[Humidifier fever].

Pollution of air ventilation and conditioning systems by microorganisms and products of their activity can lead to the development of infectious (legionnaires' disease) and allergic (humidifier fever) diseases. Clinical, immunological and hygienic investigations under natural conditions of 72 persons working in offices helped to study a respiratory disease which was similar to humidifier fever. The removal of dust and mud from the system and thorough cleaning of all conditioned rooms put an end to this disease.