# The Relationship between Radon and Geology: Sources, Transport and Indoor Accumulation
## 2 The Origin of Radon
### Accumulation of Radon in Indoor Environments
#### 2.3.6 Rn Accumulation  
Indoor Rn accumulation is a topic of extensive research due to its significant implications for public health. Numerous studies, including those of [PERSON] (2023) and [PERSON] (2005), have begun analyzing this phenomenon specifically in caves and mines, providing valuable insights into radon behaviour in these underground environments [97; 98]. They shed light on average radon concentrations, variations, and factors influencing these variations. [PERSON] (2023) conducted a comprehensive review of radon exposure in non-uranium mines globally, analyzing the reported radon measurements in a total of 474 underground non-uranium mines. The paper also provides an estimation of potential radon exposure in Canadian mines, an area where data have been lacking. The average radon concentration across these mines was calculated as 570 Bq\(\cdot\)m\({}^{-3}\), though individual mine concentrations could vary greatly, from below the detection limit to above 10,000 Bq\(\cdot\)m\({}^{-3}\). This wide range indicates the variability in radon levels in different mining environments and underlines the importance of individual evaluations. The research also calculated the average equilibrium  
Figure 1: Radon solubility in water at a partial pressure of 101.325 kPa (adapted from [96]). factor between radon and its short-lived progeny, which is known as the F-factor, to be 0.34, with the potential to vary from 0.02 to 0.9 depending on the mine operation conditions. This factor is crucial in understanding the potential radiation exposure from radon decay products, which pose a more significant health risk than radon gas itself. [PERSON]'s analysis extends to assessing the annual effective radon dose to workers in Canadian non-uranium mines. For those working underground, the estimated annual effective radon dose was 3.76 mSv, with a possible range from 0.22 to 10 mSv, depending on factors such as ventilation and other operational conditions. Given that most mines in Canada are surface mines where outdoor radon concentration is low, the average occupational exposure to radon for the entire mining workforce--including underground workers, surface workers, and indoor workers--is estimated to be 0.9 mSv. [PERSON]'s work underlines the significance of radon exposure for workers in non-uranium mines, pointing out that these levels could potentially reach or even exceed Canadian thresholds for mandatory radiation monitoring and reporting. The research also emphasizes the necessity for further investigation into radon levels in Canadian underground non-uranium mines. Table 5 compiles the results of various previous studies, as reviewed by [PERSON] (2023). This detailed table allows for a deeper understanding of the global variability in radon levels in non-uranium mines, further emphasizing the importance of [PERSON]'s conclusions. As can be seen in Table 5, Rn concentrations vary significantly both within and across countries. China shows the greatest range, from as low as 47 Bq\(\cdot\)m\({}^{-3}\) to as high as 1244 Bq\(\cdot\)m\({}^{-3}\). This wide range could be due to different measurement techniques, the geological characteristics of the mines, or differences in ventilation systems and practices. Australia and Brazil also show substantial variation. In Brazil, the measurements range from