The use of contemporary radon (222Rn) gas concentrations to estimate retrospective radon-relateddoses can introduce substantial uncertainties in epidemiological analyses. These uncertainties tend tobias the results of radon-lung cancer epidemiologic studies towards the null. Temporal variability ofradon progeny over past decades and the variability in the dose effectiveness of airborne radonprogeny caused by indoor atmospheric differences are among the main sources of uncertainties in ourregion.
A large-scale radon survey has been carried out from 1995 to 1998 in southern Greece, in order toestimate the radon concentration in Greek dwellings and the exposure of the Greek population toradon. The design was administratively orientated. The statistical criterion for the selection ofsampling locations and the distribution of radon dosimeters was the percentage of dwellings of eachlevel of the administratively classifications in respect to the above level. This way of distributionassured that all the inhabited geographical regions were covered.
Radon, radon progeny and unattached radon progeny were measured in two chambers with differentcharacteristics at the Jenolan Caves, New South Wales, Australia, in 1996. Meteorological parametersand condensation nucleus concentrations were measured in order to understand the processesgoverning the radon concentration and degree of disequilibrium with the progeny. One chamber waspoorly ventilated, and rainfall proved to be the most important influence on radon concentration.
The International Commission on Radiological Protection (ICRP) recommends the use of a singleconversion factor, derived from epidemiological studies of exposure to uranium miners, for thedetermination of the effective dose from inhalation of radon progeny. Dosimetric models of radonprogeny inhalation predict that the dose conversion factors (DCF) are dependent upon the form ofthe radon progeny activity size distribution. The measurement of these activity size distributions isdifficult and an alternative approach has been proposed.
Radon progeny concentration is measured with a total alpha counting system in 185 dwellings in thetown of Thessaloniki. The Equilibrium Equivalent radon Concentration (EEC 222Rn) follows a lognormaldistribution with an arithmetic and geometric mean value of 28 Bq/m3 and 16 Bq/m3 respectively. Simultaneous in situ alpha and gamma spectroscopy measurements were performed in 60 schools of Thessaloniki. The mean equilibrium Equivalent Concentration of radon and thoron is 22 Bq/m3 and 0.9 Bq/m3 respectively.
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