An evaluation of the effectiveness of the UK programme to protect new buildings in radon affected areas

The discovery of areas in the UK with significant indoor radon levels prompted the Building Research Establishment in 1992 to publish guidance (1) specifying protection measures, enforced by law, when building new houses in radon Affected Areas. In high risk areas, with over 10% of existing houses above the 200 Bq m-3 Action Level, primary protection in the form of a radon-proof membrane is required, as well as secondary protection in the form of a sump capable of being fitted with a low cost pump. In lower risk areas with 3 to 10% of houses above the Action Level only secondary protection is specified. This latter requirement reduces the cost of providing radon remediation to around pound 150 for the fan, rather than an average of pound 750 for providing a sump and fitting a fan, but requires measurement of the radon level to judge whether remediation is required. Northamptonshire, with 6.3% of houses above the Action Level, has areas of both high and lower risk. There has been considerable influx of population in recent years, with 12,200 new houses built since 1993. In high risk areas in Northamptonshire, the collective dose reduction of primary protection has been calculated and has now reached 23 man-sieverts per year has been avoided in the total of 7,900 houses built since 1993. Using current NRPB risk estimates this is equivalent to 0.8 lung cancers avoided each year. This is similar to that achieved by the remediation programme in existing housing, although the potential saving in existing housing is much greater if more householders can be encouraged to carry out remediation (2). In addition, two new housing estates in the lower risk area have been assessed by issuing 6-day etched track detectors to householders, and using a questionnaire to assess their knowledge of radon. Two detectors were used, one in the living area and bedroom, and results were combined using the NRPB protocol to give a weighted seasonally corrected average radon level. In one estate some 30% of houses were found to be above the Action Level. Over 85% of householders were unaware of the risks of radon, or that they had to test the radon level to judge whether a fan needed to be fitted. There is sufficient new domestic building in the UK to achieve significant health gains by specifying protective measures. However, the measures in lower risk areas rely on the householder being aware of the radon hazard and testing the level. In two estates in Northamptonshire it has been shown that no-one advised the householders, and so the secondary protection provided was wasted. In addition, the affected areas were poorly delineated in 1992, as one of the estates was shown to be on geology that should have been in the high risk category. If secondary protection is specified in lower risk affected areas, then significantly increased public awareness is required. Alternatively, the installation of a radon membrane, which does not rely on public awareness and action, should be adopted, if the remediation measures are to achieve the goal of reducing health risks from radon to the general public. (author)