MAPPING THE PROPORTION OF THE HOUSING STOCK EXCEEDING A RADON REFERENCE LEVEL

In order to identify homes with high radon levels as efficiently as po ssible, it is necessary to have accurate numerical information on rado n-prone areas. Maps based on geological indicators are generally quali tative and sometimes contain significant errors. Maps based on radon m easurement in homes are definitive if sufficient results are available . Often there are small numbers of measurements, making it difficult t o map the fraction of the housing stock which exceeds the reference le vel. However, distributions of radon levels are usually log-normal, so modelling of the distribution allows the fraction of the housing stoc k exceeding any level to be calculated. A database of 62,555 radon res ults in southwest England is used to show that the data within 5 km gr id squares are consistent with log-normal distributions and to develop techniques for estimating the fraction of homes exceeding a radon ref erence level in each grid square, even where data are sparse.