Estimation of surface deposited 210Po activity for retrospective assessment of radon exposure

The relation between increased risk of lung cancer and exposure to indoor radon is assessed in epidemiological studies. The short lived airborne radon decay products deposit on the smooth glass surfaces. After deposition, subsequent alpha decay can lead to implantation of further decay products through alpha particle recoil. Hence, the progeny can remain fixed in a very thin surface layer of the glass, where it can be detected through alpha decay by means of track etch detectors. In the present study, the estimation of surface deposited polonium activity have been carried out in the houses of Garhwal Himalaya region using (CR-LR) difference technique. In this area the polonium activity have been found to vary from 0.8 Bq/m2 to 35.2 Bq/m2 with an average of 6.4 Bq/m2. The estimated retrospective radon concentration based on the 210Po activity was found to vary from 29 Bq/m3 to 1173 Bq/m3 with an average value 241 Bq/m3. The detail significance of this study is also discussed from epidemiological point of view. (author)