Radon is a radioactive gas that occurs naturally. It has no taste, smell or colour. It is everywhere, usually at levels that are not harmful. It comes from the decay of uranium that is found in small quantities in all soil and rocks. Radon rises from soil into the air. Outdoors radon is diluted and the risk it poses is negligible. When it enters enclosed spaces, however, concentrations can build up.
Radon is everywhere. There are some areas of the UK where the geology results in higher radon levels, but even in these areas, most homes will not have a problem. The National Radiological Protection Board has produced maps to show the extent of the problem. The only way to know whether a property has elevated levels is to perform a radon test.
It should be emphasised that when the radon concentration is high, it does pose a serious risk to your health. Figures recently published show that 9% of lung cancers are caused by radon gas. A recent international study showed that smokers are at a much greater risk.
Because of the effects of wind and temperature, the air pressure in buildings is usually lower than the air pressure in the soil beneath them. This causes air from the soil to enter the house through cracks and gaps in the floor or walls. This air contains radon gas, and in areas where radon levels in the soil are quite high, indoor radon levels can rise above the Action Level.
Radon can also affect workplaces in the same way as houses. There is legislation to ensure that concentrations are reduced to an acceptable level. This is administered by the either the Health & Safety Executive, or the Environmental Health Officer.