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Variation of daily warm season mortality as a function of micro-urban heat islands
  1. A Smargiassi1,2,3,
  2. M S Goldberg4,5,
  3. C Plante6,
  4. M Fournier6,
  5. Y Baudouin7,
  6. T Kosatsky6
  1. 1
    Institut National de Santé Publique du Québec, Quebec, Canada
  2. 2
    Département de Santé Environnementale et Santé au Travail, Université de Montréal, Montreal, Quebec, Canada
  3. 3
    Centre de Recherche Léa Roback, Université de Montréal, Montreal, Quebec, Canada
  4. 4
    Department of Medicine, McGill University, Montreal, Quebec, Canada
  5. 5
    Division of Clinical Epidemiology, McGill University Health Centre, Montreal, Quebec, Canada
  6. 6
    Direction de Santé Publique de Montréal, Montréal, Québec, Canada
  7. 7
    Département de Géographie, Université du Québec à Montréal, Montréal, Québec, Canada
  1. Dr A Smargiassi, Institut National de Santé Publique du Québec/Direction de Santé Publique de Montréal, 1301 Sherbrooke Est, Montréal, Québec H2L 1M3, Canada; asmargia{at}


Background: Little attention has been paid to how heat-related health effects vary with the micro-urban variation of outdoor temperatures. This study explored whether people located in micro-urban heat islands are at higher risk of mortality during hot summer days.

Methods: Data used included (1) daily mortality for Montreal (Canada) for June–August 1990–2003, (2) daily mean ambient outdoor temperatures at the local international airport and (3) two thermal surface images (Landsat satellites, infrared wavelengths). A city-wide temperature versus daily mortality function was established on the basis of a case-crossover design; this function was stratified according to the surface temperature at decedents’ place of death.

Results: The risk of death on warm summer days in areas with higher surface temperatures was greater than in areas with lower surface temperatures.

Conclusions: This study suggests that measures aimed at reducing the temperature in micro-urban heat islands (eg, urban greening activities) may reduce the health impact of hot temperatures. Further studies are needed to document the variation of heat-related risks within cities and to evaluate the health benefits of measures aimed at reducing the temperature in micro-urban heat islands.

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  • Funding: This project was supported by funding from the Quebec Ministry of Health, the Ouranos Consortium for Climate Research in North America and from the Natural Resources Canada Climate Change Action Fund (no. A1101).

  • Competing interests: None.

  • Ethics approval: Ethics approval was obtained from the Quebec Public Health Ethical Health Surveillance Committee.

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