Extreme Heat

Due to climate change, cities across Canada, including Vancouver, Calgary, Ottawa, Toronto, and Quebec City are predicted to experience over four-times the number of very hot days in 2050 compared to 2012 (Martin et al., 2011). In cities, these extreme heat events will likely be exacerbated by the formation of urban heat islands, which occur due to heat-absorbing building surfaces and materials and the lack of greenspace or tree canopies. Urban heat islands elevate temperatures compared to surrounding rural areas and amplify heat-related health impacts (Li and Bou-Zeid, 2013). Rural areas also suffer heat-related effects, but face distinct challenges in responding to extreme heat compared to urban centers (Liang and Kosatsky, 2020).

The health impacts of extreme heat range from mild to life-threatening, depending on individual vulnerability and exposure. The symptoms of extreme heat exposure include heat rash, edema, loss of consciousness, cramps, and exhaustion, and may lead to heat stroke (loss of consciousness and death) or exacerbation of chronic cardiac or respiratory illness (Health Canada, 2021). Those most vulnerable to extreme heat include seniors, low-income and socially isolated people, and young children, as well as people on specific medications that interfere with thermoregulation (NCCEH, 2010). In areas where extreme heat is expected, effective communication with the public before and during events to convey the health risks and protective actions is essential to ensuring wellbeing (Health Canada, 2011).

This topic pages aims to provide practitioners with curated resources regarding the management of and adaptation to extreme heat events. The selection of peer-reviewed articles provides more detailed information on health impacts to vulnerable populations.

You can also find additional resources on our other topic pages:

• COVID-19 Management during Public Health
• Oil Spills
• Floods: Prevention, preparedness, response and recovery
• Indigenous Disaster Response
• Psychosocial impacts: Resources for mitigation, response and recovery
• Wildfire smoke and health

NCCEH Resources

• Extreme Heat can be a Killer (2018)
  This video provides an overview of the rising temperatures in BC cities, the associated mortalities in various Canadian provinces, the vulnerable populations most likely to be affected by extreme heat events, and also highlights some interventions and the importance of extreme heat plans to protect people's health. 
   
• Climate change adaptation in public health: Over 10 years of progress in Quebec (Campagna, 2016)
  This seminar for the NCCEH outlines the past, present, and future climate change adaptions projects at the Institute national de Sante Publique du Quebec, including urban heat island effect reductions.
   
• Heat Advice (2011)
  This collection of documents provides evidence-based advice on how the public, particularly vulnerable populations, can protect against heat-related illness.
   
• Heat Awareness and Response among Montreal Residents with Chronic Cardiac and Pulmonary Disease (Kosatsky et al., 2009)
  This report investigates the state of knowledge and awareness of heat-related complications in primarily older people living with heart and/or lung disease, as well as their knowledge and adoption of recommended protective measures.
   
• What is the Evidence on Applicability and Effectiveness of Public Health Interventions in Reducing Morbidity and Mortality during Heat Episodes? (Bassil et al., 2007)
  This report investigates the effectiveness of public health interventions for decreasing illness and death due to extreme heat, and identifies knowledge gaps regarding efficacy of initiatives and outreach.

Selected External Resources

• Global Heat Health Information Network (2021)
  This webpage produced by an international, interdisciplinary team of extreme heat experts and policy makers, provides numerous resources and other learning opportunities around how to manage, adapt to, and communicate about extreme heat.
   
• Extreme heat: heat waves (Health Canada, 2021)
  This webpage provides basic information on extreme heat events, oriented toward the public, including a useful infographic to help community members avoid heat-related illness. Health Canada has also created a detailed guidance document Reducing urban heat islands to protect health in Canada through the use of green infrastructure.
   
• British Columbia Heat Impacts Prediction System (BCHIPS) (BCCDC, 2021)
  This mapping tool provides an estimate of heat-related health risk by geographic region. For each region, the tool provides both a forecasted health risk, based on a statistical model, as well as the observed health risk (based on heat-related ambulance dispatches) for the previous several weeks.
   
• Climate Atlas of Canada (2019)
  This mapping tool allows users to zoom in on their region of interest and observe how climate change is predicted to affect the average number of very hot days (days over 30C) in a year, both in the near term (2021-2050) and in the long term (2051-2080).
   
• Heat waves and health: A special report on climate change in Canada (Prairie Climate Centre, 2019)
  This report provides a look at the climate models describing how frequently Canadian cities might expect heat waves in the upcoming decades, and provides coping mechanisms for its consequences, including droughts and wildfires.
   
• 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.
   
• OSH Answers Fact Sheets: Temperature Conditions (Hot) Canadian Centre for Occupational Health and Safety, 2017)
  This webpage gives exposure limits and health and safety regulations for people working in hot environments.
   
• Communicating the Health Risks of Extreme Heat Events: Toolkit for Public Health and Emergency Management Officials (Health Canada, 2011)
  This toolkit provides guidance on how to effective communicate extreme heat risk and evaluate effectiveness of those communications, based on experience gathered both in Canadian communities and internationally.
   
• 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.
   
• 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.
   
• In it together: Neighourhood Preparedness Guide (Prepared BC, 2015)
  This guidance document aims to help communities become more resilient to heat and other climate change-related emergencies, with a special focus on vulnerability due to social isolation and importance of building social capital as an adaptation strategy.
   
• 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

• Large model structural uncertainty in global projections of urban heat waves (Zheng et al. 2021)
  This academic article looks at how urban heat waves are predicted and demonstrates that uncertainty in the modelling techniques used show that heat risk could be underestimated, suggesting that planners and policy makers will need to account for this uncertainty in their heat response plans.
   
• Heat Exposure and Maternal Health in the Face of Climate Change (Kuehn and McCormick, 2017)
  This academic article includes a systematic review of adverse birth outcomes associated with climate change related unusually hot temperatures and gaps in the research regarding assessment and mitigation practices.
   
• A Difference-in-Differences Approach to Assess the Effect of a Heat Action Plan on Heat-Related Mortality, and Differences in Effectiveness According to Sex, Age, and Socioeconomic Status (Montreal, Quebec) (Benmarhnia et al., 2016)
  This academic article examines programs which were shown to be effective in reducing heat-related mortality in vulnerable populations in Montreal, Canada.
   
• The Relationship Between Neighbourhood Tree Canopy Cover and Heat-Related Ambulance Calls during Extreme Heat Events in Toronto, Canada (Graham et al., 2016)
  This academic article examines how areas lacking tree canopy correspond to higher heat-related ambulance calls, and areas with increased tree canopy had lower heat-related mortality.
   
• An Adaptation Index to High Summer Heat Associated with Adverse Health Impacts in Deprived Neighborhoods (Belanger et al., 2015)
  This academic article examines the adaption of disadvantaged neighbourhoods and individuals to high temperatures. The individual-level adaptation index summarizes a range of 14 easy-to-use and energy-efficient solutions for cooling off or protecting oneself against the sun, both at home and in other places, whether indoors or out.
   
• Strategies to Reduce the Harmful Effects of Extreme Heat Events: A Four-City Study (White-Newsome et al., 2014)
  This academic article investigates which strategies are effective for the specific climates and populations of four American study cities, Detroit, New York City, Philadelphia, and Phoenix, as well as some universal concerns and addresses obstacles/ opportunities for implementation of policies.

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