The present invention relates to a system for removal of airborne contaminants in a confined space comprising a primary reaction chamber which chamber comprises at least one ultraviolet light tube for the generation of ozone, in which chamber air coming from the confined space is treated with a combination of UV radiation and ozone. It is an object of the invention to provide a system for removal of airborne pollutants in confined spaces, such as a livestock stable. A further object of the invention is to overcome the problem of dust accumulation on the ultraviolet light emitting lamp and production of nitrogen containing toxic gases. This can be achieved if the ultraviolet light tube is enclosed in an oblong ozone production chamber, which oblong production chamber in one end has a further inlet for an oxygen containing air stream coming exclusively from outside the confined space, where the ozone containing air stream can be mixed with contaminated air from the inlet to form a combined air stream, where the combined air stream is subjected to ultraviolet light transmitted through the wall of the oblong production chamber. Hereby is achieved an effective system for the removal of airborne contaminants including bacteria, virus, insects, malodour, dust particles, and noxious gases such as NH3 and H2S in production buildings such as livestock tables or barns. The method is useful in a system for odour removal where it may be combined with feed-back control.