Avoid heat illness with water, rest and shade


Excessive exposure to heat can cause a range of heat-related illnesses, from less serious heat rash and heat cramps to more serious heat exhaustion and heat stroke. Heat stroke requires immediate medical attention because it can be deadly, so take precautions while working in the summer heat.

For people working in hot environments, both air temperature and humidity affect how hot you feel. The higher the heat and humidity, the hotter the weather feels, because sweat is unable to readily evaporate. If the sweat your body produces cannot evaporate, your body can’t cool down and you may be at risk for a heat illness.

Take these precautions when working in hot environments:

Caution (at least 80°F at 60% humidity)

  • Drink water every 15 minutes.
  • Take breaks in the shade if working outdoors. Use a portable tent to create a shaded rest area, if available.
  • Take extra precautions if wearing non-breathable or impermeable clothing.
  • Wear sunscreen if working in direct sunlight.
  • Learn to recognize symptoms of heat-related illness.

Extreme Caution (at least 86°F at 60% humidity)

  • Follow all of the precautions listed above.
  • Drink about 4 cups of water every hour.
  • Take frequent breaks in cool, shaded areas. Use a portable tent to create a shaded rest area, if available.
  • Protect yourself from direct sunlight.
  • Keep windows and blinds closed when working indoors.
  • Treat anyone with milder symptoms of heat illness (e.g., headache, weakness).
  • Call 9-1-1 immediately if anyone loses consciousness or appears confused or uncoordinated.

Danger (at least 92°F at 60% humidity)

  • Follow all of the precautions listed above.
  • Institute and enforce work/rest schedules.
  • Adjust job activities and work schedules to avoid physical exertion during the hottest periods of the day.

Learn how to recognize the symptoms of serious and potentially fatal heat illness.

Signs of heat exhaustion versus heat stroke

Dizziness Confusion
Headache High temperature
Sweaty skin Red, hot, dry skin
Weakness Fainting
Cramps Convulsions
Nausea or vomiting Lack of coordination
Fast heart beat  

Can wearing a facemask while working in hot weather cause you to overheat? Read frequently asked questions about heat stress and facemasks.

For more information about heat illness, visit the U.S. Occupational Safety and Health Administration’s website.