Heat Stress

Heat StressWhat is Heat Stress?

Heat stress is a condition that can take many forms, depending on the severity of external and internal factors and, of course, the condition of the individual.  The heating and cooling balance in the body depends on:

  • air temperature
  • humidity
  • radiant heat
  • physical activity
  • colling (by the evaporation of sweat)
  • body adjustments (acclimatization

Heat stress is an issue in many workplaces all year round.  Heat stress not only affects employees working outdoors, but also those who are exposed to radiant heat or who come in direct physical contact with hot equipment as part of their job.

What the law says

Employers have a duty under Section 25(2)(h) of the Occupational Health and Safety Act to take every precaution reasonable in the circumstances for the protection of the worker.  This includes developing policies and procedures to protect workers who have direct physical contact with hot equipment, are exposed to radiant heat sources, or are working in hot weather.

For compliance purposes, the Ministry of Labour recommends the current threshold limit value for heat stress and heat strain (published by the American Conference of Governmental Industrial Hygienists).  These values are based on preventing unacclimatized workers' core temperatures from rising above 38ºC.

How can heat stress affect your business?

A worker expending large amounts of physical energy in a hot and humid environment, without regular rest or water breaks may eventually experience heat exhaustion, fainting, heat stroke or heart attack.  Long-term, this can lead to reproductive problems, heart and lung strain and other complications, and may even result in death.  It is critical to address this hazard to protect employees and your business from lost productivity, reduce morale, as well as fines and penalties.

What you can do

There are many ways you, as an employer, can take measures to ensure that your staff is healthy and safe from heat stress, including:

  • Make staff aware of the hazard of heat stress and provide the necessary training on first aid reporting, emergency response, medical monitoring, etc
  • Design work to allow for adequate rest and hydration breaks
  • Conduct regular inspections to identify potential hazards and ensure that the necessary controls to prevent an incident are in place
  • Investigate heat stress incidents that occur in the workplace
  • Provide necessary protective equipment and clothing


Job Aid - Molten Metal Die Casting (Aluminum)

Job Aid - Molten Metal Die Casting (Aluminum)

Molten metal die casting can pose a variety hazards. Use our job aid to learn more.
593 KB PDF
Safety Check: Working in Hot Environments

Safety Check: Working in Hot Environments

Working in hot environments safety tips for workers
453 KB 

Consulting Services

Consulting Services Awareness Sessions

Consulting Services Awareness Sessions

Awareness sessions are presentations of up to 2 hours in length delivered at your workplace by WSPS consultants. They are designed to help meet your legal duty to provide information about workplace hazards to employees.


5 key summer hazards

5 key summer hazards

While heat-related hazards deserve particular attention during the summer months (see 5 Ways to Prevent Heat Stress), many other hazards may be present during outdoor work. For example, biological hazards such as insects and plants, or musculoskeletal disorders from equipment use are also prevalent. Here are five hazards that could affect your workers during the summer months and how you can manage them.
Jun 08, 2018
5 ways to prevent heat stress

5 ways to prevent heat stress

Working in the intense heat of the summer sun can put workers at risk of heat stress, but heat stress can also hit you in places you wouldn't expect. "Any job that causes your body temperature to rise has the potential to cause heat stress," says WSPS Occupational Hygiene Consultant Michael Puccini. "Even jobs carried out in air-conditioned environments." There are many ways to keep workers safe from heat stress. It's important to train workers to recognize the signs and symptoms of heat stress in themselves and other workers, and to take action.
May 14, 2018
The Dog Days of Summer Are Here. Prepare for the heat now

The Dog Days of Summer Are Here. Prepare for the heat now

These heat waves may last only a week or two, but in this time workers can suffer debilitating effects and even death. A few simple steps taken now can keep your people thriving and productive even in the hottest weather.

Jul 12, 2017
Prepare for the heat - You know it's coming!

Prepare for the heat - You know it's coming!

It's just a matter of time before the cold, rainy spring turns into a blistering hot summer.

Jun 01, 2017
How to prevent your employees from contracting Canada's most common form of cancer

How to prevent your employees from contracting Canada's most common form of cancer

If it were simple, the short answer would be to keep them out of the sun. But how do you protect people when research shows that even brief exposure to the sun's ultraviolet (UV) radiation can put them at risk of skin cancer?

Apr 04, 2016
Managing heat stress: new standard on the way, plus tips for today

Managing heat stress: new standard on the way, plus tips for today

Seasonal heat and humidity is coming, if not here already. We've provided essential tips on how to manage this hazard and links to resources below, but more help is on the horizon. By the end of 2016, employers will have access to a new guideline for protecting workers from a number of extreme conditions, such as high heat and humidity, cold temperatures and severe weather.

Jun 08, 2015