Alert Section


What is Radon?

  • Radon is a natural radioactive gas. You cannot see, hear, feel or taste it. It comes from the minute amounts of uranium that occur naturally in all rocks and soils.
  • Radon is present in the soil in all parts of the UK to varying degrees. Most of it seeps from the ground harmlessly into the atmosphere. However, where it enters buildings, levels can build up and occasionally become a significant radiation risk to people inside.
  • North Wales is one of the areas in the UK which has generally higher levels of radon. Radon is the second largest cause of lung cancer in the UK after smoking and therefore precautions may be needed if your staff are working in a high radon environment. For more information visit: (new window)

How does Radon affect people’s health?

The decay products can cause the following health problems:

  • Damage the cells in the lungs - the decay products emit hazardous radiation known as alpha particles; it is these particles that damage the sensitive cells in the lungs
  • Lung cancer - is the biggest cause of cancer related death in the UK. Radon is the second largest cause of lung cancer again in the UK. 

What should Employers be doing to reduce the risk of Radon exposure?

Unless you have already done so, health and safety legislation requires you to assess the radon risk in your workplace. Firstly you will need to establish whether your business premises are situated in a radon Affected Area. Large areas of North Wales are designated by government as an Affected Area and you can view the online map at (new window)

The only way to determine whether radon levels within your premises are high is to measure the concentrations in the air. Once this has been carried out you can do a risk assessment as to whether further action is needed.

Radon measurements are made using relatively cheap dosimeters that you order online and receive through the post. You then site them in areas of your building - usually for 3 months. Information on organisations that can provide measurement services, practical information about siting dosimeters, and carrying remedial action can also be found at the HSE website.

Testing - Radon Measurements

Radon surveys should be conducted in any building or basement where its location and characteristics suggest that elevated levels may be found and significant exposures to employees and/or other persons are possible. Inexpensive surveys can be carried out by leaving small plastic passive detectors in rooms of interest. These can be provided through Public Health England at (new window) or you can look online for alternative companies who offer this service.  After 3 months of sampling the detectors can be sent to the lab for testing and the results will be sent to you via post.

Results - Radon Measurements:

Where the workplace measurements show radon levels below 400 Bq/m3, as is the case for the majority of employers, then the only further action required is to decide when the risk assessment will be reviewed.

For occupied areas with levels above 400 Bq/m3, the employer may need to immediately take steps to manage occupational exposures pending any decision they may take to reduce the radon levels by engineered means. A Radiation Protection Adviser with radon experience should normally be consulted about how best to manage radon exposures but, if the employer plans to immediately remove the radon so that the Ionising Radiation Regulations 1999 do not apply, it is better to consult a specialist radon removal (remediation) contractor in the first instance. The specialist will be able to advise on the most cost effective engineered means of reducing radon levels. It is usually appropriate to continue monitoring in these areas at least until the reduction measures have been put in place. Advice on appointing an Advisor can be found at: (new window)

You will need to take into account seasonal changes. Radon is known to have higher levels in the winter than in the summer.

Monitoring in the home

As people spend most of their time in their home, in radon Affected Areas employees could also be receiving significant exposure at home.  

Employers are strongly encouraged to recommend home testing to their employees who live in a radon Affected Area.  The action level in the home is 200 Bq/m3, which is half the amount that you would expect in a workplace.Homeowners can get a Home Measurement Pack from UK Radon through the Public Health England website. They offer similar service for a small fee, to that identified in the Testing section above.

Once measurements have been undertaken and the results show that the radon level in the home is 200 Bq/m3 homeowners would be advised to rectify this using control measures to reduce the level to below 100 Bq/m3.

It is important for Employers to be aware of radon and understand the potential dangers that radon decay products can cause. It is highly recommend that you make employees aware of this so they can do the relevant tests in their home. Homeowners can get a Home Measurement Pack from UK Radon through the Public Health England website. They offer similar service for a small fee, to that identified in the Testing section above.