About Heat Stress

Heat stress is heat-related illness that is caused by extreme heat events that have been associated with climate change. Heat-related illnesses occur when the body is unable to cool itself. The most common heat-related illnesses are heat stroke (sun stroke), heat exhaustion, heat cramps and heat rash.

Not all groups of people are at equal health risk from heat. The following groups of people are more vulnerable to heat-related illness:

  • Older adults and young children
  • People who are overweight or obese
  • People who may not perspire normally. For example, people who take certain medications that cause sensitivity to the sun or interfere with the body's ability to sweat and stay cool
  • People with chronic medical conditions, such as histories of dehydration, heart problems and respiratory or lung problems
  • People who work outdoors or in hot settings
  • People who live in urban areas where air pollution may linger on hot days

Preventing Heat Stress

People who are most at risk for health effects because of extreme heat events can take steps to protect themselves by staying in air conditioned or cooler locations during heat waves, or indoors when air quality is poor. To find a facility to get cool during extreme heat in your area check out information on Cooling Centers. Other steps to prevent heat related illness are listed below.

  • If there is no air conditioning in the home, open windows and shades on the shady side and close them on the sunny side to try to cool it down.
  • Drink plenty of fluids but avoid alcohol, caffeine and sugary drinks.
  • Beat the heat with cool showers and baths.
  • Take regular breaks from physical activity, and avoid strenuous activity during the hottest part of the day (between 11 a.m. and 4 p.m.).
  • Wear loose, lightweight, light-colored clothing to help keep cool.
  • Stay out of the sun as much as possible, and try to stay in an air conditioned location if possible.
  • Wear sunscreen and a ventilated hat (e.g., straw or mesh) when in the sun, even if it is cloudy.
  • Never leave children, pets or those with special needs in a parked car, even briefly. Temperatures in the car can become dangerous within a few minutes.
  • Check on neighbors, family and friends, especially those who are elderly or have special needs.
  • Conserve water and power during heat waves by turning off lights and non-essential appliances, and reducing non-essential use of water.

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