All living organisms are exposed to ionizing RADIATION comprising cosmic rays coming from outer space, terrestrial nuclides occurring in the earth’s crust, building materials, air, water and foods and in the human body itself. The exposures are constant and uniform for all individuals everywhere including the dose from ingestion of 40K in food. Cosmic rays are, more intense at higher altitudes, and the levels of uranium and thorium in soils are elevated in localized areas. Exposures also vary as a result of human activities and practices. In particular, building materials of houses and the design and ventilation systems strongly influences the indoor levels of the radioactive gas radon and its decay products, which contributes the doses through inhalation. Component of the sources of exposures to Indian population has been assessed based on the data generated. Total contribution from the natural sources to the Indian population works out to 2.3 mSv/y as against the global value of 2.4 mSv/y. Estimated modified source including mining of heavy metals, coal fired power plants, mining of phosphate rocks and its use as fertilizers, production of natural gas, gas mantles and luminescent dial and air travel contribution to the BACKGROUND RADIATION to the Indian population works out to be 1.2 x 10-3 mSv/y; atmospheric weapon tests contributes about 0.045 mSv/y, medical exposure contributes about 0.048 mSv/y and exposure due to nuclear power production contributes about 5.0 x 10-5 mSv/y to the BACKGROUND RADIATION. Brief review and comparison of the dose rates arising from natural and man made sources to the Indian population is given.

BACKGROUND: Measurement of BACKGROUND RADIATION is very important from different points of view especially for human health. The aim of this survey was focused on determining the current BACKGROUND RADIATION in one of the highest altitude regions ( Zagros Mountains ), Chaharmahal and Bakhtiari province, in the south west of Iran . Materials and Methods: The outdoors-environmental monitoring exposure rate of RADIATION was measured in 200 randomly chosen regions using portable Geiger-Muller and Scintillation detectors. Eight measurements were made for each region and an average value was used to calculate the exposure rate from natural BACKGROUND RADIATION. Results: The exposure dose rate was found to be 28.4 m Rh-1 and the annual average effective equivalent dose was found to be 0.49 mSv. An overall population weighted average outdoor dose rate was calculated to be 49 nGyh-1, which is higher than the world-wide mean value of 44 nGyh-1 and is comparable to the annual effective equivalent dose of 0.38 mSv. Conclusion: A good correlation between the altitude and the exposure rate was observed, as the higher altitude regions have higher natural BACKGROUND RADIATION levels

BACKGROUND: The exposure of human being to ionize RADIATION from natural sources is a continuing, inescapable feature of life on earth. Direct measurement of absorbed dose rates in air has been carried out in many countries of the world during the last few decades. Such investigations can be useful for assessment of public dose rates, the performance of epidemiological studies, and keeping reference-data records to ascertain possible changes in the environmental radioactivity duo to nuclear, industrial, and other human activities.Materials and Methods: The measurements of the outdoor and indoor- environmental exposures including cosmic and terrestrial components were accomplished by a portable Geiger Muller detector (RDS -110). The measurements were made during daylight from September to October 2009, in five areas within nine big cities of Lorestan province. In each area, one building was randomly selected for indoor and outdoor measurements. Measurements were made for each region and an average value was used to calculate the exposure rate from gamma BACKGROUND RADIATION.Results: The results showed the Maximum and minimum outdoor dose rates as 166±44 and 65±8 nSvh-1 in Borujerd and Pol-e- dokhtar, respectively. The average of outdoor dose rates was determined 113±26 nSvh-1. Also the maximum and minimum values of indoor dose were 157±52 and 74±14 nSvh-1 in Borujerd and Pol-e-dokhtar, respectively. The average indoor dose rates were determined as 119±27 nSvh-1.Conclusion: The average annual effective dose for gamma BACKGROUND RADIATION in Lorestan province has been 0.72 mSv, with the range of 0.3–0.6 mSv which was more than the global value (0.48 mSv). A poor correlation coefficient between was observed altitude and absorbed dose rates.

BACKGROUND: There are relatively rich uranium mines in regions of Saghand and Bafgh in Yazd province. This survey was carried out to provide a map of ambient gamma RADIATION of Yazd province and the probable effects of the existence of these mines on BACKGROUND RADIATION dose rates. Materials and Methods: The measurements of the outdoor and indoor–environmental exposures (including cosmic and terrestrial components) were accomplished by a portable Geiger Muller detector in the five areas in each of eight big cities of Yazd province.Results: The average exposure rates of indoor and outdoor ambient of Yazd province were 13.9 ±0.7 µRh-1 and 11.6 ±0.8 µRh-1 respectively. The average dose rates in air, resulting from gamma BACKGROUND RADIATION of indoor and outdoor were 122±6.8 nSvh-1 and 101.4 ±7.4 nSvh-1 respectively. The annual average of equivalent dose in air was found to be 1.03 ± 0.05 mSv, and the annual average of effective dose was 0.72 mSv.Conclusion: The results of this study in comparison with the same measurements in some other cities in Iran such as Isfahan and Tabriz, proves that the existence of uranium mines doesn’t affect gamma BACKGROUND RADIATION of Yazd province.

BACKGROUND: Exposure to ionizing RADIATION has harmful health effects. Research shows that people spend more their time indoors than outdoors. Therefore, the indoor BACKGROUND ionizing RADIATION can pose a noticeable health risk. Objectives: Since it is well established that ionizing RADIATION can lead to serious health problems, the present study aimed to evaluate the level of ionizing RADIATION in the BACKGROUND environment in radiological centers in Ahvaz, Iran. Methods: The evaluation of indoor and outdoor BACKGROUND ionizing RADIATION levels was carried out by using the calibrated digital Geiger-Muller counter (S. E. International Inc., USA) in five radiography centers. The BACKGROUND RADIATION was measured both indoor and outdoor of the selected radiology centers in four locations. The measured locations included behind the door of the X-ray room, outdoor, waiting room for the people, and the reception section in each center. The measurements were done with a device held one meter above the floor. Results: The indoor RADIATION levels were 0. 13 ± 0. 004, 0. 11 ± 0. 004, 0. 13 ± 0. 004, 0. 16 ± 0. 007, and 0. 16 ± 0. 006 µ Sv/h for centers a, b, c, d, and e, respectively, and the outdoor RADIATION levels were 0. 12 ± 0. 02, 0. 11 ± 0. 01, 0. 10 ± 0. 00, 0. 12 ± 0. 01, and 0. 13 ± 0. 00 µ Sv/h, respectively. Conclusions: The mean equivalent dose in this study was lower than the standard level (1 mSv/y); therefore, the radiology centers were safe.

Employment of nuclear power as a main source, of energy and ever increasing application of radioisotopes in medicine and industry have increased the importance of ionizing RADIATION studies. Environmental γ RADIATION is one of the natural RADIATION components. In this research γ RADIATION levels have been measured for some stations in Azarbayjan. One of the major aims of this research was to determine the base line for γ RADIATION at the regions of interest and to recognize the effective factors. In this study, the dose rate due to environmental γ RADIATION in open air and one meter above the ground level was measured with RDS-110 Survey Meter. The average dose rates for Tabriz, Orumiyeh, Sarein, Iran-Turkey border line, Iran –Armanestan border line and Koojonogh village were 114, 114,164, 86, 66 and 260 nSv/h respectively. These results could be utilized to assess any change at the level of environmental y RADIATION in future due to geological phenomena or establishment of nuclear power stations in the regions of interest.    

Considering current controversies regarding the health effects of low doses of ionizing RADIATION, study of the high BACKGROUND RADIATION areas such as Ramsar, Iran can help scientists better evaluate the validity of linear no-threshold (LNT) hypothesis. Ramsar is a coastal city in northern Iran with some areas known to have the highest levels of natural BACKGROUND RADIATION in the world. The mean annual dose of the residents of high BACKGROUND RADIATION areas (HBRAs) of Ramsar is 10 times higher than the public dose limit recommended by the ICRP (1 mSv/year) and a proportion of the residents receive annual doses as large as 260 mSv (13 times higher than the occupational dose limit recommended by the ICRP). A report published in Popular Science proclaims that BACKGROUND RADIATION in Ramsar approaches that of the Martian surface. However, estimates show that the maximum annual RADIATION dose in HBRAs of Ramsar can be much higher than that of the Martian surface (260 mGy/y vs 76 mGy/y). Furthermore, a Guardian report introduces Talesh Mahalleh, a district in Ramsar, as an inhabited area with the highest levels of natural radioactivity in the world and C Net claims that the best Mars colonists may come from places like Iran and Brazil. In spite of current concerns, nearly all residents still live in their paternal dwellings and there are not consistent reports on any detrimental effects. It is worth noting that, due to small sample size, to draw a firm conclusion about the health effects of high level natural RADIATION in Ramsar, in particular about the cancer risk, current information is not sufficient and further studies are needed.

Time-dependent wormhole solution of the BD theory in an anisotropic RADIATION BACKGROUND is presented. It is also found that the BD scalar field depends only on time. This time dependency is in power-law form. It is shown that the wormhole geometry is valid for w≥-3/2, and for any arbitrary positive values of w. The GR limit of our solution is obtained for w=0, not for w→∞. Though the BD field can be non- exotic, the BACKGROUND material is entirely exotic.

The presence of natural BACKGROUND RADIATION and environmental radioactivity is due to distribution of radionuclides in the earth and cosmic rays. These causes exposure to biological area and human body. In most countries natural BACKGROUND RADIATION has been measured repeatedly, but there is no accurate and complete information in Iran. The contents of natural radio nuclides (uranium, actinium, and thorium) as well as the thin layer of atmosphere in the higher altitude regions are reasons of high level of human exposure. The aim of this survey was focused on determining the current BACKGROUND RADIATION of Chaharmahal and Bakhtiari province, which is the highest altitude region in Iran. The outdoors" environmental monitoring exposure rate of RADIATION was measured in 100 randomly selected regions using a portable Geiger-Muller detector. Eight measurements were made for each region and averaged as exposure rate of natural BACKGROUND RADIATION of that region. The mean exposure rate was found to be 28.2±µR/h and an overall outdoor dose rate was 49 nGy/h which is higher than the worldwide mean value of 44 nGy/h as reported in UNSCEAR, 1998. The annual effective dose equivalent was found to be 0.49 mSv/y. The results showed that there is a good correlation between altitude and exposure rate. In relation to the altitude and geological structure of the province the results also showed that the higher altitude regions has the higher natural BACKGROUND RADIATION level.