Studies on characterization of radon and its progeny

A basic study for characterization of radon and its progeny has been carried out. The main work is to establish a measurement technique of size distribution of radon progeny aerosols. The aerosols are ranged from sub-nanometer to micrometer, so that the impaction method and the diffusion method were introduced. From size measurements using the ELPI (Electrical Low Pressure Impactor), it was suggested that grease or oil coating does not interfere with the electrical size measurements but prevent particle rebound and/or redispersion. As the impactor measures two size distributions on number and activity, we can get a very important information on attachment phenomenon. In the comparison of size distribution with the scanning mobility particle sizer (SMPS) in EML (Environmental Measurements Laboratory, New York), there was a relatively good agreement with our SDB (Screen-type Diffusion Battery) or the MOUDI (Micro-Orifice Uniform Deposit Impactor). And our original GSA (Graded Screen Array) based on the SDB showed a very sharp peak of unattached fraction below 1 nm. We try to apply the measurement technique for a field study and to get radon progeny aerosol data which affects the DCF (Dose Conversion Factor). (author)