In most areas of China, rain, snow and frost have become common weather phenomena since autumn and winter, bringing people different feelings of cool, cold and freezing. The wet and cold weather not only makes the ground icy, bringing serious safety hazards for people traveling and driving. The combination of cold and moisture also brings the “greeting” of an “old friend” from winter: recurring episodes of frostbite. In China, 200 million people suffer from frostbite each year, with children, women and the elderly being the most prevalent groups. The rainy, snowy and frosty winter months provide a breeding ground for frostbite and aggravate the condition of patients. What causes frostbite? As a common winter disease, there are two main causes of frostbite: climate and individual susceptibility. Climatic causes The incidence of frostbite is higher in cold and wet areas, such as in rainy, wet and cold England, where the incidence is 10% per year. In winter, although the temperature in the south of China is significantly higher than in the north, the incidence of frostbite is close to that in the north. This is because the north has low but dry temperatures and indoor heating, while the south has wet and cold winters with lots of rain and snow and frost. Susceptibility Even when people live in the same environment, there are differences, which suggests that genetic susceptibility also has an impact on frostbite. Studies have shown that most people who are susceptible to frostbite have poor peripheral blood circulation or sweaty hands and feet, and are prone to microcirculatory disorders when exposed to cold. Occupation is also a factor in the development of frostbite. People who work outdoors or have more contact with cold water during the cold season, such as sanitation, restaurant workers, and housewives, have a higher incidence than the general population. In particular, many waiters in restaurants and hotels around the middle and lower reaches of the Yangtze River come to the clinic with mostly red and swollen hands due to their contact with washing work in winter, which is both wet and cold. Direct Triggers The direct trigger of frostbite is cold, but anemia, endocrine disorders, chronic granulocytic mononuclear cell leukemia, macroglobulinemia, cryoglobulinemia, antiphospholipid antibody syndrome, Raynaud’s disease, and anorexia nervosa can all trigger frostbite.