Heat-Related Illness Prevention

As the hot summer months approach, it is time to start thinking about heat stress prevention. While the Occupational Safety and Health Administration (OSHA) indicates that outdoor industries such as agriculture, construction, and landscaping have all suffered heat-related illnesses, heat-related illness can also be experienced at home while working in the heat. To maintain a healthy body temperature in warm environments, the body relies on its ability to dissipate heat naturally through sweating and increased blood flow to the skin. When the body is unable to dissipate heat quickly enough, the body’s internal temperature will continue to rise which may result in a heat related illness. Heat related illnesses include:

  • Heat Rash
  • Heat Cramps
  • Heat Syncope
  • Heat Exhaustion
  • Heat Stroke

To Prevent Heat-Related Illnesses:

  • Allow your body to acclimate to higher temperatures. According to OSHA, most outdoor fatalities (50-70%) occur within the first few days of working in a hot environment. This is due to the body’s need to gradually acclimatize to the heat.
  • Frequently drink small amounts of water to stay hydrated.
  • Schedule frequent rest periods with water breaks in shaded or cool areas.
  • Be aware of the signs of heat-related illnesses.
  • Wear light-colored, loose fitting clothing and a hat to reduce exposure to the sun.
  • Monitor weather reports daily and if possible, reschedule work with high heat exposure to cooler times of the day.

Determining the Heat Index and Protective Measures:

The heat index is a system that combines the air temperature and relative humidity to determine the apparent temperature or what the temperature feels like to the body. To determine protective measures for outside workers based on the heat index, OSHA developed the table shown below. By clicking on the links in the risk level column, you will be directed to a webpage that describes the precautions to take with each risk level. In addition to the table below, OSHA and the National Institute for Occupational Safety and Health (NIOSH) created the Heat Safety Tool phone app that also provides information on the heat index and protective measures.

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

For additional information and resources on heat stress prevention, visit the sources copied below.


OSHA Safety and Health Topics: Heat
OSHA Heat Index
OSHA Quick Card: Protecting Workers from Heat Stress
OSHA Fact Sheet: Protecting Workers from the Effects of Heat