The unattached fraction of radon progeny in ambient aerosols

Abstract Wire screens used for collection of the unattached fraction of airborne radon daughters collect radon progeny both attached to ambient aerosols (the attached fraction) and those in the status of ions, molecules or small clusters (the unattached fraction). The efficiencies of screens range from 0·3 to 4% and from 0·1 to 1% for the attached and unattached fractions, respectively. This study introduces new data for the application of ICRP recommendations on limits for inhalation of radon daughters.