## 4 Conclusions  
This study presents a comprehensive assessment of radon and thoron exhalation rates, alongside associated gamma radiation exposure, from various building materials commonly utilized in Ireland, and widely available in countries around the world. Results indicate substantial variability in the radiological properties of these materials, with granite and quartzite exhibiting notably high thoron exhalation rates due to their mineralogical composition. These findings highlight the potential for certain natural rock materials to contribute significantly to indoor radiation exposure, particularly in poorly ventilated environments. Building on our measurements and modeling, the following comparative contextualization places our key radiological metrics--radon (E\({}_{(222)}\)), thoron (E\({}_{(220)}\)) exhalation rates and gamma dose contributions--alongside published values for the same natural building materials:  
Granite: In this study, the mean thoron exhalation rate of tested granites was 6396 \(\pm\) 3534 Bq m\({}^{-2}\) h\({}^{-1}\), considerably higher than the 3500 \(\pm\) 800 Bq m\({}^{-2}\) h\({}^{-1}\) reported by [PERSON] et al. (2020) [2]. Its radon exhalation (0.51 \(\pm\) 0.46 Bq m\({}^{-2}\) h\({}^{-1}\)) also exceeds  
Figure 8: Elemental composition and mineral mapping with the Tescan TIGER MIRA3 FEG-SEM. the literature value of 0.20 \(\pm\) 0.05 Bq m\({}^{-2}\) h\({}^{-1}\). The annual gamma dose from granite in our work (0.17-0.40 mSv y\({}^{-1}\)) aligns with, though slightly under the upper bound of, the 0.20-0.50 mSv y\({}^{-1}\) range found by [PERSON] et al. (2017) [31]. Quartzite: Our measured mean thoron flux for quartzite (1637 \(\pm\) 277 Bq m\({}^{-2}\) h\({}^{-1}\)) is modestly above the 1200 \(\pm\) 500 Bq m\({}^{-2}\) h\({}^{-1}\) documented by [PERSON] et al. (2019) [32], while its radon exhalation (0.75 \(\pm\) 0.36 Bq m\({}^{-2}\) h\({}^{-1}\)) similarly surpasses their 0.50 \(\pm\) 0.20 Bq m\({}^{-2}\) h\({}^{-1}\) value. The gamma dose (0.18-0.20 mSv y\({}^{-1}\)) matches closely with the 0.19 mSv y\({}^{-1}\) they reported. Limestone: We observed thoron exhalation in tested limestones at 1352 \(\pm\) 1213 Bq m\({}^{-2}\) h\({}^{-1}\), relative to the 1000 \(\pm\) 400 Bq m\({}^{-2}\) h\({}^{-1}\) from [PERSON] et al. (2023) [33]. Its radon flux (0.35 \(\pm\) 0.15 Bq m\({}^{-2}\) h\({}^{-1}\)) is likewise above the 0.25 \(\pm\) 0.10 Bq m\({}^{-2}\) h\({}^{-1}\) figure in that study. The resulting gamma dose (0.16-0.19 mSv y\({}^{-1}\)) is in good agreement with the 0.15 mSv y\({}^{-1}\) noted by [PERSON] et al. (2004) [34]. Correlation analyses suggest a potential link between the factors controlling uranium and thorium distribution. Some accessory minerals (e.g., zircon) contain both uranium and thorium, potentially influencing this correlation. Conversely, other accessory minerals (e.g., monazite) contain thorium but not uranium, leading to variability in the radon-thoron correlation across samples with contrasting accessory mineralogy. This variability is further influenced by the specific chemistry of accessory minerals, such as the range of thorium concentrations observed in zircon (from negligible to relatively high). These observations indicate a degree of interaction between these factors, emphasizing the need for advanced models that consider both uranium and thorium concentrations, as well as mineralogical composition when evaluating radiological risks associated with building materials. Furthermore, the gamma dose index (I-index) suggests that materials deemed safe based solely on gamma radiation may still pose health risks due to the combined effects of radon, thoron, and gamma radiation if not adequately managed. The ventilation models proposed in this study offer insights to develop practical strategies for mitigating radon and thoron exposure in indoor settings. Adjusting ventilation rates or limiting the use of materials with high emission rates can help to maintain radiation doses below recommended safety thresholds.