Radon risk map of the city Brno

Data of radon risk mapping of the city Brno area from 1992 to 1999 were collected from databases of six private companies measuring radon risk there. The data sets are completed now. The first results are presented in this paper. In the city Brno area only low (385 measured sites) and medium (300) radon risk categories were found. The largest number of measured areas were situated in places with loess and loess loam (total quantity 344 sites, with medium radon risk category 158 sites), recent fluvial sediments (64, 32) and anthropogenous deposits (61, 23). High values of radon volume activity in soil gas were found predominantly in Quaternary sediments and in granodiorite, type Veverska Bityska, low values in leucotonalite and metabasalt. (author)