Radon is a natural radioactive gas, which enters buildings from the ground where it is formed from the minute amounts of uranium that occur naturally in all rocks and soils.
Radon levels indoors depend on the concentration of radon in the ground, details of construction of the house, and the way the house is heated and ventilated.
Levels can vary widely between apparently identical houses. The only way to find out whether there is a high level in a particular house is to measure it.
Indoor radon has been found to be the second most important cause of lung cancer after smoking. Although levels in most homes are low, the concentrations exceed the action level of 200 Becquerels per cubic metre in a significant number of homes. At this level it is recommended that remedial action is taken to reduce radon levels.
There are two types of radon area in the district; a 'radon affected area', where more than 1% of homes are estimated to have levels of radon at or above the radon action level, and a 'radon protection area', where radon protection measures are required in new and altered buildings.
More information is available from the UKradon website which is run by the British Geological Survey and the Health Protection Agency:
The website offers the following online services:
The Building Research Establishment's (BRE) radon website has advice on how to reduce radon levels in buildings, offers guidance on the Building Regulations requirements for protecting new buildings in radon affected areas and has indicative maps defining areas where radon protective measures may be required in new buildings and extensions to existing buildings.