MEASUREMENTS OF NATURAL RADIOACTIVITY IN SOIL SAMPLES FROM SOUTHERN ONTARIO AND ESTIMATION OF THE ACTIVITY CONCENTRATION INDEX IN BUILDING MATERIAL OF LOCAL ORIGIN

This paper reports on the measurement of natural radionuclides in soil samples collected from southern Ontario, Canada. The mean activity concentrations in soil are 28, 28 and 641 Bq/kg for Ra-226, Th-232 and K-40, respectively. Assuming activity concentrations in masonry materials such as brick and concrete are similar to soil in the surrounding area, the activity concentration index for masonry materials of Southern Ontario origin is estimated as 0.45, ranging from 0.15 to 0.83. The results indicate that the annual effective dose from exposure to gamma radiation in buildings constructed using masonry materials of southern Ontario origin for all structures (floor, ceiling and walls) would be <1 mSv.