Assessment of natural radioactivity and radiation hazards of building materials in Kinondoni District, Dar es Salaam, Tanzania

Abstract

Natural radionuclides from building materials are one of the potential sources of external as well as internal radiation exposure to the human body. Currently, this exposure has been increasing since people spend more than  of their time indoors (ICRP 1991). Commonly used building materials from Kinondoni District were investigated using γ-spectrometry; their activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in Bq/kg were measured. The results showed that average values of activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K were 15.62, 21.51 and 237.99 Bq/kg, respectively. All the activity concentrations in the studied samples were lower than the world average values of 35 Bq/kg for ²²⁶Ra, 30 Bq/kg for ²³²Th and 400 Bq/kg for ⁴⁰K. The radium equivalent activity ( ), external ( ), internal hazard index ( ) and gamma activity concentration index ( ) were calculated to assess the radiological hazards due to presence of natural radionuclides in the building materials.  The results showed that the average values of Ra_eq, H_ex, and I_γ were 64.7 Bq/kg, 0.17, 0.21 and 0.24, respectively. These values were lower than the world criteria values 370 for Ra_eq, ≤ 1 for H_ex, ≤ 1 for H_in and ≤ 1 for I_γ, respectively. The obtained results indicated that all the investigated building materials were safe for inhabitants.

Keywords: Building materials, Natural radionuclides, Radiation hazards, Gamma ray spectrometry, Activity concentration.