Experimental studies about the ratio between 210Po deposited on surfaces and retrospective indoor 222Rn concentrations

Conversion factor and other variables in the indoor retrospective radon activity concentration studies

Estimation of indoor retrospective radon activity concentration can be performed by measuring the ²¹⁰Po surface activity concentration of the radon progeny on mirrors. The conversion factor between the surface activity concentration of ²¹⁰Po on mirrors and the retrospective activity concentration of ²²²Rn in the air was determined. Several places and some variables have been considered. Exposures were performed in places with moderate and high concentrations of ²²²Rn. The repeatability of results has been investigated. The dependence of concentration on exposure time has been checked. The effect of cleaning the mirror surfaces has been analyzed. The experimental results obtained for the possible ²¹⁰Pb-²¹⁰Po equilibrium inside the mirrors have also been studied and compared with the theoretically expected values.

ASSOCIATION OF 210Po CONTENT IN URINE WITH CONCENTRATION OF 222Rn IN DWELLINGS

Effect of indoor radon concentrations higher than 500 Bq m-3 in dwellings on excretion of 210Po was studied in 28 volunteers. The study was further augmented by following eight individuals from the group for 5 months at 1-month intervals. Association between 222Rn concentration in homes and 210Po excretion was found when the dataset containing values of the studied 27 subjects was combined with data on 40 Prague inhabitants from the previous study. Sources of uncertainties involved in the analysis are discussed.

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.