Extreme Heat – Vulnerability Assessment

The elderly have an increased
risk for heat-related illnesses.[6]

Conditions of extreme heat are defined as summertime temperatures that are substantially hotter and/or more humid than average for location at that time of year. Humid or muggy conditions, which add to the discomfort of high temperatures, occur when a “dome” of high atmospheric pressure traps hazy, damp air near the ground.

Excessive heat events (EHEs) are and will continue to be a fact of life in the United States. Distinct groups within the population, generally those who are older, very young, or poor, or have physical challenges or mental impairments, are at elevated risk for experiencing EHE-attributable health problems.

Air-conditioning is the number one protective factor against heat-related illness and death. During conditions of extreme heat, spend time in locations with air-conditioning such as shopping malls, public libraries, or public health sponsored heat-relief shelters in your area.[1]

Demographic Vulnerabilities

Individuals possessing any combination of the following characteristics or conditions are at greater risk for experiencing an EHE-attributable adverse health outcome:[2]

Physical Constraints
It is difficult for some people to increase their circulation and perspiration during an EHE to help them remain cool. This at-risk group includes infants, older people (age 65 and older, who may also be less likely to recognize symptoms of excessive heat exposure), the obese, the bedridden, those with underlying medical conditions (e.g., heart disease, diabetes), those taking certain medications (e.g., for high blood pressure, depression, insomnia), and individuals under the influence of drugs or alcohol.

Mobility Constraints
People with mobility constraints are at higher risk during EHEs if the constraints limit their ability to access appropriately cooled locations. This group includes the very young and the bedridden.

Cognitive Impairments
People with mental illnesses, with cognitive disorders, or under the influence of drugs or alcohol may be unable to make rational decisions that would help limit their exposure to excessive heat or to recognize symptoms of excessive heat exposure.

Economic Constraints
The poor may be disproportionately at risk during EHEs if their homes lack air conditioning or they are less likely to use available air conditioning because of the cost.

Social Isolation
Socially isolated individuals are less likely to recognize symptoms of excessive heat exposure. This can delay or prevent treatment and result in more serious health outcomes. Members of this group, which include the homeless and those living alone, may also be less willing or able to reach out to others for help.


Regional Vulnerabilities

Regional characteristics can also help determine an individual’s health risks during EHEs. These characteristics include:[3]

  • Geographic location: Climate variability is largely a function of location, and increased variability has been associated with elevated heat-attributable mortality
  • Urbanization and urban design: As buildings, especially those with dark roofs, and dark paving materials replace vegetation in urban areas, the heat absorbed during the day increases and cooling from shade and evaporation of water from soil and leaves is lost. Urban areas can also have reduced air flow because of tall buildings, and increased amounts of waste heat generated from vehicles, factories, and air conditioners.
  • Figure 1. Impact of the urban heat island on ambient temperatures[4]

Vulnerability Assessment Questions

To assess your vulnerability to the threat of Extreme Heat to your family and property, perform an assessment to determine if you have knowledge of, are prepared and/or have a plan by answering the following questions:

General All-Hazard Questions:

  • Have you determined the disaster risks in your locale and the hazards that accompany them?
  • Do you know the emergency warning signals and alert notifications used in your community?
  • Have you instructed family members how to shut off water, gas and electricity to your house?
  • Have you made the necessary property preparations to reduce the damage from the hazard?
  • Do you have a backup generator in case of a prolonged power failure?
  • Have you purchased insurance (property, health, life, and/or hazard type)?
  • Have you made the necessary financial arrangements in case of a sudden evacuation and power outage that shuts down local ATMs and banks?
  • have you organized important documents and records and stored them in a portable lock box or safe-deposit box?
  • Have you performed a home inventory video taping the contents stored them in a portable lock box or safe-deposit box?
  • Does your family have an established Emergency Communication Plan and evacuation plan in place and asked an out-of-state person to serve as the “family contact”?
  • Have you assembled a shelter-in-place Emergency Supplies Kit in case you have to shelter at home and you are without power?
  • Have you assembled a mobile Emergency Supplies Kit that can serve as a “grab and go” bag?
  • Are you or someone in your family trained in first aid and CPR?
  • Have you made they necessary preparations and arrangements for pets, seniors, and the disabled?
  • Have you familiarized yourself with the emergency plans of your family member’s employment building, school, day care center, or nursing home?

Hazard Specific Questions:

  • Have you protected your windows that receive sun by hanging draperies or shades?
  • Do you know the signs or symptoms of Heat Exhaustion or Heat Stroke?
  • Do you know what to do for someone experiencing Heat Exhaustion or Heat Stroke?
  • Do you know the best way to replace salts and minerals in your body?
  • Do you know how much water to consume during extreme heat?
  • Do you understand how alcohol increases your chances of heat related illness?
  • Do you realize that you should reduce, eliminate, or reschedule outdoor strenuous activities?
  • Are you aware that you should never leave children or pets alone in closed vehicles during extreme heat?
  • Have you made sure older adults have enough good drinking water, and be sure they drink it. Older adults can be at risk for dehydration because of:
    • a decreased thirst sensation and do not feel the urge to drink as often as younger people;
    • medications that increase the risk of dehydration; and
    • physical conditions that make it difficult to drink.

Average Annual Max Temperature Map (°F)

The following map indicates the regions of average annual high temperatures of the United States:[5]




  1. EPA – Excessive Heat Events Guidebook: http://www.epa.gov/heatisland/about/pdf/EHEguide_final.pdf
  2. EPA – Excessive Heat Events Guidebook: http://www.epa.gov/heatisland/about/pdf/EHEguide_final.pdf
  3. EPA – Excessive Heat Events Guidebook: http://www.epa.gov/heatisland/about/pdf/EHEguide_final.pdf
  4. Image Source: http://www.epa.gov/heatisland/about/pdf/EHEguide_final.pdf [Accessed September 14, 2013]
  5. Image Source: http://en.wikipedia.org/wiki/File:Average_Annual_High_Temperature_of_the_United_States.jpg [Accessed September 14, 2013]
  6. Image Source: http://www.cdc.gov/media/dpk/2013/dpk-extreme-heat.html [Accessed July 14, 2013]