Properties that lie in certain areas of the UK are more likely to contain high levels of radon, due to the underlying geology and varying amounts of uranium present. The latest set of indicative maps published by the Health Protection Agency (HPA) shows that large areas of Northern England, the Midlands, the South Coast and the whole of Wales are also at risk. Areas such as these, where it has been estimated that more than 1% of properties will contain high levels of radon, are classed as radon Affected Areas. The Radon Council has been advised that claims are sometimes made that certain properties are “free from radon”, based on their not being in a designated area. It should be understood that radon is a natural gas and even if the property is in a non-affected area it could still be affected with high levels of radon Buildings with basements are also more susceptible to high levels of radon accumulating, as there is a larger surface area in contact with the soil through which the gas can permeate.