Natural radioactivity measurements in the city of Ptolemais (Northern Greece)

Specific activities of the natural radionuclides U-238, Ra-226, Th-232 and K-40 were measured by means of gamma-ray spectrometry in surface soil samples collected from the city of Ptolemais, which is located near lignite-fired power plants. The mean activity values for U-238, Ra-226, Th-232 and K-40 were found to be 42 +/- 11, 27 +/- 6, 36 +/- 5 and 496 +/- 56 Bq kg(-1), respectively. These values fall within the range of typical world and Greek values for soil. The indoor radon concentration levels, which were also measured in 66 dwellings by means of SSNTD, ranged from 12 to 129 Bq m(-3), with an average value of 36 +/- 2 Bq m(-3). This value is close to world and Greek average values for indoor radon concen trations. The total effective dose due to outdoor external irradiation of terrestrial origin and to indoor internal irradiation from the short-lived decay products of Rn-222 was estimated to be 1.2 mSv y(-1) for adults, which is lower than the global effective dose due to natural sources of 2.4 mSv y(-1). (C) 2007 Elsevier Ltd. All rights reserved.