Radioactivity from nuclear explosions in ground level air and precipitation in Sweden. NaI(T1)-measurements from mid-year 1972 to the end of 1975

From mid-year 1972 to the end of 1975 the concentrations of various fission products are reported in ground level air for 7 swedish sampling stations and at 6 of these stations the deposition of 95Sr and 137Cs. In 1973 the 137Cs-concentrations in ground level air reached its lowest value since the measurements started but increased a little after that due to the two Chinese thermonuclear tests carried out in 1973 and 1974. The activity ratios of some fission products are discussed as well as the discrepancies between the ratio 95Sr/137Cs in ground level air and the same ratio in precipitation. The distribution of the effective deposition velocity during different years is examined. A comparison is made between parallel runs for about two years on NaI(T1)- and Ge(Li)-detectors