Two-year assessment of radon exposure in the underground tourist route in the Historic Silver Mine in Tarnowskie Góry (Poland)

This paper presents the results of a two-year radon risk study conducted at the Historic Silver Mine in Tarnowskie Góry. During this period, continuous measurements of radon activity concentration were carried out in three-month cycles at 30 points distributed along the tourist route. The average radon activity concentration was 1160 Bq/m³ for the first year of measurements and 1210 Bq/m³ in the second year. Based on the collected data, seasonal correction factors considering seasonal variations in radon activity concentration (SCF) were determined. The obtained factors are in the range of 0.8-1.4. In addition, the spatial variation of radon activity concentration was studied at selected locations of the mine at different heights of the location of the detectors and their distribution on opposite sides of the excavation. Based on the collected data, effective doses were calculated. Assuming annual working time of 300 h, which was specified for workers, the average annual dose is 0.6 and 1.3 mSv for the conversion factor of 1.4 mSv/(mJ/m³⋅h) indicated in Polish law and 3.1 mSv/(mJ/m³⋅h) as recommended in the ICRP report no 137 for underground mines respectively. For the annual working time of 1800 h, the corresponding doses would be 3.4 mSv and 7.4 mSv.