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The relationship between temperature and ambulance response calls for heat-related illness in Toronto, Ontario, 2005
  1. Kate L Bassil1,
  2. Donald C Cole2,
  3. Rahim Moineddin2,
  4. Wendy Lou2,
  5. Alan M Craig3,
  6. Brian Schwartz4,
  7. Elizabeth Rea2
  1. 1Faculty of Health Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
  2. 2Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
  3. 3Toronto Emergency Medical Services, Toronto, Ontario, Canada
  4. 4Sunnybrook Osler Centre for Prehospital Care, Toronto, Ontario, Canada
  1. Correspondence to Kate L Bassil, Mount Sinai Hospital, Suite 8–500, 700 University Avenue, Toronto, ON M5G 1X6 Canada; kbassil{at}


Background Concern over the adverse effects of heat on human health has led to numerous studies assessing the relationship between heat and mortality. Few studies have quantified the impact of heat on morbidity, including ambulance response calls. This study describes the association between temperature and ambulance response calls for heat-related illness (HRI) in Toronto, Ontario, Canada during the summer of 2005.

Methods Data sources included daily temperature, relative humidity and humidex information from Environment Canada, and Medical Priority Dispatch System data from Toronto Emergency Medical Services. Time series and regression analyses were used to examine the relationship between daily temperature and ambulance response calls for HRI during the summer (1 June to 31 August) of 2005.

Results In 2005, there were 201 ambulance response calls for HRI. On average, for every one degree increase in maximum temperature (°C) there was a 29% increase in ambulance response calls for HRI (p<0.0001). For every one degree increase in mean temperature (°C) there was a 32% increase in ambulance response calls for HRI (p<0.0001).

Conclusions Given these associations, we urge further exploration of ambulance response calls as a source of HRI morbidity data particularly given the increasing health concerns associated with climate change.

  • Heat stress disorders
  • temperature
  • emergency medical services
  • morbidity
  • environment
  • environmental health
  • public health epidemiology

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  • Funding KB was funded by a University of Toronto Open Fellowship as part of her doctoral work.

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the University of Toronto, Toronto Public Health and a data sharing agreement with Toronto Emergency Medical Services.

  • Provenance and peer review Not commissioned; externally peer reviewed.