Many people are exposed to heat on the job, outdoors or in hot indoor environments. Operations involving high air temperatures, radiant heat sources, high humidity, direct physical contact with hot objects, or strenuous physical activities have a high potential for causing heat-related illness. Workplaces with these conditions may include iron and steel foundries, nonferrous foundries, brick-firing and ceramic plants, glass products facilities, rubber products factories, electrical utilities (particularly boiler rooms), bakeries, confectioneries, commercial kitchens, laundries, food canneries, chemical plants, mining sites, smelters, and steam tunnels.
Outdoor operations conducted in hot weather and direct sun, such as farm work, construction, oil and gas well operations, asbestos removal, landscaping, emergency response operations, and hazardous waste site activities, also increase the risk of heat-related illness in exposed workers.
Why is heat a hazard to workers?
When a person works in a hot environment, the body must get rid of excess heat to maintain a stable internal temperature. It does this 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 way the body cools off. 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.
If the body cannot get rid of excess heat, it will store it. When this happens, the body’s core temperature rises and the heart rate increases. As the body continues to store heat, the person begins to lose concentration and has difficulty focusing on a task, may become irritable or sick, and often loses the desire to drink. The next stage is most often fainting and even death if the person is not cooled down.
Excessive exposure to heat can cause a range of heat-related illnesses, from heat rash and heat cramps to heat exhaustion and heat stroke. Heat stroke can result in death and requires immediate medical attention.
Exposure to heat can also increase the risk of injuries because of sweaty palms, fogged-up safety glasses, dizziness, and burns from hot surfaces or steam.
Anyone can develop heat stress. However, the following groups of people have higher risks for experiencing heat stress or heat-related death:
- Infants and children up to four years of age,
- People 65 years of age and older,
- People who are overweight, and
- People who are ill or on certain medications
How do I know if it’s too hot?
- The temperature rises
- Humidity increases
- The sun gets stronger
- There is no air movement
- No controls are in place to reduce the impacts of equipment that radiates heat
- Protective clothing or gear is worn
- Work is strenuous
The heat index, which takes both temperature and humidity into account, is a useful tool for outdoor workers and employers
|Heat Index||Risk Level||Protective Measures|
|Less than 91°F||Lower (Caution)||Basic heat safety and planning|
|91°F to 103°F||Moderate||Implement precautions and heighten awareness|
|103°F to 115°F||High||Additional precautions to protect workers|
|Greater than 115°F||Very High to Extreme||Triggers even more aggressive protective measures|
Heat-related death or illnesses are preventable if you follow a few simple steps.
- Stay in an air-conditioned area during the hottest hours of the day. If you don’t have air conditioning in your home, go to a public place such as a shopping mall or a library to stay cool. Cooling stations and senior centers are also available in many large cities for people of all ages.
- Wear light, loose-fitting clothing.
- Drink water often. Don’t wait until you are thirsty.
- Avoid unnecessary hard work or activities if you are outside or in a building without air-conditioning.
- Avoid unnecessary sun exposure. When in the sun, wear a hat, preferably with a wide brim.
Air conditioning is the strongest protective factor against heat-related illness. Exposure to air conditioning for even a few hours a day will reduce the risk for heat-related illness.