Carpathian Journal of Earth and Environmental Sciences

The purpose of this research is to provide the distribution of radon levels in three underground environments of tourist interest from Romania (“Urşilor” Cave, “Muierilor” Cave and Turda Salt Mine). This study is of great interest since it identifies the values that could present a potential long-term health risk for the full-time staff (guides) spending extended periods conducting tours or carrying out maintenance within these underground environments and less for tourists. Furthermore, a possible relationship between the radon values and the local geology was disscused. Indoor radon concentrations were measured by using solid state CR-39 type RSKS nuclear track-etch detectors that were exposed from 3 to 6 months. The results reveal low radon levels in salt mine with the annual average concentration below the detection limit (around 8 Bq m^-3), related to the salt plastic rock without fissures, fractures and consequently, without circulation pathways for radon into the salt mine chambers. This type of environment is proper to be used for speleotheraphy and spa tourism. “Muierilor cave” has relatively low radon concentration varying between 63 and 172 Bq m^-3, with only one value of 1184 Bq m^-3, as compared with “Urșilor”Cave, which values are in the range of 783-1795 Bq m^-3 indicating the need offurther long term monitoring by using both the passive and the active methods. Our results arecomparable with radon concentration in different underground environments reported from otherEuropean surveys, lower than many of them. Geological background of these areas could sustain themeasured values, on the one side due to the presence of granitic plutons and even the uraniferousmineralizations proximity, and on the other side due to the presence of limestone and its gneiss and micaschistrocks basement that causes the low diffusion coefficient of radon.