Radon comes from uranium, which is present to a small extent in all soils and rocks. It seeps out of the ground and can collect in enclosed spaces, such as houses and other buildings.
As amounts of uranium in the ground vary from place to place and because some ground allows air to move more freely, radon levels are higher in some parts of the country than in others. Some of the largest emissions in the country originate from rocks present in the geology of the South West of England.
Radon in buildings
In open spaces, when radon mixes with air, it is quickly diluted in the atmosphere. But when air containing radon rises from the rocks and soil beneath your home it may find its way inside. This is mainly through cracks in floor, walls and gaps around service pipes. The level of radon indoors depends mainly on how much radon is in the ground and on the way in which the house is built.
Radon only becomes hazardous to health when it builds up in enclosed spaces. Health studies around the world have linked radon with lung cancer. People who are exposed to high levels of radon are at risk of getting lung cancer. This risk is much higher to smokers than it is to non-smokers.
Measuring radon levels
Surveys have shown areas of the country that are at risk of radon and most homes in the United Kingdom do not have significant radon levels. However, some parts of Somerset are at risk from levels that require action.
The government has set an action level for radon in houses of 200 becquerels (a becquerel is a measure of a unit of radioactivity). If the levels in a house are higher than this, the householder is advised to take action.
The British Geological Survey can examine available data – there is a charge – and offer advice about whether precautions may be required in a particular location.
The UK Health Security Agency website helps you to check your area for radon. If you are concerned, you can also order a radon measurement pack to find out the yearly average radon level for a property, and if it is above or below the action level.
Precautions where there are higher levels of radon
The Government has drawn up three categories of precautionary actions relating to radon:
- not affected by radon – no precautions required.
- basic radon precautions required – a well sealed damp proof course, including a cavity tray.
- advanced radon precautions – include a sump beneath the floor, connected to the air outside, with a pipe to which a pump can be connected at a later date.
Building regulations require precautions to be taken, where necessary, to prevent radon gas getting into new dwellings. The council’s Building Control team can give advice about radon precautions in new dwellings.
Buying land and property
Even in affected areas, most homes do not have a radon problem. In some cases, we may be able to provide an estimated probability that a particular property is above the action level for radon.
You can get a more accurate estimated probability from the UK radon website – there is a charge. The only way to accurately find out is to carry out a radon test.
If you are buying a home, ask whether it has been tested for radon. Sellers are not legally obliged to volunteer the information that they know. But if you ask for it, they must give it. Ask to see a letter giving the result.
If, as in most cases, the result is under the action level, the home does not need to have the radon level reduced. If the result is above the action level, then there may be a problem.
In homes that do have a radon problem, the radon level can usually be reduced with simple, effective and relatively inexpensive measures.
Employers and their employees
Employers have a legal duty to ensure employees are not exposed to high levels of radon in the workplace.
You can find more advice and information about radon in the workplace on the Health and Safety Executive website The website has publications for download and advice on how to comply with the law.
The council’s Building Control Team can also provide information regarding radon in existing and new build properties.