Study on radon and radon progeny in some living rooms

In the first part of this work, the potential alpha energy concentration (PAEC) of radon progeny, the equilibrium factor (F), the activity concentration of 222Rn gas (Co) and the unattached fraction (fp), were determined in 15 living rooms at El-Minia City (Egypt)). The activity size distribution of 214Pb was measured by using a low pressure Berner impactor. Based on the parameters of that distribution the total effective dose through the human lung was evaluated by using a dosimetric model calculation of ICRP. An electrostatic precipitation method was used for the determination of 222Rn gas concentration. The mean activity concentration of 222Rn gas (Co) was found to be 123±22 Bq m-3. A mean unattached fraction (fp) of 0.11 ± 0.02 was obtained at a mean aerosol particle concentration (Z) of (3.0±0.21) x 103 cm-3. The mean equilibrium factor (F) was determined to be 0.35 ± 0.03. The mean PAEC was found to be 37 ± 8.1 Bq m-3. The activity size distribution of 214Pb shows mean activity median diameter of 290 nm with mean geometric standard deviation (σ) of 2.45. At a total deposition fraction of ∼23% the total effective dose to the lung was determined to be ∼1.2 mSv. The second part of this paper deals with a study of natural radionuclide contents of samples collected from the building materials of those rooms under investigation given in part one of this paper. Analyses were performed in Marinelli beakers with a gamma multichannel analyser provided with a NaI(Tl) detector. The samples have revealed the presence of the uranium-radium and thorium radioisotopes as well as 40K. Nine γ-lines of the natural radioisotopes that correspond to 212Pb, 214Pb, 214Bi, 228Ac, 40K and 208Tl were detected and measured. The activity concentrations of 226Ra, 232Th and 40K were determined with mean specific activities of 65 ± 22, 35 ± 12 and 150 ± 60 Bq kg-1, respectively. These activities amount to a radium equivalent (Raeq) of 126 Bq kg-1 and to a mean value of external hazard index of 0.34. (authors)