We've got the same problem over here in Sweden, granite in a lot of places. We also, just for good measure, constructed a lot of buildings in the 50s and 60s fr

We've got the same problem over here in Sweden, granite in a lot of places. We also, just for good measure, constructed a lot of buildings in the 50s and 60s from radioactive autoclaved aerated concrete made from alum shale containing high concentrations of uranium. Fun days. Apparently there's still half a million homes here exceeding the radon limit of 200 Bq/m3 indoors.