15 years repeated investigations of the radon levels in 105 remediated Swedish dwellings, mostly single-family buildings

The object of this project was to investigate the long time effectiveness of different radon remedial methods. The ten years project started in 1991. From the start the investigation comprised 105 dwellings (91 single-family houses and 14 flats in multi-family buildings). In all of the dwellings remedial measures were carried out in the eighties. Before and immediately after the reduction the local authorities measured the radon concentrations. New measurements of the radon concentrations have been made every third year: in 1991, 1994, 1997 and in 2000. Twelve different radon remedial methods and method combinations were used. The radon sources were building materials as well as sub-soils. In all of the dwellings the radon concentrations were measured by nuclear track films over 3 month (January-March) measurement periods [1] and in half of them the air change rates by passive tracer gas methods [2].