In Canada, extreme temperatures aren’t just uncomfortable, they’re a safety risk. Whether working outdoors in summer heat or in refrigerated environments during winter, exposure to thermal stress can quickly lead to serious health effects.
For project managers and safety professionals, managing heat and cold stress is about more than responding to symptoms—it’s about preventing them. A proactive approach to thermal hazard management protects workers, maintains productivity, and ensures compliance with occupational health and safety (OHS) requirements.
Understanding Thermal Stress
Thermal stress occurs when the body’s ability to regulate its internal temperature is overwhelmed by environmental conditions, clothing, or workload.
There are two main types:
- Heat stress – occurs when the body can’t cool itself fast enough, leading to dehydration, heat exhaustion, or heat stroke.
- Cold stress – occurs when body heat is lost faster than it can be produced, leading to frostbite or hypothermia.
Both can develop quickly, especially in physically demanding work or when proper precautions aren’t taken.
Heat Stress: Key Risks and Warning Signs
Heat stress is a growing concern, especially as Canada experiences more frequent periods of extreme heat. According to CCOHS, factors that increase risk include high humidity, radiant heat from equipment, heavy physical work, and inadequate hydration.
Early signs:
- Dizziness, headache, fatigue
- Muscle cramps or excessive sweating
- Nausea or confusion
Severe symptoms:
- Disorientation or fainting
- Rapid heartbeat
- Core body temperature above 40°C (heat stroke — a medical emergency)
Workplace Examples
- Construction sites with limited shade
- Foundries, manufacturing, or energy plants with radiant heat sources
- Outdoor maintenance, roadwork, or roofing during summer months
Cold Stress: Key Risks and Warning Signs
Cold stress can affect both outdoor and indoor workers. In Canada’s northern regions or during winter months, cold exposure remains one of the top seasonal hazards.
Early signs:
- Numbness or tingling in extremities
- Shivering and reduced coordination
- Pale, cold skin
Severe symptoms:
- Frostbite (localized tissue freezing)
- Hypothermia (core temperature drops below 35°C) — a medical emergency
Workplace Examples
- Outdoor construction or utility work in winter
- Working in freezers or refrigerated warehouses
- Emergency response or remote work in cold environments
Canadian Standards and OHS Requirements
Across Canada, employers are required to assess and control thermal stress under provincial and federal OHS legislation.
Key references include:
- CCOHS – Thermal Comfort and Temperature Conditions guidance
- ACGIH Threshold Limit Values (TLVs®) for heat and cold stress exposure
- CSA Z1018:21 – Management of Work in Extreme Conditions (a Canadian standard for monitoring and mitigation)
- Provincial OHS Codes and Regulations (e.g., Alberta OHS Code Part 2, Ontario Regulation 851, and WorkSafeBC guidelines)
Employers must evaluate temperature, humidity, air movement, radiant heat, clothing insulation, and metabolic work rate to determine risk levels.
Canadian Standards and OHS Requirements
- Assess and Monitor Conditions
- Measure temperature, humidity, and radiant heat using Wet Bulb Globe Temperature (WBGT) monitoring.
- Track weather conditions and set thresholds for modifying work.
- Adjust Work Practices
- Schedule heavy work during cooler hours.
- Rotate workers to limit exposure time.
- Provide shaded or heated rest areas as needed.
- Hydration and Nutrition
- Provide easy access to cool drinking water.
- Encourage regular hydration breaks, even if workers don’t feel thirsty.
- Clothing and PPE
- Heat: lightweight, breathable fabrics.
- Cold: layered, moisture-wicking clothing with windproof outer layers.
- Use PPE that balances protection with ventilation and comfort.
- Training and Awareness
- Train workers and supervisors to recognize early signs of heat or cold stress.
- Encourage immediate reporting of symptoms.
- Establish emergency response procedures for suspected heat stroke or hypothermia.
The Role of Project Managers and Safety Professionals
Effective prevention starts with planning. Project managers should:
- Include thermal stress in their hazard assessments and job safety analyses.
- Coordinate with safety professionals to implement monitoring and control strategies.
- Ensure workers have the resources, rest breaks, and facilities they need to recover safely.
A proactive approach not only protects workers but also reduces downtime, absenteeism, and the risk of costly incidents.
Final Thoughts
In Canada’s diverse climate, thermal stress management is a year-round priority. Whether battling summer heat or winter cold, maintaining safe work conditions requires planning, monitoring, and ongoing awareness.
By following Canadian standards and integrating thermal risk management into project planning, organizations can protect their workforce and maintain operational resilience.
Keeping workers safe from temperature extremes isn’t just compliance – it’s good leadership.
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