Evaluating the City’s Heat Alert and Response System

In 2011, the City of Ottawa, Ontario, undertook a workshop evaluating the effectiveness of their Hot Weather Response Plan. Since the early 2000’s, Ottawa has been working on improving their resilience to extreme heat events and making continual improvement over the years. However, a city is not a static system; nor is the climate. As time goes by, demographics shift and urban form changes. This alters the distribution of vulnerable groups across the city and the conditions that can exacerbate or mitigate the negative health effects of extreme heat. Additionally, the projections for anticipated extreme heat events in the future are dependent on climate projections are both being refined by improved understanding and modified by anticipated political, economic, technological, and other factors. As such, it is important to conduct regular evolutions of the heat response system and to consider changes in these or other factors that might necessitate changes to the system. The 2011 evaluation revealed five key characteristics that would affect the efficacy of the program in the near future.

Understanding and Assessing Impacts

Extreme heat events can pose substantial health risks. Such events are often exacerbated in large cities where the urban heat island effect can significantly raise temperatures during both the day and night. Ottawa’s Hot Weather Response Plan seeks to address these issues. However, such a plan must be carefully evaluated to ensure it is delivering on the protections that it promises. There are multiple ways in which a hot weather response plan can be evaluated. Process evaluations analyze the performance of key alert, response and communications mechanisms and activities (e.g. sending of alerts, outreach to key service providers of vulnerable populations, and the dissemination of heat-health messages that underpin the Heat Alert and Response System in a community). Outcome evaluations gauge whether the Heat Alert Response System has actually resulted in a reduction in morbidity and/or mortality over time. These kinds of analysis need to be conducted on a frequent basis, as the conditions that affect the success of a hot weather response plan can change over time. The demographics and locations of vulnerable groups may shift, a city might embrace an aggressive tree planting campaign that changes the locations of greatest heat stress, carbon mitigation programs may alter the projected long-term effects of climate change, and many other potential factors all affect such a plan’s effectiveness.


In 2013, the City of Ottawa’s Public Health Unit hosted a Heat and Health Vulnerability Assessment Workshop. The participants of this workshop completed a pre-workshop survey and received a workshop handbook before the meeting. Facilitated discussions examined the people currently identified as being vulnerable to extreme heat in Ottawa, including the subgroups that are most at risk and the characteristics that make each group vulnerable to heat. The workshop had three stated goals: (1) Discussing and providing information on how Canadian communities are vulnerable to the health impacts from extreme heat events and what might be needed to improve adaptive capacity to impacts from heat in the City of Ottawa; (2) Identifying vulnerable populations and discussing opportunities for collaboration among stakeholders, service providers, and volunteers to reduce the health risks associated with an extreme heat event; and, (3) Introducing available information and tools for addressing these risks. The participants in this workshop were drawn from an assortment of organizations including Emergency Preparedness, Social and Housing services, municipal childcare centres, the Salvation Army, the Ottawa Farm Safety Association, and pharmacy professionals.

Outcomes and Monitoring Progress

There were several key findings of the Heat and Health Vulnerability Assessment Workshop. The results indicated that there are strong networks in place in Ottawa that assist identified vulnerable populations (i.e. church and social groups for older adults, new parents as well as day care and child drop-in centre professionals for young children, and street outreach and emergency shelter staff for the homeless). These networks are part of extreme weather outreach activities and are efficient and effective at reaching vulnerable groups. Additionally, service providers develop effective strategies to deal with extreme heat events as a result of phone calls with their clients. This feedback has resulted in important changes to policies and procedures to build organizational capacity. The workshop also found that rooming house residents and isolated seniors remain at risk during extreme heat events due to social isolation and lack of air conditioning. There is a need for fans and air conditioning for low-income renters. It also found that young outdoor workers may need more awareness of heat risk factors so they come to work adequately hydrated and protected from the sun and heat. And finally, the workshop concluded that policies, procedures and resources need to be in place and shared within an organization well in advance of hot weather events – the summer is prime vacation time and back-up and replacement staff need to know what to do and feel confident in adapting programming if they are to be effective.

Next Steps

The City of Ottawa Interagency Extreme Weather Committee has been working to address the finding of Heat and Health Vulnerability Assessment Workshop by reaching out to service providers of newly identified at-risk populations. The Committee has also offered to assist community agencies with developing and updating extreme weather policies. The City of Ottawa’s Hot Weather Response Plan will continue to be updated, incorporating the results of the workshop.


Link to Full Case Study

Using climate change projections enables better adaptation decisions, as it allows you to better understand how the climate may change. To learn how to choose, access, and understand climate data, visit ClimateData.ca’s Learning Zone.

To further understand how climate information can be applied in health-related work explore the Health Module on ClimateData.ca.