210Pb and 210Po radionuclides in the urban air of Lodz, Poland

The concentration of two important radionuclides: Pb-210 and its decay product Po-210 in the urban air in the center of the Polish city of Lodz were measured during the winter and spring seasons of 2008-2009. Urban airborne particulate matter was collected using two methods: an Anderson 9-stage impactor, and a high-volume aerosol sampler type ASS500 working in the frames of the aerosol sampling network in Poland, established for radionuclide monitoring. Average concentrations for 10 months sampling period for Pb-210 and Po-210 were 0.556 and 0.067 mBq/m(3), respectively. However remarkable fluctuations due to meteorological condition were observed: from 0.010 to 0.431 mBq/m(3) for Po-210 and from 0.167 to 1.847 mBq/m(3) for Pb-210. The highest concentrations, almost 60% of the total activities, of both radionuclides were found in the first two fine aerosol fractions with particle diameters below 0.36 mu m. The aerosol residence times calculated from the Po-210/Pb-210 ratio ranged from 7 to 120 days.