Notes: There is no separate requirement directly for the need for measurements of the Radon, and the distinction between the buildings (for existing dwellings and for existing buildings with high public occupancy) is not made. The same requirement specified in point 40 of the Radiation Safety Norms is valid for all cases. It stipulates that the annual equivalent activity concentration of 222Rn and 220Rn daughter isotope in the air of operated residential buildings shall not exceed 300 Bq/m3.  