Coals mined in some regions of the Transdanubian Middle Mountains in Hungary have elevatedconcentrations of 226Ra. The slags and ashes derived from these coals have been used as buildingmaterial for schools and kindergartens. As the 226Ra reached up in these waste products of coal-firingsystems, the gamma dose contribution in the buildings, which contained them, was calculated.

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.

Indoor radon concentrations were determined with the use of track-etched detectors and two monitors,both for radon and one for the decay products, in various regions of Greece. Until now, 1137 dwellings have been measured. Some factors, that influence the radon concentration in dwellings, are discussed in this paper. The factors, used in this analysis, were derived from the householders answers to the relevant questions about various physical features of the dwelling. Different statistical methods were used, as the unpaired t-test and the ANOVA method.

In Poland as in many other countries regulations limiting permissible level of radon concentrations indoors are in force. It implies a need for a methodology of searching for houses with elevated radon concentration. Since it was discovered that the bedrock was the most powerful source of radon indoors it has been observed by many researchers that homes with enhanced radon concentrations occur more frequently in particular areas.

Mapping the geogenic radon potential in Germany is a research project initiated by the German Federal Ministry for the Environment, Conservation and Reactor Safety. The project was aimed to develop a standard methodology for the estimation of a geogenic radon potential and to apply this method to map the region of Germany as an overview for planning purposes. The regionalization results from a distance-weighted interpolation of the site-specific values of radon concentration in soil gas and in-situ gas permeability of soils on a regular grid considering the corresponding geological units.

The evaluation of the geogenic radon potential is based on field measurements of radon activity concentration in soil gas. The values obtained through such spot measurements depend strongly on the geological background [1] [2] but also on the soil properties like grainsize distribution, porespace watersaturation and also on meteorological conditions. The goal of this study was to estimate the variability of the radon activity concentration in soil gas and to relate it to the variations of soil properties induced by seasonal changes.

To clarify the mechanism of radon transport from soil to surface, long term continuous measurementsof radon exhalation were conducted at one site in combination with measurements of radon concentration in soil gas, soil temperature, pressure difference, soil moisture and meteorological parameters. Based on the results of measurements over a two year period, the influence of meteorological and soil parameters on the exhalation was estimated.

Questions have been raised about the economic implications of the regulations governing radon gas level identification and remediation in buildings. Attempts to answer the economic questions related to proposed policy have been varied and criticised for lack of scope and comparability. It is imperative therefore that a general model for the evaluation of radon remediation programmes is adopted by participating interests to ensure the comparability and usefulness of ratios in decision making.

Basic considerations1. Legal base fixing the limiting value for radon in residential and recreational premises.(Radiological Protection Ordinance of 22 June 1994)2. Engagement in a campaign measuring the radon concentrations, finding the areas with radon prone buildings, and mapping those areas.3. Collaboration with the homeowners living at a high radon concentration to define a project how to reduce it.

An Austrian farmhouse has been mitigated; it was built around the turn of the century in theconventional farmhouse style of that time.