This article is from the Aerobics Fitness FAQ, by firstname.lastname@example.org (Robles) with numerous contributions by others.
Frostbite involves the freezing of tissue, and can range from
mild to fairly severe. The skin will generally look yellowish, and
will be cold to the touch. First aid generally involves warming the
affected area using moderately warm water - remember that sensation
will be reduced in the area, and the temperature of the water
should be verified by running it on unaffected skin! Do *not*
rub the area, as this can cause further tissue damage.
Frostbite should be examined by a physician to assess the extent
of the damage. It is best prevented by proper clothing and limited
exposure to cold.
Hypothermia is a life-threatening condition wherein the core body
temperature has become dangerously low. Many of the same symptoms
as heat exhaustion, including dizziness, nausea, loss of appetite,
vision problems, etc., may be present. In the case of hypothermia
it is important to call 911 immediately, and use any means present
to warm the victim, such as removing excess clothing and putting
them in a sleeping bag with an unaffected person who
can provide body warmth until help arrives.