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Average temperature -

A person's core body temperature usually hovers around 8.6°F (37°C). But it can range between 97°F (36.1°C) and 99°F (37.2°C).

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Core temperature drop -

Hypothermia occurs when core body temperature drops to around 95°F (35°C) or lower. However, people can also experience hypothermia in non-freezing temperatures, especially if they're wet from rain, sweat, or submersion in cold water. The body loses heat about 25 times faster in water than in air.

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When it gets dangerous -

However, hypothermia at these relatively cool temperatures is unusual. The real danger is when it gets to freezing temperatures.

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Freezing cold -

At -30°F (-34°C), an otherwise healthy person who isn't properly dressed could experience hypothermia in 10 minutes. At -40 to -50°F -40 to -45°C), hypothermia can set in much quicker—just five to seven minutes.

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What are the symptoms? -

Mild symptoms of hypothermia, such as weakness and confusion, set in when the core body temperature reaches about 95°F (35°C). Lower than that, and bad things start to happen. 

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It can happen slowly - Hypothermia can progress slowly, and affected people may not even be aware they need medical help.

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Further symptoms -

The person may feel exhausted and their skin may be pale. And as hypothermia advances, so do other symptoms such as fumbling hands, slurred speech, confusion, and drowsiness.

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Critical organs stop working -

A drastic drop in body temperature prevents critical organs from working properly, including the brain, heart, and the nervous and respiratory systems.

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Organs shut down -

Improper functioning of the heart results in reduced blood flow to many organs. This puts the body in a state of shock and increases the risk of conditions like liver and kidney failure.

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When it gets lethal -

Once body temperature reaches below 70°F (21°C), the person has reached profound hypothermia. With no treatment, the condition is likely to lead to death.

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The most vulnerable -

People who are at the highest risk for hypothermia are young children and the very old. This is because they generally have weaker heart muscles.

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Medications can make them weaker -

In addition, older people are more likely to take medications such as beta blockers, which can slow heart rate. This can further increase their risk of developing hypothermia in the cold.

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The record of lowest surviving body temperature -

The record for the lowest body temperature which an adult has been known to survive is 56.7°F (13.7°C). It occurred after the person was submerged in cold, icy water for quite some time.

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Built-in cold protection -

Yet, human bodies are pretty strong in the cold, as we have two built-in mechanisms to protect us from frigid conditions.

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The body's response -

As soon as the cold air hits your face, the body will try to insulate itself by moving blood away from the skin and outer extremities, such as fingers and toes. This process is known as vasoconstriction, and it helps limit the amount of heat lost.

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Shivers bring the heat -

The second response from your body is shivering, which produces heat and helps raise body temperature. Shivering usually stops when a person progresses into severe hypothermia.

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Frostbite danger -

Although extreme conditions are often needed to induce hypothermia in a healthy person, frostbite is more common in less severe weather.

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Most affected body parts -

Your fingers and toes are more prone to frostbite, because those areas get reduced blood flow in cold temperatures. At the same time, our body will try to keep its core warm.

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Sweat can contribute to frostbite -

And even if your feet are protected by socks and shoes, toe temperatures can get very low. Plus, if you sweat, the moistness will draw even more heat out of the area.

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Developing frostbite -

Because frostbite is brought on by freezing conditions, you can't get it if the air temperature is above 32°F (0°C).

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Frostbite symptoms -

Apart from cold skin, symptoms also include a prickling feeling followed by numbness and inflamed, or discolored, skin. As frostbite worsens, skin may become hard or waxy-looking.

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Frostbite occurs in several stages -

The first stage is frostnip, which is mild and doesn't cause permanent skin damage. Then there's superficial frostbite, which causes slight changes in skin color and blisters when the skin is rewarmed. And, finally, there's deep frostbite, which affects all layers of the skin as well as the tissues that lie below. Muscles might stop working, and the tissues turns black and hard as these very tissues die.

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Treating frostbite -

Frostnip can be treated by rewarming. All other frostbite needs medical attention because it can permanently damage skin, muscle, bone, and other tissue.

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How long it takes -

How long it takes you to develop frostbite will depend on the conditions. For example, if it's 0°F (-18°F) with a wind chill of -19°F (-28°C), you could be frostbitten in 30 minutes.

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How long it takes -

But if it’s -15°F (-26°C) with a wind chill of -55°F (-48°C), you could get frostbite in five minutes.

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How to stay safe -

As the temperatures drop, it's not just important to stay warm—you need to stay safe, too. Keep a cold weather safety kit in your car. It should include emergency blankets, candles, and matches.

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Dress for the conditions -

It's recommended that you wear at least three layers: a wicking layer that wicks moisture away from the skin, an insulating layer, and a protective outer layer. Proper headwear, gloves, socks, and footwear are also essential.

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Only travel if you have to -

When it's extremely cold, only travel if it's absolutely necessary. Staying inside will reduce the chances of getting frostbite or risk traveling through uncertain road conditions.

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Plan breaks from the cold -

If you need to be out in the cold, for example due to your job, make sure to plan warm-up breaks inside. Limit the amount of time you spend outdoors, and nourish yourself with hot drinks and food.

Sources: (Live Science) (NSW Health) 

See also: How people die from extreme heat 

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