- June 3, 2026
- Kevin Kholer
Heat Stress in the Workplace
A Complete Guide for Construction, Oil & Gas, Manufacturing, Transportation, and Trades
As temperatures rise across Canada and the United States, heat stress is becoming an increasingly serious workplace hazard.
Many workers associate heat-related illnesses with tropical climates or extreme environments, but heat exposure causes illnesses, lost productivity, and fatalities every year in industries such as construction, oil and gas, manufacturing, transportation, and the skilled trades.
Whether a worker is paving roads in July, repairing equipment in a fabrication shop, driving long hours in a truck cab, or working in flame-resistant clothing on a drilling site, heat can quickly become a significant risk.
Understanding the causes of heat stress, recognizing warning signs, and implementing effective controls can prevent serious injuries and save lives.
What Is Heat Stress?
Heat stress occurs when the body’s cooling system can no longer effectively regulate internal temperature.
The human body normally cools itself through sweating and evaporation. When environmental conditions or work demands overwhelm this process, body temperature begins to rise.
If left unmanaged, heat stress can progress from mild discomfort to life-threatening medical emergencies.
Industries Most at Risk
Construction
Construction workers often face direct sunlight, physical exertion, reflective surfaces, and limited shade. Roofing, paving, concrete work, and earthworks are particularly high-risk activities during summer months.
Oil and Gas
Workers in oil and gas operations frequently wear flame-resistant clothing and additional PPE that limits the body’s ability to release heat. Remote work locations can also delay access to medical assistance.
Manufacturing
Manufacturing facilities may contain furnaces, welding operations, industrial ovens, or other heat-generating equipment. Indoor environments can become hazardous even when outdoor temperatures appear moderate.
Transportation and Trucking
Truck drivers, delivery personnel, mechanics, and yard workers are often exposed to long periods of heat. Loading docks, maintenance facilities, and vehicles without adequate cooling can contribute to heat stress.
Skilled Trades
Electricians, plumbers, HVAC technicians, welders, millwrights, and maintenance workers often perform physically demanding tasks in confined spaces, rooftops, mechanical rooms, or other environments where temperatures can rise quickly.
What Causes Heat Stress?
Air Temperature
Higher temperatures increase the body’s cooling demands and reduce the effectiveness of natural heat regulation.
Humidity
Humidity is one of the most significant contributors to heat stress. When humidity levels rise, sweat evaporates more slowly, reducing the body’s ability to cool itself.
Radiant Heat
Direct sunlight, hot equipment, furnaces, engines, asphalt, and industrial processes all contribute additional heat exposure.
Air Movement
Moving air promotes evaporation and cooling. Poor ventilation or stagnant air can significantly increase risk.
Clothing and PPE
Certain protective clothing, including flame-resistant garments, coveralls, respirators, and chemical protective suits, can trap heat and restrict airflow.
Physical Activity
Heavy lifting, repetitive motion, climbing, digging, and other physically demanding work generate internal body heat that compounds environmental exposure.
Who Is Most Vulnerable?
- New workers who have not acclimatized
- Workers returning after time away
- Older workers
- Individuals with certain medical conditions
- Workers taking medications that affect hydration or temperature regulation
- Workers who are dehydrated
- Employees performing strenuous tasks for extended periods
Understanding Heat-Related Illnesses
Heat Stress
Heat stress is the earliest stage and often results in fatigue, discomfort, reduced concentration, and decreased productivity.
- Excessive sweating
- Headaches
- Fatigue
- Irritability
- Reduced focus
Heat Exhaustion
Heat exhaustion occurs when the body loses excessive amounts of water and electrolytes through sweating.
- Weakness
- Dizziness
- Heavy sweating
- Nausea
- Muscle cramps
- Intense thirst
- Rapid heartbeat
Without intervention, heat exhaustion can quickly progress into heat stroke.
Heat Stroke Is a Medical Emergency
Symptoms may include hot, dry skin, confusion, loss of coordination, slurred speech, seizures, or loss of consciousness.
Heat stroke can cause permanent organ damage and may be fatal if treatment is delayed.
Warning Signs Supervisors Should Never Ignore
- Sudden changes in behaviour
- Difficulty concentrating
- Unusual fatigue
- Excessive sweating or lack of sweating
- Complaints of dizziness
- Vomiting
- Confusion
- Unsteady walking
Any worker displaying signs of heat stroke should receive immediate medical attention.
Heat Stress Prevention Strategies
Encourage Hydration
Workers should drink water regularly throughout the day, not just when they feel thirsty.
- Accessible drinking water
- Regular hydration reminders
- Electrolyte replacement during prolonged exposure
- Monitoring for dehydration symptoms
Schedule Work Strategically
- Complete heavy work during cooler hours
- Rotate workers through demanding tasks
- Increase rest breaks during peak temperatures
- Limit exposure during extreme heat events
Provide Shade and Cooling Areas
Workers need access to shaded or air-conditioned recovery areas where body temperature can return to safe levels.
Increase Air Movement
Fans, ventilation systems, and natural airflow can significantly improve worker comfort and reduce heat stress risk.
Use Appropriate PPE
PPE remains essential but should be selected with heat management in mind whenever possible.
- Lightweight flame-resistant clothing
- Cooling garments
- Ventilated helmets
- Moisture-wicking base layers
Implement Acclimatization Programs
Workers gradually adapt to hot conditions over time. New and returning workers should increase heat exposure gradually over 7 to 14 days to allow their bodies to adjust safely.
Creating a Workplace Heat Stress Program
Hazard Assessments
- Temperature
- Humidity
- Work intensity
- PPE requirements
- Exposure duration
Training
- Heat stress hazards
- Symptoms of heat-related illnesses
- Emergency procedures
- Hydration requirements
Emergency Response Procedures
Every workplace should have clear procedures for responding to heat-related incidents, including emergency contact information and medical response protocols.
Monitoring
Supervisors should continuously monitor environmental conditions and worker wellbeing during hot weather.
The Role of Training and Documentation
Heat stress management should not rely solely on worker awareness.
- Hazard assessments
- Training records
- Heat stress procedures
- Incident investigations
- Corrective actions
Proper documentation demonstrates due diligence and helps organizations continuously improve their heat stress prevention efforts.
Final Thoughts
Heat stress is a preventable workplace hazard, but only when organizations actively manage the risks.
Construction crews, oil and gas workers, manufacturers, truck drivers, and skilled tradespeople all face unique challenges when temperatures rise. By recognizing the warning signs, educating workers, implementing effective controls, and maintaining strong safety programs, employers can significantly reduce the risk of heat-related illnesses and fatalities.
A proactive approach to heat stress doesn’t just protect compliance—it protects lives.