Assessment of Indoor Gamma Radiation and related Annual effective dose in dwellings of Iran

Full text: Due to importance of ionizing radiation on human health, many studies have been performed to measure the background gamma radiation all round the world as well as some cities in Iran. According to this fact that everybody spends almost 80% of his time in indoor areas, this study was carried out to measure the amount of background gamma radiation in indoor areas in Zanjan City located in the northwest of Iran to determine the annual effective dose of the city residents. To determine the dose rate of background gamma radiation in indoors, 30 dwelling (in the main geographical directions and in the downtown areas) were selected. All of them ware one floor and iron roofed. A Geiger-Muller detector (RDS-110) calibrated by Cs-237 was used in each livings room of each dwellings. In 30 minute 30 values was recorded . The mean value was considered as indoor gamma dose rate in each dwelling. The mean value of dose rate and the annual effective dose due to indoor gamma radiation in Zanjan were determined 146±25 nGy/h and 0.87 mSv respectively. The results show that the annual effective dose for the city residents due to the gamma radiation in indoor areas is almost twice as much as international mean value reported by UNSCEAR-2000 (0.48 mSv)