What is radon gas?

Key information
  • Radon Gas is formed by the decay of a small amount of uranium occurring naturally in the ground.
  • Using a radon map will help determine if an area is affected by high radon levels.
  • If your home or business premises exceeds the limits of what is considered a healthy Radon gas reading (100 Bq m-3), there are several remediation options for you to reduce the contamination to a healthy level.

Where does radon gas come from?

Radon gas is formed by the decay of the small amount of uranium that occurs naturally in the ground and is both invisible and odourless. Radioactivity is where unstable elements break down releasing energy and forming different elements. Measured in becquerels per cubic metre of air (Bq m-3), the gas is emitted from the ground in part of the uranium decay series: Uranium > Radium > Radon.

How can it affect human health?

When someone breathes radon gas, it exposes them to small amounts of radiation. Over a long time, the damage to the cells lining the lungs can increase someone’s risk of lung cancer. This risk increases with every year someone spends in a radon-contaminated premises. In the UK radon causes 1,100 deaths a year, the second leading cause of lung cancer after smoking. Overall, the risks to individuals remain relatively low for radon gas levels below 100 Bq m-3, and with the average radon gas level in the UK sitting at 20 Bq m-3 the majority of buildings are at a safe level.

Where are the areas of high radon activity?

Radon gas levels vary significantly depending on location and the amount of gas that may end up in a building depends largely on two factors: the concentration of radon beneath the ground, and the permeability of buildings above. The first step you can take to check if you live in an area of high radon concentration is to use a digital radon map. If the area has a moderate to high radon rating, carrying out a radon assessment is advisable. 

If you are not the property owner your landlord or employer is legally required to carry out appropriate checks. For landlords, compliance with the Housing Health & Safety Rating System includes conducting a risk assessment for radon and taking appropriate measures to mitigate any risks identified. Employers also have a duty of care to their employees and must comply with legislation related to radon in the workplace.

It's worth noting, just because an area has high levels of radon gas doesn’t mean the space inside a building will have high levels. The gas enters the building through cracks in floors or walls, or pipes, so if you have a well-insulated building you may have low inside radon gas levels, even when ground radon levels are high.

What mitigations can be installed?

In buildings that are contaminated with high radon levels over 100 Bq m-3, don’t worry, depending on the floor type and radon level of the affected areas, a number of actions can be taken:

Cases under 500 Bq m-3

Most cases for both solid and suspended floors experiencing radon levels below 500 Bq m-3 can be fixed using a simple positive ventilation system to blow fresh air from the roof space into the building, typically costing between £500 - £1000.

Solid floors with over 500 Bq m-3

Radon sumps are generally known as the most effective way to mitigate radon gas radiation. Properties with solid floor types can be fitted with a unit in the foundations of the building that collects radon and other ground gasses. Radon sumps typically cost £800 - £2000.

Suspended floor with over 500 Bq m-3

For radon levels greater than 500 Bq m-3 to reduce the level of radiation to a healthy level fitting an underfloor ventilation system may be the best solution. Natural under-floor ventilation where the vents are fitted to allow the natural flow of air through the ground levels, typically costing £200 - £600. Where natural underfloor ventilation is inadequate active underfloor ventilation can be installed, where the air is blown with a fan beneath the suspended floor, usually costing £700 - £1500.

Search through Addland's radon layer now to see if your building may need remedial action.

Published: 23 March 2023
Last updated: 30 March 2023

Share this story


Frequently asked questions about radon gas