Human health and air conditioning systems.

In air-conditioned buildings indoor air quality is closely dependent on the efficiency of air-conditioning and humidifier systems since these systems provide a suitable environment for the proliferation of microorganisms. Pollutants released by microorganisms are termed 'bioaerosols' and may be spread in the indoor environment through the air-conditioning system. Moreover, the tightening of the buildings in which central air-conditioning systems are usually located increases the levels of indoor pollutants. Both hypersensitivity and infectious diseases are associated with bioaerosol exposure, whereas the sick building syndrome (a complex of symptoms described among workers in modern office buildings which are hermetically sealed and mechanically ventilated) is very unlikely to have a bioaerosol component.