Hypothermia, Frostbite, and Submersion Incidents – Environmental Hazards


Hypothermia, Frostbite, and Submersion Incidents – Environmental Hazards

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Some of the most common environmental injuries are related to cold weather. Ideally, you and your group should have the perfect clothing for your stay in the great outdoors, but sometimes the weather changes unexpectedly, or your two- hour hike, for which you’re completely prepared, turns into an eight-hour ordeal involving a black bear and an unexpected dive into a lake.


When your core body temperature falls below 95°F you are suffering from hypothermia. Untreated, it can lead to severe injury or death. If your temperature is 90–95°F, you are mildly hypothermic, but you should still address the problem

immediately. If your core body temperature falls below 90°F you are severely hypothermic.

The first thing to do is to get into warmer temperatures, either by finding a shelter or building a fire. The environment should be dry rather than wet. Eat a carb-heavy diet and stay covered in dry, warm clothing.

Severely hypothermic people are extremely sensitive to touch. If you’re administering to one avoid sudden movements of his body. Watch his breathing carefully; you may have to perform rescue breathing.

If the patient’s clothing is wet, remove it carefully. Place him on a blanket on top of at least 4" of compressed material so as to insulate him from the ground and wrap him in blankets or spare clothes. Heat metal canteen bottles and put them around his neck and groin, as well as under his arms. Create a vapor barrier from a drum liner or trash bag and wrap him in this. The barrier will trap heat in his body. Evacuate the patient as soon as possible.



The first step in self-aid is always prevention, but if you start to become cold, shiver, etc., you can check your current state by attempting to touch your pinky finger to your thumb. If you can still do this then you have gross motor dexterity and now is the time to act. Fire is your friend in these conditions. Building a fire and using the reflectivity of a space blanket will help warm you up. Do not sit directly on the cold ground. It takes 4" of compressed insulative material to combat conduction, so take care of that as well. These activities—building a fire, creating an insulating pad for the ground—will also increase metabolic heat, which in itself will help as a quick treatment. Make sure you remove and change any wet clothing if possible and also pay attention to a simple acronym (COLDER) when operating in cold environments.

C = Clean: Clothing clogged with dirt cannot breathe properly and will trap heat and moisture causing sweat, which can make you feel colder from convection.

O = Avoid overheating: This causes you to sweat, making you colder from convection more quickly.

L = Dress loose and in layers: This helps you adjust clothing easily to release excess heat or trap needed body heat between layers of clothing.

D = Keep clothing dry: This goes back to sweating, but also you need to be attentive to where you sit or kneel.

E = Evaluate your clothing: Review what you’re wearing and make adjustments accordingly.

R = Repair: Mend clothing if needed. Clothing with large holes, tears, etc., cannot perform as designed.


Frostbite happens when you’re exposed to severe cold. When your skin temperature drops below 59°F, your body dilates the blood vessels to pump

warm blood to the skin in surges. This is called cold-induced vasodilation (CIVD). If you grew up in a cold-weather climate, your body has likely developed a stronger CIVD response than other people have, and you may be less susceptible to frostbite.

When skin temperature drops to 37–50°F, your body will start drawing blood away from your skin in order to protect the vital organs of the body. When this happens, your skin temperature, particularly in extremities like fingers and toes, can drop as rapidly as 1°F per minute.

Assessing the Severity of Frostbite

There’s a tendency, especially among inexperienced outdoors people, to think that numb equals frostbite. The reality is better than that. If your skin temperature falls to 50°F, you’ll lose sensation (in other words, become numb). But you’re not frostbitten yet. To find out if you’re in the early stages of frostbite, use your thumbnail to push down on the area affected. If the skin dents and stays that way, you’re heading for frostbite. If you can’t dent the skin at all, the freeze has penetrated deeper than the surface layer of skin.

For sufferers from early frostbite, rewarm your hands gently. If you can’t dent the skin at all, you’ll need medical treatment. The most important thing is to get somewhere warm.

Walking on frozen feet is painful and likely to cause significant damage. For this reason evacuation of the injured person should not rely on him walking if at all possible.

Frostbite Enhancers

Mere cold temperatures sometimes aren’t the only factors in creating frostbite. There are several other possible elements. You or someone in your group is more likely to experience frostbite if various contributing factors exist. These include wind chill (the speed and strength of the wind makes it colder); drinking alcohol (something you should never do when hiking in cold weather); smoking (again, not recommended, since it makes blood vessels constrict); hypothermia; exhaustion; imperfectly fitting boots; and wet skin, since any wetness is going to cool things further.



Remember the old urban legend about a kid who licked a pump handle and froze his tongue to it? Well, there’s some truth behind that. If you touch very cold metal, your skin may instantly freeze. That’s especially true if you handle a metal fuel container, since petroleum fuels have a lower freezing point. Be smart and always wear gloves in the cold.

Warning Signs of Frostbite

Numbness is your body’s warning sign that your skin temperature is getting too low. If you can’t get in a shelter or near a fire to warm up, try stamping and wiggling your toes to restore circulation. Put your hands under your armpits or in your pockets. But it can be difficult to rewarm your body once circulation begins to withdraw. Remember the lessons we taught here and in other Bushcraft books about starting a fire under difficult conditions? This is where that training pays off. If you can get them, also keep portable hand warmers in your pack where they’re easily accessible.

To treat frostbite, whether in its early or advanced stages:

• Put the affected part, whether hand or foot, in water heated to 104–108°F, which will feel hot but tolerable to the skin. If you cannot tolerate the water, then your patient also cannot, and it will more likely slow-cook the frozen limb rather than aid in recovery.

• If you’re the caregiver in this situation, ask the victim to try to move the affected area.

• Warm the hand or foot with heated water for up to thirty minutes or until the skin changes color to red and can be moved and bent.

• When you’re finished warming fingers or toes in water, put dressings on them that separate each digit.

Rewarming aims to restore circulation before the tissues are damaged. Tissues need oxygen; without it they can’t do their job and they die. So circulation is essential if the patient is going to keep healthy tissues in hands and feet. Properly immersing in water and providing external support by keeping the patient warm, comfortable, and calm is all you can do to ensure circulation returns quickly.



You may be wondering why we don’t recommend a fire as the first step in treating frostbite. The answer is that even though a fire is a good idea, it can’t heat the air fast enough to combat tissue damage. Warm water is a more effective immediate solution.


It sometimes happens that a hiker falls through ice and is submerged in cold water for a time. Not only is he cold from the surrounding air, but he is also wet. Combined, these conditions can bring on hypothermia very quickly. Get the

person into a warm shelter as quickly as possible and remove his wet clothing. Dry him thoroughly and wrap him in warm dry blankets while setting out his wet clothing to dry. If he has a change of clothing, so much the better. If no fresh clothing is available, a blanket alone is better than wet clothing. Insulative wrap or an emergency blanket are good choices for wrapping the victim, since they’ll help his body retain heat. Keep him out of the wind and use a fire with a reflective wall to warm him. Keep a close eye on him to make sure he doesn’t develop any other symptoms. Falling through ice can be a very frightening experience. As he recovers, a cup of tea or hot soup is a good idea.



Chilblains are inflamed areas of skin, usually on the fingers, caused by repeated exposure to the cold, particularly in wet or windy weather. The inflamed skin is red, itchy, and tender. It may blister. Any type of soothing lotion can ease the symptoms. To prevent chilblains, wear gloves. Although chilblains are usually a minor problem, they can sometimes get infected, so keep an eye out for signs of infection (warmth, red streaks, any type of fluid drainage).


You and a friend have gone canoeing down the Kentucky River in early March. The weather has started to warm up, with highs in the low 50s, and you both have been looking forward to shaking off your cabin fever. The trip goes off as planned until your buddy decides to get a little overanimated telling a story and lets his paddle go, which results in it floating away quickly. He sees it and scrambles to grab it, tipping the canoe, and you both fall into the cold water. It immediately takes your breath, and you struggle to stay above water; your woolen shirt is becoming heavy and saturated, pulling you down. Your friend was wearing synthetic materials, and he’s already made it to shore, so you continue to struggle until your toe touches bottom and you walk up to shore. Your main gear has floated down into an eddy along with your canoe. Your friend is shivering uncontrollably, as are you. Now what?


You instruct him to strip down while you do the same. He’s not dressed for the weather, wearing mostly cotton clothes and socks with a thick parka-like jacket. He begins wringing his clothes out. You are wearing wool underclothes, canvas pants, wool socks, and a wool blanket shirt. Since your gear has been lost and you don’t have a change of clothing, you wring out your wet clothing and immediately put it back on. Since your clothing is wool, it will retain some of its insulative value even when damp. Your friend, however, is no longer able to manipulate his fingers and cannot unfasten his buttons.

You perform a quick fine-motor skills test and ask him to touch his pinky to his thumb on the same hand, which he’s unable to do. Thankfully, you keep a ferrocerium rod in your pocket at all times along with a knife attached to your belt. So, you start a fire within a few minutes. You get your friend next to the fire and begin to heat stones, wrapping them in his wet clothes to aid in drying them out enough for him to put them back on. You feel well enough, so you give him your blanket shirt, which helps him considerably.

His teeth are still chattering, and he’s shaking like a leaf, but he’s able to speak and barely touch his thumb to his pinky, which is a sign he’s improving. As he curls up on the rocky shore,

you help him place heated rocks wrapped in his clothing under his armpits and around his core, and he gives a sigh of relief. After about thirty minutes, his clothes are dry enough to put on, and his shivering and chattering has stopped. He’s still a little cold but feels much better. You, however, have worked up a sweat trying to care for your patient. Remember, sweat can affect you just as easily when the temperatures are low, so take the time to dry off and cool down before deciding what to do about your canoe and gear.

you help him place heated rocks wrapped in his clothing under his armpits and around his core, and he gives a sigh of relief. After about thirty minutes, his clothes are dry enough to put on, and his shivering and chattering has stopped. He’s still a little cold but feels much better. You, however, have worked up a sweat trying to care for your patient. Remember, sweat can affect you just as easily when the temperatures are low, so take the time to dry off and cool down before deciding what to do about your canoe and gear.



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