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Radon in the workplace

Radon-222 is a naturally occurring, colourless, odourless, radioactive gas. It is the second largest cause of lung cancer in the UK and all employers have a duty to assess the risk of exposure to their employees.

Measuring radon is cheap and simple and if levels are found to be excessive there are a number of solutions available to reduce the concentration of radon gas within buildings.

What is radon?

Radon-222 is a naturally occurring radioactive gas that comes from traces of uranium found in many rocks and soils. It can seep out of the ground and build up to become a hazard in houses and workplaces. When radon gas is breathed in the highly radioactive decay products of radon can become lodged in the lungs and damage the sensitive cells in the lung lining. Radon accounts for around half the total radioactive dose received by the UK population and is the second largest cause of lung cancer in the UK.

Where is it found?

Much of the Stroud District is affected by radon to some extent. Public Health England has extensively mapped the occurrence of radon in buildings in the UK and produced a colour coded radon indicative atlas to indicate where the higher levels are found (all of the coloured, 1 km square grids on the map have “Affected Area” status). It is easy to locate your workplace on the map and a more specific report for your building can be obtained for a few pounds.

What do I have to do?

All employers are required to carryout a risk assessment of potential exposure of employees to radon gas. If:-

  • the workplace is in a radon affected area, or
  • below ground rooms are occupied for more than 1 hour per week/ 52 hours per year, or
  • workrooms contain an open water source

the risk assessment should include radon measurements.

All buildings built after 2000 in radon affected areas are required to have protective measures installed during construction. However, since the severity of radon on a site cannot be predicted until after the building has been constructed, employers must still test for radon in newer buildings if the above circumstances apply.

How do I test for radon?

Radon surveys involve placing inexpensive passive detectors in rooms where radon levels are most likely to be high (usually occupied basement and ground floor rooms). The detectors are left in place for several months and then returned to a validated laboratory for analysis. PHE’s UKRadon website contains details of how to obtain detectors and carryout radon measurement.

What will the test results mean?

Radon is measured in units of becquerels per cubic metre of air, Bq/m3 ( i.e. the concentration of radioactivity in the air). The action level for workplaces is 300 Bq/m3. If measurements are below 300 Bq/m3 then no further action is required other than to review the risk assessment in a few years time. If measurements in occupied areas exceed the action level then the Ionising Radiation Regulations 2017 apply you may need to take immediate steps to manage exposures while you decide how to reduce radon levels by engineered means. A specialist radon remediation contractor will be able to advise you on the most cost effective methods. If you decide not to take immediate action to reduce radon levels then you will need to consult a Radiation Protection Advisor (RPA) on how best to manage exposure in the meantime.

How often should risk assessments be reviewed?

Risk assessments must be reviewed after significant changes are made to the fabric of the building. If you have consulted an RPA they will be able to advise you on appropriate intervals. In other cases the frequency set out below is suggested:-

  • radon levels significantly less than 300 Bq/m3 - around once every 10 years
  • radon levels slightly less than 300 Bq/m3 - around once every 3 years
  • radon levels initially above 300 Bq/m3 and remediation measures taken - around once every 5 years.

Where radon is controlled by an engineered solution (such as a radon sump) your risk assessment should include regular checks that the control measures are functioning correctly and are properly maintained.

What if my employees are concerned about their exposure?

If employees live in radon affected areas they could also be receiving significant exposure at home. They can also arrange domestic radon testing at low cost (around £50 per house) through the verified laboratories. Employees may be concerned about their possible radon exposure at work and PHE has provided information on their website to help answer these questions.