The influence of meteorological factors on the occurrence of trauma and motor vehicle collisions in Tokyo

Background: Previous studies have suggested a possible association between meteorological factors and the occurrence of trauma, but with conflicting results. This study investigated the relation of the occurrence of trauma with meteorological factors, including barometric pressure, ambient temperature, relative humidity and rainfall. Methods: Hourly data were collected on traumatic injuries through ambulance transport records of the Tokyo Fire Department from 1 January to 31 December 2005. Hourly meteorological data for Tokyo were also collected from the Japan Meteorological Agency during the same period. A time-series analysis was performed using an autoregressive integrated moving average (ARIMA) model to control for autocorrelations in time-series data. Results: Of a total of 643 849 patients who were transported to hospitals by ambulance, there were 226 339 trauma patients, including 94 916 patients from motor vehicle collisions (42% of all trauma patients). Based on the ARIMA model, higher temperature (p<0.001), greater rainfall (p<0.05) and holidays (p<0.001) were significantly associated with the occurrence of trauma. These factors were also significantly associated with the occurrence of motor vehicle collisions. Barometric pressure and humidity were not associated with the occurrence of trauma. Conclusions: This population-based study shows that, in addition to high temperature, rainfall and holidays are associated with the occurrence of trauma including motor vehicle collisions.