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What is cold exposure?
Cold exposure, sometimes known as cold stress, is the collective name for several conditions that can affect the body when it is exposed to cold temperatures.
You can often suffer from cold exposure even when the outside temperature itself is above freezing, especially in wet conditions. Exposure time, the body's constitution and energy levels have a significant effect on the degree of harm the body sustains.
In extreme cases, cold exposure that is not recognised or treated in time can lead to serious harm, and potentially death.
Exposure to cold temperatures can have both localised and generalised effects. These include:
Hypothermia occurs when the body's core temperature, which is normally around 370C, drops below 350C.
Symptoms of hypothermia include:
- Cold, pale skin;
- Rapid breathing;
- Urge to urinate, and;
- Confusion, drowsiness, and unconsciousness.
Hypothermia interferes with the temperature regulation function of the brain, so that a person experiencing hypothermia sometimes also feels as if they are extremely hot. This explains the phenomenon known as 'paradoxical undressing', where people experiencing hypothermia undress themselves despite the freezing conditions. Hypothermia can also impair thinking, causing individuals to become less aware of the danger they are in, and less willing to do anything about it (such as move into shelter, warm up, or change clothes).
As hypothermia advances, and the body's core temperature drops further, the breathing and heart rate slow down. The body shuts down all 'non-essential' processes in order to prevent energy loss. The person may slip into unconsciousness.
Hypothermia is a medical emergency and requires professional medical attention. Treatment of hypothermia includes preventing further heat loss and rewarming the person until the core temperature is restored to normal. Re-warming a person with hypothermia can be a dangerous process in itself, especially in more extreme hypothermia cases, and requires a controlled approach to prevent complications and further damage.
It is important to note that, in some cases, people in an extreme state of hypothermia may appear to be dead as they are not breathing and have no pulse or consciousness. They can be revived through controlled re-warming.
Cold water immersion
Immersion in water is a dangerous risk factor for hypothermia, even if the water is not particularly cold. Hence, hypothermia is a serious added complication in drowning cases. Additional problems associated with cold water immersion are:
Cold shock is the body's physiological response to sudden cold. It is commonly the result of falling or jumping into cold water (such as falling through ice, or overboard a boat into cold seawater).
The cold shock response is short - it lasts a few minutes. However, it can be very dangerous, since the sudden cold:
- Constricts blood vessels in the skin, making blood rush back to your heart and increasing your blood pressure;
- Makes breathing difficult and causes hyperventilation, and;
- Causes a 'gasp response' - an uncontrolled gasp, which may cause water to enter your airways.
Also, a cold shock response dramatically increases the risk of having a heart attack, panicking and drowning.
When immersed in cold water, you will gradually lose the ability to control the muscles of your fingers, hands and legs within about 10 minutes. This will prevent you from swimming or keeping your head above water without a lifejacket or other flotation device.
Chilblains (also known as pernio) occur when the skin is exposed to severe cold, but does not freeze. Chilblains are caused by cold damage to blood vessels in the skin. The affected area becomes reddish, swollen and painful. Blisters and sores can appear. Chilblains will take a few days to heal. The affected area will remain damaged and sensitive to cold.
Trench foot, also known as 'immersion foot', is a condition caused by feet being wet and cold for days at a time. Trench foot can occur even when the temperature is not particularly low.
In trench foot, blood circulation in the foot is slow, and feet begin to ache and grow numb. The foot can appear red, swollen and rubbery to touch. Blisters and open sores can appear, increasing the danger of infection. In serious cases of trench foot, the foot may develop gangrene, turning dark blue, purple or black and emitting a rotting stench.
The human body is mostly water. Frostbite happens when exposure to the cold causes water in the tissues to freeze and form crystals. This results in tissue damage, reduced function and increased susceptibility to infections.
Frostbite usually affects the skin and the body's extremities - toes, fingertips, nose and ears. The affected area becomes cold and numb. It appears pale and bluish and may ache.
Superficial frostbite affects only the outer layers of the skin. In more severe frostbite, the deeper layers of skin and the tissues beneath it will also freeze.
Frostbite is a medical emergency and requires immediate medical attention. Treatment of frostbite involves getting the person out of the cold, removing wet clothing and warming the area without rubbing or applying direct heat. Soaking in warm (not hot) water is a popular treatment method, as is passive warming (covering in clothes, blankets, etc.). Rewarming a person with frostbite should be carefully performed as it may be quite painful.
In the hospital, frostbite will be treated according to its severity. Treatment may include warming methods, medications (to dilate blood vessels, relieve pain and prevent infection) and/or surgery.
Frostnip is a mild case of exposure of the skin to cold. The skin may appear pale or bluish-white, and may itch, ache, or feel numb. Frostnip is like frostbite, but the skin or tissue does not freeze. Frostnip improves quickly and usually heals completely.
Those at an increased risk of sustaining cold damage in cold conditions include:
- People living, visiting, or working in cold environments;
- People sleeping outdoors (homeless or campers) in cold temperatures;
- Participants in winter sports and activities;
- People wearing wet or inadequate clothing in cold temperatures;
- People suffering physical exhaustion, tiredness and fatigue in cold temperatures;
- Undernourished people, people with low body fat and the elderly;
- Young people - children and especially babies. Due to their small size and under-developed temperature control system, babies can sustain cold damage rapidly;
- People with circulatory diseases, such as Raynaud's phenomenon or diabetes, and;
- People under the influence of alcohol, drugs or certain medications (such as beta blockers).
Complications of cold exposure can include:
- Loss of use of the affected limb;
- Infections of the affected area, which can then spread throughout the body;
- Heart and circulation problems, such as having a heart attack, and;
Cold damage is usually preventable, if you take sensible precautions. Steps you can take to prevent cold damage include:
- Planning ahead for excursions and other exposure to cold environments, preparing for emergencies and weather changes, being mindful of temperature, rain, wind and snow;
- Using weatherproof and protective clothing and gear (waterproof jacket, woollen hat, mitts, thick socks, scarf, insulated boots);
- Wearing a lifejacket near cold water;
- Taking care not to touch or handle extremely cold or frozen objects without gloves;
- Dressing in layers when visiting cold weather areas;
- Packing a spare change of clothing sealed in a waterproof bag;
- Changing clothes immediately if they get wet;
- Using warm (not hot) heat pads;
- When in cold conditions, eating and snacking frequently to maintain body energy levels;
- Drinking plenty of fluids;
- Moving around and exercising, avoiding long periods of sitting or lying down. However, regulating physical exertion to avoid exhaustion and fatigue, and;
- Avoiding alcohol and recreational drugs in extreme conditions, which can affect reasoning.