Indoor and Outdoor Gamma Dose Rate Exposure Levels in Major Commercial Building Material Distribution Outlets and Their Radiological Implications to Occupants in Ibadan, Nigeria

Abstract

The indoor and outdoor gamma exposure levels at commercial distribution stores/shops where different brands of building materials are sold at Iwo road market in Ibadan, Nigeria have been determined. The direct measurements of the gamma exposure levels were made using a calibrated RADEYE G-10 gamma survey meter.  Typical mean dose rate obtained in the stores/shops were 0.140 ± 0.01 ?Sv/h (indoor) and 0.124 ± 0.02 ?Sv/h(outdoor) for floor Tiles, 0.11± 0.01 ?Sv/h (indoor) and 0.103 ± 0.020 ?Sv/h (outdoor) for wall tiles and 0.098 ± 0.010 ?Sv/h (indoor) and 0.089 ± 0.020 ?Sv/h(outdoor) for water closet respectively. The calculated annual effective doses for indoor and outdoor were 0.520 ± 0.01 mSv and 0.46 ± 0.02 mSv for floor tiles respectively while it was 0.42 ± 0.01 mSv and 0.37 ± 0.02 mSv and 0.367 ± 0.01 mSv and 0.333 ± 0.02 mSv for wall tiles and water closet respectively. The results showed that the building materials at these stores/shops have slightly increased the natural radiation dose exposure levels in the area and to the occupants. The study also indicated that the occupants at the shops may be subjects for elevated levels of radon exposure due to confined space and poor ventilation.

Keywords: Indoor gamma exposure, Outdoor gamma exposure, Building materials, Building material shop outlets, Annual effective dose