THE CHALLENGE IN USING THE RETROSPECTIVE ASSESSMENT OF RESIDENTIAL RADON CONCENTRATION.

In the present study, the contemporary indoor radon activity concentration and the surface-deposited 210Po activity were measured in 65 Romanian dwellings. The activity of trapped 210Po on the glass surface was measured using the (CR-LR) difference technique. The retrospective radon activity concentration estimated on the basis of age-adjusted 210Po activity was found to have a geometric mean of 318 Bq m-3, being higher than the geometric mean (250 Bq m-3) of the contemporary indoor radon measurements, measured with two types of track detectors (RSKS and Radtrak2®). By applying Lin's concordance correlation coefficient, a substantial strength of agreement (rC = 0.94) was obtained between RSKS and Radtrak2® results, respectively a poor agreement (rC = 0.71) between the retrospective and contemporary methods. The ratio between contemporary and retrospective radon concentrations has a geometric mean of 0.8 and range from 0.2 to 3.9.