1, infection: the human body is in a closed indoor space for a long time. Because the air is not circulating, bacteria, viruses, dust mites and other disease microorganisms can multiply in large numbers. If you are tired and stay up late, your body's resistance will drop, or your body temperature will drop. At this time, you will catch a cold, have a fever or be infected by other pathogens. In hospital wards, train carriages, cafes and other public places, windows are usually not often opened for ventilation, which will cause air circulation. In this environment, if there are infectious diseases such as tuberculosis, or people infected with influenza virus and novel coronavirus, if these people are in an indoor environment without circulation, then healthy people may be infected by factors such as droplets in the air and physical contact, and symptoms of related diseases may also appear;
2. After stimulating allergic people, the growth of dust mites will stimulate allergic people and cause symptoms of respiratory diseases such as shortness of breath and asthma;
3, hypoxia: long-term air circulation will cause indoor oxygen consumption, hypoxia, the human body is in a state of mild hypoxia, there will be mild dizziness, headache, drowsiness, fatigue, chest tightness and other symptoms.