Radon is a colourless, odourless radioactive gas. It comes from the radioactive decay of radium, which in turn comes from the radioactive decay of uranium which is found in small quantities in all soils and rocks, although the amount varies from place to place. It is particularly prevalent in granite and limestone areas but not exclusively so. Radon levels vary not only between different parts of the country but even between neighbouring buildings.
Radon in the soil and rocks mixes with air and rises to the surface where it is quickly diluted in the atmosphere. Concentrations in the open air are very low. However radon that enters enclosed spaces, such as buildings, can reach relatively high concentrations in some circumstances.
When radon decays it forms tiny radioactive particles which may be breathed into the lungs. Radiation from these particles can cause lung cancer which may take many years to develop. In addition, smoking and exposure to radon are known to work together to greatly increase the risk of developing lung cancer.
The principal areas of the country in which radon is a problem are the granite areas of Cornwall and Devon, and the limestone areas of Derbyshire, Northamptonshire, North Oxfordshire, Lincolnshire, and Somerset, however there are many other areas in England and Wales affected by radon.
For the purpose of considering risk in the home the Health Protection Agency Radon Protection Division formerly the National Radiological Protection Board has advised the Government that the level of 200 Bq/m3 should be considered the Action Level. If the radon level in your home is close to or above the Action Level you should take action to reduce the level, ideally to well below the action level.
If radon levels in your home are above the recommended action level the health protection agency recommends that measures should be taken to reduce the amount of radon entering your home. The remedial measure required will depend on the amount of radon entering your home and the associated costs involved are likely to increase if the levels of radon are high. Further information about reducing levels of radon in the home can be obtained from the British Research Establishment website. If your house was built after 1988 it is likely that radon will have been considered and the necessary protection put in place in order to comply with Building Regulations.