If they haven't reached your neck of the woods yet, they will soon. Heat and humidity are as much a part of Ontario summers as beer and barbecues. While hot weather is great when you’re relaxing at the cottage, at work it can become a serious health hazard.

To ensure that you and your workers are prepared to work outdoors in high temperatures, make your next safety talk about the prevention, symptoms, and treatment of heat stress.

The best way to prevent heat stress is to drink water regularly throughout the day. On really hot days, take frequent breaks in a shaded or air-conditioned area.

The effects of heat stress range from mild to severe: heat rash and heat exhaustion on the mild to moderate side and heat stroke on the severe side. Make sure your workers know how to recognize the symptoms and what to do about them.


Heat rash

Heat rash usually goes away in a few days if treated.

Symptoms of heat rash include

  • red blotches and extreme itchiness on areas damp with sweat
  • a prickling sensation on the skin where you are sweating.

Rest in a cool environment, take a cool shower, and dry your clothes and skin thoroughly.


Heat exhaustion

If not treated promptly, heat exhaustion can lead to heat stroke. It takes at least 30 minutes to cool your body after suffering heat exhaustion.

Symptoms of heat exhaustion include

  • weakness
  • headache
  • breathlessness
  • nausea or vomiting
  • feeling faint.

Rest in a cool environment (for at least 30 minutes), drink cool water, remove unnecessary clothing, and take a cool shower. If you can’t take a shower, sponge your body with cool water.


Heat stroke

Heat stroke occurs when the body can no longer cool itself and its temperature rises to critical levels. It can be fatal. Immediate medical attention is required. If a worker on your site may be suffering from heat stroke, call 911 right away.

Symptoms of heat stroke include

  • irrational behaviour
  • confusion
  • loss of consciousness
  • convulsions
  • hot, dry skin (not sweating).

Call 911. While waiting, immerse the worker’s whole body in a tub of cool water or spray the worker with cool water from a hose. If possible, wrap the worker’s body with sheets soaked in cool water. Get the worker to hospital immediately.


For more information and resources on heat stress, including a guide to setting up a work-rest schedule and an online tutorial about the effects of heat stress, visit IHSA’s Heat Stress page.