The analysis of the literature data on the nature of Radon, about its physical and chemical properties is carried out. The danger of Radon is presented for a person from the point of view of medicine. The ways to reduce its danger are listed. At the same time, the literature data are presented in which the possibilities of using radon with benefit are outlined, namely: as precursors of an earthquake, for human treatment - when used in moderate doses. Modern radon detection devices are analyzed, and a conclusion is made about the need to create a new generation of
radonometers