Outdoor operations conducted in hot weather and direct sun, such as construction, landscaping, emergency response operations, and hazardous waste site activities, increase the risk of heat-related illness in exposed workers.
Every year, thousands of workers become sick from occupational heat exposure, and some even die. These illnesses and deaths are preventable.
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.
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.
Workers exposed to hot and humid conditions outdoors are at risk of heat-related illness, especially those doing heavy work tasks or using bulky or non-breathable protective clothing and equipment. Some workers might be at greater risk than others if they have not built up a tolerance to hot conditions, or if they have certain health conditions.
Factors that put workers at greater risk:
- High temperature and humidity
- Radiant heat sources
- Contact with hot objects
- Direct sun exposure (no shade)
- Limited air movement (no wind, ventilation or no breeze)
- Physical exertion
- Use of bulky or non-breathable protective clothing and equipment
When do you 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
Heat-related illnesses can be prevented. 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.
The heat index, which takes both temperature and humidity into account, is a useful tool for outdoor workers and employers.