[Assessment of indoor gamma radiation and related annual effective dose in Zanjan, Iran]

Due to importance of ionizing radiation on human health, many studies have been performed to measure the background gamma radiation all around the world as well as some cities in lran. 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 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 were one floor and iron roofed. A Geiger-Muller detector [RDS-110] calibrated by Cs-137 was used in each livings room of each dwellings that performed in one meter far from the earth. 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 in Zanajn indoor areas due to gamma background radiation was determined 146 +/- 25 nGy/h. According to the results and findings in our previous study about gamma background radiation in outdoor areas in Zanjan, the annual effective dose was determined and 0.87 mSv for Zanjan city residents. The annual effective dose of Zanjan city residents due to the gamma background radiation is 0.87 mSv that in comparison with UNSCEAR-2000 report is higher than the mean value for the world [0.48 mSv]

[Assessment of background gamma radiation in outdoor areas in different seasons in Zanjan]

Due to importance of ionizing radiation on human health, many studies have been performed to measure the background gamma radiation all around the world as well as some cities in lran. This study was carried out to measure the amount of background gamma radiation in outdoor areas in different seasons in Zanjan to determine the annual effective dose of the city residents. To determine the dose rate of background gamma radiation in outdoor areas, 8 stations [4 in the main directions and 4 in the downtown areas] were selected using the map of the city. Eight measurements were performed for each station [twice in each season] using Geiger-Muller detector [RDS-110] calibrated by Cs-137. The mean value of dose rate and the annual effective dose due to background gamma radiation in different season in Zanjan were determined 126 nGy/h and 0.15 mSv respectively. The minimum and maximum mean values of dose rate were found 120 +/- 21 nGy/h and 134 +/- 18 nGy/h in summer and spring respectively. The results show that the dose rate and the annual effective dose for the city residents due to the background gamma radiation in outdoor areas is twice as much as international mean value reported by UNSCEAR-2000. To determine the total annual effective dose of Zanjan residents, measuring the dose rate in indoor areas is necessary