A UV irradiation apparatus for coating systems that coat rigid or film-like workpieces, in particular furniture parts, having a transport apparatus for transporting workpieces provided with coating material from an inlet to an outlet through the UV irradiation apparatus, a UV light source arranged above the transport apparatus that irradiates the coated workpieces with UV light in an irradiation region between the inlet and the outlet, and a reflector or cover which shields the UV light source upward. A housing covers the irradiation region and the UV light source, which generally extends above the transport apparatus. A sensor of a measuring apparatus for direct or indirect automated measurement of radiant flux of the UV light source is arranged in the housing, and the sensor is in particular fitted fixed or movably on the housing or a holder. A method for quality assurance using this UV irradiation apparatus is also provided.