A study on radon and radon progeny in surface air of El-Minia, Egypt

Activity concentrations of Rn-222 gas and its long-lived progeny (Pb-210, Bi-210) attached to aerosol particles were determined in surface air of El-Minia (ARE). Fluctuations of activity concentrations were observed during the measurements. An elcctroprecipitation method was used for the determination of Rn-222 gas concentration while a high volume air sampler was used for collecting the attached Pb-210 and Bi-210. A mean activity concentration of 4.8 +/- 0.74 Bq.m(-3) was determined for Rn-222 gas while mean values of 0.25 +/- 0.04 and 0.142 +/- 0.02 mBq.m(-3) were determined for Pb-210 and Bi-210, respectively. From the ratio between the activity concentrations of Pb-210 and Bi-210 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 I 7.4 mu g.m(-3) was also determined during the measurements. Small fractions of attached Pb-210 and Bi-210 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 Pb-214 and Bi-214 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 Pb-214 and Bi-214 were evaluated using the ICRP lung deposition model.