English

The application of a radon model is useful to understand the processes that drive the radon gasbehaviour from its sources to its accumulation indoors. Since in a given inhabited house the detailedknowledge of the values of all the parameters that affect indoor radon levels is not available, theresponse of the model has to be explored in a reference site in which all the parameters are supposedto be known. We call this site the reference configuration.

Radon goes through four stages from its formation until it reaches a living environment: i) itsgeneration in the source medium, ii) its migration in the source medium, iii) its entry into a dwelling,and iv) its accumulation indoors. Many parameters of different origin take part at each stage, and mostof them are time-dependent. In this paper we discuss the requirements that an ideal model, whichconstitutes a Global Dynamic Radon Model (GDRM), should fulfil to predict indoor radon levels inliving areas of inhabited houses.

The radon concentrations in indoor air and in soil air vary both on short term (daily, weekly) and onlong term (seasonal). The radon level and its changes depend on a few parameters, which may bedifferent from one building to another and from one type of soil to another. It is important to know theseasonal variation of the indoor radon levels if the level is to be compared with the national upperlimits in Europe for indoor radon concentrations.

In situ gamma spectroscopy is widely utilised to determine the outdoor gamma dose rate from the soiland to calculate the natural and artificial radionuclide concentration and their contribution to the doserate. The application of in situ gamma spectroscopy in indoor environments can not supplyquantitative information about activity concentration of radionuclides in buildings materials, but thistechnique can provide interesting information about building materials as radon source.

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.