Working outdoors in Canada means meeting both ends of the thermometer, sometimes in the same year on the same site. Heat stress in a humid summer and cold injury in a hard winter are real hazards that can move fast from uncomfortable to dangerous, and severe cases are medical emergencies. Both are preventable, and both come with warning signs your body gives you before things get serious, if you know what to watch for. This guide covers heat illness and cold injury, the signs to act on, and how to protect yourself and your crew through the seasons. A serious heat or cold injury suffered at work can also be a workers' compensation claim.
Heat stress: the warning signs
Heat builds up when your body cannot shed it fast enough, and humidity, heavy work, hot enclosed spaces, direct sun and PPE that traps heat all make it worse. It runs along a scale, and the early signs are your cue to act:
- Heat cramps and heavy sweating, thirst, tiredness. Early signals. Stop, get into shade, drink water.
- Heat exhaustion: heavy sweating, weakness, dizziness, nausea, headache, clammy pale skin, a fast pulse. This is serious. Stop work, cool down, rest in shade and rehydrate.
- Heat stroke is a medical emergency. Call 911. The danger sign is the body's cooling failing: skin may turn hot and dry or the person becomes confused, stops making sense, collapses or has a seizure. While waiting for help, move them to shade and cool them aggressively with water, wet cloths and fanning.
Confusion and a change in behaviour are the red flags. A workmate who stops sweating, slurs, or starts acting strangely in the heat needs help now, not later.
Preventing heat illness
- Drink water regularly, before you are thirsty, small amounts often through the day.
- Build up gradually. It takes a week or two to acclimatise to working in heat. The first hot days, and the first days back after time off, are the riskiest.
- Take breaks in the shade or a cool space, and schedule the heaviest work for the cooler parts of the day.
- Dress for it. Light, breathable clothing, a hat and sunscreen for sun exposure; recognise that some PPE traps heat and plan extra breaks for it.
- Watch each other. Heat stroke can hit fast, and the affected person is often the last to realise. A buddy system catches it.
Cold stress: the warning signs
Cold pulls heat out of the body, and wind and wet make it far worse than the air temperature alone suggests. The two dangers are hypothermia (the whole body getting too cold) and frostbite (tissue freezing, usually fingers, toes, ears, nose and cheeks):
- Hypothermia: starts with shivering, cold and numbness, then clumsiness, slurred speech, confusion and drowsiness. As it worsens the shivering may stop, which is a dangerous sign, not a good one. Severe hypothermia is a medical emergency. Call 911.
- Frostbite: skin that goes white or greyish and waxy, hard or numb, often without much pain at first. Get out of the cold and warm the area gently. Do not rub it, and do not thaw it if it might refreeze. Severe frostbite needs medical care.
Confusion, slurred speech and stumbling in the cold are the same kind of red flag as in the heat: the brain is affected, and the person needs warming and help now.
Preventing cold injury
- Layer up. Several thinner layers trap warmth better than one thick one, and you can shed a layer to avoid sweating, because damp clothing chills you fast. Keep a dry change handy.
- Protect the extremities. Insulated, waterproof gloves and boots, and cover the head, ears and face. Most frostbite hits the parts furthest from the core.
- Stay dry and out of the wind. Wind and wet are the multipliers. A windbreak and a waterproof shell make a big difference.
- Take warm-up breaks in a heated space, and have warm drinks. Schedule the work so people are not standing still in the cold for long stretches.
- Eat and stay fuelled. Your body burns energy to make heat, so cold work needs more food, not less.
Work-related heat and cold injury is claimable
A serious heat illness or cold injury suffered because of your work can be a workers' compensation claim through your provincial board: the WCB in most provinces, the WSIB in Ontario, and CNESST in Quebec. Report it, get medical care, and document the conditions you were working in.
Common mistakes
- Pushing through the early signs. Cramps, dizziness, heavy shivering or numbness are the warning, not a phase to tough out. Act on them.
- Skipping water until thirsty. By the time you feel thirsty in the heat, you are already behind. Drink steadily.
- Cotton and a single thick layer in the cold. Damp cotton chills you; layers you can adjust keep you dry and warm.
- Ignoring a workmate acting strangely. Confusion in heat or cold is a medical red flag, not someone messing about. Step in.
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