Adapting to Extreme Heat Events: Guidelines for Assessing Health Vulnerability

Table of Contents

• Foreword
• 1. Introduction
  • 1.1 Benefits of Conducting an Extreme Heat and Health Vulnerability Assessment
  • 1.2 Structure of the Guidelines
• 2. Vulnerability to the Health Impacts of Extreme Heat
  • 2.1 Exposure to Extreme Heat
  • 2.2 Sensitivity of Canadians to the Health Impacts of Extreme Heat
  • 2.3 Adapting to Protect Health: Heat Alert and Response Systems
• 3. Guidelines for Conducting Extreme Heat and Health Vulnerability Assessments
  • 3.1 Assessment Methodology
  • 3.2 Assessment Steps
    • Step 1: Initiate the assessment
    • Step 2: Describe current vulnerability to extreme heat events
    • Step 3: Assess future health risks associated with extreme heat events
    • Step 4: Identify and prioritize adaptation options to address current and projected health risks from extreme heat events
    • Step 5: Examine the potential health risks and benefits of adaptation and mitigation measures implemented in other sectors
    • Step 6: Develop protocols for evaluating adaptation options and monitoring heat-health risks
• 4. Conclusion
• Glossary
• References

Foreword

1. Introduction

It is now well established that climate change poses significant risks to the health of Canadians and people around the world.^{Footnote 1} One of the key issues - health risks from extreme heat events^{Footnote a} - is an emerging public health concern. The 2003 extreme heat event in Europe that resulted in 70,000 deaths^{Footnote 4} and the 2010 event in Russia that resulted in an estimated 55,000 deaths^{Footnote 5} demonstrate the significant toll on health that such events can have.

Extreme heat is a health concern in Canada as well; research indicates that in Toronto alone an average of 120 people died from extreme heat annually between 1954 and 2000.^{Footnote 6} In 2005, Toronto experienced 41 extremely hot days exceeding 30°C/86°F^{Footnote 7} during which health officials called a total of 26 heat alert days to warn the public of the dangerous conditions. In British Columbia, an extreme heat event from July 27 to August 3 in 2009 resulted in 156 excess deaths as temperatures reached 34.4°C/93.9°F.^{Footnote 8}

Heat-related deaths are preventable, and assessments of individual and community vulnerability can help in efforts to reduce mortality associated with extreme heat events. The Intergovernmental Panel on Climate Change (IPCC) defines vulnerability to climate change as the degree to which a system is susceptible to, or unable to cope with, the adverse effects of climate variability and change.^{Footnote 18} Current and future factors influencing health outcomes, including potential risks and protective measures, are investigated when assessing heathealth vulnerability.^{Footnote 9}

The vulnerability of individuals and communities will vary according to the level of exposure to extreme heat, the sensitivity of individuals to health impacts, and the programs and activities that directly or indirectly lower risks to health. Examples of factors that affect vulnerability include regional climate, population health status, socio-economic conditions, the state of local infrastructure, knowledge of heat-health risks and protective measures, the presence or absence of Heat Alert and Response Systems (HARS), and the strength of social networks and agencies. A vulnerability assessment examining these kinds of factors can provide decision makers and the public with the knowledge of characteristics and trends that increase or decrease their communities' resilience to extreme heat events. This knowledge then allows for the development of effective interventions (e.g., public health programs, transportation services, urban heat island mitigation) so that individuals and communities can protect those most vulnerable to extreme heat-health impacts.^{Footnote 1,Footnote 3}

Several documents and conceptual frameworks provide direction for the application of methods to assess vulnerability to a broad range of climate change impacts and to develop adaptation strategies.^{Footnote 11} In this regard, the World Health Organization (WHO) and the Pan American Health Organization (PAHO) have developed guidance to be used by both developing and developed countries for assessing the vulnerability of individuals and communities to all climate change impacts on health.^{Footnote 16}

However, little information is available to address considerations specific to the assessment of vulnerability to the health impacts of extreme heat events. This document, Adapting to Extreme Heat Events: Guidelines for Assessing Health Vulnerability (the Guidelines), addresses this need. The stakeholders and assessment steps relevant to the investigation of heat-health vulnerabilities in Canadian communities are presented along with examples of method application and information on key challenges and limitations.

1.1 Benefits of Conducting an Extreme Heat and Health Vulnerability Assessment

Assessments can help health agencies manage competing demands by describing current heat-related health risks, vulnerable groups, existing public health interventions, and adaptive actions, thereby focussing attention and resources on addressing specific needs. A well-designed and executed assessment provides sufficient information to assist in making policy and program recommendations to agencies that lead community efforts to reduce heat-health risks. In Canada, the responsibility for mobilizing these efforts can reside with a range of agencies - local, regional, or provincial public health departments, and emergency management organizations. Partnering organizations and officials, such as city planners, parks and recreation departments, transportation planners, health care practitioners, and social service providers (e.g., Canadian Red Cross) can contribute to and benefit from the results of an assessment. The process of completing an assessment will identify key players and establish a set of cross-cutting institutional linkages, and can be used to garner senior management support that can convert the recommendations into action.

Other benefits that result from completing an assessment include the development of baseline information about vulnerability to extreme heat events as well as an increased capacity to acquire and analyze needed data. An assessment can also serve as a mechanism to mobilize interdisciplinary groups and stakeholders to come together and collaborate in the identification of actions to increase the resiliency of a community.^{Footnote 1} Whatever the current level of knowledge and coping ability, the long-term benefits of conducting an assessment include moving an organization, or an entire community, towards increased awareness, capacity, and expertise on extreme heat and health issues.

1.2 Structure of the Guidelines

This document is structured to provide practical guidance for conducting extreme heat and health vulnerability assessments as a means to inform actions that can be taken to prepare communities for an increase in the number, intensity, and duration of extreme heat events. Development of the Guidelines was informed by input from a group of international and Canadian experts and stakeholders to ensure that the information presented meets the needs of decision makers tasked with protecting the health of the public.

This document provides information on understanding the health risks of extreme heat events and undertaking an assessment. Section 2 discusses the exposure of Canadians to extreme heat events, provides information on the sensitivity of individuals to health impacts, and highlights the role of HARS as an adaptation strategy. Section 3 presents the assessment steps for identifying current and future vulnerability of individuals and communities to extreme heat events using both qualitative and quantitative methods. Key assessment tasks and methods for each step are explained in table form, and are accompanied by examples to aid in the application of the Guidelines.

2. Vulnerability to the Health Impacts of Extreme Heat

Every individual reacts differently to heat stress, and some communities in Canada are at much greater risk from extreme heat events than others. The health impacts from extreme heat depend upon the vulnerability of individuals and communities; this vulnerability is a function of exposure to extreme heat, physiological sensitivity to heat stress, and the capacity to adapt by taking measures to protect health. Assessments of vulnerability use analyses of data and expert knowledge acquired through consultation with local stakeholders to identify the factors that are most relevant to an investigation for a specific community. Vulnerability to the health effects of extreme heat can often be traced to a combination of factors operating at both the individual and community levels as is shown in Figure 1.

Figure 1: Factors that influence individudal and community level vulnerability to extreme heat events

Figure 1: Factors that influence individudal and community level vulnerability to extreme heat events

A circle diagram has an outer (community factors) and inner ring (individual factors), and an individual at the centre of the rings. Community factors include summer outdoor festivals or events, health system capacity, urban design, social networks, income, health system preparedness, public buildings with air conditioning, lack of health warning systems, local climate, air pollution, type of housing, and cooling options. The individual factors include income, age, medications, personal behaviour, type of housing, fitness level, health status, acclimatization, and access to cool places. A stylized person is at the center of the two rings indicating that both individual and community factors influence a person's total vulnerability.

2.1 Exposure to Extreme Heat

Extreme heat as a health risk is a growing concern to individuals and communities in Canada. Most jurisdictions define extreme heat events based on the potential for hot weather conditions to result in an unacceptable level of health effects, including increased morbidity and mortality. Given the differing nature of meteorological factors and heat-related vulnerabilities across Canadian communities, and the requirement to set different alert triggers to reduce impacts on health, multiple definitions are used in practice. Environment Canada defines a "heat wave" as "three or more consecutive days in which the maximum temperature is greater than or equal to 32°C/90°F."^{Footnote 7} However, temperature is only one component of heat, which also depends on humidity, wind speed, and radiant load. At the level of the individual, health risks depend on exposure, sensitivity, acclimatization, and adaptability to extreme heat - that is, heat vulnerability.

Climate projections reveal that many Canadian communities can expect a significant increase in extreme heat events (hot days and warm nights) that can negatively impact health (Figure 2). Without effective actions to reduce health risks, the impacts of climate change could increase heatrelated illness and deaths among Canadians.

Figure 2: Historical and projected number of hot days and warm nights for selected cities in CanadaFootnote c

Figure 2: Historical and projected number of hot days and warm nights for selected cities in CanadaFootnote c

Two bar charts show the number of hot days and warm nights, respectively, for seven Canadian cities (Fredericton, Montreal, Kingston, Toronto, Hamilton, Windsor, Winnipeg). The numbers are based on the observed temperature data between 1961 and 2000, and projected for 2011-2040, 2041-2070 and 2071-2100 using Canadian climate models (Scenario A2).

Bar chart for hot days above 30°C/86°F reads:

• 1961-2000: Fredericton = 9, Montreal = 9, Kingston = 4, Toronto = 13, Hamilton = 15, Windsor = 22, Winnipeg = 14
• 2011-2040: Fredericton = 16, Montreal = 18, Kingston = 9, Toronto = 28, Hamilton = 24, Windsor = 35, Winnipeg = 30
• 2041-2070: Fredericton = 24, Montreal = 27, Kingston = 15, Toronto = 48, Hamilton = 36, Windsor = 48, Winnipeg 35
• 2071-2100: Fredericton = 40, Montreal = 44, Kingston = 32, Toronto = 59, Hamilton = 56, Windsor = 64, Winnipeg = 58

Bar chart for warm nights above 22°C/72°F reads:

• 1961-2000: Fredericton = 0, Montreal = 2, Kingston = 3, Toronto = 2, Hamilton = 2, Windsor = 5, Winnipeg = 2
• 2011-2040: Fredericton = 1, Montreal = 6, Kingston = 10, Toronto = 5, Hamilton = 4, Windsor = 10, Winnipeg = 3
• 2041-2070: Fredericton = 3, Montreal = 10, Kingston = 17, Toronto = 7, Hamilton = 7, Windsor = 22, Winnipeg 4
• 2071-2100: Fredericton = 4, Montreal = 22, Kingston = 32, Toronto = 22, Hamilton = 19, Windsor = 40, Winnipeg = 8

Source: Casati, B. and Yagouti, A. (In Press).^{Footnote 23}

Larger cities can be especially susceptible to extreme heat events because of the urban heat island effect (Box 1). Furthermore, high temperatures can increase the chemical reactions involved in the creation of air pollution resulting in greater risks to health.^19,20

2.2 Sensitivity of Canadians to the Health Impacts of Extreme Heat

Physiologically, extreme heat can affect the body's thermoregulation by impairing the mechanisms that allow it to maintain a constant core temperature. During extreme heat events, many people with underlying health conditions (e.g., respiratory and cardiovascular conditions) may experience a worsening of, or succumb to, those conditions.²⁴ Some may experience direct impacts on health, such as heat stroke, exhaustion, fainting, cramps, rash, and edema.^{Footnote d} Access to intervals of cooler temperatures (e.g., air conditioning or cool nights) helps to reduce heat stress. Longer durations of extreme heat including high nighttime temperatures, and poor air quality are all factors that can negatively affect health outcomes. Heat illness and deaths are preventable, but they do occur - mainly because people have been overexposed by not changing their behaviours to adjust to the heat. For example, individuals are at a greater risk if they overexert themselves for their age and physical condition or do not check with their medical practitioner about how the medications they are taking may increase their sensitivity to heat. Moreover, the health risks are higher for those who are not regularly exposed to hot environments.^{Footnote 25,Footnote 26}

Extreme heat events early in the summer generally result in higher morbidity and mortality than those later in the season partially because of a lack of acclimatization.^{Footnote 25} Acclimatization occurs owing to gradual exposure to heat resulting in physiological changes that make a person better able to handle heat.^{Footnote 27} The body's ability to acclimatize may be limited for some vulnerable populations - older adults, infants and young children, and people with chronic illnesses.^{Footnote 28} Table 1 describes heat-vulnerable groups and their challenges, which have been identified in the literature. Understanding heat vulnerabilities of specific populations is important for identifying effective public health interventions that can reduce the harmful effects of extreme heat.

 

2.3 Adapting to Protect Health: Heat Alert and Response Systems

To reduce negative health impacts from extreme heat events, public health and emergency management officials should assess local vulnerabilities and develop necessary policies and programs, such as HARS. Heat alert and response systems centre on efforts to alert health authorities and the public when hazardous conditions arise, provide advice on how health risks can be minimized, and offer assistance to those in need during emergency situations. Although these systems have been in place in some cities across the United States since the mid-1990s and in Toronto since 1999, only during the last few years have a number of Canadian cities and communities begun to develop formal HARS. Typically, HARS include some or all of the following components:

An effective HARS requires coordinated action across government authorities, involvement of private sector participants and community service organizations, and the ability to address multiple risk factors in the population.^{Footnote 47} There is wide variation in the types of HARS used in communities across Canada. Box 3 provides information on the City of Greater Sudbury's Hot Weather Response Plan.

Vulnerabilities within a community may increase or decrease over time as demographics, health status, exposure to extreme heat events, and access to health and social services change. Therefore, HARS should be evaluated regularly to ensure that they are contributing to a reduction in heat-related illnesses and deaths. Assessments of vulnerability help to inform the improvement of existing systems and the development of new ones in communities where they do not exist.

3. Guidelines for Conducting Extreme Heat and Health Vulnerability Assessments

3.1 Assessment Methodology

3.2 Assessment Steps

To conduct a comprehensive assessment of health vulnerability to extreme heat events, six steps should be completed. Figure 3 identifies key components of each step, and emphasizes that stakeholder engagement should occur throughout the entire assessment. Examples of the types of methods that can be used to investigate and reach a step's desired outcome are provided in the centre of the figure. Some methods (e.g., literature review) may be used in a number of steps, whereas other methods (e.g., developing climate projections) may be employed only for a specific component of the investigation. An assessment need not cover all steps if public health authorities determine that a focus on specific aspects of current or future vulnerability is warranted, if there are certain limitations (e.g., time, data, expertise), or because of the nature of the objectives identified through stakeholder consultation.

Figure 3: Steps for conducting an extreme heat and health vulnerability assessment

Figure 3: Steps for conducting an extreme heat and health vulnerability assessment

A circular figure illustrates how the assessment guidelines are broken-down into six steps. The objective of the each step is shown on the outside of the parameter of the circle: step 1) initiate the assessment; step 2) Describe current vulnerability; step 3) assess future risk; step 4) identify adaptation options; step 5) examine measures in other sectors, step 6) develop performance protocols. The individual tasks associated with each step's objective are included in boxes that form a ring in the circle figure. The task listed for each step read: step 1) identify assessment scope, objectives, and develop work plan; identify and organize stakeholders; step 2) Characterize heat exposure, and heat and air pollution exposure; characterize community vulnerability; characterise individual vulnerability; inventory programs and activities to address heat-health risks; evaluate the effectiveness of existing programs and activities; step 3) describe trends expected to influence heat-related health outcomes; describe projected increase in temperature and extreme heat events; describe possible additional health outcomes due to projected increases in temperature; step 4) inventory possible adaptation options; prioritize adaptation options; assess barriers to adaptation options and how they can be overcome; step 5) assess how changes in other sectors may influence heat-health risks: step 6) develop protocols for evaluating adaptation options; develop protocols for monitoring the burden of heat-sensitive health outcomes. In the centre of the circular figure, the following assessment methods that may be applied during an assessment are listed: literature reviews, inventory of data, surveys and interviews, geographic information systems, public health mapping and climate modelling. Stakeholders are also located in the center of the circular figure to signify that they have an essential role throughout the assessment process.

The steps for conducting an assessment follow. Each step is accompanied by a table providing detailed information on key tasks, methods, and expected outcomes. The implementation of each step should be tailored to meet the specific objectives of the individual assessment being undertaken.

Identifying the health outcomes of interest is important in the initial phase of the assessment. Studies have indicated that increases in ambient temperature have important impacts on morbidity as well as mortality.^{Footnote 50} If morbidity is being examined, then decisions will need to be made as to how it will be assessed (e.g., hospital admission records), which illnesses associated with heat will be investigated (e.g., ischemic stroke, respiratory diseases, dehydration, diabetes, renal failure),^{Footnote 50} and whether sufficient local data exists for this type of analysis.

Engaging Stakeholders

Special consideration needs to be given to the identification and engagement of stakeholders that should be included in the assessment. In general, stakeholders may come from local, regional, or provincial public health departments, emergency management organizations, parks and recreation departments, transportation planning agencies, health care organizations, and social service providers. Community planners, citizen groups, faith-based organizations, and private sector officials who provide essential services may also be included.

When identifying possible stakeholders, consideration should be given to the degree to which they:

• will be involved in the design, implementation and monitoring of public health and health care interventions to reduce risks from extreme heat
• are affected by the issue
• represent vulnerable populations
• can facilitate achievement of the assessment objectives
• can influence policy and program development

Because some organizations may not have the breadth or depth of in-house expertise available to conduct or participate in some aspects of an assessment, the addition of external expertise may be both desirable and necessary.

Once stakeholders are identified, the project lead will need to develop a process for acquiring input from them to contribute to the design and conduct of the assessment, and communication of the results. Developing a stakeholder engagement plan may assist in organizing stakeholders into categories, such as stakeholders who are partners and directly involved and those who may be consulted or regularly informed of progress. Community consultations, a community committee, a project advisory committee, and an expert review group are mechanisms to engage various stakeholders throughout the assessment.

If necessary, training workshops can be hosted by the project lead to build capacity and increase the knowledge of stakeholders about issues relevant to the assessment. Stakeholders should be engaged throughout the entire assessment process. However, stakeholders may change at various steps of the assessment as different information requirements arise - for example, input from experts in other sectors (e.g., transportation, infrastructure, urban planning, energy systems).

There are challenges associated with estimating future vulnerability based on projections of climate conditions, air quality, and expected demographic, health status, and socio-economic changes in society. In particular, use of this data requires specialized knowledge of climate science and health models, as well as their assumptions, limitations, and the degree of uncertainty associated with their application (Figure 6). Public health officials need to build expertise and capacity in this area and collaborate closely with the climate science community to address risks to health from extreme heat events. This collaboration will help to ensure that the communication of assessment results to decision makers will clearly convey information about any uncertainties related to possible future vulnerabilities. Assessment findings that suggest trends in key vulnerability factors are increasing within a population or community may be sufficient to warrant the adoption of proposed adaptation options.

Meteorological variables (e.g., temperature, humidity), and demographic, health status, and socio-economic data can be plotted on maps using GIS to spatially show current and future health vulnerabilities associated with extreme heat events (Box 6).

4. Conclusion

Glossary

Adaptation:

Process by which strategies and measures to moderate, cope with, and take advantage of the consequences of climatic events are enhanced, developed, implemented, and monitored. ^{Footnote 11} In public health, the analogous term is prevention. Various types of adaptation exist, including anticipatory and reactive, private and public, autonomous, and planned.

Adaptive Capacity:

General ability of individuals, communities, and institutions to effectively prepare for and cope with the consequences of climate variability and change.

Climate:

"Average weather" in a particular place over a particular time period. It is the statistical description of the mean and variability of weather variables (i.e., temperature, precipitation) over a period of time ranging from months to thousands or millions of years; the typical time period is 30 years.

Climate Change:

Statistically significant variation in either the mean state of the climate or in is variability, persisting for an extended period (typically decades or longer). Climate change may be due to natural internal processes or external forcings, or to persistent anthropogenic changes in the composition of the atmosphere. The United Nations Framework Convention on Climate Change defines climate change as "a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods." ^{Footnote 18}

Climate Model:

Numerical representation of the climate system based on the physical, chemical, and biological properties of its components, and the interactions and feedback processes that account for all or some of the known properties. Models may vary in complexity; as research tools, they are applied to study and simulate the climate, but are also used for operational purposes including monthly, seasonal, and inter-annual climate predictions.

Climate Scenario:

Plausible and often simplified representation of the likely future climate, based on an internally consistent set of climatological relationships that has been constructed for explicit use in investigating the potential consequences of anthropogenic climate change, and often serving as an input to impact models.

Climate Variability:

Variations in the mean state and other statistics (e.g., standard deviations, the occurrence of extreme events) of climate on all temporal and spatial scales beyond that of individual weather events. Variability may be due to natural internal processes within the climate system or to variations in natural or anthropogenic external forcing.

Co-Benefits:

Benefits (often health benefits) associated with reductions in greenhouse gas emissions. For example, reduced emissions of air pollutants can have immediate health benefits such as reduces respiratory and cardiovascular diseases. In addition, co-benefits can be associated with adaptation measures, such as new surveillance systems that monitor climate-related and nonclimate-related infectious diseases.

Epidemiological Study:

Science of public health and preventative medicine that studies the distribution and determinants of health-related states or events in specific populations, and that applies study findings to control and/or mitigate health problems.

Expert Judgement/Key Informant Interviews:

Statements that represent a process of evaluation, which can be a set of conditions and criteria, by someone widely recognized as a reliable source of knowledge, technique, or skill, and whose judgement is accorded authority and status by the public or their peers.

Health:

state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity.

Literature Review:

Comprehensive survey of publications that aims to critically analyze, summarize, and compare prior research in a specific field of study. This may also include "grey literature" refering to a body of materials that is produced by all levels of government, academia, business, and industry in electronic and print formats, but is not traditionally published. Examples of grey literature include technical reports, policy frameworks, and guidance documents from government agencies, scientific research groups, or related committees.

Mitigation:

Policies and measures to reduce greenhouse gas emissions and/or enhance carbon sinks.

Resilience:

Ability of a natural or human system to absorb disturbances while retaining the same basic structure and ways of functioning, the capacity for self-organization, and the capacity to adapt to stress and change.

Risk (i.e., Climate-Related Risk):

Product of likelihood of exposure and the consequence(s) of exposure. It arises from the interaction of a physically defined hazard (i.e., floods and other extreme weather events, increasing temperature) with the properties of the exposed system (vulnerability). ^{Footnote 11} System vulnerability is a critical determinant of the risk a region or subpopulation faces when exposed to a particular hazard. This means that programs to decrease vulnerability will decrease risk.

Sensitivity:

An individual's or subpopulation's increased responsiveness, primarily for biological reasons, to a particular exposure. Biological sensitivity may be related to developmental stage, pre-existing medical conditions, acquired factors (e.g., immunity), and genetic factors. ^{Footnote 9} Socioeconomic factors also play a critical role in altering vulnerability and sensitivity by interacting with biological factors that mediate risk (e.g., nutritional status), and/or lead to differences in the ability to adapt or respond to exposures or early phases of illness and injury.

Stakeholder Consultation:

Canvassing the views of stakeholders in the process of developing useful information, often through forums, round tables, and advisory bodies. Stakeholders may be drawn from governments, non-governmental organizations, research institutes, and private entities focussing on the issue being investigated.

Vulnerability:

Susceptibility to harm, which can be defined in terms of a population or a location. Vulnerability to climate change is the degree to which a system is susceptible to, or unable to cope with, the adverse effects of climate variability and change. Vulnerability is dynamic and may itself be influenced by climate change (e.g., extreme weather events affecting health infrastructure). From a health perspective, vulnerability can be defined as the summation of all risk and protective factors that ultimately determine whether a subpopulation or region experiences adverse health outcomes due to climate change. ^{Footnote 18} Characteristics of a region, such as baseline climate, abundance of natural resources (i.e., access to fresh water), elevation, infrastructure, and other factors can alter vulnerability.

References