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Workers who are exposed to extreme cold or work in cold environments may be at risk of cold stress. Extremely cold or wet weather is a dangerous situation that can cause occupational illness and injuries such as hypothermia, frostbite, trench foot, and chilblains.

How cold is too cold?

Cold environments force the body to work harder to maintain its temperature, and as temperatures drop and wind speeds increase, heat escapes the body more rapidly. Wind chill, the temperature your body feels when air temperature and wind speed combine, can significantly amplify this effect; for example, an air temperature of 40°F with a wind speed of 35 mph feels like 28°F on exposed skin. When the skin temperature drops, it can eventually lower the body’s core temperature, leading to cold stress, which may result in serious health problems, tissue damage, or even death.

What are the risk factors that contribute to cold stress?

Several factors can contribute to cold stress, including:

  • Wet or damp clothing, improper dress, or exhaustion.
  • Predisposing health conditions such as hypertension, hypothyroidism or diabetes
  • Poor physical conditioning.

How does the body react to cold conditions?

In cold environments, most of the body’s energy is used to maintain core temperature. To conserve heat, blood flow shifts away from the extremities (hands, feet, arms, and legs) and outer skin to the core (chest and abdomen). This increases the risk of frostbite and hypothermia. Exposure to wet conditions can further elevate risks, potentially leading to trench foot.

Preventing Cold Stress Tips

  • Train workers on how to prevent and recognize cold stress illnesses and injuries and how to apply first aid treatment. The NIOSH Fast Facts: Protecting Yourself from Cold Stress outlines cold stress illnesses and treatments.
  • Provide engineering controls such as heaters to warm outdoor workers. If possible, shield work areas from drafts or wind to reduce wind chill.
  • Implement safe work practices:
    • Provide plenty of warm sweetened liquids to workers to prevent dehydration.
    • Schedule heavy work during the warmer part of the day.
    • Assign workers to tasks in pairs (buddy system), so that they can monitor each other for signs of cold stress.
    • Reduce the physical demands of workers (for example, use relief workers or rotate extra workers in and out of work for long, demanding jobs).
    • Give workers frequent breaks in warm areas.
    • Acclimatize new workers and those returning after time away from work, by gradually increasing their workload, and allowing more frequent breaks in warm areas, as they build up a tolerance for working in the cold environment.
  • Dress properly
    • Wear at least three layers of loose-fitting clothing.
      • An inner layer of wool, silk or synthetic to keep moisture away from the body.
      • A middle layer of wool, fleece, or synthetic to provide insulation even when wet.
      • An outer wind and rain protection layer that allows some ventilation to prevent overheating.
    • Avoid wearing wet clothes.
    • Wear a hat or hood.
    • Use a knit mask to cover the face and mouth (if needed).
    • Carry extra socks, gloves, hats, jacket, a change of clothes in case you get wet and need to change.
    • Use insulated gloves to protect the hands (water resistant if necessary).
    • Wear insulated and waterproof footwear.
  • Know the symptoms of cold stress.
  • Monitor your physical condition and that of your coworkers.
  • Take regular breaks to warm up when needed.
  • Drink warm sweetened fluids (no alcohol).
  • Avoid touching cold metal or wet surfaces with bare skin.
  • Use proper engineering controls, safe work practices, and personal protective equipment (PPE) provided by your employer.

Contact Environment, Health and Safety

Departments with employees who normally work outdoors or in unconditioned indoor environments need to address cold stress in their Hazards Management Plan by including written safe job procedures appropriate to their work.  Supervisors are to provide cold stress training for these employees.  For assistance, please contact Environment, Health and Safety (EHS) at 919-962-5507. EHS can also suggest appropriate controls to reduce your risk of cold-related illness.