Investigation of naturally-occurring radioactive materials (NORM) in building materials in Ireland

Abstract Naturally-occurring radioactive materials (NORM), primarily from the decay chains of uranium (U-238) and thorium (Th-232), as well 1as potassium (K-40), are commonly found in raw materials used in the construction industry. These radionuclides contribute to indoor radiation exposure, particularly in enclosed environments. As part of the NORM-BMI project, this study evaluated the activity concentrations of Ra-226, Th-232, and K-40 in commonly used building materials in Ireland, specifically tiles, cement, and concrete. The assessment focused on calculating the Gamma Index (Iγ) to determine radiation safety, using high-resolution gamma spectrometry in three independent laboratories (University of Cantabria, University College Dublin, and the Environmental Protection Agency Laboratory). The results indicated that tile samples exhibited the highest concentrations of radionuclides, particularly Ra-226 and K-40, with Gamma Index values approaching the recommended threshold (Iγ ≈ 1). In contrast, cement and demolition concrete samples showed low activity concentrations and Gamma Index values well below 1, indicating minimal radiological risk. Comparison with European datasets confirmed the relative safety of these building materials, particularly concrete and cement. These findings support the development of national screening protocols and contribute to safer, more sustainable construction practices, while also informing EU initiatives focused on the recycling and reuse of building materials.