July 15, 2024
Heat stress has become a greater threat to workers’ health and safety.

As more workers around the globe are exposed to extreme heat on the job greater protection and specific workplace action is urgently needed.

A new report by the International Labour Organization estimates about 2.4 billion workers are likely to be exposed to excessive heat at some point during their work. The proportion of the global workforce at risk of exposure to excessive heat has increased from 65.5 per cent to 70.9 per cent since 2000.


Heat stress is a life-threatening, occupational illness with both short and long-term health effects. It affects thousands of workers across Canada every year. Left unaddressed, heat stress can be deadly. A study published in the Lancet Planetary Health concluded that in Canada an estimated 220 workers die annually from occupational heat stress. As summer approaches workplaces need to act now if workers are to be protected from this serious occupational health threat.


New Heat Stress Toolkit

To empower and protect workers and guide workplaces in addressing heat stress-related hazards, the Occupational Health Clinics for Ontario Workers, in collaboration with the Centre for Research in Occupational Safety and Health have launched a new Heat Stress Toolkit. Building on an Awareness Guide produced by the Occupational Health and Safety Council of Ontario in 2009, the Toolkit was developed with Ontario Health and Safety Prevention System partners in consultation with workers, their representatives, and their unions.

Like the previous Guide, the expanded Toolkit is intended to provide workplaces with a practical and simplified way to assess and control heat in their workplace. The Toolkit includes an Updated Heat Stress Awareness Guide and two new guides on Prevention Tools & Strategies and Physiological Monitoring. Other resources include posters, infographics, videos, and an updated online Heat Stress Calculator.

The evidence-based resources are based on the 2023 American Conference of Governmental Industrial Hygienists (ACGIH) Heat Stress/Heat Strain Threshold Limit Value (TLV). In the absence of a specific regulation under the Occupational Health & Safety Act, Ministry of Labour, Immigration, Training and Skills Development inspectors use these TLVs as a guideline when enforcing employers’ general duty clause under the Act which requires them to take every precaution reasonable to protect workers’ health and safety. In response to concerns raised by workers and their representatives Ontario has proposed a heat stress regulation. It is currently undergoing a Regulatory Impact Analysis. Meantime, the Ontario Federation of Labour is calling on the government to enshrine protections for heat stress in the Occupational Health and Safety Act much in the same way workplace violence and harassment were included directly in the Act.

Essential training too

Awareness of heat stress symptoms is critical but workers, their supervisors, joint health and safety committee members and worker health and safety representatives need proper training and resources to participate in developing workplace-specific heat stress policies and plans.  

WHSC’s three-hour Heat & Cold Stress training offers this essential knowledge. Participants will learn how the body reacts to temperature extremes, conditions which may expose workers to dangerous temperatures and measures for identifying and assessing health risks. Participants will explore methods of controlling exposure to temperature extremes including how to develop and implement an effective action plan to reduce these hazards.


Workplace heat stress resources:

WHSC hazard bulletin Heat Stress: Cool Solutions

Heat Stress Toolkit


ILO Report: Climate change and safety and health at work

Workers’ health and productivity under occupational heat strain: a systematic review and meta-analysis

Need more information?

Contact a WHSC training services representative in your area.

Email: [email protected]

Visit: whsc.on.ca

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