Abstract

The activity size distributions of both unattached and attached fractions of short-lived radon progeny (218Po, 214Pb and 214Bi) were measured in indoor air of El-Minia University, Egypt. The measurements were performed with a wire screen diffusion battery and a low pressure cascade impactor (Berner type). The results for parameters of derived distributions demonstrate that the distributions for the unattached 218Po and 214Pb are similar. The mean diffusion equivalent diameters (de) of 218Po and 214Pb were determined to be 1.73 and 1.69 nm with relative mean geometric standard deviations (sg) of 1.63 and 1.69, respectively. The distributions of the attached 214Pb and 214Bi are also similar. Most of the attached activities were associated with the aerosol particles of accumulation mode. The mean activity median aerodynamic diameters (AMAD) of this mode for 214Pb and 214Bi were determined to be 0.32 and 0.34 µm, respectively, with the same relative mean geometric standard deviation of 2.7. Based on the obtained results of radon progeny size distributions (unattached and attached), the deposition fractions in each airway generation of the human lung were evaluated by using a deposition model of Koblinker and Hofmann.

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