Radon on the ground floor in the buildings of pre-university education in Montenegro

A national radon survey was performed recently in all buildings of pre-university education in Montenegro. During the school year 2016/2017, radon (²²²Rn) was measured with passive detectors (Radosys, RSFV type) in 2855 ground-floor rooms of 468 buildings. The average 9-month radon activity concentrations above the level of 300 Bq/m³ were found in 728 rooms, which belong to 213 buildings, while in 111 rooms, belonging to 47 buildings, they were above 1000 Bq/m³. Radon concentrations in the educational buildings, averaged over all sampled ground-floor rooms in a building, range from 16 Bq/m³ to 2810 Bq/m³, with arithmetic mean (AM) = 275 Bq/m³. They follow a log-normal distribution with geometric mean (GM) = 174 Bq/m³ and geometric standard deviation (GSD) = 2.58. There are 135 buildings with average indoor radon concentrations on the ground floor above 300 Bq/m³ and 18 buildings where they are above 1000 Bq/m³. The influence of the nine factors (climate, urban/rural area, age of building, number of stories, building materials, basement, foundation slab, window frames, and heating) on radon concentrations in the buildings was analysed by univariate (UVA) and multivariate (MVA) methods. The univariate analysis revealed the significant relationship of the four factors: age of buildings, basement, building materials, and window frames with radon concentrations on the ground floor in the buildings, while multivariate analysis added to those factors urban/rural area and number of stories, but excluded building materials as a factor influencing significantly radon concentrations.