When the weather is hot in summer or cold in winter, many people will turn on the air conditioner to adjust the room temperature, which will cause the nose to be uncomfortable. The main reason is that after the air conditioner is turned on, cold air will be blown out from the air conditioning vents, resulting in the inhalation of cold air after the nose mucous membrane is stimulated and feel uncomfortable. In addition, many pathogenic microorganisms exist at the air conditioning vent, such as viruses, bacteria, mycoplasma, chlamydia and even mold. And open air conditioning is in a closed environment, the air is relatively uncirculated and dirty, it is easy to stimulate the mucous membrane of the nasal cavity, causing nasal congestion, runny nose, and even nose itching symptoms; easy to trigger pathogenic infections, such as upper respiratory tract infections, acute rhinitis, and even induce asthma attacks.