New public dose assessment from internal and external exposures in low- and elevated-level natural radiation areas of Ramsar, Iran

Abstract

A detailed dosimetry study was carried out in 12 regions of Ramsar having some elevated-level natural radiation areas (ELNRA) for the determination of effective doses of public from internal and external exposures indoors and outdoors. The 222Rn levels were measured by using the AEOI passive radon diffusion chambers indoors of about 500 houses in two separate studies in autumn and in winter, and also in some locations outdoors. The 222Rn and its progeny and equilibrium factors were also determined indoors and outdoors of some buildings by the active Pylon AB-5 system based on which the effective equivalent dose (E) of the public was determined. The annual mean effective equivalent dose (Ē) in different regions due to 222Rn ranges from 2.48 to 71.74 mSv with maximum levels up to 640 mSv determined in one house in Talesh Mahalleh. The annual Ē value from external exposures, as determined in 1000 locations outdoors and in 800 locations indoors, were reported in another paper before which range from 0.6 (in normal background areas) to 6 mSv (in the ELNRA) with maximum values up to 135 mSv in the above-stated house with a high radon level. This paper mainly reports the 222Rn levels indoors and outdoors and the effective equivalent doses due to 222Rn and its progeny and concludes some results of total annual effective equivalent doses of public due to external and internal exposures. © 2004 Elsevier B.V. All rights reserved.