Buyer guides
Radon in a house: maps, tests and results
You cannot smell a radon problem
Radon is a naturally occurring radioactive gas. An area map indicates the likelihood of homes exceeding a reference level; it does not measure the air in the home you are buying. A lower map category is not an individual test result.
Ask for the actual test report
Ask the seller whether testing has been carried out and whether remedial work has followed. Check the address, test period and report, rather than accepting “the area is fine”. If no usable result exists, discuss testing and the transaction timetable with the conveyancer.
How a home measurement works
UKHSA describes using detectors in a bedroom and living room for three months to estimate the annual average. A brief reading can fluctuate with weather and ventilation. Agree where detectors will be placed and who will receive the final laboratory result.
Reading the result
UKHSA recommends reducing levels where the annual average exceeds 200 Bq/m³; the target level is 100 Bq/m³. These concentrations are different from a map percentage. Discuss elevated results with a radon specialist and retain evidence of any remedial work and follow-up testing.
Keep the test tied to the home
Retain the full laboratory report rather than a cropped number. Note where the detectors were placed, the dates and whether a mitigation system was running. If the seller describes previous work, ask for its records and subsequent test results. A photograph of installed equipment alone does not explain current indoor levels.