AARST_Radon_Reporter_Q32022_FINAL

8 | January 2023 RESEARCH Radon Measurements On Higher Floors In Swedish Multi-Family Houses Tryggve Rönnqvist Technical Manager for Radonova Laboratories AB in Uppsala, Sweden. Abstract The Swedish radon measurement protocol for multi-family houses requires that 20% of the apartments on non- ground contact floors be measured. Radonova has analyzed its radon measurements to estimate how often buildings have apartments on higher floors above the reference level of 200 Bq/m 3 (5.4 pCi/L), where no measurements on the ground floor are above the reference level. Buildings without the radon emitting building material “Blue Concrete,” and with five or more measured apartments, were selected in the analysis. In this dataset, 17% of the buildings didn’t have any measurements above the reference level for the measured apartments on the ground floor. The data are discussed in more detail with respect to parameters such as foundation type, ventilation, and building year. About 15- 20% of Swedish multi-family houses, without the radon-emitting building material “Blue Concrete,” with basements and with radon levels above the Swedish reference level of 200 Bq/m 3 (5.4 pCi/L), would not have been found if no measurements were made on floors above the ground floor. Introduction In Sweden, many multi-family buildings have been measured during the last 20 years. A reason for this large number of measurements is that the local authorities have required measurements from multi-family house owners to meet a national environmental goal for testing all multifamily homes before 2020. The Swedish Radiation Safety Authority (SSM) developed measurement protocol (Strålsäkerhetsmyndigheten, 2013) that can be applied to measurements in both single-family and multi-family houses. This measurement protocol is similar to the measurement protocol (ANSI/ AARST MAMF, 2017) used in the United States (US) for multi-family buildings. The Swedish and US measurement protocols are compared in Table 1. There are differences in the required number of measurements on non-ground contact floors, although both protocols require measurements on these floors. The need for measurements on higher floors is sometimes questioned, as if it could be measurements on the ground floor are sufficient. An analysis of the multi-family data in the measurement database of Radonova has been done to compare radon levels on higher floors to the ones on the ground floor. Methodology Currently, the radon database of Radonova consists of more than 340,000 long-term average measurements in Swedish single-family houses and more than 440,000 measurements in multi-family houses. The majority of the measurements in single-family houses (55%) were performed during 2005-2010 and the majority of the measurements in multi-family houses (43%) were performed during 2015-2020. An analysis of these data has been conducted and Measurement requirements US (ANSI/AARST) Sweden (SSM) Measure in every building YES YES Measure on every floor with apartments YES YES Apartments on floor with ground contacts ALL ALL Apartments above non-measured basement ALL > 20 % Apartments on higher floors > 10 % > 20 % Detectors per apartment (minimum) 1 2 TABLE (1) MEASUREMENT PROTOCOL REQUIREMENTS IN US AND SWEDEN FOR MULTI-FAMILY BUILDINGS