Extreme Heat

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According to Environment Canada, a heat wave is a period of more than 3 days when temperatures are more than 32°C (Health Canada, 2012); the US Environmental Protection Agency (EPA) defines excessive heat events as “summertime temperatures that are substantially hotter and/or more humid that average for a location for that time of year”(US EPA, 2016). Due to climate change, by 2050, cities across Canada, including Vancouver, Calgary, Ottawa, Toronto, and Quebec City are predicted to experience over four-times the number of very hot days as compared to 2012 (Martin et al., 2011; Kharin et al., 2007).

  • Health impacts of extreme heat can be mild, including heat rash, edema, loss of consciousness, cramps and exhaustion, or severe, including heat stroke or exacerbation of chronic cardiac or respiratory illness (Health Canada, 2012).
  • Persons most vulnerable to extreme heat include seniors, low income and socially isolated people, and young children (NCCEH, 2010).
  • People on specific medications, such as antidepressants and antipsychotics can be predisposed to heat related illness, as these medications can interfere with thermoregulation (NCCEH, 2010).
  • In areas where extreme heat is a health hazard, effective communication with the public before and during events to convey the health risks and protective actions that can be taken is essential for ensuring communities, and particularly their most vulnerable members, are prepared for and alerted to heat emergencies (Canada, 2011).
  • Because social isolation is a major factor in heat vulnerability, building social capital may help communities become more resilient to heat and other climate change related emergencies (BC Neighbourhood Preparedness Guide, 2015).
  • Urban Heat Islands (UHI) are areas that are warmer than the surrounding rural areas due mainly to building surfaces and materials such as concrete absorbing more solar radiation; further, lack of greenspace or tree canopies decreases the cooling and shading effects of evapotranspiration. UHI effects amplify heat wave-related health impacts (Li and Bou-zeid, 2013).
  • Rural and urban areas have different considerations to take into account when dealing with extreme heat events (Berry et al., 2014).

NCCEH Resources

Selected External Resources

  • Developing a Municipal Heat Response Plan: A Guide for Medium-sized Municipalities (BCCDC, 2017)
    This document provides best practices for how to integrate heat preparedness into existing emergency plans for communities without many resources.
  • Review of Municipal Heat Response Planning in British Columbia, Canada (BCCDC, 2017)
    This report examines the state of preparedness of various size municipalities and health authorities for extreme heat events in BC, as well as gaps in knowledge.
  • Extreme Hot or Cold Temperature Conditions (Canadian Centre for Occupational Health and Safety, 2017)
    This webpage gives exposure limits and health and safety regulations for people working in hot environments.
  • Approaches for Building Community Resilience to Extreme Heat (Berry et al., 2016)
    This book chapter outlines the state of knowledge of development of Heat Alert and Response Systems (HARS) in Canada, social determinants of health which may impact citizens, government and community stakeholders who must be engaged in the process, and case studies of capacity building in at risk communities.
  • Excessive Heat Events Guidebook (US EPA, 2016)
    This guidebook is designed to provide local health and public safety officials with the information they need to develop excessive heat events (EHE) criteria and evaluate the potential health impacts of EHEs, and second, to offer a menu of EHE notification and response actions to be considered.
  • Cities Adapt to Extreme Heat: Celebrating Local Leadership (Institute for Catastrophic Loss Reduction, 2016)
    This book gives case studies of municipalities which are completing projects to adapt to the risks of extreme heat, including issuing targeted warnings; opening cooling centres in public facilities such as libraries, community centres and public pools; providing water for those in need; educating the public; planting trees and other actions to cool urban environments and reduce urban heat islands.
  • Health Care Workers Guide to Extreme Heat Events (McMaster University, 2014)
    This short course is designed to provide health workers, including public health workers, nurses and doctors with the current state of knowledge on heat-related illness and what can be done.
  • Guide for the Evaluation of a Warning System for People Vulnerable to Heat and Smog (Institute national de Sante Publique du Quebec, 2013)
    This guide investigates an analytical framework for defining heat waves and smog events and methods for evaluating heat and smog warnings systems.

Peer-reviewed Articles

This list is not intended to be exhaustive. Omission of a resource does not preclude it from having value.

Last updated Sep 18, 2019