Before you go into the cold, know the weather forecast and be prepared for the worst possible conditions. Physical activity makes you sweat, and this makes you wet, causing heat loss. Learn how to dress for your specific activity, and avoid over-activity.

2. Stay Dry

Being wet is a leading cause of heat loss and hypothermia. If there is rain or snow in the forecast, bring a waterproof layer of clothing. If you’re not prepared for wet weather, take shelter before it turns wet. Stop physical activity before sweating dampens your clothing. Change your socks as they get damp and before your feet get cold.
Wear several layers of loose-fitting clothing made of fabric that breathes, and keeps you warm even when it is wet.

Wicking layer against the skin to ‘wick’ moisture off the skin and to the next layer.
Light insulating layer that insulates even when wet - wool and polyester are good choices, cotton is a poor choice.
Heavy insulting layer(s) to keep you warm in the specific conditions - wool sweater, synthetic fleece are good choices.
Windproof/waterproof layer to protect you from the elements - choose a fabric appropriate for your activity

2. Stay Safe

When weather conditions are extreme, shorten the time you’ll be outside. Use the ‘buddy’ system and check on each other often for signs of cold injuries.

2. Nourish Yourself

Bring high-energy foods with you – raisins, dried fruits, nuts and candy bars are good choices. Also bring plenty of liquids for drinking to prevent dehydration. Hot sweet drinks, weak tea and herbal teas without caffeine are best. Cool water is also a good choice. Avoid eating snow as this contributes to heat loss. Never drink alcohol (or use tobacco) - these add to heat loss.

2. Keep Your Furnace Running

The best way to make your body generate more heat is to use your big muscles -- the muscles in your legs, buttocks and arms. Jog on the spot, do knee bends or swing your arms to generate heat. When exercising to warm up, tighten your collar and cuffs to prevent the warm air inside your clothing from escaping. And remember that to exercise, your body needs fuel - don’t forget to eat and drink.

How the body loses heat

Core body temperature drops when the body loses more heat than it produces. There are five ways the body loses heat detailed below. In an outdoor emergency, heat loss by conduction and convection (wet and wind) are often the main contributors to hypothermia but if someone is suffering from exposure, you must look for all the ways the body is losing heat.

How the body adapts
to heat loss

The body has a number of ways to reduce heat loss and keep its core warm. One of the first things the body does to try to warm itself is shivering. The muscle action of shivering generates heat. If the body continues to get colder, the blood vessels in the arms, legs and at the skin surface get smaller. This keeps the blood in the core where it is warmest. By doing this, the body core is using the surface tissues to insulate itself from the cold.

With continued heat loss, the body processes get slower. This includes thinking, muscular action and the senses. Shivering slows down and then stops. The muscles become stiff and movements jerky. Thinking becomes confused, speech difficult and the senses dulled. The heart and breathing rate slow and the person eventually loses consciousness. At this point, the condition is very serious. The heartbeat becomes unsteady and faint, and finally the heart stops beating.

When the heart stops beating, the person is considered dead. However, when the body tissues are cold, they aren’t damaged as easily by a lack of oxygen. For this reason, there is often a chance of reviving a hypothermic person who doesn’t show any signs of life. There are many examples of children and adults who have seemingly “frozen to death” and later recovered after intensive hospital care. This means that as long as you aren’t putting yourself or others at risk, you should continue your rescue efforts to get such a person hospital. With hypothermia, a person isn’t dead until he is warm and dead.

About hypothermia

Who gets hypothermia?

Anyone can become hypothermic, but the following groups are especially prone:

Elderly people, because they often have poor circulation, less ability to sense the cold, and may be on medication that promotes heat loss.
Babies have less ability to recover from mild and moderate hypothermia because they lose heat more quickly and their bodies don’t control body heat well.
People who are already weakened due to illness, injury, lack of food, fatigue or through the use of alcohol or drugs.
Teenagers, because they often do not dress warmly enough for the weather conditions and then ignore early warning signs.

Signs of hypothermia

There are three stages of hypothermia: mild, moderate and severe. The table below lists the signs for each stage, but it may be hard to tell exactly when one stage ends and another begins. Body temperatures are not listed here because the first aider has no practical way to take the temperature of the body’s core.

How the Body Loses Heat

Examples & Prevention

1 Radiation

Heat escapes from the body into the air around it. Example: A lot of heat is lost from the head. Prevention: Wear a warm hat.

2 Breathing

Cold air is inhaled, warmed by the body and exhaled, causing heat loss. The steam you see when you exhale on a cold day comes from air that your body has just warmed, and lost heat in doing so. Wear a parka with a ‘tunnel’ hood or ‘ski-tube’ – the air you breathe will be warmer than the outside air.

3 Evaporation

Body heat is used to evaporate liquid on the skin. Sweating is how your body tries to keep cool on a hot day. Keep your skin as dry as possible.

4 Conduction

Heat moves directly from the body to a cold object that the body is touching. Sitting on the cold ground or wearing wet clothing – your heat moves from you into the ground or wet clothing. Stay dry. Wear fabric such as poly-propylene that draws moisture away next to your skin.

5 Convection (wind chill)

The thin layer of warm air around the body is replaced by cooler air, which the body must now heat. The wind blows through openings in your clothing and blows away the warm air layer against your skin. Wear windproof clothing with snug cuffs and collar to keep the wind out.

Recognizing hypothermia

The key to successful first aid for hypothermia is recognizing the person’s condition as soon as possible, and preventing it from getting worse. Hypothermia is the obvious thing to look for on a winter day, but it is less obvious when the temperature is above zero. Be on the lookout for hypothermia whenever the temperature is below 20C, the weather is windy, wet or both, or the person is in one of the groups at risk for hypothermia.

Sometimes hypothermia is mistaken for other conditions. Hypothermia has been mistaken for drunkenness, stroke and drug abuse. This often happens in the city where a warm environment doesn’t seem far away. For instance, an elderly person’s home may not feel cold to you if you are warmly dressed. But if the room temperature is 15C and the elderly person is not dressed warmly, this could be the problem.

And don’t forget yourself – as soon as you begin to shiver, think “I’ve got to prevent further heat loss.” If you don’t, hypothermia will soon affect your mind, and then you won’t think clearly enough to take the right actions.

First aid for hypothermia

First aid for hypothermia aims to prevent further heat loss and get medical help.

If the person’s temperature is lower than 35˚C or you detect some of the other symptoms mentioned earlier, suspect hypothermia either as the main problem or as a complication of an injury or other condition.
Take measures to prevent further heat loss:
- Cover exposed skin with suitable clothing or covers; make sure the head is well insulated.
- Adjust the person’s clothing to keep out wind or drafts. Wrap the person in something windproof - reflective “space blankets” and plastic garbage bags are good for this.
- If possible, move the person out of the cool or cold environment. If you cannot move indoors, provide protection from the wind.
Loosen tight clothing.
Wet clothing causes severe heat loss. If you are in a shelter and have a dry change of clothes, gently replace wet clothes with dry ones. If you are not sheltered, put the dry clothes over the wet clothes. If you don’t have dry clothes, press as much water out of the wet clothes as possible and wrap theperson with something windproof.
Insulate the person from cold objects – use a rolled-up jacket or a blanket as a place to lie or sit.
Get medical help. If you have to transport the person, use the recovery position.
Stay with the person until medical help arrives. If there is no pulse and you know how to give CPR, begin this but don’t delay getting the person to help.

Cautions in first aid for hypothermia

Handle the person very gently and keep horizontal if possible. Cold affects the electrical impulses that make the heart beat. As a result, the hypothermic person’s heartbeat is very delicate. The heart can stop with rough handling.

When checking for pulse in a person who may be hypothermic, continue checking for one to two minutes. The heart may be beating very slowly or very faintly – it may take longer to feel a pulse.

Don’t allow the person to smoke or take alcohol – these can cause heat loss.

Don’t rub the person body to improve circulation – this will cause cold blood to flow back to the body core and cool the body further.

Immersion hypothermia

Immersion hypothermia refers to hypothermia caused by being in cold water. A person loses heat 25-30 times faster in water than in air of the same temperature. Immersion hypothermia happens very quickly, within minutes, if a person falls into cold water. Suspect hypothermia whenever someone falls into water, even in the summer. Immersion hypothermia can also happen more slowly, for instance while swimming or scuba diving in a lake. In these cases, hypothermia creeps up on the person and may not be suspected right away.

Do the following when a person appears to have immersion hypothermia:

Tell the person not to take off any clothing – clothing helps keep heat in.
Tell the person to move as little as possible – moving around causes more heat loss by convection.
Give first aid for hypothermia to prevent further heat loss and get medical help.

About rewarming a person

Types of rewarming

There are two types of rewarming: passive rewarming and active rewarming. Passive rewarming means preventing further heat loss and letting the person’s body rewarm itself – this usually works well for mild and moderate hypothermia. Active rewarming can cause complications and should only be done at a hospital but active rewarming is what a person in severe hypothermia needs. This is why in severe hypothermia the first aid is to prevent further heat loss and safely transport the person to medical help.

What a first-aider should do

In mild hypothermia, you can give the fully conscious person something warm and sweet to drink. Although it probably will not add much heat to the person’s body, it will provide comfort. Don’t give a person in moderate hypothermia anything to drink. The swallow muscles may not work well and a drink could cause choking. The effectiveness of rewarming a person by skin-to-skin contact has not been proved, and neither has the use of warmth such as hot water bottles. Also, these can cause complications. The best first aid is to prevent further heat loss and get medical help.

Frostbite

Frostbite refers to the freezing of tissues when they are exposed to temperatures below zero. It is a progressive injury with three stages: frostnip, superficial frostbite and deep frostbite.

Cautions in first aid for frostbite

Do not rub the area - the tiny ice crystals in the tissue may cause more tissue damage.

Do not rub snow on the area - this may cause further freezing and tissue damage from the rubbing.

Do not apply direct heat - this may rewarm the area too quickly.

First aid for deep frostbite

How much tissue is permanently damaged by deep frostbite depends on how long the part was frozen, how much the part was used while frozen and how the part was thawed. Deep frostbite needs medical help as soon as possible.
Prevent further heat loss from the frozen part and the rest of the body. Handle the frozen tissue very gently to prevent further tissue damage.

Do not rub the arms and legs. Keep the person as still as possible.
Get medical help. If the feet or legs are frozen, do not let the person walk if possible - transport using a rescue carry or stretcher.
Make the person as warm and comfortable as possible. Gently remove the clothing from the affected part. Find a container that is large enough to hold the entire frozen part. Fill this with water that feels warm when you put your elbow in it (about 40C.) Make sure you have more water at this temperature available.
Remove any jewellery and put the whole frozen part in the water. Keep adding warm water to keep the water in the container at a constant temperature. Keep the part in the water until it is pink or does not improve any more – this can take up to 40 minutes and may be painful.
Gently dry the affected part. Put sterile dressings over wounds and between fingers or toes.
Keep the part elevated and warm. Do not break any blisters that form.
Get medical help and stay with the person. If the person must walk, do not thaw the frozen parts - there will be less tissue damage and pain if the part is left frozen. Make sure the rest of the body is well protected from the cold and the person has plenty of food and water during the journey to safety.

The advice given in this article cannot, nor is it intended to, replace the first aid skills that can only be learned in an approved first aid course. Readers are encouraged to take a first aid course from their local St. John Ambulance Branch or other recognized organization.

Hypothermia and Frostbite First aid for the big chill

Five Ways to Prevent Cold Injuries

1. Dress for the weather and your activity