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What is radon?

Radon is a radioactive gas that occurs naturally in the ground; levels are measured in Becquerels per cubic metre of air (Bq m-3). When the gas escapes from the ground, it can dissipate in the open air or become trapped inside buildings. You cannot see, smell or taste radon so unless you have carried out a test, you have no way of knowing whether there are elevated levels of radon in your home. Long-term exposure to high levels of radon is associated with an increased risk of developing lung cancer, particularly if combined with cigarette smoking.

An interactive map can be found on the UK Radon website that shows which areas of the country are more likely to be radon affected. It is important to recognise that the maps are only a guide as to which parts of the country are most likely to be affected by high levels of radon - they are not definitive.

Some areas of the Cherwell district are 'radon affected areas'. This means that at least 1% of the domestic properties have a radon level at or above the Action Level of 200 Bq m-3.

The average level in UK homes is 20 Bq m-3. For levels below 100 Bq m-3, your individual risk remains low and not a cause for concern; however, the risk increases as the radon level increases.

Image depicting Radon Graphic
How Radon gets into the home

How do I know if my home is affected?

The only reliable guide to the level of radon in a building is to measure it using a radon testing kit. Testing for radon is easy and inexpensive; simply purchase a radon test kit from a trustworthy source, place the detectors in your home according to the instructions and then return them to the laboratory for analysis. A home radon test will usually cost less than £50 and is carried out over a three month period. Tests can be purchased from UK Radon.

If you are buying a property or wish to know what levels of radon are likely to be present you can purchase a radon risk report from UK Radon. This will tell you the estimated probability that an address is above the Action Level for radon.

What if my home is affected by high levels of radon?

Where a property is found to be above the Action Level (200 Bq m-3), remedial work should be undertaken to reduce the level. Homes with radon levels between 100 and 200 Bq m-3 should strongly consider taking remedial action. It is also advised that when carrying out remedial action, the aim should be to reduce levels to below 100 Bq m-3 (this is referred to as the Target Level).

The solution very much depends upon the radon level and property construction. At lower levels, the solutions can be simple and cheap to install e.g. replacing old air bricks with more efficient modern ones. At higher levels some form of mechanical system may be necessary. The Building Research Establishment has been working on radon solutions for many years and more information can be found on their web site.

What about new builds or extensions?

In February 2000 the government introduced a requirement for the protection against radon within new dwellings and extensions (set out in Approved Document C1 of the Building Regulations).

The level of radon protection required in your new build or extension depends on the location of your property; protective measures can be included relatively easily and cost-effectively.

All new buildings/extensions which fall within a full or basic radon protection area will be required (through the Building Regulations) to incorporate an appropriate level of radon protection if a new ground floor is provided.

Full radon protection:

The damp proof membrane (minimum 1200g) acts as the radon barrier. It is important that the membrane extends through the cavity and is linked with a cavity tray.

A sub floor sump is also required. Where the existing house has a solid floor the sump could be used to reduce the level of radon in both the extension and the existing building.

Basic radon protection:

Only the continuous damp proof membrane is required.

The detailing in both cases will depend on the type of construction used and the positioning of the damp proof membrane (your Building Control Surveyor will be able to give you further guidance). Wherever possible the construction joint between the new floor and the existing house should be sealed.

If the existing house has a beam and block or suspended timber floor, care should be taken to ensure that the provision of sub floor ventilation is maintained.

If you are considering carrying out building work, you can get general information as to what level of radon protection would be required within your area by contacting your local Building Control Surveyor. You can contact the Building Control Team at Cherwell District Council by emailing or phone 0300 003 0200.

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