Quality control of measured data from an environmental monitoring network is of great importance to assure that further dose assessments and measures are based on reliable data. The demand for a fast data flow requires a clear concept and predefined criteria. Even if data have passed technical check procedures. according to daily experience, some of them will still be inconsistent with others in a radioecological sense. A model of interdependencies for six well established fast detection methods for radioactivity: in the air and on the ground is presented and the checks for consistency are discussed. In a further step it is shown how data from stations with an imcomplete set of instrumentation can be interpreted on the basis of the model results. An expert system written in PROLOG and presently running as a demo version has been developed on the basis of this model in cooperation with DORNIER.