High altitude, polar region excursions or unusual cold snaps, prolonged exposure to negative temperatures leads to two main health risks: frostbite and hypothermia. Good preparation and rapid care in the event of a problem can effectively reduce these risks.

HOW DO I PREPARE FOR THE COLD?

To limit the risks of frostbite and hypothermia, carefully prepare your outing.
Dress warmly. By multiplying the layers of clothing, you trap warm air between each layer. First put on a close-fitting garment that will absorb perspiration (this increases the sensation of cold), then pile on the layers to finish with a final waterproof and windproof layer.
The body loses a lot of heat through the extremities: hands, feet and head. So cover these areas especially (thick gloves, socks, waterproof shoes, hat, scarf).
In case of extreme cold, put a cloth, such as your scarf, over your mouth and nose to avoid inhaling freezing air.
Eat and drink regularly. Contrary to popular belief, alcohol does not warm you up! It should even be avoided completely: the feeling of heat, while you are losing heat, may mask the symptoms of hypothermia, preventing you from reacting quickly.
As soon as you feel cold, move constantly. Be careful, however, to avoid excessive physical exertion: the cold forces the heart to beat faster to maintain a normal internal temperature. The risk of cardiovascular problems is therefore higher.
Never go out alone in extreme conditions. Always make sure that several people know your route and your departure and return times.

WHAT ARE THE SYMPTOMS OF FROSTBITE?

In case of extreme cold, our body promotes blood circulation to the vital organs, the heart and the brain, to the detriment of the extremities. The toes, fingers, and sometimes the face are the most affected by frostbite. Frostbite is when the skin and the tissues it protects begin to freeze: it is a cold burn.
At first, the skin turns red, tingles, and becomes painful. This pain increases, then the area gradually becomes numb, with a feeling of numbness. While some frostbite is superficial, other deeper frostbite causes tissue necrosis, i.e. the death of the affected cells. This serious frostbite can lead to amputation of the affected area.

WHAT TO DO IN CASE OF FROSTBITE?

Always take the first signs of frostbite very seriously. At the time, it is impossible to know whether it is a superficial frostbite without any seriousness or a deep destruction of cells leading to serious complications.
In the field, the main thing is to remove yourself from the action of the cold and to only start treatment if conditions allow it. Under no circumstances should you warm up a frozen area unless you are sure that this warming can be sustainable and permanent until help arrives. The most dramatic situation would be that of "re-frostbite" on a previously warmed lesion.
It is strongly advised not to massage, rub, rub or burn (with the flame of a lighter or very hot water for example) frostbite, you risk aggravating the destruction of cells.
If you can, quickly go to a warmer place and place the affected area in warm clothing, against your skin or that of another person.
You can immerse the frozen skin in water, if possible with an antiseptic, at 38 or 39 °C, slightly warmer than body temperature. Thawing it may cause very severe pain.
In the case of frostbite on your feet, do not take off your shoes if you still have to walk or ski: swelling caused by frostbite would prevent you from putting them back on.
If the frostbite is severe, call for help quickly to get medical treatment as soon as possible.

WHAT ARE THE SIGNS OF HYPOTHERMIA?

Hypothermia occurs when your body's internal temperature drops below 35°C. You start to get chills, goosebumps and sometimes feel tired.
If your internal temperature continues to drop, you may paradoxically feel hot. The chills intensify, you become confused and have difficulty walking or handling objects.
When your internal temperature drops below 32°C, hypothermia is severe and can lead to death. You no longer shiver, you have difficulty speaking and may even suffer from amnesia. Your skin becomes blue and swollen, your pulse and breathing slow down dramatically.

WHAT TO DO IN CASE OF HYPOTHERMIA?

In the event of the onset of hypothermia, continue to move and drink a warm, non-alcoholic drink. Severe and prolonged hypothermia requires immediate medical attention. Call emergency services as soon as possible, telling them your condition (the emergency number 112 is valid throughout the European Union).
While waiting for help, wrap yourself in a dry blanket or warm yourself “skin to skin” with another person. Warming up should not be too abrupt: do not rub your limbs, do not use a hot water bottle or electric blanket.
You will sometimes have the impression that it is colder than the temperatures announced by the weather forecast. This is called the perceived temperature or wind chill: the wind increases the sensation of cold and therefore the risks of frostbite and hypothermia. For example, at -5°C, a 50 km/h wind will give a perceived temperature of -15°C. Water also greatly accelerates heat loss: the body cools down 25 times faster than in air.