Reducing radon risk in commercial property

Radon is a naturally occurring radioactive gas that can seep out of the ground and build up in houses and any indoor workplaces. Under UK regulations, the risk from radon in commercial property must be assessed.

Under the Health and Safety at Work Act 1974, landlords and employers occupying commercial premises have responsibility to ensure that their properties are safe places for employees and other persons. The Management of Health and Safety at Work Regulations 1999 also require the assessment of health and safety risks. This includes considering the risk of radon. If an occupied workplace is located below ground or in the ground floor of a building in a radon Affected Area, the risk assessment should include radon measurements.

Commercial properties are affected in different ways depending on whether they are over or below ground. Any below ground properties, such as basements and cellars, can have significant levels of radon irrespective of their geographical location. In addition, the slightly lower air pressure in these parts of buildings means that the basement draws radon gas from the soil around it and ‘feeds’ it to the ground floors above.

For above ground workplaces incorporating a ground floor, including premises such as factories, offices, shops, pubs and residential care homes, the risk of having high radon levels can be estimated from a map of the UK produced by the Health Protection Agency (HPA) and British Geological Survey. The high risk areas are designated as radon Affected Areas.

Risk assessment for radon should be carried out for all occupied below ground workplaces in the UK, and for all workplaces located in radon Affected Areas.

For above ground workplaces, landlords and employers can consult the definitive HPA radon online website ukradon.org to identify the status of a specific building. There is a small charge on this website for each postcode search. Alternatively the radon Affected Areas maps (HPA-RPD reports) for England, Wales, Scotland and Northern Ireland, can be downloaded for free from the HPA website hpa.org.uk.

Experience has shown that radon concentrations in adjacent buildings, even adjoining ones, can differ by as much as a factor of ten (for reasons including local geology or building design and construction), so measurement results from neighboring properties are not reliable indicators.

Radon surveys should be conducted over a three month period in any building where its location and characteristics suggest that elevated levels may be found. It is cheap and easy to do and does not involve specialist consultants roaming the premises with Geiger counters. Inexpensive surveys can be carried out by leaving small plastic detectors in potentially affected rooms. These detectors are then returned by post. The HPA website contains details of the ‘validated laboratories’ capable of supplying such detectors.

New buildings can be protected during construction by installing a radon-proof membrane within the floor structure. In more seriously affected areas, a ventilated ‘radon sump’ may be necessary. This is a small, bucket sized, cavity under the floor with an electric pump drawing air from it. This reduces the normal under floor air pressure and helps draw the gas outside where it quickly dissipates. Testing to verify the effective operation of these systems is however, essential.

In existing buildings, other approaches are necessary. Measures include improved under floor and indoor ventilation in the area, sealing large gaps in floors and walls in contact with the ground, positive pressure ventilation of occupied areas, and installation of basic radon sumps and extraction pipework.

For more information visit hse.gov.uk/radiation/ionising/radon.htm or call 0845 345 0055