Owing to differences in geology, radon in Belgium is recognised to be a more serious problem in the southern part of the country than in the northern part. From national and regional surveys, it became clear that in the province of Luxembourg indoor radon concentrations exceeding the European reference level of 400 Bq.m-3 frequently occur. As many people - children as well as adults - spend an important part of the day indoors at school or at work, it was decided by the local authorities to conduct a more systematic survey. In all schools and public buildings, measurements with integrating etched track devices have been performed. The results of these campaigns are discussed and a limiting scheme for radon in schools and public buildings, based mainly upon the existing Belgian regulations for protecting against ionising radiation is presented.