Population doses due to indoor gamma radiation exposure in Ramsar

The coastal area of ​​Ramsar in northern of Iran located in the province of Mazandaran has been known as the highest levels of natural radiation background in the world. The background radiation is mainly due to the presence of radioactive isotopes of the radium element and its decay products, which is brought to the surface by hot springs. In this study, the indoor gamma dose rate in Ramsar was directly measured and the public annual effective dose due to indoor gamma radiation was calculated. To measure the gamma dose rate, a portable gamma spectrometer with sodium iodide detector (Na I) was used. 100 houses are randomly selected and the measurements were carried out at one meter height above the ground surface in each place, which was mostly occupied by people in each house. The public annual effective dose due to indoor gamma exposure was calculated. The maximum, minimum, and average dose rates were 222 nSv h-1, 44 nSv h-1 and 94 nSv h-1, respectively. The highest, lowest, and average public annual effective dose of Ramsar residents due to indoor gamma exposure were 1.55, 0.31 and 0.66 mSv, respectively. The results of this study indicate that average of the public annual effective dose of Ramsar people due to indoor gamma exposure is equal to 0.66 mSv and it is approximately 1.6 times greater than the worldwide average exposure to indoor gamma radiation reported by the United Nations Scientific Committee on the Effects of Atomic Radiation (0.41 mSv). In addition, it is not significantly different from the other reported results (average of 0.7 mSv) for the homes in normal radiation background areas in Ramsar.