Cold Weather Hazards

During winter months, hikers face the exposure to the cold. Prolonged exposure to freezing temperatures can result in serious health problems, such as trench foot, frostbite, and hypothermia. We all need to be mindful of the weather, its effects on the body, proper prevention techniques, and treatment of cold related disorders.

An individual gains body heat from food and muscular activity and loses it through convection, conduction, radiation and sweating to maintain a constant body temperature.

When body temperature drops even a few degrees below its normal temperature of

98.6°F (37°C), the blood vessels constrict, decreasing peripheral blood flow to reduce heat loss from the surface of the skin. Shivering generates heat by increasing the body's metabolic rate.

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The four environmental conditions that cause cold-related stress are low temperatures, high/cool winds, dampness and cold water. Wind chill, a combination of temperature and velocity, is a crucial factor to evaluate when working outside. For example, when the actual air temperature of the wind is 40°F (4°C) and its velocity is 35 mph, the exposed skin receives conditions equivalent to the still-air temperature being 11°F (-11°C). ). A dangerous situation of rapid heat loss may arise for any individual who is exposed to high winds and cold temperatures and is not properly dressed in layers.

LOW TEMPERATURE + WIND SPEED + WETNESS = INJURIES & ILLNESS

Frostnip

Frostnip (sometimes referred to first degree frostbite) occurs when the face or extremities are exposed to cold wind.

Symptoms

Mild blush on both cheeks.
Firm, cold, white areas on the face, ears or extremities

First Aid

The frost-nipped area should be treated by re-warming the area with an unaffected hand or a warm object.

Frostbite

Frostbite occurs when ice crystals form either superficially or deep within the fluids and underlying soft tissues of the skin. Frostbite commonly occurs on the extremities of the body including the fingers, toes, nose, cheeks and ears. This typically occurs at temperatures below 30°F (-1°C). In practice, the combined effects of temperature, wind speed and exposure time is a better predictor of frostbite. (See National Weather Service link at the end of this document).

Symptoms: Initial effects of frostbite include sensations of coldness, tingling, stinging or aching feeling of the exposed area.

The skin changes from a red to white or grayish yellow with a waxy appearance. There may be pain at first, but then it goes away. The area will feel cold and numb. Blisters may form later.

Damage from frostbite can be serious; scarring, tissue death, and amputation are all possible as is permanent loss of movement in the affected parts.

First Aid

Gently move the victim to a warm area.
Remove any wet or frozen clothing as well as any jewelry from the area.
If the victim is conscious, provide hot liquids to drink (no alcohol).
If possible, re-warm the frostbitten area quickly by immersing it in warm water ranging from 102°F to 105°F. If the area has been thawed and refrozen, warming should be done at room temperature. Stop after the area has become flushed. Do not warm an area if there is a danger of it re-freezing.
Do not rub the area! Rubbing can cause internal tissue damage that may result in gangrene.
Do not use a heat lamp, hot stove or hot water bottles.
Cover the area with sterile dressings. Carefully separate fingers and toes with the dressings.
Blisters may form after re-warming has occurred. Be careful and do not break any blisters.
Elevate the frostbitten area and monitor victim closely.
Initiate procedures to obtain emergency medical assistance (call 911 or other emergency number or transport to nearest medical facility).

Hypothermia

Hypothermia occurs when body temperature falls to a level where normal muscular and cerebral functions are impaired.

Symptoms: The first symptoms of hypothermia are shivering, an inability to do complex motor functions, lethargy, and mild confusion. Normal body temperature drops to or below 95°F (35°C).

Next, the individual falls into a state of dazed consciousness, and fails to complete even simple motor functions. The victim's speech may become slurred and his or her behavior may become irrational.

First Aid

Gently move the victim to a warm area.
Check and maintain airway and circulation.
Remove any wet or frozen clothing and cover the victim with dry, warm blanket or by placing them in a warm, not hot, tub of water. Heat packs and warm water bottles next to the victim also can be used.
If the victim is conscious, provide hot liquids to drink (no alcohol).
Initiate procedures to obtain emergency medical assistance (call 911 or other emergency number or transport to nearest medical facility)
Monitor body temperature. If the body temperature does not improve, seek advice from emergency medical responders and follow their instructions.

General Safety Precautions for Outings in the Cold

Wear appropriate clothing. Dress in layers and keep clothing dry, if possible.
Wear a hat. You lose up to 40 percent of your body heat through your head if it is not covered.
Wear a facemask and/or scarf if it is windy or extremely cold and cover your mouth to protect your lungs
Remain hydrated.
Be aware of icy slippery conditions.
Be very careful to avoid overexertion. Keep relatively active, but not so active that you become damp with sweat.
Do not touch any cold objects with bare hands.
Wear UV protective eyewear if you must work outdoors in snow or ice-covered terrain.
Know the symptoms of cold related effects - heavy shivering, uncomfortable coldness, severe fatigue, drowsiness, or euphoria.
Use a buddy system or other method to remain in contact with others when working in the cold.

People at Increased Risk

People who are taking certain medications, are older, or overweight, have allergies, smoke, or have poor circulation (diabetics, for example) are more prone to cold injuries and should take extra precautions.

Additional Information

Medline

http://www.nlm.nih.gov/medlineplus/ency/article/000038.htm

CDC

http://www.bt.cdc.gov/disasters/winter/faq.asp

National Weather Service

http://www.nws.noaa.gov/om/windchill/