The measurements of the Rn-222 daughters in residential buildings of North-East Poland

The concentration of indoor Rn-222 daughters in 185 residential buildings in the area of Bialystok, Lomza, Suwalki country was measured by the Markow's method. The average potential alpha energy concentration of the radon daughters radiation was stated as 694 x 10-4 μJ/m3 and the average equilibrium equivalent concentration was 12 Bq/m3. Analysis of the results from the point of view of the used building material has shown the highest average equilibrium equivalent in the dwellings from the burnt brick (17±14 Bq/m3). The results for dwellings made from the prefabricated building element (7±5.4 Bq/m3) were twice lower, and the lowest value was observed in the houses from a timber (5±3.1 Bq/m3). The comparison of the results between particular countries shows the highest equilibrium equivalent concentration in Bialystok country (16±17.5 Bq/m3) and lower in Suwalki country (11±7.9 Bq/m3) and Lomza country (10±8.4 Bq/m3). The annual collective effective dose equivalent due to radon daughters for the population of the three administrative districts was 1399 man-Sv/year. The effective dose equivalent per capita is equal 0.91 mSv/year. (author)