Radon is a naturally occurring radioactive gas that is the second leading cause of lung cancer in the UK after smoking. It enters buildings from uranium-bearing rock and soil. The UK Health Security Agency (UKHSA) action level for homes is 200 becquerels per cubic metre (200 Bq/m²). Landlords with properties above this level have an obligation under the HHSRS to take remediation action, and a disclosure obligation under the Material Information rules.
Cornwall, Devon, Somerset (Mendips), Derbyshire (Peak District), Northamptonshire, Rutland, Lincolnshire, and parts of the Cotswolds are the highest-risk areas in England. Check the UKHSA interactive postcode map for your property.
HHSRS and enforcement
- 200 Bq/m² or above: High HHSRS hazard, local authority has a duty to act if it inspects. Improvement Notice can require remediation
- 100 to 200 Bq/m²: UKHSA recommends remediation even below the action level
- Failure to comply with an HHSRS Improvement Notice: criminal offence, fine up to £5,000
Testing
- Minimum 3-month passive alpha-track measurement (winter preferred for accuracy)
- UKHSA-approved laboratory required, approximately £50 to £80 including lab analysis
- Test in ground floor main habitable room and bedroom. Basement flats: test in the lowest occupied space
Remediation options
- Positive pressure unit (PPU): fan pressurises living space, £400 to £600 supply and install
- Sub-floor sump depressurisation: most effective (80 to 90% reduction), best under concrete slab, £800 to £1,500
- Sub-floor ventilation (suspended timber floors): air bricks or powered sub-floor fan, £200 to £600
- Re-test after 3 months (winter) to confirm reduction
Material Information disclosure
National Trading Standards Material Information Part B (2023) requires landlords and agents to disclose whether a property is in a radon-affected area. Non-disclosure of known elevated radon risk is likely a breach of the Consumer Protection from Unfair Trading Regulations 2008.