Frost Bite

Frostbite can occur whenever the ambient temperature falls below 32° F ( 0°C).   The danger of frostbite is increased when heat is lost from the interior of the body to the skin, to the layer of insulating air surrounding the skin, and finally to the ambient cold air.   High velocity wind that blows away the insulating air cover, as well as wetting of the skin, hastens the outward loss of body heat.

• First Degree - least severe.  The skin becomes pale and, as in sunburn, the uppermost layer of skin later peels off.
• Second Degree - the skin develops blisters.
• Third Degree - the skin actually freezes.  Small blood vessels of the skin become blocked by blood clots and the surrounding tissue dies.

If frostbite, particularly in the third degree stage, is not treated early, the tissues may be so seriously damaged that gangrene may result, and amputation of the affected part may be necessary.

OTHER INJURIES CAUSED BY FRIGID CONDITIONS

Chilblain is a localized skin condition caused by repeated exposure to cold and dampness.    Chilblain and trench foot, which takes its name from a condition which soldiers developed due to standing in wet trenches in World War I, are additional disabling results of exposure to cold environments.

Chilblain may result after prolonged and intermittent exposure to low , but not freezing, temperatures.  Poor nutrition and impaired circulation are contributing causes.  The affected body parts - usually hands, feet, face and ears - become swollen and purplish with a sensation of itching, burning and pain.  They are also cold, sweaty and tacky to the touch.

These conditions are the result of loss of heat from the exposed parts.  Another danger of exposure to cold is general hypothermia, or depression of the inner body temperature.  It is critical and can be fatal.  If body temperature falls below 93°F (34°C) metabolic control is unstable.  If cooling persists, coma and death may result.

It is important to understand that the "core temperature" of the body plays a controlling role in the retention of heat by the body parts that are exposed to the cold.    A human being's constant, cold-repelling temperature is maintained by a complex metabolic furnace.  Ingested food is fuel for the furnace.  Some of the energy from its oxidation is converted into heat, which is transferred throughout the body, principally by the blood.  The body heat is contained in a skin shell (the largest organ of the body) that traps or dissipates warmth.

CAUSES OF FROSTBITE

Frostbite can occur when a person is exposed to temperatures of 23°F or lower.    In addition to temperature, other environmental conditions affect the rate and extent of tissue freezing.

• Wind velocity - high winds dissipate radiant body heat rapidly
• Moisture - wet clothing transmits body heat by conduction.  Wind further increases the heat loss.
• Contact with cold objects - such contact, especially with metal, transfers heat from the body rapidly.
• Altitude - the lower oxygen level at higher altitudes aggravates the impact of the cold because there is reduced oxygenation of the tissues.

• Mental state - an altered mental state is often associated with frostbite, because the person is rendered incapable of recognizing the cold environment or taking protective measures to avoid injury.
• Susceptibility to cold - a previous injury renders a person susceptible to tissue damage from a repeat exposure to cold.  Dark-skinned individuals are at a greater risk of cold injury.

PEOPLE MOSTLY AT RISK

Men and women whose jobs require that they work mostly or entirely outdoors in wintry conditions stand to be at greatest risk of frostbite injury.  These jobs include:

• Police, fire and security forces
• Construction workers
• Airport workers and airline crews
• Sanitation crews
• Commercial fishing and shipyard workers
• Postal workers
• Railroad workers
• Truckers
• Automotive and heavy duty service technicians
• Agricultural workers, stockmen
• Plant maintenance personnel
• Game and forest rangers
• Utility workers
  

FACTORS THAT MAKE WORKERS MORE SUSCEPTIBLE TO FROSTBITE

In addition to the temperature and other environmental conditions stated above, some other factors affect the likelihood of a worker's sustaining frostbite injury and the severity of the injury:

• Conditions that encourage heat loss: Excessive intake of alcohol and/ or drugs; wet clothing; exposed skin; fever, with radiation of heat; injury, with attending hemorrhage, anoxia, and shock; over-exercise that drains calories and heat that are not replaced.
• Mechanical or physical impedance of blood circulation:  Tight boots, belts, gloves; blood vessel diseases that diminish the flow of blood to the extremities; injury to the blood vessel network; constriction of small blood vessels from use of drugs.
• Conditions that decrease the ability to avoid frostbite: Emaciation an fatigue; dehydration, a major problem in the cold; neuromuscular disease or previous freezing or nonfreezing injury, with resulting sensory loss; psychosis from any cause.

TREATING FROSTBITE INJURY

Often, a victim of frostbite is not aware of the seriousness of the injury.   treatment should be started as quickly as possible, and in most cases the patient should receive hospital treatment.

Efforts should be made to return the frostbitten part (s) to normal body temperature.   This should be done in a warm room by bathing the affected area with warm (not hot) water.  Removing tight clothing helps.  To prevent injury to the skin, the area should never be rubbed or massaged with snow.

The patient should be placed in a warm, dry bed, and care should be taken not to cause damage to the skin before professional treatment is available.

HOW YOU CAN GUARD AGAINST FROSTBITE INJURY

People whose jobs require that they work outdoors in cold environments can do a number of things to reduce the chances of frostbite injury:

1. Stay in good physical condition.  Good health is one of the best preventatives.   Good blood circulation comes with a healthy body.
2. Eat right.  A proper diet provides the fuel (heat) for the body's "core temperature" that flows to body extremities.
3. Avoid alcohol and drugs.  They cause capillary dilation and dissipation of heat.   Instead of making you warmer, alcohol actually makes you colder.
4. Wear proper protective clothing to protect the skin surfaces most often injured by sub-freezing weather.  Wear gloves, face masks, jackets, hoods, boots, ear muffs, that were designed to protect you.  And zip them up!
5. Preserve natural defenses.  It is important that your skin retain as much of the natural oil as possible.  Some dermatologists suggest that you bathe instead of showering because less of the protective oils will be washed away.  And use tepid or warm water instead of hot.
6. Protect your skin.  Use commercially-available products that are designed to supplement the body's natural defenses against heat loss.

The cold can cause significant damage to body tissues. But, an awareness of the body's natural defenses, along with prudent protective measures, can allow workers to perform safely and effectively, even in uncomfortably cold conditions.