Radon is measured in Becquerels per cubic metre of air (Bqm-3). The average level in UK homes is 20 Bqm-3.
For levels below 100 Bqm-3, your individual risk remains relatively low and not a cause for concern. However, the health risk increases as the radon level increases.
Within domestic properties Public Health Wales recommends that radon levels should be reduced where the average is more than an Action Level of 200 Bqm-3. This Action Level refers to the annual average concentration as measured using two detectors (in a bedroom and living room) over three months, to average out short-term fluctuations.
A Target Level of 100 Bqm-3 is the ideal outcome for remediation works in existing buildings and protective measures in new buildings.
If the result of a radon assessment is between the Target and Action Levels, action to reduce the level should be seriously considered, especially if there is a smoker or ex-smoker in the home.
For workplaces health and safety legislation requires employers in radon ‘hotspots’ to assess radon exposure. This duty also applies to any workplace where there are underground workplaces, even if they are not in a radon hotspot. The Ionising Radiations Regulations 2017 come into effect where radon is present above 300 Bqm-3 (annual average). Employers must take action to reduce radon exposure in these cases.