Epidemiologic study of deaths and injuries due to tornadoes.

A case-control study, using both matched and unmatched controls, was carried out on individuals who were injured or killed by a series of tornadoes that passed through Ontario, Canada, on May 31, 1985. Many serious injuries (25%) and almost all (83%) deaths were the result of becoming airborne, while most minor injuries (94%) were due to being struck by objects. Head injury was the most common injury type. Few (21%) of those in buildings chose the recommended location, and most (61%) were not in the least damaged part. Most (91%) had less than one minute's warning, and only 47% had a functioning radio at the time the tornado hit. The following risk factors for injury and death were identified: poor building anchorage; location other than in a basement, especially outdoors; age over 70 years; and high wind strength. These findings support previous findings and point to measures which have potential for preventing death or serious injury in future tornadoes: adequate warning systems and public education to ensure that individuals understand the warning and respond by seeking appropriate shelter. Those in adequately anchored buildings should shelter in an interior room or basement. Those who are outdoors, in poorly anchored buildings, mobile homes, or portable classrooms require access to an adequately anchored building, preferably with a basement, during severe storm warnings. This should be arranged by local authorities.