Application of Air Cleaning Methods for the Removal of Radon Decay Products

In a series of comprehensive studies, a wide range of air cleaning methods has been evaluated related to their effectiveness in removing radon decay products. Data show that while filtration and electrostatic precipitation were effective in reducing total potential alpha energy concentrations (PAECs), they caused a greater percentage of the radon decay products, subsequently formed, to be unattached. This resulted in a substantial increase in the dose to the bronchial tissues. While enhanced convection removed both the attached and unattached decay products, its overall removal effectiveness was only 50% to 60%. The optimal form of treatment appears to be a combination of enhanced convection and nonuniform space charging. Laboratory studies showed that this combination provides PAEC reductions up to 95%; reductions in the mean dose to the brochial tissues ranged up to 87%. Tests of a portable fan-ion generator in homes yielded PAEC removals from 75% to 90%. Other applications of the fan-ion generator concept include the combination of ion generators with overhead ceiling fans, and with within the wall cavity and between rooms air circulating systems.