Radon risk mapping in southern Belgium: an application of geostatistical and GIS techniques

A data set of long-term radon measurements in approximately 2200 houses in southern Belgium has been collected in an on-going national radon survey. T he spatial variation of indoor Rn concentrations is modelled by variograms. A radon distribution map is produced using the log-normal kriging techniqu e. A GIS is used to digitise, process and integrate a variety of data, incl uding geological maps, Rn concentrations associated with house locations an d an administrative map, etc. It also allows evaluation of the relationship s between various spatial data sets with the goal of producing radon risk m aps. Based on geostatistical mapping and spatial analysis, we define three categories of risk areas: high risk, medium risk and low risk area. The cor relation between radon concentrations and geological features is proved in this study. High and medium Rn risk zones are dominantly situated in bedroc k from the Cambrian to Lower Devonian, although a few medium risk zones are within the Jurassic. It is evident that high-risk zones are related to a s trongly folded and fractured context. (C) 2001 Elsevier Science B.V. All ri ghts reserved.