Number of ambulance transportation due to indoor heatstroke classified by perception time and effect of air conditioner on reducing the risk of severe indoor heatstroke

Deterioration of thermal environment due to the global warming and urban heat island causes the increase of the number of ambulance transport due to heatstroke. For the efficient ambulance operation, it is preferable to know when heatstroke is likely to occur during the day. However, the onset of heatstroke, particularly indoor heatstroke, depends on not only outside temperature and other meteorological condition, but also on health status and the use of air conditioner. It is therefore difficult to grasp the actual situation of indoor heatstroke and predict when indoor heatstroke is likely to occur. In order to contribute to above problem, as a first step, the number of indoor heatstroke at each perception time (time when the fire department receives an emergency call) was investigated using ambulance transport data provided by the Toyohashi Fire Department, Japan. The data period is June to October from 2013 to 2019. In addition, the effect of air conditioner status on reducing the severity of indoor heatstroke was evaluated using a logistic regression model. Obtained results showed that 1) the number of ambulances transport due to indoor heatstroke in case of air conditioner OFF increased sharply from 7 am, peaking at 9 am and 1 pm 2) more patients were diagnosed with moderate or severe heatstroke in the morning than in the afternoon. These results suggested that high number of indoor heatstroke in the morning was attributed to the possibility of heatstroke occurred while sleeping, as well as to the delay in calling for ambulance. Furthermore, 3) the use of air conditioner may reduce the probability of moderate or severe heatstroke by an average of 26 points compared to not using air conditioner.