Possibilities for harmonising controls on the radioactivity of building materials within the EuropeanUnion are being discussed in the Working Party on Natural Radiation Sources established by theArticle 31 Group of Experts (Euratom Treaty). The Working Party is preparing a document to aid theArticle 31 Expert Group and the European Commission in considering possible recommendations andtechnical guidance to the Member States for the implementation of the new Basic Safety StandardsDirective concerning the radioactivity of building materials.

In recent years a number of case-control epidemiological studies have taken place and others are inprogress to evaluate the lung cancer risk to the general population from exposure to radon and itsshort-lived progeny in the indoor residential environment. While it is actually long term exposure overpast decades to radon progeny by inhalation that dominates lung doses, for a number of practicalreasons it is radon gas that is measured in these studies.

The short-lived decay product (Rn-d) of radon gas (222Rn, 220Rn) have been identified as a healthhazard in occupational exposure situations. For the past 30 years Rn-d have also been the subject ofintensive research for their role as a public health risk in general.In the European Union this has reached the stage where decisions will have to be made concerning theinitiation and scale of national Rn-mitigation programmes.

Part 1: Introduction and procedures for reducing health risks from radon.Part 2: Properties of radon and radon daughters - includes a suggested table of radiation sourcesand percentage doses within the EC .Part 3: Health Risk Considerations - summarises health risk factors and refers to the WHOguidelines of 1986 and the EC report on radon research in the Union of 1997.Part 4: Detection Techniques and Equipment - alpha-track, charcoal canister, electret, grab samplers, continuous working level and continuous radon monitors.

The study aims at measuring the gamma activity concentration (226Ra, 232Th and 40K) of sub-slabfilling gravel of Finnish houses. This study forms a part of a wider study aiming at exploring factorsaffecting high indoor radon concentrations in Finnish dwellings. The gamma activity and radonemanation were measured from gravel samples sent from 229 Finnish municipalities, the gammaactivity was reported. Gamma activity was determined by HPGe gamma spectrometry. The averageradium and thorium concentrations of the filling gravel were 23 and 27 Bq/kg, respectively.

The council directive 96/29 EURATOM laying down the Basic Safety Standards for the protection ofthe health of workers and the general public against ionising radiation might force some Europeanwater supply companies to take technical measures for lowering the indoor air radon contents in theirwaterworks. A suitable method for this, is the installation of water aeration equipment to remove radondirectly from raw water and lead it out off the building.

Indoor radon concentrations in Athens and neighborhooding areas are relatively low compared withvalues in the northern part of Greece [1,2]. Nevertheless, we have localized a dwelling near Athens(N. Makri), with an elevated radon concentration. We attained this result from the integrative sampling etched track detector placed in open mode (nitrated type film Kodak) for one year long.The etching procedure and estimation of concentration (Bq/m3 with an uncertainty of 20%) wereconducted by the radon facilities of the Institute for Testing and Disaster Medicine, Milin, CzechRepublic [3].

In accordance with the Basic Standards of Radiation Protection issued by EURATOM and the recommendations of the Federal Commission of Radiation Protection (SSK), radon measurements were carried out at 80 of a total of 240 waterworks in the state of Baden-Wrttemberg from the end of 1994 to mid-1997. The measurements covered more than 1000 working places. The waterworks were selected among others on the basis of the number of employees, the size of the supply area, the geological and hydrological parameters, and the surface coverage.

Analysis of a comprehensive database containing all available indoor radon measurements which were carried out in Israel between 1989 and 1994 (total of 31,842 assays) coupled with Geographical Information System (GIS) capabilities and geophysical data, shows a significant correlation between indoor radon levels and its levels in the underlying bedrock.

From the end of 1996 through March 1999, the spatial and the temporal variability of the soil 222Rnconcentration was investigated at a 20m x 20m test field with porous soil in 0.5 m and 1.0 m depth atnine positions each and at 1m x 1m plots at four positions each. For this, soil gas was collected weeklyinto evacuated scintillation cells and was analysed subsequently for radon activity. In the 20m x 20mfield the spatial variability is characterised by coefficients of variation (C.V.) of 26% at 0.5m, and13% at 1.0 m depth. Within the 1m x 1m plots the C.V. Were 4% and 2%, i.e.