Seasonal Variation of Unattached fraction and Equilibrium factor of 222Rn and 220Rn using DRPS/DTPS and Pin –hole cup dosimeters.

Abstract:

²²²Rn (Radon), ²²⁰Rn (Thoron) and their progenies are naturally occurring radionuclides in environment and responsible for the radiological dose to population. The ²²²Rn, ²²⁰Rn concentration and their separate attached and unattached progeny concentration (season-wise) in units of EEC have been measured in the dwellings of Muktsar and Mansa districts of Punjab (India), using Pin- hole cup dosimeters and deposition based progeny sensors (DTPS/DRPS). The indoor ²²²Rn concentration was maximum in the rainy season (60 Bqm^-3) while ²²⁰Rn concentration was maximum in winter season (57 Bqm^-3). However EEC of ²²²Rn and ²²⁰Rn has distinct seasonal demeanour than their parent nuclides. The unattached EEC for both ²²²Rn and ²²⁰Rn (EERC_U and EETC_U) were higher in summer and rainy season as compared to winter season. The equilibrium factor ( for ²²²Rn and for ²²⁰Rn) and unattached fraction ( for ²²²Rn and for ²²⁰Rn) has been calculated separately. The (0.44 ± 0.04) in the studied area was similar to 0.4 that proposed by UNSCEAR and for (0.05 ± 0.01) it was greater than specified value 0.02 by UNSCEAR. The was higher in summer season as compared to rainy and winter season. Due to very smaller value of , a proper relation has not been observed seasonally. The unattached fraction in environment may increase the risk of radiological exposure and absorbed at faster rate into blood then the attached ²²²Rn and ²²⁰Rn progeny. The overall arithmetic mean (rainy, winter and summer seasons) of and were 0.09 ± 0.02 and 0.10 ± 0.03 respectively. The and were lower in winter season as compared to rainy and summer seasons due to higher value of attached EEC present in winter season. A positive and significant correlation (0.56) has been observed between the and aerosol concentration (Z (cm^-3)).