%A"Arvela, H" %A"Maekelaeinen, I" %A"Holmgren, O" %A"Reisbacka, H" %D2010 %I; Radiation and Nuclear Safety Authority STUK, Helsinki (Finland) %2 %J[] %K61 RADIATION PROTECTION AND DOSIMETRY, 54 ENVIRONMENTAL SCIENCES, FINLAND, RADON, CONSTRUCTION, HOUSES, MITIGATION, RADIATION PROTECTION, REGULATIONS, ACTIVITY LEVELS, INDOOR AIR CONTAMINATION, RADIATION MONITORING, FOUNDATIONS %PMedium: X; Size: 94 p. pages %TRadon prevention in new construction. Sample survey 2009.; Radon uudisrakentamisessa. Otantatutkimus 2009 %XThe building code for radon prevention and the associated practical guidelines were revised in Finland in 2003 to 2004. Thereafter, preventive measures have become more common and prevention practices more effective. Consequently, indoor radon concentrations in new construction have been markedly reduced. In this study, the indoor radon concentration was measured in 1 500 new lowrise residential houses. The houses were randomly selected and represented 7 % of houses that received building permission in 2006. The average radon concentration of all houses measured, which were completed in 2006 to 2008, was 95 Bq/m3, the median being 58 Bq/m3. The average was 30 % lower than in houses completed in 2000 to 2005. The decrease was 50 % in provinces with the highest indoor radon concentration and 20 % elsewhere in the country. In houses with a slab-on-ground foundation that had both passive radon piping and sealing measures carried out using a strip of bitumen felt in the joint between the foundation wall and floor slab, the radon concentration was on average reduced by 55 % compared to houses with no preventive measures. Preventive measures were taken in 50 % of single family houses, and in provinces with the highest radon concentration in 90 % of houses. Active prevention in areas with high indoor radon concentrations has reduced the regional differences in the radon concentration. Slab on ground is the prevailing type of foundation and necessitates careful radon prevention measures throughout the country. The most serious defects were observed in prevention practices in houses with walls made of lightweight concrete blocks that were in contact with soil. The foundation types with the lowest radon concentrations were those with a crawl space and a monolithic slab. (orig.) %0Technical Report %NSTUK-A-244;Other: ISBN 978-952-478-531-0; ISBN 978-952-478-532-7; TRN: FI1104018 %1 %CFinland %Rhttps://doi.org/ Other: ISBN 978-952-478-531-0; ISBN 978-952-478-532-7; TRN: FI1104018 FIN %GFinnish