While we may be thankful that the weather has turned warmer and we can spend our free days out for hikes or at the beach with our friends and family, as we dive deeper into the warmer months it’s important to be wary of what the heat can do to our bodies, especially while working in these high temperatures.  

Do you know the risks of overexposure to heat and the signs of heat-related disorders? High temperatures, physical labour, fatigue and/or preexisting medical conditions can be a dangerous combination that can stress the body’s cooling system and lead to fainting and dehydration, various heat-related disorders, disabilities, and even death. Looking after yourself and others is of high priority during this time of the year. Detecting early signs and treating symptoms of heat stress can save lives. 

What is Heat Stress? 

Heat stress is the combined heat load on the body to which an employee may be exposed from several sources, including high temperature and humidity, poor physical condition, direct sun or radiant heat sources, certain medications, and more. While milder cases of heat stress cause your body to feel discomfort, there are serious implications as body temperature rises, leading into the heat disorder territory.  

Should Your Workplace be Concerned? 

While every workplace in any sector should have a certain level of concern when it comes to heat stress, some should consider it a higher priority given the environment workers face daily: 

• Has anyone been affected by heat in your workplace? 
• Is work done in direct sunlight? 
• Are there heat producing processes or equipment in the workplace? 
• Do workers wear extra clothing/protective equipment that can make them hot (e.g., overalls, respirators, hard hats)? 
• Are fans needed to keep workers cool? 
• Have workers ever expressed concern about heat in the workplace? 

If you said “yes” to any of the above questions, you should be diligent when it comes to protecting yourself and workers from heat stress.  

Know the Signs 

Enhancing workers’ awareness of the signs of heat stress can prevent serious injuries, disabilities and death. As your body heats up, it tries to rid itself of excess heat through the evaporation of sweat. When you reach an internal temperature above 38-39°C, the brain starts to overheat, leading to a shutdown of your body’s cooling system and the sweat you were producing earlier begins to stop. The continued rise in temperature can lead to serious conditions like heatstroke and possibly death. Early identification is essential. By taking steps early on, it may be possible to prevent escalation of symptoms. 

Some signs of heat stress to remember are: 

Low Risk 

• Heat rash 
• Sunburn 
• Heat cramps 

High Risk 

• Fainting 
• Heat exhaustion 
• Heat stroke 

Tips on Preventing Heat Stress 

While the answer that makes the most sense when it comes to preventing heat stress is to avoid the heat altogether, sometimes this isn’t possible. Here are a few steps you can take to reduce heat stress in the workplace, and prevent things from escalating: 

For the Worker: 

• Allow for an acclimatization period. 
• Wear sunscreen. 
• Wear a hat when you can. 
• Keep a bottle of water handy to stay hydrated.  
• Take breaks often. 
• Avoid alcohol consumption the day before a shift. 

For the Employer: 

• Build heat stress awareness into your training program so workplace parties know the signs and symptoms of heat stress, and how to treat them early. 
• Take into consideration the type of clothing workers are wearing and the impact of the heat. 
• Keep track of temperatures within your workplace. Divide the workplace into zones that have similar heat exposures. 
• Provide water. Workers should always keep a bottle of water handy. Check out this pamphlet with a heat stress action chart for recommended periods of time to drink water while working in high temperatures. 
• Build in breaks. As the temperature rises, workers should take breaks often. Check out page 13 of the Heat Stress Awareness Guide for a breakdown of recommended breaktimes during various humidexes  
• Look at the humidex reading for the day. Environment Canada provides a humidex calculator so your organization can take appropriate precautions for your employees during high temperatures. Learn more on humidex and view temperature tables here. 

Under Section 25 (2)(h) and 27 (2)(c) of the Occupational Health and Safety Act, employers must take every reasonable precaution in the circumstances to protect their workers, like creating policies and procedures to protect workers in hot environments. For recommended thresholds for heat stress and strain, check out the “Heat Stress Health and Safety Guidelines” provided by the Ministry of Labour, Training and Skills Development. 

Contact your health and safety consultant for additional guidance specific to your workplace needs. For more information on heat stress and heat-related disorders, check out our resources here: 

Managing Heat Stress at Work | Ontario Ministry of Labour, Training and Skills Development 

Preventing Heat Stress 

Heat Stress Awareness Toolkit 

Beat the Heat: Preventing, Identifying and Treating Heat Related Disorders