THE GEESE ARE GOING SOUTH, the trees are bare and the hockey rinks are doing a booming business. It can mean only one thing: winter is on the way. That also means plunging temperatures and the risk of frostbite, but it's no reason to hide under the covers for the next three or four months. Preventing frostbite isn't rocket science, says Dr. Richard Morris of Calgary, whose common-sense advice includes going inside if your fingertips or toes start to tingle. In his six years as an emergency physician, Morris says he hasn't found frostbite to be a major problem. "Amazingly, it's not that common, considering the volume of people that live in Canada." Of the cases he has treated, the lion's share have involved alcohol. "Most of the people who are injured from frostbite are intoxicated," Morris says. "They're drunk and they're exposed for long periods of time because they're outside or they fall asleep. Those are the ones that really get damaged." Drugs that alter one's perception of cold should also be avoided. As well, Morris cautions that people taking such medications as diuretics are at risk of frostbite, since these types of drugs cause dehydration. For those who work or play outdoors for long periods during the winter months, dressing in layers is the most important strategy for preventing frostbite, he says. Morris describes frostbite as a freezing injury that kills tissue. The symptoms may include numbness, tingling and blistered skin. Frostbite differs from frost nip, in which tissue isn't damaged and the painful, tingling symptoms are only temporary. On the other hand, more than 75 percent of those who suffer from frostbite complain of numbness. "Some people will actually say, 'My hands are clumsy,' or 'It feels like my legs are a chunk of wood,'" Morris says. If frostbite is suspected, Morris advises rapid rewarming of the affected body parts, preferably by submersing them for 10 to 30 minutes in water that is warm, not hot, to the touch. The frostbite victim should be encouraged to make gentle motions, as in wriggling toes or flexing fingers, in the warm water. Frozen tissue should never be massaged and, contrary to folk wisdom, should never be covered with snow. Once frozen appendages have been thawed, they should be elevated above the level of the heart. Apply antibiotic ointment and a dressing. Frozen tissue will hurt, and Morris recommends the victim take a combined dose of ibuprofen and acetaminophen. Seek medical attention as soon as possible, and be prepared to get a tetanus shot if the last one was more than 10 years ago. One word of caution: if you can't guarantee that, once thawed, the affected body part won't freeze again, keep it frozen until you reach reliably warm conditions. The secondary injury will be worse than the initial damage.