Heat Exhaustion

Heat exhaustion can develop quickly when you work in hot, humid weather. Your body overheats and raises your core body temperature from 37° to 40° Celsius or 98.6° to 104° Fahrenheit.

What causes heat exhaustion?

  • Exposure to hot weather or working conditions (like in a furnace or an area with steam pipes).
  • People with medical conditions like diabetes, heart disease, or skin diseases and rashes may be more susceptible to heat.
  • Loss of water and salt from heavy sweating.
  • Clothing that traps heat and doesn’t ‘breathe’.

What are the signs of heat exhaustion?

Heat exhaustion victims may not recognize they have the symptoms below. Watch your fellow co-workers for the following signs:

  • Cool, pale clammy skin
  • Heavy sweating
  • Dizziness or fainting
  • Headache
  • Fatigue
  • Nausea
  • Vomiting
  • Muscle aches / heat cramps
  • Intense thirst
  • Very high body temperature, over 40° Celsius or 104° Fahrenheit.

How can you avoid heat exhaustion?

  • Acclimatize yourself to working in hot conditions if you’ve been away from work or are just starting a new job.
  • If possible, move tasks indoors or into the shade.
  • Stay out of the sun between 11 a.m. and 3 p.m.
  • Drink plenty of water (about 1 litre every hour).
  • Avoid drinks with caffeine or alcohol which can dehydrate you.
  • Wear a hat, sunglasses and loose-fitting protective clothing.
  • Take a cool shower or bath.
  • Apply sunscreen regularly.
  • Sprinkle water on skin or keep a damp cloth on back of neck.

Canadian Centre for Occupational Health & Safety
British National Health Service
Environment Canada
Mayo Clinic
Merck & Co. Inc

For more information on working under hot conditions, see the WorkSafe publications, Working Under Hot Conditions and Hot Conditions Guidelines, below:

Working Under Hot Conditions
Hot Conditions Guidelines