The short answer
Radon is a naturally occurring radioactive gas. A home test measures your exposure; a building assessment helps identify the right reduction method if the result is elevated.
An invisible gas, a measurable issue
Radon comes from the natural breakdown of uranium in rocks and soil. Outdoors it disperses; indoors it can accumulate. It is not a stain, a smell or something a normal smoke or carbon monoxide alarm detects.
Start with information about your property
Official area information gives context, but neighbouring properties can have different indoor concentrations. Record whether the home has a basement, a solid or suspended ground floor, and any previous radon test results.
Measure before choosing a remedy
Use a radon test and follow the laboratory’s instructions. A standard domestic test runs over three months to account for short-term variation. The result, rather than the appearance or age of a house, informs the next step.
Build a plan around your result
If reduction is recommended, discuss the available methods with someone experienced in radon work. Keep the report, installation details and follow-up test together as part of your property records.
Sources & further reading
UKHSA: information about radon ↗UKHSA: measuring radon in homes ↗UKHSA: Action Level and Target Level ↗Checked 13 September 2026. General property guidance; use the original source and seek professional advice for your circumstances.