Indoor radon concentrations in kindergartens in three Bulgarian districts.

This article examines the results of a study of radon concentrations in kindergartens in three districts of north-western Bulgaria. For the period from December 2019 to May 2020, passive radon measurements were accomplished in 1490 premises of 130 kindergartens. The highest arithmetic mean (AM) value of 219 Bq m and geometric mean (GM) value of 156 Bq m radon concentration were found in the state kindergartens of the Vratsa district.

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.