Cold Stress


Hypothermia is a serious health condition that occurs when body heat is lost faster than it can be replaced from being in a cold environment.
  • Symptoms
    • Shivering
    • Lack of coordination
    • Slurred speech
    • Memory loss
    • Pale, cold skin
As the hypothermia worsens, these symptoms will worsen, and a primary indicator -- shivering -- will stop. If you notice these symptoms in yourself, or a coworker, leave the cold environment and move to a warm area.
Remain active, remove any wet clothing, and cover up with blankets. Drink warm, but not hot, liquids. If severe hypothermia conditions are suspected, dial the emergency number, x3333.

Frost Bite

Frost bite occurs when the skin becomes frozen and loses water content. Frost bite usually occurs when temperatures are below freezing, but can also occur when the wind chill drops below freezing. Frost bite typically affects the extremities, particularly the feet and hands.
  • Symptoms
    • Cold, tingling, stinging, or aching feeling followed by numbness.
    • Skin color changes from red, to purple, to white or pale and becomes cold to the touch.
If frost bite is suspected, transport the victim to the OMO or call ESU.

Trench Foot

Trench foot is caused by having feet immersed in cold water for a long period of time. It is similar to frost bite, but typically not as severe.
  • Symptoms
    • Tingling, itching, or burning sensation
    • Blisters
  • What to do
    • Seek medical attention from the OMO or ESU.


Please see the main article on cryogenics for more information.


Engineering Controls

The primary engineering control to eliminate cold stress are heating systems. Portable heaters may be necessary to warm a cold area if it must be occupied. For outdoor work that must be performed in cold, windy conditions, a wind break could be setup to shield workers from the wind chill, reducing exposure.

Work Practices

Staying hydrated is important, just as it is in hot situations. Avoid caffeine and alcohol.
Schedule work during warmer parts of the day, or not at all during very cold periods. When working in cold environments, take frequent breaks to warm up.
Working in a buddy system can keep you safer in cold conditions. Both workers can be on the lookout for the signs and symptoms of cold stress.

Protective Clothing

Layers, layers, layers. At least three layers are recommended for cold environments.
  • An outer layer to break the wind.
  • A middle layer made of down or wool to absorb sweat and provide insulation, even when wet.
  • An inner layer made of cotton to allow ventilation.
Wear a hat. Up to 40% of body heat can be lost when the head is left uncovered.
Wear insulated boots or other footwear, and keep your feet dry.
Keep a dry set of clothing available, in case your work clothes become wet. Water conducts heat away from the body more efficiently (quicker) than air, so staying dry is key to staying warm.