抄録
Individual external doses of inhabitants were examined in high levels of natural radiation areas (HLNRAs) in Ramsar. Each of 15 inhabitants in HLNRAs and 10 inhabitants in a control area carried an electronic personal dosimeter (EPD) for one day in April and in December 2005. In addition, their individual doses were estimated from indoor and outdoor radiation dose rates determined with a NaI (Tl) survey meter. A good correlation existed between the dose rate values obtained through estimation and personal measurement, and estimated annual doses ranged from 0.5 to 32 mGy/y. Each of the dosimetric subjects carried also an optically stimulated luminescence dosimeter (OSLD) for about one month in September 2005, but a few values obtained by these measurements deviated widely from those obtained by one-day measurements with EPDs and those estimated by environmental dosimetry. This deviation might have been due to the fact that these OSLDs were left behind somewhere in houses. Hence, the observed dose values depended heavily on the place where dosimeters had been left, because of the non-uniform distribution of Ra-226 contained in building materials as well as the structure of the house and the existence of shields.
