Heat illness related emergency ambulance transports before and after the Great East Japan Earthquake

A magnitude 9.0 earthquake struck off east coast of Japan on 11 March 2011. The tsunami triggered by the earthquake damaged the second largest electricity generating station in Japan. The government invoked electric power saving order for industrial enterprise and also urged general households to save electricity. There was a great concern about heat illness induced by suppression of air conditioning use. We compared the effect of air temperature on heat illness before and after the earthquake in Kanto area where the electric power saving order operated. Meteorological data and heat illness related emergency department visits by ambulance were collected from eight prefectures. Linear regression analyses were performed to evaluate the association between heat related emergency department visits and maximum air temperature and period (reference: 2008-2010). Heat illness related emergency ambulance transports per 100,000 population was 17.4±14.1 (mean±SD) before the earth quake and 30.1±5.2 after the earth quake. The number of heat illness related emergency ambulance transports per 100,000 population was positively associated with average maximum air temperature and period. The estimated increase of heat illness related emergency transports per 100,000 population with 1°C increase of maximum air temperature was 10.85 (95%CI, 9.52-12.2) in 2008-2010 and 7.47 (95%CI, 3.63-11.32) in 2011-2014. Increased effect of air temperature on heat illness was not observed after the electric power saving operation.