The European Model for Inhabited Areas (ERMIN) was developed to explore recovery options following the contamination of an urban environment with radioactive material. This paper discusses the user experience of ERMIN and in particular it concentrates on the development of a description of the urban environment and how that description affects the output. The user interacts with ERMIN by defining different regions on a map. A region may be an area in which a particular combination of recovery countermeasures is applied, or where a particular level of contamination is found, or where there is a particular type of urban environment. Most of the output from ERMIN is also presented as maps with summary information that allows the user to compare different countermeasure strategies. ERMIN has been implemented within two international nuclear accident Decision Support Systems; RODOS and ARGOS. Both systems have user interfaces that exploit geographic information system (GIS) technology which complement the ERMIN map based approach.