Final results of the Austrian Radon Project.

The Austrian Radon Project started in 1992 and ended in 2001. The Austrian Radon Project had two aims: firstly, finding areas of enhanced indoor radon concentration for future radon mitigations, and, secondly, defining areas with elevated radon risk where radon safe construction is necessary for new houses. The project was based on systematic indoor measurements in randomly selected houses using different types of detectors. Successful intercomparison tests were made in a radon chamber, but simultaneous measurements by different detectors normally used in homes deviated sometimes up to a factor of two. We have to assume that this results from manipulations of the detectors by the inhabitants. The mean radon concentration in Austrian homes was found to be 99 Bq m(-3). A radon potential was derived from the results of the measurements and the information received from questionnaires. This radon potential was defined as an expected radon concentration in a standard situation and characterizes the radon risk from ground sources with all the influences of different living situations eliminated. A mean radon potential was computed for every municipality and the information is displayed as a map. The uncertainty and the reliability of the classification of municipalities according to the radon potential are discussed in more detail and compared with results from Switzerland.