Radon is the biggest single source of radiation exposure to the UK population in both homes and the workplace. It is a colourless, odourless radioactive gas that is formed by the decay of elements which occur naturally in rocks and soils. In the UK, radon is the second largest cause of lung cancer (after smoking) and is attributed to over 1,000 lung cancer deaths per year.
The greatest exposure risk from radon arises from the radioactive products which are formed when radon decays. These solid products cling to dust, which may be inhaled, causing the delicate soft tissue lining the lungs to be exposed to intensely ionising alpha radiation.
Under the Health and Safety at Work etc. Act 1974 employers must, so far as is reasonably practicable, ensure the health and safety of all those who have access to their workplace. This includes employees, contractors, students and members of the public.
The Management of Health and Safety at Work Regulations 1999 require the assessment of health and safety hazards throughout all workplaces. Where the radon concentration exceeds the relevant reference level (300 Bq/m3 as an annual average), the Ionising Radiations Regulations 2017 (IRR17) apply, and the employer is required to take certain actions to restrict exposures.
Under the requirements of the Ionising Radiation (Basic Safety Standards) (Miscellaneous Provisions) Regulations 2018, Public Health England have produced the UK National Radon Action Plan: https://www.gov.uk/government/publications/uk-national-radon-action-plan This Plan provides a comprehensive guide to radon exposures in the home and workplace.
The single largest exposure to radon in the UK comes from radon gas entering the air in buildings from the underlying soil and rock (Figure 1). The ingress of radon into buildings is driven by the lower air pressure inside created by such factors as heating, ventilation and outside wind.
Radon may also be emitted by natural radionuclides in building materials, although studies have shown the effect of this to be relatively low. Another source of radon is the use of certain radionuclides in commercially available products and in research or industrial purposes. Products of note include thoriated gas mantles and radium luminised articles.
Radon gas dissolves in water and so may enter a building via the water supply and be released into the indoor air. Radon concentrations in public water supplies are likely to be low due to the dilution, storage and treatment of this water. However, radon from private water supplies, particularly underground sources, can pose a more significant risk.
Whilst all workplaces can be affected, employers with underground work areas and poorly ventilated work spaces are more likely to experience elevated radon levels. Clearly, therefore, radon problems can be exacerbated by modern, energy efficient buildings with poor air circulation.
Figure 1: Sources of exposure to ionising radiation in the UK. Source: Public Health England
When should employers conduct a radon survey?
Employers should conduct a radon survey if either:
- The workplace is located in a known radon affected area (see link below).
- Employees spend on average more than 1 hour per week in underground work areas.
Employers should consult the interactive radon map to check if their workplace is in a known radon affected area: https://www.ukradon.org/information/ukmaps
Control measures and remediation
Where a work area exceeds an annual average radon concentration of 300 Bq/m3 employers will either have to:
- Inform employees about the radon risk and restrict access to the area.
- Conduct remediation work to reduce radon levels below 300 Bq/m3.
The role of a Radiation Protection Adviser
The Ionising Radiations Regulations 2017 apply when working in an environment where the annual average radon concentration exceeds 300 Bq/m3. As such the Employer must take the following actions:
- Notify the HSE that you are working in a radon affected environment [Reg 5]
- Conduct a suitable and sufficient radiation risk assessment [Reg 8]
- Take appropriate action to restrict exposures to ionising radiation [Reg 9]
- Consult a suitable Radiation Protection Adviser [Reg 14]
The RPA should be able to assist with:
- Arranging a radon survey
- Interpretation of results
- Remediation measures and controlling exposures
- Achieving compliance with the Ionising Radiations Regulations 2017