Radon Risk Research Articles

Evaluation of Indoor Radon Risk for Discussion on National Action in Japan

Evaluation of Indoor Radon Risk for Discussion on National Action in Japan

A simple device to simulate the radon vertical migration in soil

The knowledge of the soil radon levels is important for the planning and construction of new buildings in order to estimate the radon risk and to classify the ground for construction purposes. A simple device was developed to simulate the vertical migration of radon in soil. The device simulates the vertical migration of radon in two different cases. The first case: simulates radon vertical migration in soil in a natural environment. The top of the device is open, while the around and bottom are sealed. The second case: simulates the vertical migration of radon in soil under the surface of a concrete floor. The device is sealed all around, including the top and bottom. A total of two sets of experiments were conducted in this study, each set of experiments simulated the migration of radon under two different cases. According to the research results, the potential radon concentration under the concrete floor is much higher than the natural potential radon concentration. Therefore, this factor must be fully considered when selecting the building materials and designing radon protection materials.

Measurement of Radon Gas Concentration in Sources of Drinking Water in Makurdi, Benue State, Nigeria Using Radon Detector (RAD-7)

Study’s Excerpt Radon gas contamination across diverse drinking water sources within Makurdi, Nigeria, was investigated. The RAD-7 detector was used, and the results revealed elevated radon levels exceeding WHO limits in some specific locations. There is a need for targeted risk mitigation strategies and continuous monitoring of Radon gas contamination in the area. Full Abstract Concern over radon gas's potential health risks when used or ingested in homes is growing, as is the issue with its presence in sources of drinking water. In this study, water samples were collected from various locations in Makurdi, Benue State, Nigeria, and the amount of radon gas present was measured using the Radon Detector (RAD-7). The study used a methodical sampling strategy to gather water samples from wells, boreholes, and surface water bodies throughout various Makurdi locations. The gathered water samples were examined using the RAD-7 detector, a trustworthy and sensitive device for measuring radon gas. The radon levels ranged from trace levels (20.0 ) to higher quantities (122.0 ), raising worries about potential health implications for nearby people reliant on these water sources. Thirty (30) samples of water were gathered for this investigation. The samples' radon content ranged from 10.3 to 122.0 Bq L-1, which is within the World Health Organization's (WHO) allowable limit and other regulatory bodies (100 Bq L-1) except in the sample collected from Court 5 and Logo1, which was higher than the set limit. The results of the analysis demonstrated that there were large variations within the range of 0.61 0.39-11.80 1.85 and a mean of 57.36 in the amounts of radon gas in the water samples obtained from the different sources. More research and monitoring are advised to gain a complete understanding of radon distribution and to develop workable radon risk reduction plans for water sources.

Radon an indoor risk: In the Urban Devarakonda, Telangana state, India

Natural background radiation risk owing to radon and its progeny at indoors to the general public is a significant issue. The concern about indoor radon risk has been increasing at national and international level since its role to the overall dose is well known. The current study aims to assess the 222Rn and its progeny in different type of indoors with a passive (SSNTD) and active technique (RAD-7). The area of investigation (urban Devarakonda), is located near the proposed uranium mineralization area. The estimated radon levels in the indoors were ranging from 20 to 437 Bq. m−3 and with a geometric mean of 66 Bq.m−3. The estimated EERC values are ranging from 22 to 82 Bq.m−3 and these are higher than the range limit prescribed by ICRP. The computed average EF value in the present study (0.58) is relatively higher than the world average value of 0.4. An effort has been made to comprehend the radon distribution among the representative locations. Annual effective inhalation dose was also estimated using the occupancy factor 0.8 and it is found in the range of 0.52–11.00 m Sv y−1 with geometric mean of 2.20 mSv.y−1. The diurnal variation of 222Rn levels was studied using RAD-7 in a dwelling and seasonal variation of radon levels was also to be discussed in this paper.

The correlation between indoor and soil gas radon concentrations in Kiraz district, İzmir.

All humans are exposed to radon, the primary source of natural radiation, which can harm people due to natural processes rather than human activity. Thus, it is of significant importance to determine the levels of radon in indoor, soil gas, water, and outdoors. Radon concentration (CRn) was measured in Kiraz district, İzmir, and the correlation between the indoor and soil gas CRn values was investigated. The indoor CRn values measured in 40 randomly selected dwellings in Kiraz exhibited a wide range from 19.50 ± 2.50 to 204.70 ± 8.00Bqm-3 with an average value of 61.11 ± 4.23Bqm-3. The measured indoor CRn values were compared to the reference levels in the world to help control radon in the dwellings. Indoor CRn values were lower than the ICRP reference level of 300Bqm-3 in all of the dwellings studied. Furthermore, in 34 dwellings (representing 85% of the total number of dwellings studied), indoor CRn values were lower than the WHO reference level of 100Bqm-3. Health hazard indices, namely annual effective dose (AED) and excess lifetime cancer risk (ELCR), were also calculated for each dwelling and compared with internationally acceptable levels to estimate the risk to human health. The AED values varied from 0.49 ± 0.06 to 5.16 ± 0.20mSv y-1 with an average value of 1.54 ± 0.11mSv y-1, which exceeds the world average of 1.15mSv y-1 as reported by UNSCEAR. The ELCR values ranged from 2.05 ± 0.26 × 10-3 to 21.55 ± 0.84 × 10-3 with an average value of 6.43 ± 0.44 × 10-3, exceeding the world average of 0.29 × 10-3 as reported by UNSCEAR. The soil gas CRn values measured exhibited a wide variation ranging from 129.25 ± 6.38Bqm-3 to 6172.64 ± 44.06Bqm-3 with an average value of 1291.79 ± 18.70Bqm-3. The soil gas CRn values were less than 10,000Bqm-3; hence, the research area is categorized as "low radon risk areas" according to Sweden Criteria, and so no special constructions are required in the studied area. When soil gas CRn values were compared to indoor CRn values, no linear relationship was found between the CRn values. However, a strong positive linear correlation was found between indoor and soil gas CRn values less than 200Bqm-3 and 2500Bqm-3, respectively.

Assessing Radon Awareness and Risk Perception among Residents in Ilesa, Osun State, Nigeria

The study was conducted to assess the knowledge of the public about radon risk and possible impediment they might face for radon testing in Ilesa, Osun State, Nigeria. One hundred people from different category of discipline were the population for this research. A descriptive research design of survey type was used and a semi-structured questionnaire was administered to the people. The questions raised addresses perception of people about radon and their readiness to engage in testing. The result of the survey shows that majority of the respondents are educated and this increase the reliability of the study. Majority of the respondents are not aware of radon and the risk attached. Majority, (84%) of the respondents have not tested their homes for radon. 58% of them do not know how to carry out the radon test, 54% of them do not know where to buy radon test kits. 68% of them are unaware about the radon test, 74% of them could not afford the radon test kit because it is expensive. There was financial constraint for the testing as majority earn below the minimum wage for workers in Nigeria and majority of respondents are not unemployed. From the Chi-square test, the willingness to test of the respondents is dependent on their level of awareness. More awareness through media and lectures is therefore recommended for members of the public.

On the informative value of community-based indoor radon values in relation to lung cancer.

Radon is a radioactive gas and a major risk factor for lung cancer (LC). We investigated the dose-response relationship between radon and LC risk in the International Lung Cancer Consortium with 8927 cases and 5562 controls from Europe, North America, and Israel, conducted between 1992 and 2016. Spatial indoor radon exposure in the residential area (sIR) obtained from national surveys was linked to the participants' residential geolocation. Parametric linear and spline functions were fitted within a logistic regression framework. We observed a non-linear spatial-dose response relationship for sIR < 200 Bq/m3. The lowest risk was observed for areas of mean exposure of 58 Bq/m3 (95% CI: 56.1-59.2 Bq/m3). The relative risk of lung cancer increased to the same degree in areas averaging 25 Bq/m3 (OR = 1.31, 95% CI: 1.01-1.59) as in areas with a mean of 100 Bq/m3 (OR = 1.34, 95% CI: 1.20-1.45). The strongest association was observed for small cell lung cancer and the weakest for squamous cell carcinoma. A stronger association was also observed in men, but only at higher exposure levels. The non-linear association is primarily observed among the younger population (age < 69 years), but not in the older population, which can potentially represent different biological radiation responses. The sIR is useful as proxy of individual radon exposure in epidemiological studies on lung cancer. The usual assumption of a linear, no-threshold dose-response relationship, as can be made for individual radon exposures, may not be optimal for sIR values of less than 200 Bq/m3.

Web Search or Conversation with an Artificial Intelligence? Analysis of Misinformation and Relevance in the Case of Radon Gas

Health-related information plays a crucial role in public health management, empowering individuals to make informeddecisions and adopt behaviours that mitigate the effects of potential risks. The internet and the emergence of newtechnologies, such as conversational models equipped with Artificial Intelligence, present opportunities, and challengesin this field. This research focuses specifically on the risk of radon, a natural radioactive gas recognised worldwide asone of the leading causes of lung cancer and a persistent threat over time. The aim of this study is to analyse theinformation provided for this specific risk by two key information access tools: web search engines and AI-basedconversational agents (ChatGPT). To carry out this interdisciplinary research (journalism-communication-computerscience) we employ a mixed methodological design (quantitative and qualitative) and apply methods from the areas ofInformation Retrieval (IR), Big Data, and Artificial Intelligence (AI). The results of this study show that information onthe internet about the risk of radon often lacks relevance and does not meet the information needs of users. We alsofound that some websites provide a significant amount of good quality information but there are often some misleadingcontents. ChatGPT proves to be more accurate in providing relevant and good quality information but contains a higherproportion of misinformation. Consequently, this raises concerns about the integrity of the information provided andemphasises the need to monitor and improve the accuracy of these computational tools.

A sensitive system based on radon amplification at soil-air interface: Aiming to advance earthquake precursor research

Radon, a natural radioactive gas, serves as a valuable tracer in geophysical research and atmospheric science such as detecting stress induced signal in bedrock. However, the conventional radon monitoring methods often lack the sensitivity required to accurately capture such signals. This limitation, coupled with interference from meteorological effects, poses challenges in distinguishing genuine stress-induced signals. In this study, we propose a novel approach utilizing radon concentration gradients at the soil-air interface to enhance sensitivity and detect stress induced radon signals more effectively. Drawing from pressure diffusion models, we demonstrate how seismic stress accumulation in bedrock alters radon profiles in the sub-soil, providing insights into the mechanisms underlying stress-induced radon variations. Building upon this theoretical framework, we introduce the “Bhabha Radon Observatory for Seismic Application (BhaROSA)," a remote sensing, solar-powered radon observatory designed for widespread deployment and continuous unattended monitoring for big database generation. Field experiments comparing BhaROSA's performance to conventional soil probe techniques validate and confirm the superior sensitivity in line with theoretical predictions. This innovative approach holds promise for improving our understanding of stress dynamics in bedrock and has potential applications in various geophysical and atmospheric science such as earthquake precursory research, geo-genic radon potential and risk assessment. To progress, we propose international alliance and application of deep learning to a big database of precursor signals, which may lead to more informed conclusions on earthquake predictability-an enduring and unsolved challenge for humanity.

Exploring radon risk in groundwater: insights from few investigated areas in Morocco

Exploring radon risk in groundwater: insights from few investigated areas in Morocco

Predictive Geogenic Radon Potential (P-GRP): A novel approach for comprehensive hazard assessment and risk modeling in subsurface environment

Geogenic radon potential (GRP) is traditionally used for mapping radon-prone areas. However, this has challenges in the accurate assessment of radon risk because of limitations such as oversimplified soil measurements and lack of geological profiles. This study presents predictive geogenic radon potential (P-GRP), integrating geological characterization and advanced modeling for the emanation and transport of radon in the subsurface environment. Seoul, South Korea, was selected as the research area for the evaluation of hazards using P-GRP, while subway station A was selected for the assessment of indoor health risks. The geology was characterized by the layers of bedrock and soil using uranium contents and porosity. The emanation of radon was modeled considering the radioactive decay chain of uranium and the pore structures. The vertical transport of radon was modeled considering the porosity variation within geological media, which was used for the calculation of P-GRP. Without loss of continuity, the P-GRP map was constructed by calculating P-GRP at a specific depth over the Seoul area. The calculation of P-GRP in the case of subway station A demonstrates that the radon concentration in the bedrock at the platform depth was expected to be 382 million Bqm−3. The indoor radon risk was calculated using the P-GRP by coupling the vapor intrusion process. This presented a high cancer risk for the employees as well as commuters. The P-GRP map of Seoul demonstrated higher hazards in granite zones compared to banded gneiss zones. These results have demonstrated that the P-GRP could be a novel and promising approach for assessing hazard and risk by geogenic radon during subsurface development.

Human Health Risk Assessment of Radionuclide Contamination in Drinking Water

This study investigates the human health risks of uranium, radium, radon, and other drinking water radionuclides and their mitigation strategies. It was implemented through literature review, field sampling, and analytical methods. Samples were taken from various sources, including groundwater, surface water, municipal supplies, and private wells. ICPI-MS and liquid scintillation counters were used for radiation measurements. Statistical analysis and risk assessment models were used to measure health risks and treatment effectiveness. Groundwater sources were the main sources of radionuclides, with private wells being the main sources. The elimination efficiencies of reverse osmosis were exceptional, reaching up to 99%. The elderly population (60+ years) were the most likely to have cancer, with the highest risks for bladder cancer, lung cancer, kidney cancer, and leukemia. The frequency of radionuclide contamination in drinking water sources varied, with the U.S. Environmental Protection Agency, Nigerian EPA, and Canada having the strictest schedules. The results emphasize the urgent need for monitoring programs, effective treatment technologies, and targeted risk management strategies to cope with radionuclide contamination. Government advice includes improving the regulatory system, developing advanced treatment methods, long-term epidemiological studies, public awareness, interdisciplinary collaboration, scientific exploration of alternative water sources, and prioritizing interventions for vulnerable populations.

Radon Exposure and Risk of Leukemia: A Protocol of Systematic Review and Meta-Analysis

Introduction: Radon is a naturally occurring radioactive gas that is considered a risk factor for many health problems, including leukemia. Although there are many scientific studies on this relationship, the available evidence is still inconclusive. This review and meta-analysis aims to provide a comprehensive overview of the existing literature to provide a more in-depth understanding of the relationship between radon exposure and leukemia risk. Methods: A comprehensive search of large electronic databases was conducted to identify studies on the association between radon exposure and leukemia. Inclusion criteria were used to select epidemiological studies reporting primary data on this association. Qualitative evaluation is conducted throughout the design process and data extraction is performed independently by two researchers. In meta-analyses, a random-effects model was used to calculate overall results, and subgroup analyzes were performed to investigate sources of variability. Results: The systematic review identified several studies that met the inclusion criteria. Meta-analyses show overall effect sizes and confidence intervals that indicate the nature of the relationship between radon and leukemia. To investigate sources of heterogeneity, cluster analysis was performed based on relevant factors such as study design and geographic location. A sensitivity analysis was performed to assess the robustness of the findings and assess potential reporting bias. Conclusion: The systematic review identified several studies that met the inclusion criteria. Meta-analyses showing overall effect sizes and confidence intervals illustrate the nature of the relationship between radon and leukemia. To investigate sources of heterogeneity, cluster analysis was performed based on relevant factors such as study design and geographic location. A sensitivity analysis was performed to evaluate the effectiveness of the study results and assess the potential for publication bias.

Communicating radon risks: the impact of different risk formulations on risk perception and protection intention

Communication campaigns addressing radon-related health risks have struggled to promote health-protective behaviour effectively. Typically framed as a ‘naturally occurring gas’, this study explores whether this framing might attenuate radon risk perception. It compares the impact of framing radon as an ‘indoor air pollutant’ versus a ‘natural gas’ on risk perceptions and on intentions to protect against radon. It also explores the role of perceptions of the burdensomeness of mitigation, self-efficacy and stigma as potential moderators of the framing effect for health protection intentions. Using Computer-Assisted Web Interviewing (CAWI), 2,012 stratified respondents, representative of the Slovenian adult population, completed a survey. Respondents were randomly assigned to one of two radon frames: ‘indoor air pollutant’ or ‘natural gas’. Results reveal low compliance to test and mitigate radon, regardless of residing in high- or low-risk areas. Risk perception was significantly higher when framed as ‘Indoor air pollution.’ However, the ‘natural gas’ frame resulted in slightly stronger intentions to test and mitigate radon. The impact of framing on intentions was significantly moderated by (a) perceptions of the burdensomeness and (b) the stigma. In conclusion, how radon risk is framed in communication strategies needs careful attention, as it influences risk perception and individuals’ intentions to take action.

Indoor Radon Surveying and Mitigation in the Case-Study of Celleno Town (Central Italy) Located in a Medium Geogenic Radon Potential Area

Indoor radon surveying and remediation were implemented in a single-family home affected by high levels of indoor radon in the Celleno municipality (central Italy) with the aim of identifying the contribution of radon sources, evaluating the factors affecting radon entry into the building, and reducing radon risk. Average radon levels were relatively low at the ground floor (286 ± 202 Bq m−3) and first floor (167 ± 84 Bq m−3) in autumn when the temperature was still warm and the windows were open, but increased up to 2776 ± 1768 Bq m−3 and 970 ± 202 Bq m−3 in the first half of December, when the heating system was on and the windows were closed. The inner walls of the pilot room at the ground floor, semi buried on one side, were then treated with a waterproof product (a silane terminated polymer) and the average radon was halved (1475 ± 1092 Bq m−3) in the following month, which was still characterised by winter conditions. Radon entry in the room was identified and sealed with the same product, and a radon accumulation space behind a NE-SW oriented wall was naturally ventilated, reducing radon below the reference level in April with northerly winds conditions.

Experience from radon in soil gas comparison measurements held in Czech Republic and in other countries, 1992–2022

Radon 222Rn, an inert natural radioactive gas, a daughter product in the 238U natural decay series, a source of alpha radiation, together with its short-lived decay products is a dominant source of absorbed radiation doses in the population. Rocks and building materials are fundamental sources of radon in dwellings. Elevated indoor radon activity concentration in houses and workplaces, surpassing recommended reference levels, is not desirable. Since radon penetrates into the houses from the geological basement, various technical aids for protection of houses have been developed. Their individual application derives from the radon potential of a building site. Radon risk mapping of building sites became a standard procedure for gauging the local radon potential. Various instruments and techniques of measurements of radon activity concentration in soil gas (Bq/m3) at building sites are available. Since radon in soil gas and radon measurement techniques are affected by several natural and technical conditions, resultant values of radon risk mapping by individual organizations vary, sometimes fundamentally. Radon comparison measurements at selected reference sites are an important tool for single organizations to verify their radon measuring procedures and reliability of their reported results. Based on legislative regulations, comparison measurements at established radon reference sites are a part of the obligatory activities for radon risk mapping at building sites in the Czech Republic. Experience and analyses of 30-year radon in soil gas comparison measurements in the Czech Republic show the dispersion of values reported by participating organizations and indicate that more than 10% of participants do not fulfill the established local criteria. This paper introduces requirements for the establishment of radon reference sites, documents their natural variability, recommends the procedure of radon comparison measurement, and analyses its results. A long-term experience was gained by testing organizations from the Czech Republic (1992–2022) as well as from the international comparison measurements organized in the Czech Republic and in several other countries (2010–2021).

Assessment of primordial radionuclides and radon exhalation in granitic terrain of Bengaluru, India

This study delves into an investigation of primordial radionuclides and radon exhalation potential in natural soil and rock samples collected from the granitic terrain of Bengaluru, Karnataka, India. Employing a Smart RnDuo monitor and HPGe-based gamma spectrometry, the analysis reveals significantly elevated average specific radium, thorium, and potassium activities compared to the global averages documented by UNSCEAR. The research work evaluates radiological parameters in these samples, confirming compliance with global safety limits. Absorbed dose rates, hazard indices, and dose levels align with recommended standards, underscoring the safety of the assessed environment. Notably, the radon exhalation potential of these samples spans a range of 17 ± 1.3 mBq/kg/h to 179.42 ± 10.6 mBq/kg/h, accompanied by corresponding radon emanation factors varying from 5.1 ± 0.3 % to 45.4 ± 3.1 %, with an arithmetic mean of 18.0 ± 1.1 %. Intriguingly, a positive correlation emerges between the radon exhalation rate and both radium content and emanation factor. This research sheds light on the unique radiological characteristics of the Bengaluru granitic terrain, offering insights into the local radon risk and contributing to the broader understanding of radionuclide distribution in geologically diverse regions.

Radon Exposure and Incident Stroke Risk in the Women's Health Initiative.

Little is known about the role of radon in the epidemiology of stroke among women. We therefore examined the association between home radon exposure and risk of stroke among middle-aged and older women in the United States. We conducted a prospective cohort study of postmenopausal women aged 50-79 years at baseline (1993-1998) in the Women's Health Initiative. We measured exposures as 2-day, indoor, lowest living-level average radon concentrations in picocuries per liter (pCi/L) as estimated in 1993 by the US Geological Survey and reviewed by the Association of American State Geologists under the Indoor Radon Abatement Act. We used Cox proportional hazards models to estimate risk of incident, neurologist-adjudicated stroke during follow-up through 2020 as a hazard ratio and 95% CI, adjusting for study design and participant demographic, social, behavioral, and clinical characteristics. Among 158,910 women without stroke at baseline (mean age 63.2 years; 83% white), 6,979 incident strokes were identified over follow-up (mean 13.4 years). Incidence rates were 333, 343, and 349 strokes per 100,000 woman-years at radon concentrations of <2, 2-4, and >4 pCi/L, respectively. Compared with women living at concentrations <2 pCi/L, those at 2-4 and >4 pCi/L had higher covariate-adjusted risks of incident stroke: hazard ratio (95% CI) 1.06 (0.99-1.13) and 1.14 (1.05-1.22). Using nonlinear spline functions to model radon, stroke risk was significantly elevated at concentrations ranging from 2 to 4 pCi/L (p = 0.0004), that is, below the United States Environmental Protection Agency Radon Action Level for mitigation (4 pCi/L). Associations were slightly stronger for ischemic (especially cardioembolic, small vessel occlusive, and large artery atherosclerotic) than hemorrhagic stroke, but otherwise robust in sensitivity analyses. Radon exposure is associated with moderately increased stroke risk among middle-aged and older women in the United States, suggesting that promulgation of a lower Radon Action Level may help reduce the domestic impact of cerebrovascular disease on public health.

Radon Levels and Risk Assessment due to its Ingestion and Inhalation from Groundwater of Lapai, North-Central Nigeria

Radon exposure through ingestion or inhalation from groundwater can be a significant public health concern due to its carcinogenic effects. This study assessed the health risks of radon exposure from groundwater in Lapai, Nigeria, using a Rad7 detector to measure radon concentration levels. The measured concentrations ranged from 5.36 ± 0.22 BqL-1 to 0.52 ± 0.06 BqL-1 with an average value of 2.82 ± 0.14 BqL-1. The annual effect dose due to ingestion of Radon obtained varies in the range of 2.76 to 28.34 μSva-1, 1.02 to 10.43 μSva-1, and 1.33 to 13.69 μSva-1 for infants, children, and adults, respectively. While the effective dose per year from inhalation of Radon released from water by adults has values in the range of 1.31 to 13.50 μSva-1. Radon levels were within permissible limits of UNSCEAR and USEPA, and the annual effective doses from inhalation and ingestion were within WHO's safe range. Nonetheless, monitoring is advised, especially during the rainy season when contamination levels may increase.

Simultaneous measurements of radon, thoron and thoron progeny and induced cancer risk assessment in Djeno, Pointe-Noire, Republic of Congo.

In this study, the activity concentrations of radon (222Rn), thoron (220Rn) and thoron progeny were measured simultaneously in Djeno (Pointe-Noire, Republic of Congo) using RADUET detectors to evaluate the air quality and the radiological risks due to the inhalation of these radionuclides. Activity concentrations of radon progeny were calculated from those of radon. Indoor radon, thoron and progenies followed a lognormal distribution ranging between 20 and 40, 6 and 62, 8 and 17.6 and 0.4 and 19.6Bqm-3 for radon, thoron, radon progeny and thoron progeny, respectively. Mean values for radon were lower than the worldwide values estimated by the United Nation Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), which are 40Bqm-3 (arithmetic mean) and 45Bqm-3 (geometric mean). Radon concentrations in the dwellings under study were below the World Health Organization and the International Commission on Radiological Protection recommended reference levels, which are, respectively, 100 and 300Bqm-3. The mean concentration of thoron was twice the world average value of 10Bqm-3 estimated by UNSCEAR. Thoron progeny mean concentration was sharply greater than the typical value (0.3Bqm-3) for indoor atmosphere provided by UNSCEAR. Annual effective dose ranges were 0.40-0.87mSv (arithmetic mean, 0.57±0.11mSv) for radon and 0.10-4.14mSv (arithmetic mean, 0.55±0.77mSv) for thoron. The mean value for radon was lower than the value (1.15mSv) estimated by UNSCEAR, while the mean value for thoron was five times higher than the UNSCEAR value (0.10mSv). The study showed that the use of the typical equilibrium factor value given by UNSCEAR to compute effective dose led to an error above 80%. Finally, the results of this study showed that the excess relative risk of radon-induced cancer was low, below 2% for the population under 55y. The results presented in the present study prove that the population of Djeno is exposed to a relatively low potential risk of radon- and thoron-induced cancer.