Evaluation of natural concentrations of ²²⁶ Ra, ²³² Th, and ⁴⁰ K in some granite tiles used as building material in Erbil City – Kurdistan region, Iraq

Natural radioactive materials present in rocks, soil, water, and air contribute to daily radiation exposure, particularly in indoor environment where people spend approximately 80% of their time. This exposure is further influenced by building materials such as granite, which is commonly used in construction. This study investigated 21 varieties of granite tiles commercially available and commonly used as decorative finishing materials in residential building in Erbil City - Kurdistan region of Iraq. Gamma-ray spectrometry employing a "3 × 3" NaI(Tl) scintillation detector was used to determine the activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K. The activity of ²²⁶Ra was arranged from 12 ± 05 to 163 ± 09 Bq.kg^-1 with an average value of 81 ± 16 Bq.kg^-1. In contrast, the activity concentration of ²³²Th varied from 0.7 ± 0.40 Bq.kg^-1 to 153 ± 12 Bq.kg^-1, with an average of 59 ± 07 Bq.kg^-1. For ⁴⁰K, the average activity concentration ranged from 220 ± 15 Bq.kg^-1 to 2177 ± 46 Bq.kg^-1 with an average of 1548 ± 39 Bq kg^-1. When compared with established global average values, the majority of the analyzed granite tiles exhibited elevated levels of natural radioactivity. To assess the potential radiation hazard effects associated with ²²⁶Ra, ²³²Th, and ⁴⁰K in granite samples, several radiological hazard indices were calculated.