Differences between the activity size distributions of the different natural radionuclide aerosols in outdoor air

The results of the activity size distribution of the short-lived (218Po, 214Bi/214Po) and long-lived (210Pb, 210Po) radon decay product aerosols, the thoron decay product aerosols (212Pb, 212Po) and 7Be of the outdoor atmosphere are presented. The results were obtained from measurements averaged over an extended period (4 weeks) and were carried out with a low-pressure On-Line Alpha Cascade Impactor (OLACI). The size distributions of the radionuclides were obtained from the same measurement run with the OLACI, so that the size classification technique and the atmospheric and weather conditions for all radionuclides were identical. This measurement technique made it possible to measure the correct differences between the size distributions of the different natural radionuclides in the environmental air. The differences between the activity size distributions of the long- and short-lived radionuclides could be explained by coagulation with aerosol particles of the atmosphere as for instance 210Pb was shown.