July 2019


Heat can be a hazard when a person works in a hot environment. Workers exposed to hot indoor or hot and humid conditions outdoor are at risk of heat related illness, especially those doing heavy work tasks or using bulky or non-breathable protective clothing and equipment. The body must get rid of excessive heat to maintain a stable internal temperature, mainly through circulating blood to the skin and through sweating. When the air temperature is close to or warmer than normal body temperature, cooling of the body becomes more difficult. Blood circulated to the skin cannot lose its heat. Sweating then becomes the main source for the body to cool itself. But sweating is effective only if the humidity level is low enough to allow evaporation, and if the fluids and salts that are lost are adequately replaced.

Indoor workplaces with hot conditions include iron and steel foundries, brick-firing and ceramic plants, glass products facilities, electrical utilities (particularly boiler rooms), bakeries, commercial kitchens, laundries, chemical plants, material handling and distribution warehouses, and many other environments.

Outdoor workplaces with in hot weather and direct sun, such as farm work, construction, oil and gas well operations, landscaping, emergency response operations, and hazardous waste site activities, also increase the risk of heat-related illness in exposed workers.

Every year, many workers become sick from occupational heat exposure, and some are fatally injured. These illnesses and fatalities are preventable. Important ways to reduce heat exposure and the risk of heat-related illness include engineering controls, such as air conditioning and ventilation, that make the work environment cooler, and work practices such as work/rest cycles, drinking water often, and providing an opportunity for workers to build up a level of tolerance to working in the heat. Employers should include these prevention steps in work site training and plans.


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. HEAT STROKE IS A MEDICAL EMERGENCY THAT MAY RESULT IN DEATH! CALL 911 IMMEDIATELY.

  • Signs include : Confusion, fainting, seizures, excessive sweating or red, hot, dry skin, very high body temperature
  • First Aid*: Call 911. While waiting for help: place worker in shady, cool area. Loosen their clothing and remove any outer clothing. Fan air on worker; place cold packs in armpits. Wet the worker with cool water; apply ice packs, cool compresses or ice if available. Provide the worker fluids, water preferably, as soon as possible. Stay with them until help arrives.

HEAT EXHAUSTION is the body’s response to loss of water and salt from heavy sweating.

  • Signs include : Cool, moist skin and heavy sweating. Headache, nausea or vomiting, dizziness, light headedness, weakness, thirst, irritability and fast heartbeat
  • First Aid* : Have worker sit or lie die in cool shady area. Give the worker plenty to water or other cool beverages to drink. Cool them down with cold compresses/ice packs. If their conditions worsen or do not improve in 60 minutes take them to a clinic or ER for a medical evaluation or treatment.

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 preforming the work, are usually the ones most affected by cramps. Cramps may occur during or after working hours.

  • Signs include : Muscle spasms and pain, usually in abdomen, arms, or legs
  • First Aid* : Have the worker rest in shady, cool area. They should drink water or other cool beverages. Have the worker wait a few hours before allowing them to continue strenuous work. The worker should seek medical attention if cramps do not go away.

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.

  • Signs include : Clusters of red bumps on skin that often appear on neck, upper chest and folds of skin.
  • First Aide* : 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 to help workers in need.

For more information, visit or call OSHA at 1-800-321-OSHA (6742)