The process is based on the effective interaction of UV-light and a catalytic converter. In the UV-chamber the Photoionization process is initiated by the generation of strong oxidants like oxygen radicals and hydroxyl radicals. Simultaneously, the linkages of odour molecules are broken up. While some of the contaminants are oxidized immediately others are adsorbed to the surface of the catalyst and are degraded through the interaction of catalyst and UV-light. The result is a constantly odourless cleaned gas which meets international environmental requirements.