The Management of Health and Safety at Work Regulations 1999 require the assessment of health and safety risks, this should include radon in specific circumstances including: it is a building in a radon Affected Area, it has a basement area that is occupied for more than about 50 hours each year,it is a mine, cave, or other underground environment, it has a suspected radon source such as ground water (e.g. treatment works) or geological samples.