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Physical Agent Data Sheet (PADS) - Cold Stress


Other PADS:
Cold Stress
Hand-Arm Vibration
Ionizing Radiation (PDF)
Radio Waves
Ultraviolet Radiation

Preventing Hypothermia
Treatment of Hypothermia


Protection from the cold

Essential Clothing
Special Warnings

Other Factors

How to Recognize Frostbite

Early Treatment
Exposure to cold can cause the body's internal temperature to drop to a dangerously low level. This is called hypothermia. Exposure to temperatures below freezing can cause frostbite of the hands, feet, and face.

Hypothermia Can Kill

Hypothermia occurs when a person's body loses heat faster than it can be produced. The body's "normal" deep body temperature is 99.6 degrees Fahrenheit. . If your body temperature drops to 95 degrees Fahrenheit, uncontrollable shivering occurs. If cooling continues, these other symptoms may occur:

  • Vague, slow, slurred speech
  • Forgetfulness, memory lapses
  • Inability to use hands
  • Frequent stumbling
  • Drowsiness
  • Exhaustion, collapse
  • Unconsciousness
  • Death
  • Hypothermia impairs your judgment. You may not be able to make good decisions about your situation. Preventing hypothermia is the best way to avoid being a victim.

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    Preventing Hypothermia: Be Prepared

    Hypothermia can occur at temperatures above freezing. Cold, wet, windy conditions make prime hypothermia weather.

    Stay Dry - Avoid Exposure

    Wet clothing draws heat very quickly away from the body. Whenever you may be away from shelter or your vehicle, carry waterproof, windproof outer clothing. Put this clothing on before you get wet. Wear inner clothing which retains warmth even when it's wet, such as wool or polypropylene. Avoid cotton clothing. Down clothing is good for cold, dry weather but it loses almost all insulating value if it gets wet. Wear layers of clothing which may be removed or put back on depending on the degree of physical activity. Being wet from sweat is just as dangerous as being wet from rain or snow.

    Terminate Exposure

    If you do not have adequate clothing to stay warm and dry, get out of the wind and rain or snow. Return to shelter or make camp while you still have a reserve of energy. Build a fire. Make your camp as secure and as comfortable as possible.

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    Treatment of Hypothermia

    Be able to recognize the symptoms of hypothermia in yourself and others. The victim may deny he/she is in trouble. Even mild symptoms demand attention.

    1. Get the victim out of wet and windy weather.
    2. Remove all wet clothing.
    3. If the person is only mildly affected:

    a. Give warm drinks

    b. Put into dry clothing and a warm sleeping bag.

    If more seriously affected (very clumsy, confused, unable to shiver):


    1. Treat very gently.
    2. Place the victim naked into a warm sleeping bag.
    3. Place a rescuer, also naked, into the same sleeping bag. If you have a double bag, place the victim between two rescuers. Warmth from skin to skin contact is the safest method of rewarming. Any warm objects such as rocks, hot water bottles, or heat packs should be wrapped in towels or clothing. Arrange for evacuation. Do not give warm drinks until the victim has regained a clear level of consciousness, the ability to swallow, and is already starting to warm up.

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    Frostbite is the freezing of some part of the body. Fingers, toes, and even whole arms and legs can be lost as a result of frostbite. Such injuries have happened in cities and villages as well as in more isolated areas of Alaska.

    Protection From the Cold

    In extreme cold it is important to prevent heat loss from as many areas of the body as possible. Exposed limbs and head are major areas of heat loss, but keeping enough blood flowing to the hands and feet is the key to preventing frostbite. The trunk and the head, then, should be warm enough so that the brain is able to command the blood vessels in the hands and feet to open up.

    Essential Clothing

    This includes thermal underwear, insulated footwear or mukluks with liners, double mittens and a parka, preferably down-filled with a good ruff. A parka which can be opened at the neck to allow heat to escape will prevent overheating and sweating. Quilted or skin pants are necessary if no warm shelter is immediately available. Tight clothes, especially tight gloves or tight boots, should not be worn. They interfere with the blood flow and reduce insulation against the cold.

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    The traveler, even on a snowmobile, or in a heated automobile, should always be prepared to walk in severe cold. This means carrying along proper clothing and more extensive survival gear. If an accident, mechanical breakdown, or other interruption occurs during travel, the clothes you have must provide enough warmth to sustain life. Hands and feet should be well protected at all times to hinder the development of frostbite until help arrives.

    Some Special Warnings

    Don't touch cold metal with bare or wet hands. You will freeze to the metal and tear away skin. If necessary, thaw gently with heat, warm water or urine.

    Be careful when handling gasoline, kerosene or liquids other than water. Contact at cold temperatures can cause immediate frostbite.

    Remember that frostbite is more likely to occur when you are injured, frightened or careless.

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    Other Factors Leading to Frostbite

    Tall thin persons are more likely to get frostbite than those of stocky build.

    People in poor physical condition are more susceptible than those in good health.

    Certain diseases slow down the blood flow in the hands and feet, especially in elderly people, and encourage frostbite.

    Heavy smokers often have poor circulation in the vital organs and to the arms and legs, and are also susceptible.

    Children and elderly people, unable to produce large amounts of body heat for long periods of time, may experience a lowering of deep body temperature and, ultimately, frostbite.

    Alcohol causes the blood vessels to dilate (become larger). This lends a sense of warmth, but it also insures a faster loss of body heat. More important, people act with poor judgment after drinking.

    In short, poor circulation and poor production of body heat will lower resistance to frostbite.

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    How to Recognize Frostbite

    Pain in the hands and feet is felt only when the temperature of the tissue is changing very rapidly. There may be no pain with gradual freezing.

    Loss of the sensations of touch, pressure, and pain may occur without awareness of any numbness or other sensation. Therefore, it is important to test these sensations often and to wear clothing that is loose and does not restrict the flow of blood to the limbs.

    Exposed parts of the body should be inspected routinely. This is done best by a partner. Just before freezing, the skin, especially the face with its many blood vessels, becomes bright red. Then small patches of white appear, as freezing actually occurs.

    The skin also becomes less elastic. This is best noted in the finger pads, which remain pitted when touched or squeezed. Any further cooling will surely result in frostbite.

    Serious freezing is most common in the feet because of less awareness of them, poor circulation and sensation, and inadequate foot gear. Hands are next in order of serious injury. Exposed head parts are less likely to become frostbitten than feet because they are conditioned to exposure and have a better blood supply.

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    Early Treatment of Frostbite: Proper Rewarming

    1. Next to the extent of freezing, inadequate or improper treatment of a frozen part is the most common cause of serious loss of tissue.
    2. In many cases rewarming cannot be done without the part again becoming frozen. For example, removing clothing from other parts of the body to warm a frozen part may only result in the loss of more body heat, greater extent of injury, and the ultimate refreezing of the afflicted part.

      Thawing and refreezing should always be avoided. It is best to continue, even if it means walking on a frozen foot, until shelter is available and rewarming can be. done satisfactorily.
    3. Limbs should be rewarmed in stirred water just above normal body temperature (about 100 - 105 degrees Fahrenheit). Using a thermometer is the only accurate way to measure this temperature. Never try to thaw in cold water or snow. Since feeling is lost, fires, stoves, exhaust pipes, etc., should never be used. Serious damage to the tissue could result.
    4. If the major part of the limb is frozen when rewarming is started, deep body temperature will fall as the cooled blood begins to flow throughout the body. To prevent such cooling, warm liquids by mouth should be given. Even total immersion of the body in a warm bath may be necessary.
    5. Rewarming is an acutely painful experience and medication to alleviate pain should be given if available. After thawing, a deep aching pain may persist for several days, depending upon severity of the injury. Pain is actually a good sign, since it indicates that nerve function is still present.
    6. The afflicted part should be moved gently and voluntarily during rewarming.
    7. A dull purple color indicates more serious injury and requires medical attention. So does swelling or blisters. Other means for improving circulation are available but must be administered by medical personnel.

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    Most cases of frostbite occur as a result of lack of knowledge, careless preparation, unavoidable accident, or the effects of alcohol on judgment. Intelligent forethought can prevent injury.

    If freezing does occur, proper rewarming in warm water will give maximum benefit. The injured limb should be handled gently and a medical judgment be made of the extent of the injury and the need for further treatment.



    1. Frostbite information compiled and distributed by the Providence Hospital Thermal Unit.

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