The geographical differences and similarities of radon affected areas in England

Abstract

The geographical distribution of radon gas is very uneven. The gas occurs naturally in all buildings at concentrations which can vary from below the United Kingdom national average of 20 Bq m(^-3) to more than 2,000 Bq m(^-3). Five counties have been identified by the NRPB as 'Affected Areas' where more than 1% of homes have radon levels in excess of the current Action Level of 200 Bq m(^-3) (Miles et al., 1992). These counties are Cornwall, Devon, Somerset, Derbyshire and Northamptonshire. The level of radon gas in buildings is largely dependent on the underlying geology but geology does not always provide a full answer as to why spatial variations in radon occur. The implication of land capability on indoor radon levels in the five Affected Areas has been assessed using ARC/INFO and in Northamptonshire die influence of social factors (population density, social class and the proportion of households consisting only of pensioners) has been analysed. There are some similarities in the results for the Affected Areas (especially between the counties located in the south-west of die country) as well as some striking differences (for example, the relationship between urban areas and radon levels differs in all the Affected Areas). Results in Somerset and Northamptonshire are strongly influenced by one or more dominant radon category or land capability grade. In general, higher radon levels are associated with poor quality agricultural land and, in Northamptonshire, with high population density at ward level. The areas of Northamptonshire which have above average proportions in social classes I and II (1991 Census) are more likely to be associated with low radon levels (at district level), whereas areas with high proportions of households consisting only of pensioners tend to be associated with areas where more than 10% of homes are above the Action Level (at ward level).