Radon Monitoring in the Workplace (UK) – 2026 Compliance & Risk Guide
Radon monitoring in the workplace is a legal responsibility for every UK employer. Radon is a naturally occurring radioactive gas that can build up inside buildings, particularly in below-ground areas. This poses a significant risk to lung health and other health complications.
Under UK legislation employers must assess and manage radon risk where applicable.
This guide aims to explains when radon testing is required, how radon monitoring works, and what action you must take if elevated levels are found within your premises.
What Is Radon and Why Is It Dangerous?
Radon is a colourless, odourless radioactive gas formed naturally from the decay of uranium in rocks and soil. It can enter buildings through little cracks in floors, service ducts, joints and any other openings that come in contact with the ground. Once inside the buildings radon can accumulate to very high concentrations levels, particularly in basements, cellars, mines, and other workspaces below the ground.
Radon is a naturally occurring radioactive gas and should be considered as indoor air pollution. In fact, exposure to radon gas is the leading cause of lung cancer in non-smokers and is responsible for over 1100 deaths in the UK every year.
It produces tiny radioactive particles in the air we breathe, and when inhaled, radiation from these particles can damage lung tissue and, over prolonged periods of exposure, may lead to lung cancer. The higher the radon concentration and the longer the exposure, the greater the health risk.
High radon levels can be found in buildings of any type, size or location. It’s typical that the occupants are unaware of the potential danger that lies beneath them because radon cannot be seen, smelled, or tasted. Because radon cannot be seen or smelled, the only way to determine whether a workplace has elevated levels is through radon measurement and monitoring.
Monitoring Required by Law?
Under the Health and Safety at Work 1974 Act, all UK employers have a duty to protect the health and safety of their employees and members of the public that may be affected by their activities in the workplace.
The Ionising Radiations Regulations 2017 (IRR17) states action is required where radon concentrations is above the defined level of 300 Bq/m3 (annual average). The Health and Safety Executive (HSE) and Local Authorities are responsible for enforcing these regulations in certain types of workplace. For residential developments and schools, it’s above 200 Bq/m3.
Employers must carry out a full radon risk assessment to determine whether monitoring is required. Failure to assess radon risk where applicable can result in enforcement action against your company or business.
When Is Workplace Radon Testing Required?
- Above-Ground Workplaces
If your premises are located in a designated Radon Affected Area (as defined by UK Health Security Agency mapping), or “at risk area”, radon monitoring should be carried out.
Even outside of the defined affected areas, radon can still occur, particularly in older buildings or where ground conditions allow gas migration. So these “outside” areas need assessing too.
- Below-Ground Workplaces
Radon measurement is required in all occupied below-ground workplaces in the UK, regardless of affected area status. This includes:
- Basements
- Cellars
- Mines
- Caves
- Tunnels
- Underground car parks
For occupied below-ground workplaces (for example those occupied greater than an average of an hour per week or approximately 50 hours per year), or those containing an open water source, the risk assessment should include radon measurements.
If a room has walls in contact with soil, it should be considered for radon monitoring.
Below-ground environments typically present a much higher risk due to the limited ventilation and proximity to radon sources in the soil.
How Is Radon Measured in the Workplace?
Workplace radon measurement typically involves:
Long-Term Radon Monitoring
Passive single-use radon detectors are usually the standard and will be placed in occupied areas for approximately three months to determine the annual average radon concentration and exposure. This method aligns with HSE guidance.
Continuous Radon Monitoring
Continuous Radon Monitoring, or CRM systems are electronic radon monitors that can provide ongoing measurement. These are particularly useful in higher-risk environments, and track radon gas in real time, offering instant data without having to rely on laboratory assessments and analysis.
What Happens If Radon Levels Exceed 300 Bq/m³?
If the monitoring shows radon levels above the level of 300 Bq/m3 (annual average), employers must take immediate steps to reduce exposure. They will also need to work on the following:
- Consider mitigation measures (e.g. improved ventilation, radon sumps)
- Appoint a Radiation Protection Adviser (RPA) where required
- Notify the HSE if applicable
- Implement ongoing exposure monitoring
Prompt and immediate action reduces health risk and demonstrates regulatory compliance. Ignoring this can lead to further health implications as well as prosecution and fines. Remember, it is your legal duty to assess any risks to your employees.
If high levels are found, the HSE may enforce a closure on the building you occupy or work in, allowing for return when remedial actions have been implemented.
For residential developments and schools, it’s above 200 Bq/m3.
What Are the Industries Most at Risk from Radon Gas Exposure?
Industries with the highest risk to radon has exposure tend to be those working underground and in areas not ventilated. This can range from:
- Construction and civil engineering Utilities
- Utilities and water treatment facilities
- Education buildings with basements
- Healthcare premises
- Heritage and listed buildings
- Industrial and manufacturing sites
- Underground infrastructure
However, elevated radon levels can occur in any workplace in contact with the ground.
How Often Should Radon Monitoring Be Carried Out?
Radon risk assessment should be reviewed when acquiring new premises, after any large structural changes, and periodically in the above mentioned higher-risk environments. If mitigation systems are installed, follow-up radon testing is required to confirm effectiveness.
Workplace Radon Monitoring Services
Earth Environmental & Geotechnical provides compliant radon monitoring and radon risk assessments across the UK.
At Earth Environmental & Geotechnical we have also invested in the MARKUS 10 instruments which allows for in-situ measurement of radon gas in the soil. This allows for some assessment to be completed pre-development and can help in determining the level of protection required at a design stage.
At Earth Environmental & Geotechnical we provide specialist radon gas survey, monitoring, and radon gas assessment services across the UK.
We work with employers, facilities managers, local authorities, commercial property developers, engineering firms and many more to ensure compliance with HSE and IRR17 requirements.
Need Radon Monitoring in Your Workplace?
If your workplace is in a radon affected area, contains below ground rooms, or hasn’t been tested, arranging radon measurement is the only way to confirm safety and compliance in the UK. Contact Earth Environmental & Geotechnical today to discuss your workplace radon monitoring requirements and ensure your organisation meets UK regulatory standards.
Alternatively, email headoffice@earthenvironmental.co.uk or call our head office on 0161 975 6088
