Select a topic for more information:

• Supervisors' responsibilities
• Risk factors
• Reducing the risk
• Symptoms and signs of heat illness
• What to do when heat illness occurs

Supervisors of employees who work outdoors in hot conditions must:

• Be aware of risk factors that contribute to heat illness
• Reduce the risk by taking special precautions to prevent heat illness
• Be alert for the symptoms of serious heat illness
• Train employees about the risks and how to protect themselves
• Make sure employees working in hot conditions are accounted for at the end of the work shift
• Know what to do and how to summon emergency medical care should a heat illness emergency occur

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Risk factors: Heat illness results from a combination of environmental and personal risk factors described below:

• Environmental factors are working conditions that create the possibility that heat illness could occur. They include:
• High temperature and/ or humidity
• Direct exposure to the sun or heat sources
• Limited air movement
• Physical exertion and duration
• Protective clothing and protective equipment worn by employees

• Personal factors affect how well an individual deals with excess heat. They include:
• Age, weight, and physical condition
• Acclimation to working in the heat
• Consumption of water, alcohol, and caffeine
• Use of medications that affect tolerance to heat

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Reduce the risk of heat illness by taking these precautions:

• Recognize the hazard. There are no absolute temperature cutoffs below which work in heat ceases to be a risk. With heavy work conducted in high humidity, or if workers are wearing protective clothing, even work at 70°F can present a risk. Take steps to reduce heat illness risk when temperatures approach 80°F. At temperatures of 90°F, especially with heavy work, heat risk reduction is a major concern.
• Provide an ample supply of clean, cool drinking water. Encourage employees to drink plenty of water. Employees working outdoors in heat need to drink 3 to 4 glasses of water per hour. For an 8-hour day, provide 2 or more gallons per person.
• Provide a shaded area for breaks and relief from the sun. Perform work in the shade when possible. Otherwise, provide a shaded area with good air circulation.
• Allow workers time to acclimate, or gradually adjust to working in heat. Acclimation is especially important for those returning to work after a long absence or illness, or recently arriving from a cooler climate. Starting with about 2 hours' work per day, allow 4 to 10 days of progressively increasing work time for very hot conditions.
• Ensure that workers take rest breaks. Breaks in a cooler, shaded area allow the body to cool and dissipate the internal heat load. Rest breaks are also an opportunity to drink water.
• Summon emergency medical services immediately when you suspect even initial symptoms of heat illness. Get help even if the person protests. Never leave unattended an employee who displays symptoms of serious heat illness without a medical assessment.
• Note: In remote or temporary work areas, make sure you have communication means and knowledge of how to guide emergency services to your location.
• Train employees who work outside in heat to understand the risks of heat illness, to recognize symptoms, and to protect themselves. Make sure they:
• Know it's important to drink approximately 1 quart of water per hour
• Understand that caffeinated drinks, alcohol, and some prescription drugs can affect their ability to deal with heat by causing dehydration
• Wear wide-brimmed hats and light, loose-fitting clothing to protect them from the sun
• Take breaks in a cool, shaded area
• Rest or reduce the work pace if they become uncomfortable
• Are alert for signs of heat illness in their coworkers

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Common early symptoms and signs of heat illness include:

• Headaches, dizziness, or lightheadedness
• Muscle cramps
• Unusual fatigue or weakness

Progression to more serious illness can be rapid and can include:

• Unusual behavior, irritability, or mental confusion
• Nausea or vomiting
• Rapid pulse
• Excessive sweating or hot, dry skin
• Seizures or fits
• Fainting or loss of consciousness

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What to do when heat illness occurs:

• Call 9-1-1 for emergency medical help
• Move the person to a cool, shaded area
• Loosen or remove heavy clothing
• Provide drinking water or an electrolyte beverage, such as Gatorade
• Fan and mist the person with water

For more information, read:

• Heat-Related Illness Prevention and Information, Division of Occupational Safety and Health (DOSH)
• Heat Stress Prevention Training (PowerPoint), UCSD Environment, Health & Safety

Related policy:

• Heat Illness Prevention, California Code of Regulations, Title 8, Section 3395, California Department of Industrial Relations

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If you are a UCSD employee and have questions, contact Environment, Health & Safety, (858) 534-1075 or 534-3782.