Acta Geophysica vol. 61, no. 4, Aug. 2013, pp. 859-875 DOI: 10.2478/s11600-013-0110-8 ________________________________________________ © 2013 Institute of Geophysics, Polish Academy of Sciences Radon and Remediation Measures near Băiţa-Ştei Old Uranium Mine (Romania) Constantin COSMA 1 , Alexandra CUCOŞ (DINU) 1 , Botond PAPP 1 , Robert BEGY 1 , Tiberiu DICU 1 , Mircea MOLDOVAN 1 , Lucia Adina TRUğĂ 1 , Dan Constantin NIğĂ 1 , Bety-Denissa BURGHELE 1 , Liviu SUCIU 2 , and Carlos SAINZ 3 1 Faculty of Environmental Science and Engineering, Babeş-Bolyai University, Cluj-Napoca, Romania; e-mail: constantin.cosma@ubbcluj.ro 2 Research and Design Institute for Electrical Engineering (ICPE) BistriĠa S.A., BistriĠa, Romania 3 Department of Medical Physics, Faculty of Medicine, University Cantabria, Santander, Spain Abstract BăiĠa-Ştei mine is an open pit mine in NW Romania (West Carpa- thian Mountains). It was the largest surface uranium deposit in the world. Two means of uranium transport and dissemination were used over time. The first was the natural way, represented by transportation of geological sediments by Crişul-BăiĠa River that crosses the BăiĠa surface deposit. These sediments were used as building materials (stone, gravel, sand). The second way was related to the people living in this valley, who used also the uranium waste as building material. The preliminary indoor radon concentrations measured in the buildings ranged from 40 to 4000 Bq m −3 with a mean value of 241 Bq m −3 . A focused radon survey facilitated the selection of 20 houses with the highest indoor radon that were therefore proposed for remediation. To find the radon sources of these houses, systematic investigations on radon were performed. The remedial measures for these 20 houses were tested on a chosen pilot house. Key words: Baita uranium mine, indoor radon, radon potential, prone area, remedial measures, pilot house. Author copy