differences. This study examined the relationship between the number of ambulance dispatches related to heat illness (ADRHI) and the Japanese heat hazard classification from 2010 to 2019, focusing on monthly and regional differences. Data from 47 prefectures during the 10-year period were collected and analyzed. ADRHI and wet bulb globe temperature (WBGT) data were collected from Japan's Ministry of Internal Affairs and Communications and the Ministry of the Environment Heat Illness Prevention Information website, respectively. The findings showed a significant relationship between ADRHI and WBGT.sub.max (p < 0.05, r = 0.74). ADRHI per 100,000 people showed significant differences across months. The post hoc test detected the first steep increase in ADRHI at a WBGT.sub.max of 23°C than at 22°C in June, and at a WBGT.sub.max of 26°C, 27°C, and 25°C in July, August, and September, respectively. Moreover, the first significant increase in ADRHI per 100,000 people at WBGT.sub.max differed across each region, at a WBGT.sub.max of 24°C in Hokkaido-Tohoku, 25°C in Kanto, Kansai, and Chugoku, 26°C in Chubu, 27°C in Shikoku, and 28°C in Kyushu-Okinawa. Further, Poisson regression analysis revealed that the relative risks differed across each region and month. These results imply that the hazard classification should be adjusted according to region and month in Japan.