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Heat-related mortality: a review and exploration of heterogeneity
  1. Shakoor Hajat1,2,
  2. Tom Kosatky1
  1. 1British Columbia Centre for Disease Control, Vancouver, Canada
  2. 2London School of Hygiene & Tropical Medicine, London, UK
  1. Correspondence to Dr S Hajat, Public & Environmental Health Research Unit, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK; shakoor.hajat{at}


Although rapid response capacity has been instituted in many cities following recent catastrophic heatwave events, the recognition that theoretically preventable heat-related deaths may occur throughout the summer has provoked much less response. This essay reviews published estimates of the general summertime temperature–mortality relationship characterised in different settings around the world. A random-effects meta-regression is applied to the estimates in relation to a number of standardised city-level characteristics of demography, economy and climate. Heat thresholds were generally higher in communities closer to the equator, suggesting some population adaptation. In almost half of the locations, the risk of mortality increased by between 1% and 3% per 1°C change in high temperature. Increasing population density, decreasing city gross domestic product and increasing percentage of people aged 65 or more were all independently associated with an increase in the heat slope. Improved care of older people, residential architecture and urban planning measures to reduce high temperatures in densely populated areas are likely to play a key role alongside targeted heat-health warning systems in reducing future heat burdens.

  • Heat
  • weather
  • mortality
  • climate change
  • urbanisation
  • climate
  • environmental epidem
  • environmental health

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  • Funding SH is funded by a Wellcome Trust Research Career Development Fellowship (076583/Z/05/Z) TK is funded by the British Columbia Centre for Disease Control.

  • Competing interests None.

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