Radiological hazards assessment of building materials used in Swakopmund, Namibia

Abstract

A Canberra coaxial High Purity Germanium (HPGe) gamma-ray spectrometry detector was used to measure activity concentrations of radionuclides in commonly used building materials in Swakopmund, Namibia. The activity concentrations in, Bq.kg−1, for 226Ra, 232Th and 40K in all sample groups of building materials (cement, sand, cement bricks and roof tiles) were found to be in the range of 18.002–499.266, 14.069–132.508 and 162.794–1747.260, respectively. The average activity concentration of 40K was found to be two times higher than the critical level of 500 Bq.kg−1 in sand, cement bricks, clay bricks and roof tiles. The measured activity concentrations were used to estimate average dose rates and radiological hazard parameters. The absorbed dose rate (D) both due to indoor and outdoor exposure was higher than the international acceptable safe limits in all sample groups while the annual effective dose equivalent (AEDE) due to indoor exposure was higher in sand, cement bricks and clay brick samples. AEDE due to outdoor exposure was within acceptable safe limits for all sample groups. Radium equivalent (Raeq), external hazard (Hex) and gamma (Iγ) hazard indices were found to be higher than the acceptable safe limit only in clay bricks samples. The internal hazard (Hin) index was only higher than the acceptable safe limit in cement and clay bricks while the alpha (Iα) index was higher in sand, cement bricks and clay bricks. The Excess Lifetime Cancer Risk (ELCR) exceeded the acceptable safe limits in all sample groups. Our study showed that most of the computed radiological parameters were significantly higher than prescribed safe limits in most of the samples and therefore may pose a health risk to the inhabitants of Swakopmund.