Assessment of natural soil radioactivity in Una National Park, Bosnia and Herzegovina and radiological hazards for public

This paper evaluates natural environmental radioactivity and assesses potential radiation hazards from primordial radionuclides 226 Ra, 232 Th and 40 K across various surface areas within Una National Park, Bosnia and Herzegovina. This study represents the first systematic radiological survey conducted inside the park boundaries. Using high-resolution gamma-ray spectrometry, the mean specific activity concentrations were determined to be 55 ± 3 Bq kg − 1 for 226 Ra, 42 ± 1 Bq kg − 1 for 232 Th, and 399 ± 18 Bq kg − 1 for 40 K. Based on these baseline empirical data, the ambient absorbed dose rate in air reached an average value of 67.48 nGy h − 1 , which corresponds to a mean outdoor annual effective dose equivalent of 0.083 mSv y − 1 . The calculated radium equivalent activity showed a mean value of 145.96 Bq kg − 1 , while the external and internal hazard indices registered safe averages of 0.39 and 0.54, respectively. Finally, the average excess lifetime cancer risk was found to be \(\:0.29•\:{10}⁻³\), aligns perfectly with the current global baseline average. These findings demonstrate that despite minor geologically-driven elevations, the protected area remains radiologically safe for the general public and tourism.