Heat-stress-related mortality in five cities in Southern Ontario: 1980-1996

Int J Biometeorol. 2000 Nov;44(4):190-7. doi: 10.1007/s004840000070.


The Toronto-Windsor corridor of Southern Ontario, Canada, experiences hot and humid weather conditions in summer, thus exposing the population to heat stress and a greater risk of mortality. In the event of a climate change, heat-stress conditions may become more frequent and severe in Southern Ontario. To assess the impact of summer weather on health, we analyzed heat-related mortality in the elderly (older than 64 years) in the metropolitan areas of Windsor, London, Kitchener-Waterloo-Cambridge, Hamilton, and Toronto for a 17-year period. Demographic, socioeconomic, and housing factors were also evaluated to assess their effect on the potential of the population to adapt and their vulnerability to heat stress. Heat-stress days were defined as those with an apparent temperature (heat index) above 32 degrees C. Mortality among the elderly was significantly higher on heat-stress days than on non-heat-stress days in all cities except Windsor. The strongest relationships occurred in Toronto and London, followed by Hamilton. Cities with the greatest heat-related mortality have relatively high levels of urbanization and high costs of living. Even without the warming induced by a climate change, (1) vulnerability is likely to increase as the population ages, and (2) ongoing urban development and sprawl are expected to intensify heat-stress conditions in Southern Ontario. Actions should be taken to reduce vulnerability to heat stress conditions, and to develop a comprehensive hot weather watch/warning system for the region.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aging / physiology*
  • Climate
  • Demography
  • Female
  • Heat Stress Disorders / mortality*
  • Housing
  • Humans
  • Male
  • Ontario / epidemiology
  • Risk Factors
  • Social Class