UC San Diego SearchMenu

Heat Illness Prevention Program

Learn how to control the risk of heat-induced illness, train workers to protect themselves, recognize symptoms, and respond should a heat illness emergency occur.

Heat illness is a serious medical condition that results when the body is unable to cool itself by sweating. Environmental and personal factors can contribute to heat-induced illnesses, including heat stress, heat exhaustion, and ultimately heat stroke. Heat stroke can be fatal, especially if medical treatment is delayed.

If you supervise employees who work outside, learn how to respond should a heat illness emergency occur.

Expand all

Supervisor responsibilities

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 responders should a heat illness emergency occur

Heat Illness Prevention Program Forms

Use the forms below to plan and document heat illness prevention measures and emergency response:

  • Compliance Checklist (PDF) (Word)
  • Worksite Specific Procedures (PDF) (Word)

Risk factors

Heat illness results from a combination of environmental and personal risk factors.

  • 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

Reduce the risk

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 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

Symptoms and first aid

Symptoms of heat exhaustion and heat stroke are quite different.

Heat exhaustion

Heat exhaustion is characterized by loss of fluid from sweating when a worker fails to drink enough fluids.

  • Cause:
    • Body's heat-control mechanism is overactive
    • Loss of body fluids and minerals
  • Symptoms:
    • Heavy sweating
    • Extreme thirst
    • Extreme weakness and fatigue
    • Giddiness, nausea, or headaches
    • Skin is cool, clammy, and moist
    • Completion is pale or flushed
    • Body temperature is normal or slightly higher
  • First aid:
    • Move victim into shade
    • Loose and remove clothing
    • Cool the victim (web cloth, spray mist)
    • Have victim slowly drink water
    • Elevate victim's legs
    • Seek medical aid immediately if victim isn't better

Heat stroke

Heat stroke, the most serious heat illness, is failure of the body’s internal mechanism to regulate it’s core temperature.

  • Cause:
    • Body temperature rises to fatal levels
  • Symptoms:
    • Lack of sweat
    • Mental confusion, delirium, loss of concentration, convulsions or coma
    • Rapid pulse
    • A body temperature of 106°F or higher
    • Hot dry skin, which may be red, mottled, or blush
    • Convulsions, seizures, unconsciousness, or death can occur
  • First aid:
    • Call for emergency help immediately
    • Move victim into shade
    • Loosen outer clothing
    • Lower body temperature (massage body with ice or damp cloth)
    • If victim is alert, have them slowly drink water or an electrolyte beverage, such as Gatorade

Emergency response

When heat illness occurs:

  • Call 534-HELP (from a cell phone) or 9-1-1 (from a campus phone) for emergency medical help
  • Tell the dispatcher this is a heat related illness
  • Notify your supervisor and contact UCSD Workers’ Compensation, (858) 822-2979
  • If an employee is hospitalized, notify the UCSD Police dispatcher, (858) 534-4357

Regulations and policies

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

Safety training information


Expand all

Note: this page has a friendly link that's easy to remember: http://blink.ucsd.edu/go/preventheatillness