Background and Objective: Human external exposure to natural radiation sources is much more than artificial radiation sources. In this study, external annual effective doses were estimated in cities of Gorgan and Bandar-Torkman by determining ambient gamma dose rate in indoor and outdoor spaces.
Materials and Methods: Using an ionization chamber detector, the outdoor and indoor ambient gamma dose rate at 32 and 16 selected stations in Gorgan and Bandar-Torkman cities was measured for one hour, respectively. Indoor measurements were performed by 36 dosimeters in Gorgan and Bandar-Torkman cities in 11 and 6 residential buildings respectively using thermoluminescence dosimetry method.
Results: The results of this study indicate that the ambient gamma dose rate in outdoor is a little more than this quantity in indoor space. The annual effective dose received by residents of Gorgan and Bandar-Torkman were 0.720 and 0.719 mSv, respectively.
Conclusion: The annual effective dose received by residents of Gorgan and Bandar-Torkman cities is less than the worldwide average, and it is also less than the reference dose level for ordinary people (1 mSv).
