ASSESSMENT OF RESIDENTIAL RADON EXPOSURE IN BULGARIA.

In the light of the new ICRP requirements the first National radon survey has been conducted in Bulgaria in the period 2015-16. Indoor radon concentrations were measured for 1 y in 2778 dwellings of whole Bulgarian territory in order to obtain the systematic data for the distribution of radon. The arithmetic mean is 111 Bq m-3 and the geometric mean is 81 Bq m-3 with geometric standard deviation of 2.