Radon Gas Risk
Natural radioactivity from the ground beneath
Radon is a radioactive gas released as uranium decays in rocks and soils. It seeps into buildings from the ground, and long exposure indoors raises the risk of lung cancer. Radon potential is the percentage of homes expected above the UK action level of 200 becquerels per cubic metre. The UK Health Security Agency publishes the maps through its UKradon service, covering all four nations.
What This Means
The map describes the ground under the neighbourhood, not the air inside this house. Two identical homes on the same street can test very differently. The reading depends on floor construction, ventilation and how the house is used. Only a test tells you this property's level. Radon is invisible and has no smell, so a viewing will never reveal it. Where levels are high, a one-off building job can cut indoor radon by 90 per cent or more. This does not normally affect mortgage approval, buildings insurance or resale.
Score Ranges
Low Radon Potential
Under 10%Fewer than 1 in 10 homes here are expected to sit above the action level.
Medium Radon Potential
10% to 30%Between 1 in 10 and roughly 1 in 3 homes here are expected above the action level.
High Radon Potential
Over 30%More than 1 in 3 homes here are expected above the action level, so testing matters most.
Practical Advice
- Check this postcode on the UKradon map to see the property's radon potential.
- Order a radon measurement pack from UKradon, around £50, and leave the detectors in place for three months.
- Ask your conveyancer whether the environmental search flags this property as being in a radon affected area.
- If a test comes back above the action level, ask a radon contractor to quote for a sump and fan.
- Ask the builder to confirm radon protection was installed if this is a recent new build in a higher potential area.
Key Points
- An estimated 100,000 to 200,000 UK homes sit above the action level, well under 1 in 100 nationally, but parts of Cornwall exceed 1 in 3.
- Installing a radon sump and fan typically costs £800 to £2,500, a one-off cost set against the purchase price.
Additional Information
Higher potential is concentrated in South West England, the Peak District, and pockets of Wales, Scotland and Northern Ireland, though small hotspots occur almost anywhere. UKradon maps England, Wales and Scotland together, with a separate map for Northern Ireland produced with the Geological Survey of Northern Ireland.