Temporal variations of radon levels in dwellings

Several factors determine the concentration of radon in a dwelling: the uranium content and permeability of the building ground; the construction and integrity of the floor; the habits and preferences of the occupants. Whereas the geological factors are unlikely to alter over time, it is quite possible for structural changes to occur, such as settlement cracking, which increases radon ingress, and for the occupants to change their living habits, such as increasing ventilation, which may reduce radon levels. Questions arise about the variability of indoor radon levels as time progresses and as occupants change. The database of radon results for UK homes, which extends backwards for about a decade, is examined for repeat measurements, and the data are analysed so as to assess the stability or otherwise of the levels under changing circumstances. (author)