How to manage heat stress

Recognize when high heat is taxing your body—to avoid potentially serious consequences.

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Summers in Ontario can already be pretty hot—and given the potential impacts of climate change, they may get hotter. Yet even as the sun beats down and the mercury rises, hundreds of thousands of workers sweat it out on jobsites across the province. After all, it’s not like you can turn on the air conditioning while you work to fix a transmission tower or pave a road. And you certainly can’t build a house indoors.

But prolonged exposure to high temperatures can lead to heat stress, a range of conditions that result when your body loses its ability to properly cool itself.

Who is at risk?

Extreme heat poses a risk to anyone who is exposed to it. However, people who engage in heavy outdoor labour are at high risk, largely because their work is physically demanding and they cannot simply choose to avoid the heat. Among that group, heat can be even more hazardous to workers who:

  • Have pre-existing health concerns
  • Are taking medication
  • Have consumed alcohol during the previous 24 hours

Are age 40 and over, due to natural changes in the body’s ability to regulate temperature

Beyond these factors, environmental conditions such as overall air temperature, airflow, and humidity also influence how a person reacts to heat. For example, working in a poorly ventilated area on a humid day increases your risk of heat stress as your body will have a harder time cooling down.

Likewise, the extra weight and inflexibility of certain pieces of personal protective equipment (PPE) can make it difficult for your body to properly regulate its temperature.

Types of heat stress

Heat stress disorders can vary in severity, ranging from mild discomfort like sweating and increased thirst to more serious conditions such as heat rash, heat cramps, heat exhaustion, and heat stroke. It’s essential to understanding the symptoms of these conditions—and how to treat them—in order to ensure the safety and well-being of yourself and others while working in high-temperature environments.

Heat rash

Itchy, red blotches in areas that are consistently moist with sweat. (You may also feel a prickling or tingling sensation in affected areas.) Left unaddressed, the rash may worsen and could become infected. Take heed of heat rash: it’s a sign that your body may be struggling to regulate its temperature, which can lead to more serious issues.

How to treat it:

  • Move to a cool environment
  • Take a cool shower
  • Dry skin thoroughly
  • Clean skin frequently

Heat cramps

Painful muscle spasms, typically in the arms or legs—the result of excessive sweating that causes your body to lose too much salt.

How to treat it:

  • Stretch and massage muscles
  • Move to a cool environment
  • Drink electrolyte- or carbohydrate-replacement fluids (e.g., Gatorade)

Heat exhaustion

A more serious condition that occurs when your body can no longer maintain proper blood flow to vital organs and the skin. Symptoms include heavy sweating, weakness, dizziness, headache, nausea, and increased heart rate.

How to treat it:

  • Call 911
  • Move to a cool place
  • Loosen or remove any unnecessary clothing
  • Take sips of cool water
  • Sponge body with cool water

Heat stroke

Occurs when your body can no longer cool itself, causing a critical increase in your internal temperature. Heat stroke can be fatal if not immediately addressed. Its symptoms include confusion or irrational behaviour, a lack of sweat (i.e., you’re no longer capable of sweating), convulsions, and loss of consciousness.

How to treat it:

  • Call 911
  • Spray the heat stroke sufferer with cool water, wrap them in a cool, wet sheet, or immerse them in a tub of cool water
  • If they are unconscious, do not give them anything to drink

Controlling heat stress

Heat stress disorders can have serious health consequences, but there are measures you can take to minimize the risk.

“Understanding the type of environment you’ll be working in is the first step,” says Jasmine Kalsi, IHSA’s Occupational Hygienist. Knowing that you’re likely to be working outside on a high-temperature day, you can take steps such as:

  • Wearing light-coloured, loose-fitting, breathable clothing
  • Drinking plenty of fluids (avoid alcohol and caffeinated drinks)
  • Taking periodic breaks in a cool, shady place

Employers can also design work so that any heavy, physical tasks can be undertaken earlier in the day, before it gets too hot.

Once at work, the task of monitoring your body—and your colleagues—for signs of heat stress becomes crucial.

“As soon as you think you’re experiencing symptoms of heat stress, immediately remove yourself from that task or area and move to a cooler area,” Kalsi says. “It’s important that you act quickly to cool down.”

More on heat stress

VISIT IHSA’s heat stress topic page for FAQs, safety talks, and more resources to help beat the heat.

SIGN UP for our Basics of Heat Stress in Construction eLearning program to identify the signs of heat-related illnesses, recognize factors that increase your risk, and identify strategies to control your exposure.