AARST_Radon_Reporter_Q32022_FINAL

THE RADON REPORTER | 9 RESEARCH published (Rönnqvist, 2021). The multi-family data was from measurements performed during 2017-2020 in multi- family buildings with five or more measured apartments. In that study, it was found that 20% of buildings with slab on grade foundation type had higher average radon levels on higher floors compared to the ground floor. The corresponding value, where the ground floor had no ground contact, like with basement foundations, was 38%. Many Swedish buildings have been built with a radon-emitting lightweight concrete, “Blue Concrete.” More consistent radon level distributions between floors are expected in these houses compared to buildings without this material. To better understanding buildings where radon from the soil is the primary source, buildings with this building material should be excluded from the analysis. A new study has been performed where only multi-family buildings without the “Blue Concrete” building material were included. These measurements were performed during 2014-2021. The main question asked in the study was howmany buildings with levels above the Swedish reference level of 200 Bq/m 3 (5.4 pCi/L) would not be found if measurements were performed only on the basement and ground floors. Therefore, only buildings with measured apartments above the reference level were included. Sometimes, multi-family buildings have no apartment measurements on ground floors, because they may have shops and business premises on the ground floor. Therefore, an additional requirement was that the measured building should have data from both the ground floor and higher floors. The floor number for the apartment was determined using Sweden’s national standard apartment number registry to guarantee accuracy of this factor. The results from this new study are presented below. Results A general comparison of measurement data on different floors for buildings with basement or slab on grade foundation types is shown in Table 2, where average values for the measured buildings are shown. As can be seen, radon levels are higher on floors with ground contact. Measurements within the same building were analyzed to see how often higher floors have higher values than the floor with ground contact. Type of floor Foundation Measure- ments Measure points per floor Average (pCi/L) & Standard Deviation Values above 5.4 pCi/L (200 Bq/m 3 ) Basement Basement 80 3.0 2.5 (86 %) 18 % Ground floor or higher Basement 1503 12.3 1.3 (57 %) 13 % Ground floor Slab on grade 656 8.2 1.7 (66 %) 17 % Above ground floor Slab on grade 679 10.6 0.9 (50 %) 5 % TABLE (2) AVERAGE MEASUREMENT DATA FOR DIFFERENT FLOOR TYPES IN SWEDISH MULTI-FAMILY HOUSES WITHOUT “BLUE CONCRETE” BUILDING MATERIAL Floor comparison Foundation Multi-family houses Higher floors with higher values Workplaces Higher floors with higher values Higher floors / ground floor Basement 1288 30 % 1645 36 % Some value above 5.4 pCi/L Basement 164 28 % 404 28 % Higher floors / ground floor Slab on grade 568 18 % 888 26 % Some value above 5.4 pCi/L Slab on grade 110 11 % 194 20 % TABLE (3) DIFFERENCES BETWEEN DIFFERENT FLOORS IN THE SAME BUILDING The result from this analysis is shown in Table 3, where corresponding workplace data is also shown. It is less frequent that higher floors have higher values than the ground floor when radon values above the reference level are found. For these buildings, 28%, of the multi-family buildings with basements and 11% with slab on grade have higher values on higher floors compared to the ground floor. (continued)