The equilibrium factor in the radon dose calculation in the archaeological site of Acquedotto Augusteo del Serino in Naples

Summary. — The calculation of the dose from exposure to radon gas is regulated by the Italian Legislative Decree 241/2000. It takes into account the activity concentration of the radon gas, the exposure time and the conversion factor (equal to 3 nSv/Bq·m3·h) which includes the value of the equilibrium factor (F), set to be 0.4. Since high concentrations of radon are found in particular in some underground environments, it is important to evaluate the real exposure dose of workers, by estimating the value of F on a case-by-case basis exposure dose of workers. Measurements have been made with the E-RPISU system, which allows the simultaneous assessment of the concentration of radon gas activity in air and of its progeny. In this preliminary investigation, measurements were carried out in locals of the ancient site of the Acquedotto Augusteo del Serino in the Sanità district in the historic center of Naples, and the results confirmed the importance of calculating the value of the equilibrium factor in order to obtain a correct and realistic estimate of the exposure dose