Heat Stress Safety

High temperatures and humidity stress the body's ability to cool itself, and heat illness becomes a special concern during hot weather. There are three major forms of heat illnesses: heat cramps, heat exhaustion, and heat stroke, with heat stroke being a life threatening condition.

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Heat Stress Symptoms Heat Stress Symptoms
  1. Fainting

    Heat syncope is a fainting (syncope) episode or dizziness that usually occurs with prolonged standing or sudden rising from a sitting or lying position. Factors that may contribute to heat syncope include dehydration and lack of acclimatization.


    Symptoms of heat syncope include:

    • Light-headedness
    • Dizziness
    • Fainting

    First Aid

    Workers with heat syncope should:

    • Sit or lie down in a cool place when they begin to feel symptoms.
    • Slowly drink water, clear juice, or a sports beverage.
  2. Heat Cramps

    Heat cramps are muscle spasms which usually affect the arms, legs, or stomach. Frequently they don't occur until sometime later after work, at night, or when relaxing. Heat cramps are caused by heavy sweating, especially when water is replaced by drinking, but not salt or potassium. Although heat cramps can be quite painful, they usually don't result in permanent damage. To prevent them, drink electrolyte solutions such as Gatorade during the day and try eating more fruits like bananas. 


    Muscle pain or spasms usually in the abdomen, arms, or legs.

    First Aid

    Workers with heat cramps should:

    • Stop all activity, and sit in a cool place.
    • Drink clear juice or a sports beverage.
    • Do not return to strenuous work for a few hours after the cramps subside because further exertion may lead to heat exhaustion or heat stroke.
    • Seek medical attention if any of the following apply:
      • The worker has heart problems.
      • The worker is on a low-sodium diet.
      • The cramps do not subside within one hour.
  3. Heat Exhaustion

    Heat exhaustion is more serious than heat cramps. It occurs when the body's internal air-conditioning system is overworked, but hasn't completely shut down. In heat exhaustion, the surface blood vessels and capillaries which originally enlarged to cool the blood collapse from loss of body fluids and necessary minerals. This happens when you don't drink enough fluids to replace what you're sweating away.  Workers most prone to heat exhaustion are those that are elderly, have high blood pressure, and those working in a hot environment.


    Symptoms of heat exhaustion include:

    • Heavy sweating
    • Extreme weakness or fatigue
    • Dizziness, confusion
    • Nausea
    • Clammy, moist skin
    • Pale or flushed complexion
    • Muscle cramps
    • Slightly elevated body temperature
    • Fast and shallow breathing

    First Aid

    Treat a worker suffering from heat exhaustion with the following:

    • Have them rest in a cool, shaded or air-conditioned area.
    • Have them drink plenty of water or other cool, nonalcoholic beverages.
    • Have them take a cool shower, bath, or sponge bath.
  4. Heat Stroke

    Heat stroke is a life threatening illness with a high death rate. It occurs when the body has depleted its supply of water and salt, and the victim's body temperature rises to deadly levels. When heat stroke occurs, the body temperature can rise to 106 degrees Fahrenheit or higher within 10 to 15 minutes. Heat stroke can cause death or permanent disability if emergency treatment is not given. A heat stroke victim may first suffer heat cramps and/or the heat exhaustion before progressing into the heat stroke stage, but this is not always the case. It should be noted that, on the job, heat stroke is sometimes mistaken for heart attack. It is therefore very important to be able to recognize the signs and symptoms of heat stroke - and to check for them anytime an employee collapses while working in a hot environment.


    Symptoms of heat stroke include:

    • Hot, dry skin or profuse sweating
    • Hallucinations
    • Chills
    • Throbbing headache
    • High body temperature
    • Confusion/dizziness
    • Slurred speech

    First Aid

    Take the following steps to treat a worker with heat stroke:

    • Call 911 and notify their supervisor.
    • Move the sick worker to a cool shaded area.
    • Cool the worker using methods such as:
      • Soaking their clothes with water.
      • Spraying, sponging, or showering them with water.
      • Fanning their body.

    It is vital to lower a heat stroke victim's body temperature. Seconds count. Pour water on them, fan them, or apply cold packs . Call 911 and get an ambulance on the way as soon as possible.

  5. Precautionary Steps to Prevent Heat Stress Issues

    Workers should avoid exposure to extreme heat, sun exposure, and high humidity when possible. When these exposures cannot be avoided, workers should take the following steps to prevent heat stress:

    • Condition yourself for working in hot environments - start slowly then build up to more physical work. Allow your body to adjust over a few days.
    • Drink lots of liquids. Don't wait until you're thirsty, by then, there's a good chance you're already on your way to being dehydrated (Approximately 1 cup every 15-20 minutes). Electrolyte drinks are good for replacing both water and minerals lost through sweating. Never drink alcohol, and avoid caffeinated beverages like coffee and pop.
    • Take a break if you notice you're getting a headache or you start feeling overheated. Cool off for a few minutes before going back to work.
    • Wear light weight, light colored breathable clothing such as cotton when working out in the sun.
    • Monitor your physical condition and that of your coworkers.
    • Take advantage of fans and air-conditioners.
    • Get enough sleep at night.

    With a little caution and common sense, you can avoid heat illnesses. 

  6. Precautions Steps for Supervisors to Protect Workers

    Supervisors should take the following steps to protect workers from heat stress:

    • Schedule maintenance and repair jobs in hot areas for cooler months.
    • Schedule hot jobs for the cooler part of the day.
    • Acclimatize workers by exposing them for progressively longer periods to hot work environments.
    • Reduce the physical demands of workers.
    • Use relief workers or assign extra workers for physically demanding jobs.
    • Provide cool water or liquids to workers.
      • Avoid alcohol, and drinks with large amounts of caffeine or sugar.
    • Provide rest periods with water breaks.
    • Provide cool areas for use during break periods.
    • Monitor workers who are at risk of heat stress.
    • Provide heat stress training that includes information about:
      • Worker risk
      • Prevention
      • Symptoms
      • The importance of monitoring yourself and coworkers for symptoms
      • Treatment
      • Personal protective equipment