... has multi-function such as air anion ,air humidifition and air purifition9.0.5 to 7. ... air, and ions with negative charge are called anions. Anions are everywhere in nature and they come out in thunder, lightning ... , photosynthesis, water flow collision, etc. It is why people may feel fresh air in ... and absorbable for people and prevents “air-conditioner diseases”.2. Improving lung functions: ...