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

The concentration of two important radionuclides: 210Pb and its decay product 210Po 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 210Pb and 210Po were 0.556 and 0.067 mBq/m3, respectively. However remarkable fluctuations due to meteorological condition were observed: from 0.010 to 0.431 mBq/m3 for 210Po and from 0.167 to 1.847 mBq/m3 for 210Pb. 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 μm. The aerosol residence times calculated from the 210Po/210Pb ratio ranged from 7 to 120 days.