Heat stroke, the most serious form of heat-related illness, happens when the body becomes unable to regulate its core temperature. Sweating stops and the body can no longer rid itself of excess heat. Signs include confusion, loss of consciousness, and seizures. Heat stroke is a medical emergency that may result in death!Call 911 immediately.
Heat exhaustion is the body's response to loss of water and salt from heavy sweating. Signs include headache, nausea, dizziness, weakness, irritability, thirst, and heavy sweating.
Heat cramps are caused by the loss of body salts and fluid during sweating. Low salt levels in muscles cause painful cramps. Tired muscles—those used for performing the work—are usually the ones most affected by cramps. Cramps may occur during or after working hours.
Heat rash, also known as prickly heat, is skin irritation caused by sweat that does not evaporate from the skin. Heat rash is the most common problem in hot work environments.
The chart below shows symptoms and first aid measures to take if a worker shows signs of a heat-related illness.
Excessive sweating or red, hot, dry skin
Very high body temperature
While waiting for help:
Place worker in shady, cool area
Loosen clothing, remove outer clothing
Fan air on worker; cold packs in armpits
Wet worker with cool water; apply ice packs, cool compresses, or ice if available
Provide fluids (preferably water) as soon as possible
Stay with worker until help arrives
Cool, moist skin
Nausea or vomiting
Fast heart beat
Have worker sit or lie down in a cool, shady area
Give worker plenty of water or other cool beverages to drink
Cool worker with cold compresses/ice packs
Take to clinic or emergency room for medical evaluation or treatment if signs or symptoms worsen or do not improve within 60 minutes.
Do not return to work that day
Usually in abdomen, arms, or legs
Have worker rest in shady, cool area
Worker should drink water or other cool beverages
Wait a few hours before allowing worker to return to strenuous work
Have worker seek medical attention if cramps don't go away
Clusters of red bumps on skin
Often appears on neck, upper chest, folds of skin
Try to work in a cooler, less humid environment when possible
Keep the affected area dry
* Remember, if you are not a medical professional, use this information as a guide only to help workers in need.
For more information about heat-related illnesses:
OSHA Technical Manual (OTM). OSHA Directive TED 01-00-015 [TED 1-0.15A], (January 20, 1999). Includes a chapter on Heat Stress with useful sections on the signs and symptoms of heat stress, sampling methods, control suggestions, and guidelines for investigating heat stress in the workplace.
Heat Illness. National Institutes of Health, Medline Plus. Includes information in multiple languages.
Heat: A Major Killer. National Oceanic and Atmospheric Administration (NOAA), National Weather Service. Links to landing page with NWS's heat index description and chart.
Heat Stress and Strain: TLV® Physical Agents 7th Edition Documentation. Summarizes the scientific data used by the American Conference of Government Industrial Hygienists (ACGIH) used to derive its threshold limit value (TLV) for heat exposure.
U.S. Department of Labor | Occupational Safety & Health Administration | 200 Constitution Ave., NW, Washington, DC 20210 Telephone: 800-321-OSHA (6742) | TTY www.OSHA.gov
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