Assessment of radiation hazards due to exposure to radionuclides in marble and ceramic commonly used as decorative building materials in Egypt

The concentrations of ²³⁸U (²²⁶Ra), ²³²Th, and ⁴⁰K for the commonly used decorative building materials (15 marble and 15 ceramic) in Egypt were measured using gamma spectroscopy system. Radionuclides concentrations in marble samples were ranged from: ND to 49.92 ± 7.74 Bq kg⁻¹ for ²²⁶Ra, 8.30 ± 1.70 to 119.52 ± 16.00 Bq kg⁻¹ for ²³²Th, and 32.60 ± 4.25 to 2238.33 ± 242.66 Bq kg⁻¹ for ⁴⁰K while in ceramic samples the concentration ranged from: 28.42 ± 5.41 to 118.70 ± 20.34 Bq kg⁻¹ for ²²⁶Ra, 30.65 ± 5.49 to 114.15 ± 18.78 Bq kg⁻¹ for ²³²Th, and 389.54 ± 49.57 to 1069.83 ± 124.50 Bq kg⁻¹ for ⁴⁰K, respectively. These results imply that radium and thorium concentrations were below the worldwide recommended values but potassium was above the standard guideline. Radiological hazards indices of radium equivalent activity (Ra_eq), external and internal hazard indices: H_ex and H_in, respectively, and annual effective doses of the investigated materials due to the presence of those radionuclides were calculated and had values less than the worldwide recommended values of 370 Bq kg⁻¹, unity and 1 mSv y⁻¹, respectively. Therefore, the studied types of marble and ceramic can be safely used as decorative building materials.