# The Relationship between Radon and Geology: Sources, Transport and Indoor Accumulation
## 3 Health Risks Associated with Radon Exposure
The dose-response relationship appeared to be linear, with no threshold, and remained significant in analyses limited to individuals from homes with measured radon less than 200 Bq m\({}^{-3}\). The proportional excess risk did not significantly differ with the study, age, sex, or smoking status. In the absence of other causes of death, the absolute risks of lung cancer by age 75 at usual radon concentrations of 0, 100, and 400 Bq m\({}^{-3}\) would be about 0.4%, 0.5%, and 0.7%, respectively, for lifelong non-smokers, and about 25 times higher (10%, 12%, and 16%) for cigarette smokers. * The health risks associated with radon exposure increase with cumulative exposure over time [151]. This means that even low or moderate levels of radon exposure over a long period can increase the risk of lung cancer [152]. This is especially important for individuals who spend a significant amount of time indoors, such as those who work from home or the elderly [153]. Mitigation strategies, such as improving ventilation, sealing cracks and gaps in foundations, and installing radon reduction systems, can significantly reduce radon levels in indoor environments [154]. It is also important to note that individuals who smoke are at an even greater risk of developing lung cancer from radon exposure, and therefore, should take extra precautions to reduce exposure [140]. A study by [PERSON] et al. (2008) focused on examining the relationship between radon exposure and lung cancer risk in uranium miners from France and the Czech Republic [151]. They studied a group of 10,100 miners who had long-term, low-level exposure with a mean exposure time of 10 years, averaging fewer than 60 working-level months (WLM). With a total of 574 lung cancer fatalities recorded, 187% more than what would be predicted based on national statistics, the study concluded that the risk of lung cancer was much greater in this demographic. Cumulative radon exposure was closely linked to the elevated risk. According to the observed exposures, the estimated total extra relative risk per WLM was determined to be 0.027 (95% CI: 0.017-0.043). The authors discovered that for people who were exposed at the age of 30 and with 20 years since exposure, the extra relative risk per WLM was 0.042. For each ten-year rise in age at exposure and time since exposure, this risk fell by almost 50%. The study discovered no inverse exposure rate impact below 4 WL in terms of exposure rates. The outcomes were in line with the BEIR VI report's estimations based on the concentration model when the exposure rate was less than 0.5 WL. The researchers emphasised that an important element with a substantial impact on their findings was the accuracy of exposure estimations. The most significant impact modifiers were shown to be age at exposure and time since exposure. These findings offer important insights for creating efficient methods to control and lower radon-related health hazards since they imply that both the time and duration of radon exposure are key factors in lung cancer risk in uranium miners. * Children are considered a vulnerable group regarding radon exposure as they have a higher respiratory rate than adults and their lungs are still developing [155]. This means that in a given amount of inhaled air, children may absorb a higher amount of radon than an adult [156]. Additionally, children spend more time at home than adults, especially at younger ages when they attend school less frequently and spend most of their time at home. These factors increase the potential for exposure to radon in indoor environments, showing therefore, the importance of implementing mitigation measures in homes and schools to reduce the risk of exposure for children [157]. The study by [PERSON] et al. (2005) provides valuable insights into the perception of radon exposure risk among rural residents receiving public health services [158]. The study based on a cross-sectional methodology and including 31 rural families showed a serious lack of knowledge about the dangers of radon exposure.