Radon exposure in kindergartens in one Bulgarian district

The major part of the radiation dose that humans receive from natural radioactive sources is due to inhalation of radon and its decay products. The study focuses on radon concentration (CRn) investigation in kindergartens and nurseries in the district of Montana. The influence of building characteristics on CRn was evaluated. The measurement of the CRn was performed using passive detectors. The survey was carried out between December 2019 and May 2020 with a total number of 602 detectors. The average value of CRn in the premises of the studied kindergartens and nurseries in this district is 125 Bq·m⁻³, and the geometric mean (GM) value is 88 Bq·m⁻³. The buildings that have built ventilation and sewerage systems have lower CRn. The effective doses of the children and workers were evaluated in order to assess the radon exposure.