A STUDY OF NATURAL RADIOACTIVITY IN SOME BUILDING MATERIALS IN NIGERIA

Radiation doses received by humans in their dwellings - A baseline report on radionuclides exposure from construction materials used in Chennai, Tamil Nadu, India

Gamma-ray spectrometry was employed to assess the activity concentrations of primordial radionuclides (238U, 232Th, and 40K) in various construction materials, including those used for building, roofing, furnishing, flooring, and plastering. The measured activity concentrations of the radionuclides ranged as follows: 238U (25 to 477 Bq kg-1), 232Th (below detection limit to 239 Bq kg-1), and 40K (285 to 1915 Bq kg-1). Based on these values, the materials were categorized in descending order of radioactivity threat as: Furnishing > Roofing > Building > Flooring > Plastering. The potential radiation dose and radiological hazards to occupants from continuous exposure were estimated using risk parameters. The absorbed dose rates for flooring (217.7 nGy h-1), building (286.9 nGy h-1), furnishing (353.1 nGy h-1), roofing (322.5 nGy h-1), and plastering (176.8 nGy h-1) were all found to exceed both the world average value and the typical indoor gamma dose rate of 84 nGy h-1. This study highlights significant radiological risks to inhabitants associated with the use of certain materials in building construction. These include clay tiles for roofing, wood, specific granite varieties (reddish/brown granite), and certain types of bricks (fly ash, burnt, and AAS).

Evaluation of radiological risk associated with local building materials commonly used in Northwestern Nigeria

In this study, potential radiological risk due to the activity concentrations of primordial radionuclides (²²⁶Ra, ²³²Th, and ⁴⁰K) in commonly used local building materials (sand, clay, kaolin and gypsum) in Northwestern Nigeria were assessed using NaI (Tl) detector. The measured activity concentrations ranged from 47 to 63 Bq kg^-1 for ²²⁶Ra, 24-32 Bq kg^-1 for ²³²Th, and 219-257 Bq kg^-1 for ⁴⁰K respectively. The mean values of ²³²Th, and ⁴⁰K for all samples were below the respective world averages of 45 and 420 Bq kg^-1 with that of ²²⁶Ra for all the samples higher than the world average value of 32 Bq kg^-1. The potential radiological risks were assessed by determining radium equivalent activity (Ra_eq), internal and external hazard indices (H_in and H_ex), absorbed gamma dose rates (D_R), internal annual effective dose rates (IAED), and annual gonadal dose equivalent (AGDE) and activity utilization index (AUI). The assessed parameters were found to range between 104 and 125 Bq kg^-1, 0.99 to 1.15, 0.28 to 0.34, 48 to 58 nGyh^-1, 0.76 to 0.86 mSvy^-1, and 0.78 to 0.96 respectively. The Ra_eq and D_R for all the analyzed samples were found to be within International recommended limits of 370 Bq kg^-1 and 59 nGy h^-1 as recommended by UNSCEAR.

Relationship between indoor ambient dose equivalent rates and the architectural style of standalone houses in locations with high naturally occurring radionuclide soil concentrations

There have been numerous studies relating house construction materials with the indoor gamma dose rate mainly coming from natural radionuclide activities. The relationship between the outdoor gamma dose rate and the soil's naturally occurring radionuclide content is well documented. Few studies, however, have investigated the historical evolution of indoor gamma dose levels due to the principal materials used in house construction in geographical areas where outdoor natural radiation levels are significant. The present work was carried out in an area of Spain with high outdoor gamma dose levels (on average, 0.267 µSv h^-1) due to the natural radioactive characteristics of its soils, considering a great variety of standalone houses built from the beginning of the 18th century until today with different styles, architectural techniques, and materials in their construction. The measured ambient dose equivalent rates in thgese houses decreased the more recent the date of their construction was. In conclusion, today's architectural style for housing, which uses materials of practically universal origin, not only attenuates part of the irradiation due to the composition of a location's soils but also contributes less to the indoor gamma dose rate due to the relatively low naturally occurring radionuclide concentration of modern building materials.