210Pb in ground-level air in Belgrade city area

Concentrations of 210Pb in ground level air in the city area (Belgrade, Central Serbia) were measured in the period from 1985 to 1996. The activity of 210Pb in air filters was determined on a HPGe detector by standard gamma spectrometry. Total standard error of the method was estimated to be below 25%. The average monthly concentrations of 210Pb in the ground level air in the period from 1985 to 1996 were in the range of 0.30–3.17 mBq m−3 with the maxima in fall–winter periods and minimums in springs and early summers. The seasonal indices were 1.12–1.59 for fall–winter and 0.77–0.92 for spring–summer periods. The ratios of maximum-to-minimum concentrations in each year were relatively stable over the period, with slight increase in 1985, 1989 and 1995. The investigations are part of the long-term measurements of natural and man-made radionuclides in the ground-level air in the region.