Canadian Rental Service

Safety First and Last: Beating the Heat

By Jeff Thorne   

Features Business Intelligence education

Ahhhhhh summer, it’s finally upon us. The sun, the surf, the sand and that high humidity that our Canadian summers can bring! Love it or hate it, it’s our climate. With those hot, hazy summer days, comes a workplace hazard that often goes overlooked: heat stress.

Employers have a duty to ensure that reasonable precautions are taken to protect the health and safety of workers. Hot workplaces such as foundries, canneries, chemical plants, automotive manufacturing, commercial kitchens, bakeries, deep mines and sunny outdoor locations are typical environments where heat is a byproduct from the work process. Very hot environments have the potential to overwhelm the body’s coping mechanisms and lead to potentially serious and fatal conditions.

Heat stress is a less serious condition than heat stroke. Symptoms of heat stress include clammy pale skin, heavy sweating, rapid pulse, headache, dizziness, nausea, muscle cramps, fatigue, shallow breathing and dark urine.

Heat stroke is a serious, potentially fatal condition in which the body does not have the ability to cool itself. The body’s core temperature rises to a point where it can no longer produce sweat. Early symptoms of heat stroke include lack of sweat, hot dry skin, rapid pulse and difficulty breathing. If body temperature is not reduced, symptoms may progress to confusion and disorientation, seizure, loss of consciousness, coma or death.

Preventing heat stress and heat stroke in the workplace needs to be done through proper heat stress management. There are a few keys to implementing a successful heat stress prevention program. To manage heat exposure, follow some common sense steps. First, measure and monitor how much heat your workers will be exposed to, paying attention to the humidex as well as temperature. Devise a sampling strategy that defines the temperature where you start monitoring, then says how often and where you check the temperature. Have a response strategy involving rest breaks, job rotation, air conditioning and/or shutdown of operations. Implement training, thinking carefully about when and how often to deliver the heat protection message and how to get it across the best way. Obviously, you need to make sure your workers always have a sufficient supply of potable water wherever they are. Finally, encourage reporting whenever a worker needs first aid, a critical injury or an emergency.


Once the above has been competed, we can determine control measures. Controls can be broken down into general, specific and personal controls.

General controls start with implementation and training. The plan must be implemented and workers trained to recognize the signs and symptoms of heat stress and how to avoid them. On hot humid days with a sufficient workload, a cup of water should be consumed every 20 to 30 minutes. Workers must be given time to acclimatize to the heat. This could take up to two weeks. Humidex levels should be measured and work/rest cycles adjusted accordingly.

Specific controls can include shielding workers from radiant heat or providing fans when the temperature is below 35 degrees and less than 70 per cent humidity. Fan use when temperature is above 35 degrees and 70 per cent humidity will increase worker’s temperature. Additional controls include reducing manual material handling using carts, dollies and equipment, starting earlier or finishing later, ensuring that shade is available when working outdoors and rotating workers in and out of hot areas.

Finally, when it comes to the individual, avoid caffeinated beverages as these make the body lose water and increase the risk of heat stress. Use sunscreen and wear light clothing that allows sweat to evaporate. Encourage workers to make healthy lifestyle choices and try to get enough rest.

Stay safe, stay alert, stay hydrated, and heed your bodies warning signs. Have a healthy and safe summer everyone. For more information on heat stress and heat stress management, please go to  

Jeff Thorne is manager of training at Occupational Safety Group.

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