Cold stress — the inability to maintain core body temperature — is a very real hazard for workers exposed to the cold, whether outdoors (e.g. agriculture, snow removal) or in artificially cold indoor environments (e.g. frozen food processing, cold storage). It can lead to frostbite and hypothermia, which can be life-threatening.
For outdoor workers, risks are compounded by wind, rain and snow, which draw heat from the body, making these workers susceptible to cold stress in spring, winter and fall.
In addition to posing health risks, cold stress can compromise safety, says WSPS Consultant Kristin Hoffman. “The most severe stages of cold stress result in poor coordination and loss of consciousness. Work becomes not only unsafe but may be impossible.”
The science of cold stress
Kristin explains that in the cold the body’s main job is to maintain our internal body temperature. With prolonged exposure, our bodies shift blood flow from the extremities (hands, feet, arms, legs, skin) to the core. The extremities cool rapidly, increasing the risk of frostbite or frostnip (the first stage before frostbite).
With continued exposure, our internal temperature drops to dangerous levels and the body starts to shiver to increase heat production. Ongoing loss of body temperature may result in mild, moderate or severe hypothermia.
Watch for these warning signs:
- Mild — shivering, grogginess, and confused thinking
- Moderate — violent shivering, slow, shallow breathing, slurred speech, and poor coordination
- Severe — loss of consciousness, little or no breathing, and weak, irregular, or no pulse.
9 ways to reduce the risk
Kristin outlines 9 ways to protect workers exposed to cold. Use them to implement a cold stress prevention program or gauge the effectiveness of your existing program.
- Train supervisors and workers on the hazards, health effects and prevention of cold-related illness. This includes safe work practices, re-warming procedures, clothing and personal protective equipment, how to recognize cold stress/frostbite, and signs and symptoms of hypothermia, says Kristin. Include these tips:
- layer clothing to allow sweat to escape and trap heat. “Set a standard for what should be worn. Be mindful of the material, and the type and fit of the clothing. If working around moving equipment, avoid loose clothing that could become entangled.”
- keep clothing dry.
- keep bare hands away from metal objects.
- eat and drink frequently, but limit caffeine.
- work rested — fatigue is a risk factor in the cold.
- Ensure a supervisor is on hand to observe workers. You can also have a buddy system. “It’s hard for someone to recognize cold stress in themselves,” says Kristin, “especially as the condition progresses. Everyone needs to be alert to the signs and step in if necessary.”
- Acclimatize new employees to working in the cold.
- Provide adequate rest breaks and warming shelters, such as tents for outdoor workers. “Also, organize work so that people alternate between working in the cold, say a walk-in freezer, and working in a warm environment.”
- Monitor the weather. Risks increase with rain, sleet and snow. Provide additional rest breaks, and where appropriate use heaters and barriers to block wind chill.
- Pace work to prevent excessive sweating. Make sure employees have an extra set of dry clothing.
- In refrigerated rooms, keep the air speed below one metre per second.
- Provide training on emergency procedures, including first aid and obtaining medical help.
- Consider implementing CSA Z1010-18, Management of work in extreme conditions, which leads users through the requirements of a management system for managing indoor and outdoor work performed under extreme conditions.
- Quick Safety Tip: What is cold stress? What are the common signs and symptoms (video)
- Quick Safety Tip: What can employers do to protect workers from cold stress? (video)
- Canadian Centre for Occupational Health and Safety (CCOHS) - Cold Environments
- Agricultural Safety Topic: Cold Weather Exposure
- Occupational Health Clinics for Ontario Workers (OHCOW) - Cold Stress Calculator. An Excel-based tool created as a simple means for determining what precautions should be taken to protect workers from cold stress-related adverse health outcomes.
- Ministry of Labour, Immigration, Training and Skills Development — Heat and Cold Stress
- National Institute for Occupational Safety and Health (NIOSH) — Cold Stress
The information in this article is accurate as of its publication date.