Passage of air into and out of the RESPIRATORY SYSTEM.

The process by which air is purified and circulated in domestic, occupational, industrial, and other settings. Ideally, the air we breathe should be of the right temperature and humidity, and free of dust, smoke, pollen, and other contaminants. Ventilation aims to produce such an atmosphere. Air-conditioning is frequently used in hospitals, offices, and other public places. Special filters may be used to reduce the risk of airborne infections and allergies (see ALLERGY), but poorly maintained and contaminated systems may result in outbreaks of serious disorders, such as LEGIONNAIRE'S DISEASE. Sterilisation of air is rarely required, but ultraviolet light is sometimes used to kill pathogenic organisms. (See also ASTHMA; BRONCHITIS; HUMIDIFICATION.)