An analysis of radon levels in the basements of UK workplaces and review of when employers should test

Radon is a recognised lung carcinogen. The main source of radon in UK buildings is the ground. As basements have more ground contact than other parts of a building, and often limited ventilation, there is increased potential for high radon levels to occur. Regulations are in place in the UK to control radon exposure at work, to prompt employers to undertake risk assessments, test where necessary and take action if levels exceed certain thresholds. Both Public Health England (PHE) and the Health and Safety Executive (HSE) currently advise employers to test routinely occupied basements for radon, irrespective of geographical location; the minimum annual occupancy threshold has been established as one hour per week (approximately 50 h per year). PHE operates a routine measurement service for employers and holds the measurement data for radon levels in the basements of more than 3500 workplaces. Typically, radon concentrations follow a lognormal distribution over a wide range, when corrections are made for seasonal variations and the contribution of outside air. Statistical tests on these data show good correspondence in most cases for the workplace basements of seven different occupational sectors. Radon should be included in the risk assessments of basements of all workplace types irrespective of the radon-affected area status (i.e. whether they are located in a geographical unit where higher proportions of houses or workplaces are likely to exceed their reference levels). As a consequence of this analysis, however, evidence is presented that supports a change in the existing protocols on when to test the radon levels in basements, if a more sophisticated approach were to be adopted taking into account the affected area status.