Guideline No. 33: Working In extreme temperature conditions

The following procedures are recommended for all work in extreme temperature conditions, both hot and cold, and are intended to assist employers, workers, and other workplace personnel in understanding the effects of extreme temperatures on the body, and to prevent any such effects in the workplace.

As a general consideration, all persons working in these situations need to be prepared for the possibility of bodily stress due to extreme heat or cold. Extra precautions are necessary to protect against these potentially hostile environments.

The greatest dangers are heat exhaustion or heat stroke and frostbite or hypothermia. Although weather and environmental conditions inside and outside present challenges to work, there is still a need to abide by the health and safety requirements set out in the Occupational Health and Safety Act and the applicable regulations.

The legal requirements

Employers have a duty under section 25(2)(h) and supervisors under section 27(2)(c) of the Occupational Health and Safety Act to take every precaution reasonable in the circumstances for the protection of a worker. This includes developing hot and cold environment policies and procedures to protect workers in hot and cold environments.

Working in extreme heat

Working in extreme heat puts stress on a person’s cooling system. When heat is combined with other stresses such as hard physical work, loss of fluids, fatigue or some medical conditions, it may lead to heat-related illness, disability and even death.

Anybody working in extreme heat may face these risks. In Ontario, heat stress is usually a concern during the summer. This is especially true early in the season, when people are not used to the heat. It is important to understand the symptoms and take preventative measures against heat related stresses in order to function effectively in such conditions.

The employer should implement a heat stress prevention program that establishes:

  1. worker training in the hazards, health effects and prevention of heat related illness
  2. criteria or monitoring method ( e.g. acting on heat wave or alert notices by Environment Canada or calculating humidex from temperature and humidity measurements or WBGT measurements)
  3. a monitoring/sampling plan ( e.g. when, where and what to measure or monitor)
  4. responses or preventative measures ( e.g. increase frequency of breaks, reduce the work pace and workload, avoid working in direct sunlight, schedule heavy work for cooler part of day, wear hat and sun screen outdoors, etc. )
  5. a water supply plan and encourages hydration ( e.g. at least 1 cup every 20 min.) and
  6. first aid and emergency responses, including monitoring of worker symptoms, and investigating incidents of health related illnesses

How we cope with heat

People are always generating heat and passing it to the environment. The harder a body is working, the more heat it has to lose. When the environment is hot, humid or has a source of radiant heat ( i.e. a large lighting setup, a furnace, or the sun) a person must work harder to get rid of the heat. If the air is moving (for example from fans or wind) and it is cooler than the body temperature, it is easier for a person to pass heat to the environment.

Workers on medications or with pre-existing medical conditions may be more susceptible to heat stress. These workers should speak to their personal physicians about work in hot environments.

It should be noted that heat stroke is a medical emergency and as a result requires immediate medical attention (an ambulance should be called).

Other risk factors for developing heat strain besides medical conditions and certain medications are age, gender, past history of heat illness and use of PPE or heavy clothing such as costumes.

Working in extreme cold

Working in extreme cold may stress a person’s heating system. When cold is combined with other stresses such as hard physical work, loss of fluids, fatigue or some medical conditions, it may lead to cold-related illness, disability and even death.

At very cold temperatures, the most serious concern is the risk of hypothermia or dangerous overcooling of the body. Another serious effect of cold exposure is frostbite or freezing of the exposed extremities such as fingers, toes, nose and ear lobes. Hypothermia could be fatal in the absence of immediate medical attention.

Warning signs of hypothermia can include complaints of nausea, fatigue, dizziness, irritability or euphoria. Workers can also experience pain in their extremities (hands, feet, ears, etc. ), and severe shivering. Workers should be moved to a heated shelter and seek medical advice when appropriate.

Workers on medications or with pre-existing medical conditions may be more susceptible to hypothermia or overcooling. These workers should speak to their personal physicians about work in cold environments.

The employer should implement a cold stress prevention program that establishes:

  1. worker training in the hazards, health effects and prevention of cold related illness
  2. criteria or monitoring method ( e.g. acting on wind chill warnings or cold alert notices by Environment Canada or measuring wind speed, and air temperature)
  3. a monitoring/sampling plan ( e.g. when, where and what to measure or monitor)
  4. responses or preventative measures ( e.g. dressing in proper layers of clothing, acclimatizing workers to working conditions and required protective clothing, establishing warm-up schedule, provide warm shelter, use buddy system, suitable equipment, pace of work to avoid sweating or low activity)
  5. a plan to provide warm sweet drinks and soups (increases caloric intake and prevents dehydration which may increase risk of cold injury) and
  6. first aid and emergency responses, including monitoring of worker symptoms, and investigating incidents of cold related illnesses

Note: Please see Appendix C on Adverse Weather Conditions for symptoms, treatments, and preventing the physiological effects of working in extreme temperature conditions.

Additional useful references

OHCOW (Occupational Health Clinics for Ontario Workers) Heat Stress Guide discusses how to use the Humidex.