Radon concentrations inside castles and other ancient buildings

Sixty-two measurements of Rn-222 concentrations were made in 24 castles and 13 ancient buildings in 30 different places situated in the provinces of Parma and Reggio Emilia (Northern Italy). The method used was that of activated carbon canisters which were placed in selected settings for at least 48 h in the period starting from December 1990 to May 1991. It was possible to determine the amount of radon in each canister via its daughters gamma emitters counted by NaI(T1) and Ge(I) detectors. The mean radon concentrations were 72 Bq m-3 (arithmetic mean) and 49 Bq m-3 (geometric mean), a good deal higher than the values obtained from measurements carried out in modern dwellings in the same area; 30 Bq m-3 (arithmetic mean) and 19 Bq m-3 (geometric mean).