(NEW YORK) -- As many Americans feel the arctic blast moving across the country, doctors are warning people to take extra care in bundling up and staying out of the cold.
Frostbite, in particular, is a major threat; it can occur in under a minute at extremely cold temperatures. The term is shorthand for the literal freezing of body tissue, usually skin. The most vulnerable areas to frostbite include fingers, toes, noses, cheeks, and ears.
According to the National Weather Service, frostbite can occur within 5 minutes in temperatures between 0 degrees and -19 degrees Fahrenheit.
The initial stage of frostbite usually affects the top skin layers and does not lead to long-term damage. As freezing continues, second-degree frostbite may set in. The skin can become hard and waxy, and blisters may form a day or two after the freezing.
Third degree frostbite consists of a deep frostbite, where the skin turns blue or black, and the muscles, nerves, and vessels have all frozen as well. The area is temporarily debilitated, and, in some cases, permanently damaged.
In extreme cases of frostbite, the area can be infected with gangrene, where the affected body part will eventually fall off if it is not amputated first.
And, in a tidbit that could surprise even the most avid of winter athletes, Dr. Sandra Schneider, professor and chair emeritus of the department of emergency medicine at the University of Rochester Medical Center said: "It's better to leave a frostbitten area frozen then to go through a freeze, thaw, freeze, and thaw period."
Repetitive warming and freezing can cause ice crystals in the tissue, which only multiplies the damage done to the frostbitten skin.
Along with frostbite, hypothermia is another cold weather condition that can be dangerous to people unprepared for the weather. It occurs when body temperature falls below 95 degrees Fahrenheit.
"As the body temperature goes down, people will begin to shiver in order for the body to generate heat," said Dr. Lewis Marshall, chairman of emergency medicine at Brookdale University Hospital Medical Center, in Brooklyn, New York. "As the body temperature falls below 90 degrees, shivering stops and body can no longer regulate temperature. "
Other symptoms of hypothermia include clumsiness and confusion, drowsiness, a weak pulse, and shallow breathing.
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