Occupational exposure to radon and natural gamma radiation in the La Carolina, a former gold mine in San Luis Province, Argentina

Radon and gamma radiation level measurements were carried out inside the La Carolina mine, one of the oldest gold mining camps of southern South America, which is open for touristic visits nowadays. CR-39 track-etch detectors and thermoluminescent dosimeters of natural CaF₂ and LiF TLD-100 were exposed at 14 points along the mine tunnels in order to estimate the mean ²²²Rn concentration and the ambient dose equivalent during the summer season (November 2008 to February 2009). The values for the ²²²Rn concentration at each monitoring site ranged from 1.8 ± 0.1 kBq m⁻³ to 6.0 ± 0.5 kBq m⁻³, with a mean value of 4.8 kBq m⁻³, indicating that these measurements exceed in about three times the upper action level recommended by ICRP for workplaces. The correlations between radon and gamma radiation levels inside the mine were also investigated. Effective doses due to ²²²Rn and gamma rays inside the mine were determined, resulting in negligible values to tourists. Considering the effective dose to the mine tourist guides, values exceeding 20 mSv of internal contribution to the effective doses can be reached, depending on the number of working hours inside the mine.