Last edited 06 Nov 2020

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BRE Buzz Researcher Website


Approved document C, Site preparation and resistance to contaminants and moisture, describes radon as:

‘…a naturally occurring radioactive colourless and odourless gas which is formed in small quantities by radioactive decay wherever uranium and radium are found. It can move through the subsoil and so into buildings. Some parts of the country, notably the West Country, have higher levels than elsewhere. Exposure to high levels for long periods increases the risk of developing lung cancer. To reduce this risk all new buildings, extensions and conversions, whether residential or non-domestic, built in areas where there may be elevated radon emissions, may need to incorporate precautions against radon.’

Radon is a naturally occurring radioactive gas released as part of the uranium 238 decay scale. All rocks and soils contain uranium – some more than others – e.g. granite, sandstone, limestone. It travels to the surface through gaps and cracks in the rock.

Areas like Cornwall, where the rock is very fissured, means that radon can escape freely, so levels in buildings can be very high. Areas like Aberdeen, where the rock is very solid, the radon cannot escape and so radon levels tend to be very low.

Radon particles are so fine that our bodies don’t detect them – so unlike dust particles that make us cough – radon is breathed deep into the linings of our lungs. Radon gives a dose of alpha radiation, which has lots of energy, but cannot penetrate through skin, meaning that they release all of their energy in a very small area, damaging cells that can lead to cancerous growths. Radon is linked with approximately 1,100 lung cancer deaths each year in the UK and is the second cause of lung cancer next to smoking.

Radon can be drawn into buildings through cracks and gaps in the ground floor. Radon drawn up into a building gets trapped and can build to high levels, risking health with prolonged exposure. Public Health England advises government on a UK radon action level of 200 Bq per m3 (Becquerel per cubic metre).

There are tests you can do to find out your building’s radon level. Radon testing should be carried out over a long period (3 months) to allow seasonal adjustments to be made (radon levels are usually higher in winter than summer). Radon detectors are passive (small detectors placed and left – they do not need to be plugged in).

If your building has a high radon level, there are ways to combat this, including:

Other resources:

See also Methane and other gasses from the ground, for information about gasses other than radon.

Part of this article was created by --BRE_Buzz. It was originally published on BRE Buzz in November 2015 and was written by Jo Goodwin, Marketing Manager at BRE.

You can see the original article here.

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