Estimation of external natural background gamma ray doses to the population of Caspian coastal provinces in North of Iran

Background: The effect of natural background radiation on health is still controversial. However, it is clear that it depends on the dose received by the population. The estimation of external natural background gamma rays received by the population of Caspian coastal provinces in the northern part of Iran was the main goal of this study. Materials and Methods: Gamma rays was measured using calibrated radiation survey meter in 51 urban and rural health centers randomly to estimate the exposure to population (Total population = 6888118 persons) in residential areas of Gilan, Mazandaran and Golestan (Total area 59240 Km2) as Caspian coastal provinces, North of Iran. Results: Results showed that the average dose rate in the areas under study was about 60.37±14.88 nSv/h or 0.53 mSv/yr (Range 30 to 90 nSv/h or 0.26 to 0.79 mSv/yr). The data from Ramsar was excluded from the estimation because of its very high natural background radiation (Max. 240 mSv/yr). No significant difference was found among the doses of the provinces (P=0.237). Conclusion: The external natural background gamma ray dose to the population of Caspian coastal provinces, North of Iran, was found to be almost equal to the average value in the world (0.5 mSv/yr). Iran. J. Radiat. Res., 2011 9(3): 183-186