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Summer in the city: A new public health challenge

Urbanization is on the rise in Canada. StatsCan reported that nearly three in four Canadians (73.7%) lived in one of Canada's large urban centres in 2021, up from 73.2% five years earlier. There are benefits to living in a large urban centre, such as reduced commute time by living closer to work and living in a dynamic area that offers many nearby services and sources of entertainment. But our urban environments can also lead to adverse health outcomes for many, and where you live in a city can determine your proximity to hazards, access to healthy food and opportunities for exercise. 

With climate change, summers can be especially challenging for some due to the increased frequency of heat waves. The growth of our cities causes the replacement of natural land cover with dense concentrations of pavement, buildings and other surfaces that absorb and retain heat. These ‘urban heat islands’ (also referred to as ‘heat domes’) increase energy costs (e.g., for air conditioning), air pollution levels and heat-related illness and mortality.  

During summer 2021, British Columbia experienced one of the most intense heat waves in recorded history. In Greater Vancouver, the heat dome started to build on June 24, and higher temperatures were observed between June 24 to June 28. During this period, extreme temperatures were also observed overnight. More than 800 deaths were investigated by the British Columbia Coroners Service (BCCS) during that week, with 619 of these deaths later identified as heat related. Most who died were indoors, over 70 years old and living in homes without adequate cooling systems, such as air conditioners or fans. Generally, more decedents lived in socially or materially deprived neighbourhoods than the general population.  

Reports examining the consequences of these heat waves revealed gaps in our public health and emergency response and highlighted our ongoing challenges with health inequity. Major recommendations include a more coordinated provincial heat alert response system that locates, prioritizes, and supports vulnerable populations during extreme heat events, and implementing prevention and longer-term risk mitigation strategies. Going forward, public health analysts and emergency response teams could benefit from geographic tools that can support these recommendations for coordinated, location-based strategic planning and response.

When it comes to public health emergency response, location matters. Understanding where vulnerable populations live and their risk of environmental hazards is critical in swift and effective response.  

GIS is an intuitive and modern digital solution to strategizing heat wave response because analysts can readily access and integrate authoritative data. For example, analysts can overlay environmental data (e.g. temperature predictions, urban land use, tree cover, residential information) with socio-economic and demographic data (e.g., age structure, income rates, housing) to pinpoint neighbourhoods most vulnerable to potential mortality caused by heat waves. Indeed, this integrated platform enables non-expert users to monitor events closely and develop evidence-based interventions for timely and cost-effective emergency response.  

More recently, ArcGIS has been relied upon for emergency operations management to support  adaptive management and cost-effective response strategies. And given the increased frequency of infectious disease epidemics and environmental health emergencies in Canada, public health emergency analysts and responders now share these workflows. A GIS can act as a single source of truth so diverse teams of public health responders can make cohesive and coordinated decisions based on risk pattens shown on maps despite working in traditionally disconnected environments. Importantly, as public health analysts are required to reflect on emergencies to learn about barriers and bottlenecks in action, GIS can support longer-term planning to identify key areas in cities in greatest need of resiliency.  

Here is an example of an emergency response situational awareness dashboard built for wildfires using ArcGIS:  

Screenshot of emergency response situational awareness dashboard

In the example above, the GIS platform has been customized for multiple hazards, such as forest fires, flood warnings and earthquake and tsunami notifications. The platform readily integrates pre-loaded data, combining real-time event alerts in a spatially aware map visualization. GIS and non-GIS experts alike have used this platform to collaborate on action, to strategize where to deploy emergency response teams, and to locate the most vulnerable populations most in need of timely, prioritized support.  

In the next example, Esri Canada data was pre-compiled into a Situational Awareness Viewer demo, including customized datasets related to heat wave emergencies. Using Toronto as an example, we included data on hospitals, long-term care homes, and neighbourhoods with populations above 65 years in age. We also included measures of greenspace and proximity parks, long recognized as a valuable index of the health status of neighbourhoods. This demo exemplifies customized views that can be built using ArcGIS for a multitude of emergency response programs and workflows.  

Screenshot of situational awareness viewer for heat wave emergencies

With intense heat waves, additional environmental events, and ongoing circulation of infectious disease outbreaks, we need to anticipate and prepare for more frequent and even concurrent health hazards. Provincial public health teams could benefit significantly from modern GIS tools to collaborate on high-risk events, locate vulnerable populations, strategize location-based interventions, and plan for future events.  

For more information about how ArcGIS can help your team plan for urban heat waves or other environmental health programs, check out our webpage or reach out to us at  

This post was translated to French and can be viewed here.

About the Author

Alexander (Sandy) Watts is the Public Health Industry Manager for Esri Canada. He supports the digital future of Canada’s public health community by illuminating the power of GIS for health challenges unique to Canadian populations. As a spatial epidemiologist, he has led various geospatial research projects for epidemic preparedness and responses, creating GIS-driven solutions that supported policy decisions and resource allocation strategies at the Public Health Agency of Canada, the US-CDC Division of Global Migration & Quarantine and the World Health Organization. Sandy is passionate about the potential for location intelligence and GeoAI innovations to solve longstanding and future public health challenges, especially to reduce health inequities.

Profile Photo of Alexander Watts