Managing Heat-Related Illness in the Workplace

Heat-related illness can take many different forms, with heat cramps being the mildest and heatstroke being the most severe. Heat-related illnesses often occur when people are exposed and actively working outside during periods of high temperatures and humidity.

If left untreated, heat exhaustion can quickly turn to heatstroke. Without a quick response to lower body temperature, heatstroke can cause the brain or other vital organs to swell, possibly resulting in permanent damage or even death. This is why it’s crucial to mitigate employees’ risk and take action to make hot work environments better for overall safety. 

Causes of heat-related illnesses 

Maintaining normal body temperature is a delicate balance between heat load and heat dissipation, a process directed by the hypothalamus. The hypothalamus regulates body temperature, much like a thermostat regulates temperatures in a home, keeping the body within a degree or two of 98.6⁰. Body heat load comes from a mixture of metabolic processes (everything your body does to keep you alive) and the absorption of heat from the environment. Heat dissipation, your body's internal regulating system, works when heat activates sweat glands allowing water to surface on the skin. Once on the skin's surface, the water evaporates, cooling the body. 

After time in harsh environments, bodies become acclimatized to new conditions (increased sweating efficiency, stabilization of circulation). Meaning workers are more likely to experience heat-related distress within the first few days on a job, during periods of temperature change, and right after time spent away (i.e., vacation).

“Exposure limits are lower for workers who are unacclimatized to heat, who wear work clothing that inhibits heat dissipation, and who have predisposing personal risk factors.” - MedPub


There are a few variations of heat-related illness –heat rash, heat cramps, heat exhaustion, and heatstroke.


  • Health Effect: the most severe heat-related illness. Heatstroke happens when the body is no longer able to cool itself and begins to shut down entirely. Heatstroke is a medical emergency. It’s vital to treat heatstroke with professional medical attention immediately. Not treating heatstroke as soon as possible can lead to permanent disabilities or death.
  • Symptoms: Strong headache, no sweat, red- hot- dry skin, body temperature above 103⁰F, rapid strong pulse, nausea and vomiting, loss of consciousness. Signs of heatstroke are not always all present, please monitor employee health conditions closely.
  • First Aid: Call 911. While waiting for help, take immediate action to cool the person and remove them from the heat as much as possible. Place worker in a shady, cool area. Loosen clothing and remove outer clothing. Fan air on worker and place cold packs in their armpits. Proved the person with fluids and stay with them until help arrives. Any delay in action can be fatal.

Heat exhaustion

  • Health Effect: happens when the body can no longer control its internal temperature and is trying to regain control. Breathing will likely be fast and shallow, and the heart rate will be fast and weak. Heat exhaustion can lead to heatstroke in a matter of minutes, so it’s important to work fast to mitigate symptoms. Heat exhaustion can happen early in the day as an accumulation of several days of hot conditions. It can also occur alongside dehydration and exhaustion.
  • Symptoms: feeling faint or dizzy, excessive sweating, cool- pale- clammy skin, rapid weak pulse, nausea and vomiting, and muscle cramps.
  • First Aid: Get the person to a cooler (preferably air-conditioned place) and have them sit or lie down. Offer them water or a sports drink to rehydrate. Take a cool shower or use a cold compress to lower body temperature. If symptoms worsen or do not improve within 60 minutes, take the person to a clinic or emergency room for medical evaluation. Do not let them return to work that day.

Heat cramps

  • Health Effect: are muscle pains, often caused by strenuous activity in hot weather. They’re usually the result of losing too much salt and fluid due to sweating.
  • Symptoms: muscle spasms, pain, usually in the abdomen, arms, or legs.
  • First Aid: Have the person rest in a shady, cool area while rehydrating (juice or sports drinks are best to replace electrolytes). Wait a few hours before allowing workers to return to strenuous work. Seem medical attention if the pain lasts for more than a few hours.

Heat rash

  • Health Effects: a rash caused by exposure to heat, often after the skin has become irritated by excessive sweating.
  • Symptoms: Cluster of red bumps or blotches on the skin.
  • First Aid: Try to work in a cooler, less humid environment when possible. Keep the affected area dry and try applying a drying power to ease the irritation.


Under OSHA law, employers are responsible for providing workplaces free of known safety hazards. This includes protecting workers from extreme heat. An employer with workers exposed to high temperatures should establish a complete heat illness prevention program. Your company heat illness prevention program should include:

For employers

  •   Provide fluids to rehydrate, periods of rest, and accessible shade for employees when faced with harsh conditions
  •   Allow new or returning workers to gradually increase workloads and take more frequent breaks as they acclimatize or build a tolerance for working in the heat
  •   Training for workers and supervisors about symptoms recognition, emergency response, and first aid of heat stress and stroke
  •   Monitor workers for signs of illness
  •   Engineering and administrative controls to reduce heat stress (fans, light-reflecting clothes, wearable air conditioners)

For Employees

  •   Drink more fluids than normal
  •   Avoid alcohol, caffeine, and sugary drinks
  •   Use sunscreen rated at least SPF15
  •   If possible, wear light-colored, loose-fitting clothing

Using a heat index chat

The heat index is a measurement of how hot it feels when considering both relative humidity and the actual air temperature.

When using the Heat Index Chart as a tool, it’s essential to know that the heat index ‘real feel’ temperatures is measured in the shade with a light wind. If workers are in direct sunlight, it’s necessary to add 15⁰F to the displayed heat-index temperature. Reading the chart and knowing what prevention steps to take is important.

Heat Index 130⁰+F

  • Health Effect: Heatstroke is highly likely with continued exposure.
  • Recommendations: Limit strenuous activity, stay well hydrated (drink 10 gulps every 20 minutes), check on co-workers and employees, take frequent breaks.

Heat Index 105-129⁰+F

  • Health Effect: Heat exhaustion and heat cramps are likely. Heatstroke is possible with prolonged exposure and/or physical activity.
  • Recommendations: Stay well hydrated (drink 10 gulps every 20 minutes), check on co-workers and employees, take frequent breaks.

Heat Index 90-104⁰+F

  • Health Effect: Heatstroke, heat exhaustion, heat cramps are possible with prolonged exposure and/or physical activity.
  • Recommendations: Stay well hydrated (drink 10 gulps every 20 minutes), check on co-workers, take semi-frequent breaks.

Heat Index 80-89⁰+F

  • Health Effect: Fatigue is possible with prolonged exposure and/or physical activity.
  • Recommendations: Stay well hydrated (drink 10 gulps every 20 minutes), check on co-workers.

To assist with head index awareness, OSHA-NIOSH released an app [iOS | Android] that offers a simple ‘real feel’ temperature calculator. It indicates the hourly index, risk level, and provides first aid help.

If you’re interested in reading more about how employers mitigate heat-related illness with Personal Air Conditioners, below you can find links to related case studies.

-          Benefits of Using Personal Air Conditioners

-          Personal Cooling in the Marine Services Industry

-          Cooling Vest Keep Paint Booth Workers Safe

-          Electrical Equipment Recycling Facility in Alabama

You can also download our free heat-related illness symptom checklist here for quick use!

*This guidance is advisory in nature and informational in content. All information was generated from OSHA – NIOSH resources. Pursuant to the OSH Act, employers must comply with safety and health standards and regulations issued and enforced either by OSHA or by an OSHA-approved State Plan. In addition, the Act’s General Duty Clause, Section 5(a)(1), requires employers to provide their employees with a workplace free from recognized hazards likely to cause death or serious physical harm. For more heat related information, please visit OSHA’s website at:

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