Last Revised: October 13, 2023

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Each year, dozens of workers die and thousands more become ill while working in hot and/or humid conditions.

Workers become overheated from two primary sources:

  • The environmental conditions in which they work.
  • The internal heat generated by physical labor.


Heat related illnesses occur when the body is not able to lose enough heat to balance the heat generated by physical work and the external heat sources. Weather conditions are the primary external heat sources for outdoor workers.

  • Almost half of heat-related deaths occur on a worker’s very first day on the job. (Arbury 2014)
  • Over 70 percent of heat-related deaths occur during a worker’s first week. (Tustin 2018)
  • While most strongly associated with work outdoors in warm weather, heat illness also occurs at indoor work environments.

Heat-related illness can often be prevented by education, assessment of conditions, proper acclimatization, implementation of safe work practices and use of supervision and/or the buddy system to monitor the condition of employees.

The potential for heat-related fatalities can be drastically reduced if a heat emergency action plan is developed and implemented which cools the person's core body temperature to below 103 degrees F withing 30-minutes.

Penn's Heat Illness Prevention Program provides guidance to assist faculty, staff, and students prevent heat-related illness.


Additional Heat Illness Prevention Resources

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