The Search for Radon Sources, A Multidisciplinary Task

In a city in the Swiss Jura, well known for its watch industry, there are high 222Rn concentrations in many houses (up to 4 kBq.m-3 in living rooms). Clear 226Ra contamination is present in and near former workshops that had processed radium activated paint, but enhanced radon levels are also measured in houses free from any contamination; thus the origin of the radon problem in this city is by no means clear. The methods used to localise the radium sources, to reveal the origin (natural or artificial) and to study the radon transport to the houses are presented.