A Study on Radon and Radon Progeny in Surface Air of El-Minia, Egypt

Abstract

Activity concentrations of 222 Rn gas and its long-lived progeny ( 210 Pb, 210 Bi) attached to aerosol particles were determined in surface air of El-Minia (ARE). Fluctuations of activity concentrations were observed during the measurements. An electroprecipitation method was used for the determination of 222 Rn gas concentration while a high volume air sampler was used for collecting the attached 210 Pb and 210 Bi. A mean activity concentration of 4.8 ± 0.74 Bq.m -3 was determined for 222 Rn gas while mean values of 0.25 ± 0.04 and 0.142 ± 0.02 mBq.m -3 were determined for 210 Pb and 210 Bi, respectively. From the ratio between the activity concentrations of 210 Pb and 210 Bi a mean residence time of aerosol particles in the air of 12.7 ± 2.2 d could be estimated. A mean aerosol mass concentration of 33.6 ± 7.4 μg.m -3 was also determined during the measurements. Small fractions of attached 210 Pb and 210 Bi were observed at higher aerosol mass concentrations while the majority of attached activities were associated with lower mass concentrations. In addition, activity size distributions of short lived radionuclides 214 Pb and 214 Bi were determined using a Berner impactor as a sampling device. The activity size distribution of both radionuclides could be described by one log-normal distribution (accumulation mode). Activity median aerodynamic diameters of 330 and 316 nm with relative geometric standard deviations of 2.45 and 2.35 were determined for the two radionuclides, respectively. The total and regional deposition in the human respiratory tract due to inhalation of attached 214 Pb and 214 Bi were evaluated using the ICRP lung deposition model.