The Austrian radon mitigation joint research project SARAH (supported by the Austrian Ministry ofEconomy and the Government of Upper Austria), a two-year follow up study of the Austrian NationalRadon Project (NRAP), was started in 1996. Objectives of the research project were to find simple,cost effective experimental methods for the characterisation of the radon situation in dwellings and toevaluate technically and economically the implementation of state of the art remedial actions forAustrian house types.
Implanted long-lived radon decay products in glass surfaces have been used as a measure of pastradon exposure in homes. Special track-etch devices (so-called retro-detectors") attached to the glasssurface, have the ability to specifically measure the implanted activity of 210Po in-situ. Calibratingthese devices for 210Po is fairly straightforward, but the retro-detectors are also sensitive to thebackground activity of the glass substrate.
In recent years, 210Po implanted in glass artefacts has been used as an indicator of the mean radon gasconcentration in dwellings in the past. Glass artefacts have been selected in many dwellings and the?-recoil implanted 210Po concentration has been measured using various techniques. Some of theseretrospective techniques use a model to estimate the retrospective radon gas on the basis of thissurface 210Po activity. The accumulation of 210Po on glass surfaces is determined by the depositionregime over the exposure period.
The identification of a radon-affected area in the south of Yugoslavia was based on geologicalstructuraland geochemical prospecting data of radioactive and other mineral resources. An anomalousarea was recognized at a rural community Gornja Stubla (in the extreme south of Serbia), whileprospecting for uranium in the region on the margin of the large Vardar Zone geotectonic unit.
Investigations on the retrospective estimation of radon exposure in homes had already been carried outin international collaboration in the uranium mining regions of Germany since 1994. Following aConcerted Action named "Retrospectively Estimated Radon in Areas Affected by Uranium MiningActivities " was agreed upon.
The retrospective determination of radon exposure levels in dwellings by means of the measurement ofthe Po-210 surface activity is subject to various uncertainties. These result partly from the valuesassumed for the equilibrium factor F and for the unattached fraction f, and, more importantly, fromdifferences in the deposition velocities of short-lived decay products of Rn-222, caused by varyingconditions of turbulence.
The work described in this paper is based upon the results of the recently completed National Surveyof Radon in Dwellings [1] carried out by the Radiological Protection Institute of Ireland (RPII).Measurements were carried out in 11,054 dwellings, located in 832 10 km grid squares across thecountry.
This paper presents the results of the National Survey of Radon in Dwellings carried out by theRadiological Protection Institute of Ireland (RPII). Radon measurements were carried out in 11,319houses throughout the country. Indoor annual average radon concentrations ranged from 10 Bq/m3 to1924 Bq/m3. The measurement data were grouped on the basis of the 10 km grid squares of the IrishNational Grid System and used to predict the percentage of dwellings in each grid square which exceedsthe Reference Level of 200 Bq/m3.
The average indoor radon concentration in Finnish flats is 80 Bq/m3. Typically walls have been madeusing concrete elements. Building materials are the dominant source of indoor radon. However, in theflats of the lowest floor, with a floor slab in direct ground contact, the main source of radon is oftenthe inflow of radon bearing soil air. The number of these ground contact flats is less than 10 % of thetotal number of flats. The average indoor radon concentration of these ground contact flats is 150Bq/m3.
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