British Geological Survey and UK Health Security Agency
Radon Risk Map (Indicative Atlas of Radon)
A national map of radon gas risk in 1 km squares across Great Britain and Northern Ireland, showing what share of homes in each square are likely to be above the radon action level — the answer to the standard radon question asked when a property is bought.
At a glance
- Publisher
- British Geological Survey and UK Health Security Agency
- Licence
- Open Government Licence v3 — Free for commercial use; acknowledge both the British Geological Survey and the UK Health Security Agency. · what this means
- Updates
- Updated occasionally
- Cost
- Free — open data
- Last checked
- 2026-10-14
PropertySolicitors & conveyancingInsuranceConstruction & tradesFacilities managementFlood & ground risk
What your business can use it for
- Risk assessmentFlag properties and workplaces in Radon Affected Areas, where the official advice is to test, before a purchase, a lease or a survey.
- Site selectionSee which candidate sites would need radon protection built in if you extend or build new, and allow for it in the budget.
- Sales prospectingRadon testing and remediation firms can target the 1 km squares where the most homes are likely to be affected.
Works with data you already have
- Properties or sites you already have on a mapMap coordinates1 km grid squares on the British National Grid (Irish Grid for Northern Ireland); find the square each point falls in, with the 50 m buffer BGS advises.
- Property or site postcodesPostcodesTurn postcodes into coordinates with the free ONS postcode lookup, then find the square each falls in.
How to get it
- Indicative Atlas of Radon — Great Britain and Northern IrelandBulk downloadNo account or form. Mapping files (shapefile or GeoPackage), one for Great Britain and one for Northern Ireland, each with a user guide. Updated rarely — Great Britain last in 2022.
- UKHSA radon maps — look up one areaPortalThe UK Health Security Agency's public maps, for checking a single place by hand.
What's involved in using it
- It is a map of squares, not a list of addresses, so your properties have to be placed on the map before you can read off a class.
- Great Britain and Northern Ireland come as separate files on different map grids, so combining them means converting one to match the other first.
- Some coastal addresses fall just outside every square — treat that as 'not covered', not as the lowest class.
The technical detail, for whoever sets it up (4)
- Each square shows the highest radon class found anywhere inside it, so it is deliberately cautious — a site can be in a lower class than its square.
- It estimates the share of homes above the action level in an area; only a test tells you the level in a particular building. Basements and cellars carry extra risk whatever the class.
- Class 2 and above is a Radon Affected Area, where the official advice is to test. In England and Wales classes 3 and above need protective measures in new buildings and extensions; in Scotland, class 2 and above.
- Northern Ireland's map dates from 2015 and has not been revised; Great Britain's was updated in 2022.
Ask us about Radon Risk Map (Indicative Atlas of Radon)
Ask a factual question about Radon Risk Map (Indicative Atlas of Radon) — what it covers, how often it changes, whether it matches the records you keep — and we will answer, free. Or tell us what you are trying to work out, and we will tell you what it would take to get this data working next to the numbers you already have.