The national radon susceptibility data set shows areas in Norway that might be more prone to radon (or: have greater radon risk) than others. In areas marked with high susceptibility, it is estimated that at least 20 % of the homes (houses/residences) have radon concentrations above the upper recommended limit of 200 Bq/m3 at ground floor level. The data set is based on indoor measurements of radon (from NRPA database) and knowledge of geological conditions (databases of bedrock and superficial deposits at NGU). In some areas in Norway radon has been measured in many houses, whereas in other areas there are few available measurements. The data set was developed by statistically considering how the proportion of houses that exhibit high radon concentrations may relate to the local geology, and transferring this knowledge to other areas with similar geological conditions.
The national radon susceptibility data set gives the municipalities a basis for an initial evaluation of radon hazard. In areas of high or very high radon susceptibility the municipality should investigate whether there is a need to follow up radon problems according to Planning and Building Act and the Public Health Act and regulations. The data set can not be used to predict radon concentration in single buildings. The only way to get reliable knowledge about radon in a building is to complete a radon measuring.