Nasal breathing refers to breathing through the nose. The nose is one of the human respiratory organs, which plays a vital role in normal breathing. It can suck air into the nasal cavity, then discharge it through the nose, and dilute and evaporate the air in the mouth and throat, so as to achieve the purpose of breathing. Nasal breathing is an important part of human internal breathing, which is called "breathing portal" in medicine, and the nose is one of the breathing portals.

If you say that "health-preserving nose suction" is a specific health-preserving method or service, you need further information or explanation to clarify its specific content.