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NIOSH Fast Facts: Protecting Yourself from Heat Stress

April 2010
DHHS (NIOSH) Publication Number 2010-114
cover of 2010-114

Heat stress, from exertion or hot environments, places workers at risk for illnesses such as heat stroke, heat exhaustion, or heat cramps.

Heat Stroke

A condition that occurs when the body becomes unable to control its temperature, and can cause death or permanent disability.


  • High body temperature
  • Confusion
  • Loss of coordination
  • Hot, dry skin or profuse sweating
  • Throbbing headache
  • Seizures, coma

First Aid

  • Request immediate medical assistance.
  • Move the worker to a cool, shaded area.
  • Remove excess clothing and apply cool water to their body.

Heat Exhaustion

The body’s response to an excessive loss of water and salt, usually through sweating.


  • Rapid heart beat
  • Heavy sweating
  • Extreme weakness or fatigue
  • Dizziness
  • Nausea, vomiting
  • Irritability
  • Fast, shallow breathing
  • Slightly elevated body temperature

First Aid

  • Rest in a cool area.
  • Drink plenty of water or other cool beverages.
  • Take a cool shower, bath, or sponge bath.

Heat Cramps

Affect workers who sweat a lot during strenuous activity. Sweating depletes the body’s salt and moisture levels.


  • Muscle cramps, pain, or spasms in the abdomen, arms or legs

First Aid

  • Stop all activity, and sit in a cool place.
  • Drink clear juice or a sports beverage, or drink water with food.
    • Avoid salt tablets.
  • Do not return to strenuous work for a few hours after the cramps subside.
  • Seek medical attention if you have the following: heart problems, are on a low-sodium diet, or if the cramps do not subside within one hour.

Protect Yourself

Avoid heavy exertion, extreme heat, sun exposure, and high humidity when possible. When these cannot be avoided, take the following preventative steps:

  • Monitor your physical condition and that of your coworkers for signs or symptoms of heat illnesses.
  • Wear light-colored, loose-fitting, breathable clothing such as cotton.
    • Avoid non-breathable synthetic clothing.
  • Gradually build up to heavy work.
  • Schedule heavy work during the coolest parts of day.
  • Take more breaks when doing heavier work, and in high heat and humidity.
    • Take breaks in the shade or a cool area.
  • Drink water frequently. Drink enough water that younever become thirsty.
  • Be aware that protective clothing or personal protective equipment may increase the risk of heat-related illnesses.