A procedure and a filter device (1) serving the purpose of removing and/or destruction organic substances in contaminated air. The filter device comprises at least one ventilator (12) for sending an air stream through a first chamber (14) with an opening, which is connected with a source for contaminated air; a second chamber (15) with a number of sheets (20) placed abeam the main direction of the air stream in order to make the air stream change direction at least one time; a third chamber (16) with a number of perforated tubes (22) which at least at one end are in open connection to a secondary air source; a fourth chamber with a number of lamps for radiating the air stream with a short-waved ultra-violet light and; a fifth chamber (17) with a volume, which gives the air stream a predetermined duration time in the chamber, and which has an opening, through which the purified air passes in order to be released to the surroundings. The filter device (1) is extremely efficient for purifying contaminated air from organic substances without using chemicals and physical filters, such as fat- and carbon filters, and it is hygienic and fireproof, since its interior sheets are not covered with organic materials. The releasing tubes and the ventilator are furthermore easy to clean.