Monthly mean values of 137Cs, 7Be and 210Pb activity concentration in the air aerosol at MSAC of Prague
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The artificial radionuclide 137Cs is coming mainly from the resuspension of the original fallout on ground surface. At the time being the activity concentration in the air aerosol is mostly below 1 µBq/m3. A part of the 137Cs activity is from the global fallout from the nuclear weapon tests in atmosphere and the substantial part from the Chernobyl accident. The 7Be is of cosmogenic orgin with the typical seasonal variation due to character of air convection during the year; its mean activity concentration is about 3000 µBq/m3. The 210Pb is a product of radon decay; its mean activity concentration is about 500 µBq/m3.