Airborne radon daughter, behavior and removal

The major part of the mean annual internal radiological exposure of the general population is due to the airborne daughter products of radon and thoron, which are found in two states, attached to aerosols or unattached (or free), of which the latter species according to several models have the highest radiological dose efficiency of the two. The partitioning between these states is largely determined by the aerosol concentration of the air. Radon daughters may be removed from the air by as series of processes like plateout, filtration and electrostatic deposition. The paper discusses the efficiencies of these processes both as far as direct removal of radioactive material from the air is concerned and also with respect to the changes in the radiological dose from exposure to the air, caused by the change in aerosol condition and hence in unattached fractions of the radon or thoron daughter. (Author)