OSHA provides the following information about these three conditions resulting from cold stress:

Frostbite is caused by freezing of the skin and underlying tissues. The lower the temperature, the more quickly frostbite will occur. Frostbite typically affects the feet and hands, and amputation may be required in severe cases.

Hypothermia occurs when body heat is lost faster than it can be replaced. The normal body temperature of 98.6°F drops to less than 95°. Hypothermia most often occurs at very cold temperatures, but it can happen even at cool temperatures (above 40°) if a person becomes chilled from rain, sweat, or submersion in cold water.

Trench foot or immersion foot is caused by prolonged exposure to wet and cold temperatures. It can occur at temperatures as high as 60° if the feet are constantly wet. Nonfreezing injury occurs because wet feet lose heat 25 times faster than dry feet. To prevent heat loss, the body constricts the blood vessels to shut down circulation in the feet. The skin tissue begins to die due to a lack of oxygen and nutrients and the buildup of toxic products.

Dressing appropriately for all weather conditions is extremely important in preventing cold stress. The type of fabric worn can make a difference. For example, cotton loses its insulation value when it becomes wet while wool, silk, and most synthetics retain their insulation. The following are recommendations for working in cold environments:

• 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 or synthetic to provide insulation even when wet; and an outer wind- and rain-protection layer that allows some ventilation to prevent overheating;
• Wear a hat or hood to help keep your entire body warm. Hats reduce the amount of body heat that escapes from your head;
• Have a knit mask ready to cover your face and mouth, if needed;
• Use insulated gloves to protect your hands (water resistant if necessary); and
• Wear insulated and waterproof boots (or other footwear).

Working on refrigeration systems can be hazardous at times — working safely should always come first, and that includes taking steps to prevent cold stress. Don’t ever attempt to make a repair when in an unsafe situation. Remember: safety first, no exceptions. 

Publication date: 2/5/2018

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