Since indoor radon is considered a potential hazard to health, Rn prevention and mitigation are necessary in certain areas. In this article we address the issues of mapping support and resolution, and conceptually discuss two common ways of generating maps from given information. Further, a short overview is given on the sources of uncertainties which are inevitably associated to every estimate and how to treat them. Finally, some possibilities of generating classified risk indices are outlined, since it is most often necessary to classify regions by estimated hazard.