Level of natural radiation in the closed space of the public schools in Hamadan, Iran (2015-2016)

Since human beings are constantly exposed to environmentalionizing radiations, the measurement of natural background radiations is of utmost importance. This cross-sectional, descriptive study aimed to measure the annual effective dose of natural background radiation in 93 schools in two districts of Hamadan, Iran in the winter, spring, and autumn of 2015-2016. Among the public schools in Hamadan, the schools located in district one with 1.41±0.079 mSv and district two with 0.955±0.04 mSv had the highest and lowest mean equivalent annual dose caused by natural radiation (γ rays) in a closed space, respectively. The mean equivalent annual dose caused by natural radiation in the closed space of all the public schools in districts one and two of Hamadan was estimated at 1.20±0.07 mSv as separated by geographical directions. In addition, the highest mean dose caused by natural gamma rays in the closed space of the school buildings constructed for more and less than 40 years was 1.42±0.22 and 1.42±0.15 mSv, respectively, and the rate of the effective annual dose of the public schools in Hamadan was determined to be 0.83 mSv as separated by district. The equivalent effective annual dose and risk of gamma ray cancer in the lifespan of the public school students in Hamadan was higher than the global average.