Now that we have entered the winter heating period, many people feel that their skin is often abnormally dry lately, and they are very prone to thirst and fire, as well as colds and coughs. In the north, most residences are heated by heating, and there are some public places with central air conditioning for heating and air exchange. The humidity in such places throughout the year is far below the comfort and health standards required by the human body. Especially in places with central air conditioning, the average indoor relative humidity is only about 10%-15%, far from the basic needs of the human body. Experiments have shown that people live in a relative humidity of 45%-65% RH, humidity index of 50-60 environment most comfortable, if the indoor humidity is usually only 10%-15% RH, in such a room for a long time, it will make people’s skin taut, dry fire, feel uncomfortable. In 1999, Professor Chiharu Sudo, Department of Health and Environmental Medicine, Nagoya University, Japan, published a research report on “the relationship between air humidity and human health”, which found that: the frequent occurrence of influenza and low air humidity has a close relationship, warm, dry air environment is easy to breed and spread of bacteria and viruses. This is because when the air humidity is lower than 20%, indoor respirable particles increase, it is easy to make people suffer from the flu; and when the air humidity reaches 45% to 65% to, the survival environment of germs is destroyed, not easy to spread. In addition, due to the increase of indoor respirable particles in a dry environment, allergens also increase, and it is easy to invade some allergic people, triggering bronchial asthma. The symptoms are cough, chest tightness, wheezing and dyspnea, which recur and often worsen at night or early in the morning. To sum up, dry indoor air can lead to discomfort and fire, and it is easy for bacteria and viruses to breed and spread, and can also trigger bronchial asthma, leading to chronic cough. The respiratory system of infants and children is not well developed, and the body’s own immunity is low, so they are most sensitive to changes in air humidity and most likely to suffer from respiratory diseases. So how to fight against indoor dryness? First of all, drink more water. This is very simple, but also very important, the most appropriate way to drink water is “a small number of times”, that is, drink water in several times, each time the right amount. Eating more fruits is also a good choice. To prevent dry lips, dry skin, relieve the symptoms of fire are very good. In addition, a healthy indoor humidity should be created to reduce indoor respirable particles and reduce the breeding and spread of bacteria and viruses. This is very beneficial to reduce children’s winter illnesses and to have a healthy winter and New Year. Indoor humidity can be improved by using a humidifier or, if safe, sprinkling some water indoors. If you use a humidifier, it is best to use pure water, and the machine should be cleaned and disinfected regularly so as not to aggravate respiratory diseases by causing unclean air. Indoor air humidity should not be too high, such as more than 80%, will also make the child’s respiratory system and mucous membranes feel uncomfortable, immunity is reduced. Therefore, the room should be equipped with a temperature and humidity meter to monitor the indoor temperature and humidity in a timely manner. In short, indoor dryness in winter can easily lead to fire in the organism and respiratory infections, and young children and children are more susceptible to diseases. The solution is not only to drink more water, but also to adjust the humidity in the room, and an environment with a humidity index of 50-60 is most conducive to human health.