Measurement of Bithmuth (214Bi) in Indoor Air and Evaluation of Deposition Fraction

Activity size distribution of unattached as well as attached 214Bi to aerosol particles was estimated in indoor air of physics department at Minia University, Minia City, Egypt. The samples were collected using a wire screen diffusion battery technique and a low pressure Berner cascade impactor. The mean Activity Median Thermodynamic Diameter (AMTD) of unattached 214Bi was determined to be 1.25 nm with a relative mean Geometric Standard Deviation (GSD) of 1.29. A mean unattached fraction (fun) of 0.080.05 was obtained. The average activity concentration of 214Bi was found to be 4.90.42 Bq m-3. Most of the attached activities of 214Bi were associated with aerosol particles of the accumulation mode. The GSD of the accumulation mode for 214Bi was determined to be 3 with an Active Median Aerodynamic Diameter (AMAD) of 350 nm. Based on the obtained measured data values, deposition fraction of 214Bi has been evaluated by using a stochastic deposition model. The bronchial deposition efficiencies of particles in the size range of attached 214Bi were found to be lower than those of unattached progeny.