Abstract: A method for bactericidal, fungicidal, virucidal and insecticidal treatment of ambient air includes circulating air through a permeable container having at least a treating agent therein. The treating agent is used as bactericide, fungicide, virucide and insecticide additionally to mechanical air filtering, and is distributed uniformly inside the container so as to prevent micro-organisms from developing on the container itself. The method may be applied to caloric-exchanging and air-recycling installations and appliances, and to coating elements of building surfaces.