A high mortality from lung cancer among miners was reported from Central Europe already in the 19th century. In the 60s and 70s several reports have indicated an increased lung cancer mortality among uranium miners and other metal-miners, e.g. in the US, UK, France and Sweden, but also among fluorspar miners in Canada. The cause is supposed to be the decay products of radon as emanating from the rocks, i.e. the alpha-radiation from short-lived radon daughters. Radon and radon daughter exposure in dwellings have more recently attracted interest as a potential hazard to the general population, especially since radon daughter concentrations seem to have increased due to more effective insulation for energy saving. In many Swedish houses the radon daughter exposures amount to levels similar to that of mines. Some epidemiological evaluations of the relationship between lung cancer and exposure to radon daughters, i.e. residency in stone houses versus wooden houses (with and without consideration of the contribution of radon from the ground underneath the houses), seem to indicate a risk also to the general population and, moreover, the risk of smoking seems to be several times greater in stone houses than in wooden houses, the latter usually having less radon daughters on the average.