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Description
Show caves are special workplaces with increased health risk from radon exposure. Demänovská Cave of Liberty is one of the most visited show caves in Slovakia, situated at the northern side of the Low Tatras Mts. It is formed in the Middle Triassic Ramsau Dolomite and in carbonate rocks of Gutenstein Formation with Gutenstein limestone and dolomite, Annaberg limestone and organodetritic ʻDemänováʼ limestone, along the tectonic faults by the ancient ponor flow of Demänovka stream and its side hanging ponor tributaries. Radon activity concentration (RAC) in the cave was monitored from May 2021 to December 2023, using Ramarn track detectors (National Institute of Nuclear, Chemical and Biological Protection, Milín, Czech Republic), changed after one month exposure. Six monitoring stations were established in the cave, where RAC values varied in different intervals: Těsnohlídkovo Lake (190 – 1310 Bq/m3), Crossroad (650 – 6100 Bq/m3), Deep Dome (250 – 2500 Bq/m3), Tricolour Lake (270 – 3310 Bq/m3), Cemetery (190 – 2900 Bq/m3) and Pink Hall (1900 – 5400 Bq/m3). The lowest annual average of RAC was found in the Cemetery station (730 Bq/m3) situated close to the cave exit, the highest in the Pink Hall, equal to 3200 Bq/m3. Seasonal variation was observed at each station, with two maxima. The first appeared in the spring months and the second in autumn in each monitoring site. Spring maximum exceeded autumn maximum, or their levels were comparable (Tricolour Lake, Pink Hall). With exception of Těsnohlídkovo Lake, all stations were situated on or close to the tourist route. Effective dose for cave guides and visitors was estimated. Cave guides were exposed to annual effective dose in the range 1.1 – 3.5 mSv, depending to the number of their entries to the cave per month during the year and RAC in that month. Visitors who completed a short circuit (without Pink Hall) received 0.004 – 0.013 mSv per visit, who completed a long circuit received 0.009 – 0.024 mSv per visit, depending on different RAC in month of their visit. This work was supported by the Agency VEGA No. 2/0015/21.