Radon concentration and effective dose assessment in the Brestovská Cave and the Demänovská Cave of Liberty, Slovakia

Radon activity concentration was measured using track detectors with monthly exposure from May 2021 to December 2023 in two show-caves in Slovakia: the Brestovská Cave (4 monitoring sites) and the Demänovská Cave of Liberty (6 monitoring sites). Radon concentration in the Brestovská Cave ranged 500–20 400 Bq/m 3 . Seasonal variation was observed with maximum in May–October in all sites, except Entrance Hall. Cave guides received annual effective doses 9–24 mSv, depending to the number of their entries to the cave per month and radon activity in that month, temporary guides employed in tourist season received 4–19 mSv. In the Demänovská Cave of Liberty radon levels were significantly lower and ranged 190–6100 Bq/m 3 and annual variation was observed with two maxima per year, in the spring and autumn. Cave guides were exposed to annual effective dose in the range 1.5–10 mSv. Using specific equilibrium factor F determined for each cave resulted in a significant increase of effective doses in the Brestovská Cave. Monthly effective doses calculated using average monthly radon activity concentration and number of hours spend by the guides in a given months can improve the management of cave entrances and prevent an exceeding of the limit for annual effective doses.