Frostbite occurs when a person is exposed to cold temperatures for a long time and the blood leaves the extremities. Hands, feet, noses and ears are the body parts most vulnerable to frostbite. If a person who's been out in the cold shows signs of frostbite—including skin that starts out numb, hard and pale, and becomes achy when out of the cold; blisters; and develops gangrene—they may also have hypothermia.
Hypothermia should be treated before frostbite.
In the northern United States, frozen lakes and ponds are commonly used for skating, hockey and ice-fishing—but they could pose real dangers for hypothermia and frostbite if the ice isn't thick enough, or a crack suddenly develops.
Survival expert Bear Grylls, host of the Discovery Channel series Man vs. Wild, says if you fall in the frigid water, the first thing to do is not panic but get out of the water as fast as possible.
As soon as you're a safe distance away, remove your wet clothes and try to get dry. According to Bear, a former member of the British Special Forces, you lose heat 25 times faster when you're wet than when you're dry. It may seem counterintuitive, but Bear suggests using powdery snow to sop up excess water. To get the blood pumping, do push-ups, jumping jacks or run in place.