Notes: The largest randomized investigation of Danish dwellings to date was published in 2001. The radon concentration was measured in 3120 dwellings (3019 single-family houses and 101 multi-family houses) representing all regions of the country (results is presented in the answers below). A campaign measuring workplaces were last carried out in 1987. Radon concentrations were measured at 167 workplaces. 90% of the measured “permanent workplaces” had radon concentrations below 100 Bq/m3 with an average value of 50 Bq/m3. Only two measurements above 300 Bq/m3 were registered in total.  