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Extreme Heat

When the outdoor temperatures begin to rise, staying cool can become a challenge. Exposures to hotter temperatures, when outdoors, can cause serious or life-threatening health problems. During extreme heat, those most at risk include infants under one year of age, individuals 65 years of age or older, the homeless, outdoor workers, sport enthusiasts (i.e. runners), people living in homes that are poorly ventilated or without cooling devices, and people living in homes without power (usually due to other weather-related events such as a severe storms or power interruptions).

Both heat exhaustion and heat stroke are considered medical emergencies. Medical attention must be sought immediately during signs of fainting, heat exhaustion or heat stroke.


Heat Stroke
 High body temperature 41C or higher. Red, hot and dry skin. No sweating. Rapid pulse, seizures abnormal mental status, nausea.
 Reduce activity levels. Maintain fluid levels. Seek medical attention.
Heat Exhaustion
Heavy sweating, cool, moist skin. Muscle cramps/pain. Headache, nausea, weak pulse, normal or low blood pressure. Feel faint or weak. Shortness of breath. Chest or abdominal pain.
Reduce activity level. Maintain fluid levels. Seek medical attention.
Cool moist skin, weak pulse.
Reduce activity levels and heat exposure. Drink fluid regularly.
Heat cramps
 Muscle pain or spasm, normally in the legs, arms or abdomen. May be associated with activity.
 Avoid strenuous activity during high heat. Maintain fluid levels.
 Heat rash
 Red, bumpy rash, severe itching.
 Wash regularly, keeping skin clean and dry.

  • Drink plenty of fluids (consult with your doctor to see how much fluid to drink).
  • Avoid alcoholic or caffeinated beverages - water is best.
  • Wear lightweight & loose-fitting clothing.
  • Keep physical activity to a minimum.
  • Rest indoors and use a fan and draw blinds/curtains to prevent radiant heat from entering. If possible, stay in an air conditioned place.
  • Check on senior family members and neighbours.

Children have a high metabolic rate and therefore produce more heat. Also, their capacity to sweat is not as great compared to adults; so it is more difficult for them to release heat from their bodies. Additionally, the effects of dehydration are greater in children. Children also rely on others to provide adequate fluid.

Children with diabetes, anorexia, obesity, developmental delays, cystic fibrosis, heart disease and diarrhea are at an even greater risk.

  • They do not adjust as quickly to sudden changes in temperature.
  • They are more likely to have chronic medical conditions that can upset the normal response to heat.
  • They are more likely to take medications that impair the body’s ability to regulate its temperature, or that inhibit sweating.

The body's temperature control system can become overwhelmed and the body's core temperature increases. Sweating helps cool the body, however, when the humidity is high, sweat will not evaporate as quickly. This will prevent the body from releasing heat quickly and high core temperatures can damage the brain or other vital organs.Are you at risk from extreme heat?

Everyone is at risk, but some individuals are more susceptible to the effects of extreme heat:

  • Infants and children
  • Seniors
  • The homeless
  • Pregnant women
  • Individuals who are ill or on certain medications
  • Individuals who exercise vigorously or play sports outdoors
  • Individuals who do strenuous outdoor work for prolonged periods of times (e.g. construction or manual labour)
  • Individuals who are overweight (tend to retain more body heat)
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