UK Radon Gas Map & Action Level Checker
Check UK Health Security Agency (UKHSA) radon potential bands (<1% to >30%), the 200 Bq/m³ statutory Action Level, solicitor conveyancing retention bonds, and remediation costs.
Interactive UKHSA Probability & Action Level Auditor
Select your UKHSA estimated radon band and foundation construction to compute statutory mitigation requirements.
HIGH RISK (RADON AFFECTED AREA)
RECOMMENDED (£1,000 – £1,500 Solicitor Retention)
A retention clause in the purchase contract holds back funds from the seller for 6 months while the buyer conducts a 3-month UKHSA test post-completion.
Basic Radon Protection (Continuous damp-proof gas membrane under slab)
Positive Input Ventilation (PIV) or Passive Subfloor Sump (£800 – £1,600)
Radon is a radioactive gas naturally emitted by uranium in granite and limestone. The UK Health Security Agency (UKHSA) sets the statutory Action Level at 200 Bq/m³. In areas where probability exceeds 1%, standard environmental conveyancing searches flag radon risk. Because testing takes 3 months, solicitors negotiate a Radon Retention Bond (£1,000–£2,500) held in escrow from sale proceeds so completion is not delayed.
Highest Radon Exposure Areas in England & Wales
Extensive granite batholiths (Dartmoor, Bodmin, Land's End). Over 30% of properties exceed the 200 Bq/m³ Action Level.
Karst carboniferous limestone geology with deep fissures allowing radon migration into cellars and stone cottages.
Ironstone and oolitic limestone strata in Kettering, Corby, Daventry, and parts of Gloucestershire and Somerset.
Explore Connected Environmental Due Diligence Tools
Cross-reference air quality, flood risk, and building age.
Run Full 12-Point Due Diligence for SW1A 1AA
Screen flood risks, ground stability, radon, Land Registry deeds, planning buffers, and EPC efficiency in under 3 seconds with zero sign-up.
Rivers, sea, surface water flash floods, and active EA alerts.
Bands A–H, billing authorities, and parish precept breakdowns.
Street-level burglaries, vehicle crimes, and monthly frequencies.
Actual Land Registry completion prices & HPI-adjusted values.
Tree Preservation Orders, Conservation Areas, & Article 4.
Official 2025/26 progressive HMRC rates and surcharge reliefs.
Official council website, planning portal, council tax & office details.
Official planning permissions, building extensions & decisions nearby.
Statutory public rights of way, bridleways, and OS OpenData path easements.
Official RdSAP construction era, Victorian/1930s typology, and EPC data.
Grade I, II*, & II alteration rules, criminal penalty risks, and LBC checklist.
BGS clay shrink-swell hazard, foundation era & tree root zone screening.
Nearby NHS GP surgeries, patient acceptance status, and closest A&E.
Essential Environmental Conveyancing Reading
Finished your Radon Gas Risk Check? Run the Full 12-Point Due Diligence Dossier.
Individual checks only reveal one piece of the puzzle. Our comprehensive desktop baseline brief cross-references Environment Agency flood maps, British Geological Survey subsidence layers, UKHSA radon risks, Land Registry sold price comparables, and local planning buffers into one audit-ready brief.
Frequently Asked Questions: UK Radon Gas & Conveyancing
UKHSA Action Level thresholds, radon retention bonds, and Building Regulations Part C explained.
Radon is a naturally occurring, colourless, odourless radioactive gas produced by the radioactive decay of minute quantities of uranium naturally present in all rocks and soils (especially granite, limestone, and phosphatic rocks). In the open air, radon disperses harmlessly. However, when it seeps into buildings through cracks in foundations and suspended timber floors, it can accumulate to toxic concentrations. According to the UK Health Security Agency (UKHSA), radon is the single largest cause of lung cancer in the UK after smoking, causing over 1,100 deaths annually.
Statutory Diligence Guides & Legal FAQs
Official regulatory answers referencing Acts of Parliament, RICS guidance, and statutory planning orders.
How Do I Check if My Postcode is in a Radon Risk Zone in the UK?
To check if your UK postcode is in a radon risk zone, enter your postcode into the UKHSA (UK Health Security Agency) and BGS (British Geological Survey) Indicative Atlas of Radon or use our free UK Radon Gas Postcode Checker. The interactive map shows whether your 1km square has a 1% or greater probability of exceeding the UK Action Level of 200 Becquerels per cubic metre (Bq/m³). If a postcode sits in a designated Radon Affected Area (such as parts of Devon, Cornwall, Derbyshire, or the Scottish Highlands), conveyancers and environmental searches will recommend ordering a 3-month physical detector test kit.
Where in the UK Has the Highest Radon Gas Levels?
The areas with the highest radon gas levels in the UK are South West England (Devon and Cornwall), the Peak District in Derbyshire, the Mendip Hills in Somerset, parts of Northamptonshire and Gloucestershire, upland Wales (Gwynedd and Powys), and the Scottish Highlands and Grampians. In parts of Cornwall and Dartmoor, over 30% of residential properties exceed the UK Action Level of 200 Bq/m³, driven by subterranean granite batholiths and uranium-rich limestone geology.
Should I Worry About Radon Gas When Buying a House in the UK?
No, you should not panic if a house you are buying is in a radon-affected area, but you must address it during conveyancing. Modern mortgage lenders do not refuse mortgages due to radon risk, because radon is easily remediated using inexpensive positive input ventilation (PIV) or sub-floor sumps costing between £800 and £2,000. When buying in a high-risk zone, your solicitor can insert a 'Radon Bond' into the contract—holding between £1,000 and £2,500 of the seller's proceeds in escrow for 3 to 6 months post-completion to pay for testing and any necessary mitigation equipment.
What Are the Health Risks and Symptoms of Radon Gas in UK Homes?
Radon gas causes no immediate or acute physical symptoms: it does not cause headaches, coughing, eye irritation, nausea, or fatigue. Because radon is completely odorless, colorless, and tasteless, high levels go entirely unnoticed without dedicated detectors. The sole health risk of radon is long-term radioactive damage to the respiratory system. Inhaling radon decay products (alpha radiation emitters) damages lung tissue DNA, making radon the second leading cause of lung cancer in the UK after tobacco, responsible for approximately 1,100 lung cancer deaths annually. The risk is 25 times higher for cigarette smokers due to synergistic radiation-carcinogen interactions.
Can You Check Radon Gas Levels by Postcode for Free in the UK?
Yes, you can check whether your UK postcode is in a designated radon risk area 100% free of charge using the official UKHSA/BGS Indicative Atlas or our free UK Radon Gas Postcode Checker. Free online tools display the 1km statistical probability grid and Action Level thresholds. However, free tools only estimate the regional probability; discovering the actual indoor radon concentration of your specific house requires ordering a physical test kit containing two passive alpha-track detectors, which costs £50 to £60 including laboratory analysis.
What Are Safe Radon Gas Levels in UK Homes?
In the UK, radon gas is measured in Becquerels per cubic metre of air (Bq/m³). The national average radon concentration in UK homes is approximately 20 Bq/m³, which is completely safe. The UK Health Security Agency defines 100 Bq/m³ as the 'Target Level' (the ideal maximum for remediated homes and new builds) and 200 Bq/m³ as the statutory 'Action Level'. If an indoor physical test reveals concentrations exceeding 200 Bq/m³, the UKHSA strongly recommends installing remediation equipment to reduce the radioactive burden.
What Does It Mean if a Property is in a Radon Affected Area?
Under UK public health standards, a 'Radon Affected Area' is defined as any geographic 1km square where there is a 1% or greater statistical probability that residential properties will exceed the UK Action Level of 200 Bq/m³. Being in a Radon Affected Area does not mean your house definitely has high radon, but it triggers statutory obligations: local planning authorities and Building Regulations (Approved Document Part C) mandate that all new build homes and major ground-floor extensions constructed in these zones must install basic or full radon protective barrier membranes.
How Do You Use the UKHSA and BGS Radon Gas Map in the UK?
To use the UKHSA and BGS Indicative Atlas of Radon, navigate the interactive digital map using a postcode, town name, or National Grid reference. The map displays a colour-coded overlay representing 1km grid squares, where lighter yellow shades indicate low risk (<1% probability of exceeding the 200 Bq/m³ Action Level) and darkening shades of orange, magenta, and deep purple signify progressively higher risk categories up to >30% probability. Clicking on any grid square reveals the exact statistical percentage band, the recommended Building Regulations protection tier, and health advice.