Indoor gamma dose rates in the high background radiation area of Abeokuta, South Western Nigeria

Abstract

An indoor gamma dose rates survey was conducted in selected dwellings comprising homes and offices in Abeokuta, South Western Nigeria. Absorbed dose rates were measured using Gamma RAE II R (RAE Systems), which is a CsI-based dosimeter. Absorbed dose rates in the dwellings vary from 0.077 to 0.397 µSv/h, with an overall mean of 0.201 ± 0.074 µSv/h, which is more than twice the world population-weighted average indoor absorbed dose rate (0.084 µSv/h). Buildings made from mud bricks have higher absorbed dose rates than those made from cement-blocks, and houses built on rock outcrops have higher absorbed dose rates compared to those erected/built on soil. The calculated annual effective doses in the study area range from 0.540 to 2.782 mSv with an average value of 1.406 ± 0.521 mSv. The distributions of dose rates according to variations in the local geology and building materials were presented. This study provides data on the indoor component of the terrestrial gamma dose rates in Abeokuta, Nigeria, which is an update of the existing knowledge on the levels of the background radiation exposure in this high natural background radiation area. KEYWORDS Indoor gamma dose rates; Abeokuta; high background radiationCONTACT I. C. Okeyode

Background radiation level measurement using hand held dosimeter and gamma spectrometry in Ijebu-Ife, Ogun State Nigeria

“…Generally, the gamma absorbed dose rate recorded in all locations using a hand held survey meter are within the same range, which can be attributed to geological homogeneity of the study area (11) . Absorbed dose rates for all measured locations fall below the standard background radiation level of 0.133 μSv/hr, recommended by the International Commission on Radiological Protection (22) and the corresponding effective dose was below the 1 mSv/yr maximum permissible limit for the general public set by the United Nations for Scientific Committee on the Effects of Atomic Radiation (3) , and 2.3 mSv/yr in India (10,23) , 0.19-1.64 mSv/yr in Abeokuta Nigeria (24) . The low radiation levels in the area can be attributed to natural sources as there is no contribution from artificial sources or cosmic radiation (19) .…”

“…Provided by RAE Systems P/N 047-4505-000, USA), Gamma RAE II R is a rapid γ-ray (gamma) source detector and dosimeter in a single unit with high sensitivity to low radiation energy/level making contribution of gamma-rays from cosmic sources negligible (19) . During measurements, the survey meter was held at gonad height on a tripod stand such that it is one-meter above ground level (3) . At each location, absorbed dose rates (μSv/hr) were measured for 5 min and repeated six times.…”

“…At each location, absorbed dose rates (μSv/hr) were measured for 5 min and repeated six times. The mean of the six readings over the total sampling time of 30 min was recorded according to (3) to provide desirable accuracy (<10% SD) at a 95% confidence level. The mean of all the locations was computed and considered as the representative absorbed dose value for that location.…”

“…Natural radioactivity is known to be naturally present in our environment (1) , existing in various geological formations such as soils, rocks, plants, water and air (2) , since the formation of the earth (3) . Naturally occurring radionuclides are common occurrences in the environment (4) and their accumulation in air, soil, water and plant parts represents the exposure pathway to humans (1) .…”

Assessment of Outdoor Gamma Exposure Level of Some Swampy Agricultural Soils of Nasarawa West, Nigeria

“…The background ionizing gamma radiation exposures may be of little or no radiological concern in most parts of the world [7,8]. In such places the significance of assessing levels of radiation exposure from various natural components could therefore be to establish the relative importance of each component [9], or/and to provide baselines against which the radiological impacts of the practices that generate artificial ionizing radiation exposures could be measured [10]. Although the studies of atomic bomb survivors provide strong evidence of health effects such as cancer and non-cancer diseases associated with single acute exposure to moderate and high doses of ionizing radiation, the effect of low dose-rates on health and cancer risks after exposure to ionizing radiation is, as yet, unclear [7,11].…”