What Is Radon?
Radon is a naturally occurring radioactive gas. It seeps up from the ground — specifically from uranium in rocks and soil — and can accumulate inside buildings. You can't see it, smell it, or taste it.
It's the second biggest cause of lung cancer in the UK after smoking. Public Health England estimates it causes around 1,100 deaths per year.
Most people have never heard of it. Even fewer check for it before buying a house.
Where's the Risk?
Radon levels vary hugely by location. The worst-affected areas are:
But hotspots can be highly localised. Two houses on the same street can have very different radon levels depending on the underlying geology and the building's construction.
How It Gets In
Radon rises through the ground and enters buildings through:
Once inside, it can accumulate to dangerous levels, particularly in ground-floor rooms and basements with poor ventilation.
What's a Safe Level?
The UK action level is 200 becquerels per cubic metre (Bq/m³). Above this, you should take action to reduce levels. Between 100-200 Bq/m³ is elevated and worth monitoring. Below 100 is generally considered low risk.
The average UK indoor radon level is about 20 Bq/m³. In affected areas, it can easily exceed 1,000 Bq/m³.
What You Can Do
Before buying: Check the radon risk for any property. Our area reports include radon risk assessments based on the BGS/PHE radon dataset. For detailed property-specific data, you can order a radon report from ukradon.org.
If levels are high: Radon mitigation is effective and relatively inexpensive. A radon sump system (essentially a pipe and fan under the floor) costs £800-1,500 and reduces levels by 90%+. Improving ventilation can also help.
For peace of mind: Radon detectors are cheap. You can get a 3-month test kit for about £30 from the UK Radon Association. It's the only way to know the actual level in your home.
Why Buyers Should Care
Beyond the health implications, radon risk can affect:
It takes five minutes to check. There's no good reason not to.