# The Relationship between Radon and Geology: Sources, Transport and Indoor Accumulation
## 2 The Origin of Radon
### Accumulation of Radon in Indoor Environments
#### 2.3.4 Groundwater and Water Supply Systems  
Radon can also be released into groundwater and water supply systems, especially where high uranium concentrations in the soil occur [88]. When water contaminated with radon is used for cooking, drinking, or bathing, the gas can be released into the air, contributing to the accumulation of radon indoors [88]. This presents a risk to individuals who may be exposed to high levels of radon through their water supply [89]. To mitigate this risk, it is important to regularly test water sources for radon and implement appropriate treatment measures if necessary, such as aeration or activated carbon filtration [90]. Additionally, individuals can take steps to reduce their exposure to radon in their water supply by using ventilation systems or installing point-of-use treatment devices [91]. Public health officials and water treatment facilities should also be aware of the potential risks associated with radon in water supplies and take appropriate measures to mitigate these risks to ensure the safety of the public [92]. For example, the study by [PERSON] et al. (2013) focused on the relationship between the geological composition of the Amarante region in northern Portugal and radon concentrations in residential dwellings [93]. The geology of the region comprises Hercynian tardi-tectonics granites and Paleozoic metastases. The study found that uranium, which is primarily contained within heavy accessory minerals such as apatite, zircon, monazite, uraninite, thorite, and thorianite in the rock, is a significant determinant of radon concentration. The most considerable uranium concentrations were found in the granites of Padronelo and of Teloes, which contained 18.2 ppm and 10.3 ppm \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Material** & **No. of Samples** & \begin{tabular}{c} **\({}^{226}\)Ra** \\ **(Ba\(\cdot\)kg\({}^{-1}\))** \\ \end{tabular} & \
\begin{tabular}{c} **\({}^{222}\)Rn Mass Exhalation Rate** \\ **(mBq\(\cdot\)kg\({}^{-1}\)\(\cdot\)h\({}^{-1}\))** \\ \end{tabular} &
\begin{tabular}{c} **\({}^{222}\)Rn Emanation Factor** \\ **(\%)** \\ \end{tabular} \\ \hline Black sand & 6 & \(13\pm 5\) & 18.8 \(\pm\) 6.4 & 20.4 \(\pm\) 8.2 \\ Cement (PPC) & 5 & \(29\pm 4\) & 2.3 \(\pm\) 1.6 & 1.0 \(\pm\) 0.7 \\ Cement (SRC) & 4 & \(23\pm 6\) & 2.2 \(\pm\) 1.9 & 1.4 \(\pm\) 0.8 \\ Concrete & 6 & \(21\pm 5\) & 8.5 \(\pm\) 3.6 & 5.4 \(\pm\) 1.9 \\ Fired clay brick & 7 & \(16\pm 5\) & 6.1 \(\pm\) 3.4 & 7.8 \(\pm\) 3.4 \\ Flyash brick & 6 & \(81\pm 11\) & 72.8 \(\pm\) 15.3 & 11.3 \(\pm\) 4.6 \\ Glazed tile & 5 & \(68\pm 13\) & 0.8 \(\pm\) 0.7 & 0.2 \(\pm\) 0.2 \\ Lime & 5 & \(9\pm 2\) & 14.6 \(\pm\) 4.9 & 20.8 \(\pm\) 5.2 \\ Marble & 5 & \(12\pm 3\) & 1.1 \(\pm\) 1.0 & 1.2 \(\pm\) 1.1 \\ Silica fume & 5 & \(33\pm 8\) & 12.5 \(\pm\) 4.4 & 5.0 \(\pm\) 1.7 \\ Soil & 8 & \(16\pm 7\) & 23.5 \(\pm\) 11.8 & 19.2 \(\pm\) 6.1 \\ Vitrified tile & 5 & \(33\pm 5\) & 0.3 \(\pm\) 0.3 & 0.1 \(\pm\) 0.1 \\ White cement & 4 & \(38\pm 7\) & 12.3 \(\pm\) 5.6 & 4.3 \(\pm\) 1.8 \\ Yellow sand & 6 & \(10\pm 4\) & 6.5 \(\pm\) 4.3 & 8.4 \(\pm\) 4.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Emanation factors for building materials and soil samples (adapted from [87]). respectively. As a result, these granites had geometric means of 430 and 220 Bq\(\cdot\)m\({}^{-3}\), respectively, which were the highest radon concentrations. Metasediments, on the other hand, had geometric mean radon concentrations of 85 Bq\(\cdot\)m\({}^{-3}\) and substantially lower uranium levels (1.6 ppm). It is interesting that the study discovered radiometric anomalies connected to localised fault systems that are impacting granitic rocks. These anomalies, where uranium concentrations can be quadruple usual background levels, showed uranium mobility and were probably the result of major mineral supports such as uraninite being dissolved in water. This finding implies a higher radon risk in places with these particular geological characteristics.