Radon risk mapping in southern belgium: an application of geostatistical and gis techniques

A data set of long-term radon measurements in about 2200 houses in southern Belgium has been collectedin an on-going national Rn survey. The spatial variation of indoor Rn concentrations is modelled byvariograms. A radon distribution map is produced using the lognormal kriging technique. A GIS is usedto digitise, process and integrate a variety of data, including geological maps, Rn concentrationsassociated with house locations and an administrative map etc. It also allows to evaluate the relationshipsbetween various spatial data sets with the goal of producing radon risk maps. Based on geostatisticalmapping and spatial analysis, we define three categories of risk areas: high risk, medium risk and low riskarea. The correlation between radon concentrations and geological features is proved in this study. Highand medium Rn risk zones are dominantly situated in bedrock 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 tostrongly folded and fractured context.