Occupational Heat Stress

When workers are exposed to hot and humid conditions their bodies may not be able to maintain a normal temperature, leading to serious illness or death. 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.

There are three different controls that employers can institute to reduce heat illness, including engineering controls, administrative controls, and personal protective equipment. Engineering controls are the preferred way of reducing these illnesses since they are permanent solutions and employees cannot interfere with their use. Examples include general ventilation (i.e. air conditioning, local air cooling), the use of fans to increase air flow and sweat evaporation, and the use of shields or barriers to block out direct sun and other heat sources.

Administrative controls, if instituted properly, can be a great way to reduce employee exposure. It is recommended that work schedules are modified to include frequent rest periods with water breaks in shaded or air-conditioned areas, and that hot jobs are rescheduled for the cooler parts of the day. Routine maintenance and repair work in hot areas should be scheduled for the cooler seasons of the year. Additionally, employees should be provided with ample supplies of cool drinking water and encouraged to drink even when they are not thirsty. Water is and the best fluid; liquids fortified with salt are unnecessary, and energy drinks and other caffeinated drinks (coffee, soda, iced tea) should be avoided as they promote dehydration.

One of the most important administrative controls is “acclimatization,” the process of gradually increasing the exposure of new workers (or those who have been away from work) to working in the heat to allow them to adapt. This process usually takes between 5-7 days. It is also best practice to routinely check on workers who are at risk of heat stress, provide medical evaluations, develop an illness prevention plan, track the worksite heat index daily and communicate this to employees, and train your workers on how to recognize and prevent heat-related illnesses.

There is specially designed personal protective equipment that can supplement the engineering and administrative controls described above. Workers should be encouraged to wear lightweight, light colored, moisture-wicking, loose-fitting clothes and a broad-brimmed hat. It may be necessary to reexamine the PPE that your workers are currently wearing in the heat, as the use of bulky PPE can contribute to heat illnesses. Auxiliary body cooling ice vests, wetted clothing, water-cooled garments, and circulating air garments offer a high level of personal cooling.

OSHA has created a “Heat Safety Tool” phone app that allows users to input their specific temperature and humidity data and displays precautions needed to take based on the heat index. (

It’s important to recognize that heat-related injuries can impact students and athletes as well.  The family of a California college student who died during a grueling fraternity hazing hike sued the organization and the school Wednesday, saying the young man’s death was senseless and easily preventable.

The student died a year ago after collapsing during an 18-mile hike organized by a fraternity chapter. The group was hiking in blazing hot temperatures with little water and inadequate shoes, a school investigation found.

The suit claims frat members forced pledges to go on the dangerous hike without adequate supplies as a last ritual before they could become official members. The lawsuit says the university had a responsibility to oversee fraternity activities and should’ve been aware of and stopped any hazing activities. (