Variation Of Radon Concentration Research Articles

Measurement and characteristics of radon flow in an extremely arid region based on a closed-system earth-air model

Radon (222Rn) is a radioactive gas that occurs naturally in the soil and is harmful to the environment and health. However, the measuring the amount of radon flowing is challenging. This study reveals the mechanism responsible for radon transportation and concentration variation, the main driving forces acting, and the key factors operating in the vadose zone. In this study, two separate holes were used to monitor the amount of earth-air and radon flowing in and out of the soil in the extremely arid region in China where the Mogao Grottoes are located. Using a closed-system model, the quantity, characteristics, and regularity of the flow of earth-air and radon were thus determined on daily and yearly timescales. The same patterns of variation in earth-air flow and radon concentration were found at the two sites, both depending on the variation in the atmospheric pressure (AP). When the AP decreases, earth-air flows out from the soil with a high radon concentration. Conversely, when the AP increases, earth-air enters into the soil with a low radon concentration. Thus, radon is continuously emitted from the soil. The concentration of radon in the earth-air is proportional to the rate of flow of earth-air and therefore increases as the AP decreases. The radon emission also varies with the seasonal variation in temperature and AP, which is high in summer and low in winter. On a daily timescale, the radon varies in a bimodal manner. Therefore, the net amount of radon emitted from the soil is positively correlated with the amplitude of the AP fluctuation, temperature, soil porosity, and thickness of the vadose zone. The atmospheric pumping is the main driving force responsible for the radon emission. However, the surface closure, landform, cracks, faults, grain size, pore structure, soil adsorption, basal uranium/radium, salts, wind, lunar cycle, latitude and altitude have important effects on the number of radon emission. As such, it provides a scientific basis for the effective utilization of radon and prevention of its emission from soil.

The dynamics of Rn-222 cyclic flow within the shallow geological subsurface media as a daily temporal variated source for exhalation into the air

Extensive research on the dynamics of radon gas (Rn-222) originating from the radioactive decay of radium (Ra-226) in geological subsurface media, sheds light on its periodic release into the atmosphere. Radon is a product of the uranium-238 decay chain found within rock and soil grains. While only a fraction of the generated radon escapes (emanates) into porous spaces due to nuclear recoil, it serves as the source for subsurface gas flows and for cyclic exhalation into the soil-atmosphere interface.Ongoing study of radon movement in shallow and deep subsoil, and its emergence at the surface, reveals complete semi-diurnal, diurnal, and seasonal gas flow cycles in the subsoil. Complementary emissions occur nocturnally as radon is released into the atmosphere. Moreover, two natural driving forces govern complex semi-diurnal and diurnal flows below and above the surface. Subsurface gas movement in porous media exhibits nonlinear behavior influenced by surface temperature gradients, resulting in downward flow to depths of up to 100 m. This flow exhibits daily periodicity with depth-dependent time delays, correlating with the diurnal surface temperature cycle. Additionally, pore gas transport into and out of open boreholes responds linearly to semi-diurnal barometric pressure changes, known as barometric pumping.Beyond subsurface phenomena, Europe and Australia increasingly employ nocturnal radon measurements to study atmospheric stability and air quality, assuming that variations in local stationary near-surface radon concentrations reflect atmospheric mixing processes. Recognizing mechanisms governing radon's temporal changes within geological subsurface media highlights the need for continuous underground radon monitoring to validate variations in daily radon exhalation to the surface.On the other hand, monitoring radon at considerable depths minimizes climatic contributions and enhances the ability to discern non-periodic pre-seismic radon signals, independent of atmospheric compulsion. This research offers potential insights into seismic precursors and the complex interplay between subsurface geodynamics and atmospheric conditions.

Variation of indoor radon concentration in a walk-in type test chamber under controlled environmental conditions

Variation of indoor radon concentration in a walk-in type test chamber under controlled environmental conditions

Radon transport to indoor air in groundwater plants as a by-effect of different water treatments

Radon released from groundwater into indoor air is the main radiation safety problem for water treatment plants. This study investigated the release of radon from different water treatment processes and the effect of ventilation on the indoor radon concentration at six waterworks. In addition to various aeration processes, groundwater pretreatments, such as activated carbon and pre-ozonation, were demonstrated to be associated with the indoor radon concentration. This study revealed that accurate assessment of radon exposure at water treatment plants is very difficult because of the large and sudden temporal variations in the radon concentration and smaller local variations that follow the steps of the water treatment process and ventilation. Based on the study, concrete proposals are also presented for improving radiation safety and the reliability of measurements.

Risk Assessment of Lung Cancer Caused by Indoor Radon Exposure in China during 2006–2016: A Multicity, Longitudinal Analysis

Indoor radon is a well-documented environmental factor as a second cause of lung cancer. Based on the chronological data on indoor radon concentration, lung cancer incidence, and the distribution of sex-age-specific population, the risk of lung cancer caused by indoor radon exposure in a total of 15 cities in China was assessed by using the risk model developed by the U.S. Environmental Protection Agency (EPA) in this study. The estimate revealed that both the excess relative risk (ERR) and lifetime relative risk (LRR) have obviously increased after 2010. The population attributable risk (PAR) in 2016 was estimated in a range from 6.66% to 22.42%, with a median of 15.33% for the 15 cities. The lung cancer incidence attributed to indoor radon in 2016 ranged from 3.96 to 15.07 per 10,000 population in males and 1.21 to 8.27 per 10,000 population in females. Across age and sex, the risk of lung cancer caused by indoor radon was found more pronounced in males and 40-45 age groups. The chronological variation of radon concentrations was considered in this study; the estimate of lung cancer caused by indoor radon in China is considered more reasonable than ever before.

Preliminary data of potentially hazardous radon concentrations in Modrič Cave (Croatia)

Instigated by relatively high cave-air CO2 concentrations in Modrič Cave (Croatia) recorded for the purpose of speleothem-based paleoclimate research, we established preliminary monitoring of radon (222Rn) concentrations within the cave for a 4.5-year period (2018–2022). As radioactive geogenic gas, radon, which often correlates with cave-air CO2 concentrations, presents a potential health hazard in cases of longer exposure time in high concentration conditions. Since the Modrič Cave is open to tourists and long-term scientific research has been performed within, a safety assessment for radon concentrations was essential. The integrated measurements of radon concentrations were performed by passive LR115 detectors that were exposed from three to six months at eight sites within the cave. Preliminary results showed seasonal variations of radon concentrations (0.08–13.6 kBq/m3) governed by the cave ventilation patterns, but superimposed on this, cave morphology and bedrock architecture control the radon variations on finer spatial scale. The 3-months average 222Rn concentration of up to 13.6 kBq/m3 during summer in one of the cave passages is among the highest measured seasonal averaged radon concentrations in Croatian caves, but maximum concentrations were even higher. Based on obtained results and calculations, potential negative health effects of radon exposure for cave visitors, guides and scientists were assessed and the results showed values of exposure to be below recommended levels. Calculated worst-case scenario for cave guides (most affected by radon and its progeny) revealed that they would receive dose slightly below the occupational dose limit of 20 mSv/y (19.0 ± 5.2 mSv/y) in the touristic part of the cave and significantly higher doses (34.1 ± 9.2 mSv/y) in the non-touristic part of the cave. To detect precise spatio-temporal radon concentration variations (up to diurnal scale) we recently established continuous radon measurements. This will enable detection of possibly health threatening short-term peaks in radon concentration and consequently further improve cave management.

The temporal variation of radon concentration at different depths of soil: A case study in Beijing

Variations in soil radon concentrations are a potential precursor of earthquake and volcanic events. However, the unclear migration and variation mechanisms of radon concentrations in soil still limit its effective application. To elucidate the temporal variation and its possible influence factors on radon concentrations at different soil depths, a case study was performed at a suburban site in Beijing. A long-term continuous measurement system consisting of ten radon-in-soil monitors at depths from 0.1 to 5.0 m and other meteorological sensors was employed. The monitoring was carried out from January 8th to July 29th, 2022, covering 3445 h in total. Radon concentrations generally increased with soil depth. Diurnal variation of soil radon concentrations at depths of 1.2 and 1.6 m in winter and spring was observed, and a negative correlation between the soil radon concentration and the residual air pressure was found. This finding indicates a possible air exchange channel between the soil and the atmosphere at the study site. In addition, the soil radon concentration at 4.0 m depth was unexpectedly lower than that of neighboring depths and was steady throughout the measurement period. This is attributed to a possible clay layer in the soil structure at 4.0 m depth. The results of this field study indicate that the complexity of temporal variation of soil radon concentrations should be considered for its application in predicting earthquake and volcanic events.

IRREGULARITIES THE RELATIONSHIP OF VARIATIONS IN THE VOLUME ACTIVITY OF RADON AND ATMOSPHERIC PRESSURE DURING SEISMIC ACTIVITY (ON THE EXAMPLE OF THE BAIKAL REGION)

A comparison was made of temporal variations in atmospheric pressure and soil radon concentration measured in loose sediments at three monitoring stations in the Baikal region for the period of manifestation of three fairly strong earthquakes – Bystrinsky (21.09.2020, K = 14.6), Kudarinsky (09.12.2020, K = 14.0) and Khubsugulsky (11.01.2021, K = 16.0). It has been established that the release of radon is controlled in the region by variations of atmospheric pressure. Irregularities of this dependence, first identified in the course of a formalized statistical analysis, occur for each of the studied seismic activations. They are connected with the process of preparing an earthquake, which opens up real opportunities for developing an emanation approach to medium-term forecasting.

Extreme reverse seasonal variations of indoor radon concentration and possible implications on some measurement protocols and remedial strategies

Indoor radon levels in dwellings are typically higher in cold months than in warm ones. The indoor radon concentration might experience an inverse seasonal behaviour – i.e., radon levels much higher in summer than in winter – under specific circumstances.In the framework of a study on long-term variations of annual radon concentration carried out in some tens of dwellings in Rome and surrounding small towns, two dwellings with very high – up to extreme – reverse seasonal variations were accidently discovered. These dwellings were located in a volcanic area, and they are both south-oriented and located on the lower part of a hill.In one of them, radon concentration was monitored by a continuous radon monitor for two years to find out when the greatest rises in radon levels occur. The indoor radon concentration resulted to experience extremely rapid, i.e. very few hours, increases up to 20 000 Bq m−3 during the spring period (i.e., April, May, and June especially). After about ten years from the first observation, the indoor radon concentration of the same house was monitored again for about five years: radon concentration peaks previously observed were found to be unchanged in terms of absolute values, duration, rising time and occurrence period.These reverse seasonal variations may lead to significant underestimation of the actual annual average radon concentration in case of measurements lasting less than one year if performed during the cold season and especially when seasonal correction factors are used. Moreover, these results suggest adopting specific measurement protocol and remediation strategies in houses having some peculiar characteristics, mainly regarding orientation, position, and attachment to the ground.

Indoor radon survey in Whitehorse, Canada, and dose assessment

Radon-222 (222Rn) and its decay products are the primary sources of a population’s exposure to background ionizing radiation. Radon decay products are the leading cause of lung cancer for non-smokers and the second leading cause of lung cancer after smoking for smokers. A community-driven long-term radon survey was completed in 232 residential homes in different subdivisions of Whitehorse, the capital of the Yukon, during the heating season from November to April in 2016–2017 and in 2017–2018. Radon concentrations were measured in living rooms and bedrooms on ground floors. The arithmetic and geometric means of indoor radon activity concentrations in different subdivisions of Whitehorse ranged from 52 ± 0.6 Bq m−3 and 37 ± 2.3 Bq m−3 in the Downtown area of Whitehorse to 993.0 ± 55.0 Bq m−3 and 726.2 ± 2.4 Bq m−3 in Wolf Creek. Underlying geology and glacial surfaces may partly explain these variations of indoor radon concentrations in subdivisions of Whitehorse. A total of 78 homes (34.0%) had radon concentrations higher than 100 Bq m−3, 47 homes (20.5%) had concentrations higher than 200 Bq m−3 and 33 homes (14.4%) had concentrations higher than 300 Bq m−3. The indoor radon contribution to the annual effective inhalation dose to residents ranged from 3.0 mSv in the Downtown area to 51.0 mSv in Wolf Creek. The estimated annual average dose to adults in Whitehorse, Yukon, is higher than the world’s average annual effective dose of 1.3 mSv due to the inhalation of indoor radon. The annual radon inhalation effective dose was assessed using radon measurements taken during winter; hence the assessed dose may be overestimated. Cost-efficient mitigation methods are available to reduce radon in existing buildings and to prevent radon entry into new buildings.

Semi-empirical modeling of the temporal variation of indoor radon concentration over short periods

The time rate of change of the indoor radon concentration is studied in a semi-empirical frame. The differential equation that describes the radon mass-balance inside a room is used, with taking into account all sources of indoor radon. Rather than solving the equation numerically, an analytical form is obtained with applying some approximations that are based on experimental observations. This makes the describing model more realistic and updatable. After fitting some of the parameters to the experimental data, the model is found to be successful for describing the indoor radon concentration over a couple of days. Moreover, the model predicts some important characteristics of the radon flow to the indoors from the soil and from the building materials. For the room considered in this study, it is found that the radon diffusion transfer coefficient inside the building material is while the radon diffusion and advection transfer coefficients inside the soil are and respectively. The model can also predict the amount of contribution to the indoor radon by any sources that may be unknown. It was found to be The obtained results show the feasibility and convenience of the model.

A national comparison between the collocated short- and long-term radon measurements in the United States.

Knowing the geographical and temporal variation in radon concentrations is essential for assessing residential exposure to radon, the leading cause of lung cancer in never-smokers in the United States. Tens of millions of short-term radon measurements, which normally last 2 to 4 days, have been conducted during the past decades. However, these massive short-term measurements have not been commonly used in exposure assessment because of the conflicting evidence regarding their correlation with long-term measurements, the gold standard of assessing long-term radon exposure. We aim to evaluate the extent to which a long-term radon measurement can be predicted by a collocated short-term radon measurement under different conditions. We compiled a national dataset of 2245 pairs of collocated short- and long-term measurements, analyzed the predictability of long-term measurements with stratified linear regression and bootstrapping resampling. We found that the extent to which a long-term measurement can be predicted by the collocated short-term measurement was a joint function of two factors: the temporal difference in starting dates between two measurements and the length of the long-term measurement. Short-term measurements, jointly with other factors, could explain up to 79% (0.95 Confidence Interval [CI]: 0.73-0.84) of the variance in seasonal radon concentrations and could explain up to 67% (0.95 CI: 0.52-0.81) of the variance in annual radon concentrations. The large proportions of variance explained suggest that short-term measurement can be used as convenient proxy for seasonal radon concentrations. Accurate annual radon estimation entails averaging multiple short-term measurements in different seasons. Our findings will facilitate the usage of abundant short-term radon measurements, which have been obtained but was previously underutilized in assessing residential radon exposure. Tens of millions of short-term radon measurements have been conducted but underutilized in assessing residential exposure to radon, the greatest cause of lung cancer in non-smokers. We investigate the correlations between collocated short- and long-term measurements in 2245 U.S. buildings and find that short-term measurements can explain ~75% of the variance in subsequent long-term measurements in the same buildings. Our results can facilitate the usage of massive short-term radon measurements that have been conducted to estimate the spatial and longitudinal distribution of radon concentrations, which can be used in epidemiological studies to quantify the health effects of radon.

Radon Dynamics and Effective Dose Estimation in a Touristic Volcanic Cave: La Cueva del Viento, Tenerife (Canary Islands, Spain).

La Cueva del Viento is a volcanic lava tube located in Tenerife Island (Canary Islands, Spain). Its touristic section, 180m long, receives more than 28,200 visitants each year. According to the European and Spanish legislation, a radon monitoring program is required to minimize the radon exposition of workers, tourists, and cavers. In this work, we studied the radon concentration dynamics in the touristic section of the cave for ca. 1year, using both passive and active radon detectors. Pluviometry and external air temperature played an important role in the seasonal and daily variations of indoor radon concentrations. Daily fluctuations during the dry season were analyzed using time series (Box-Jenkins methodology) and frequency analysis (Fourier and Wavelet transforms) methods. The experimental radon time-series was well-fitted using a seasonal autoregressive integrated moving average model: Seasonal Auto-Regressive Integrated Moving Average (2,0,1) (2,1,0)24, and its value, in a short-time window (ca. 1week) was conveniently forecasted. Finally, this work revealed that the annual effective doses received, during the observation period (1year), by the touristic guides and visitors was ca. 2mSv/yr and 4μSv/hr, respectively. We concluded that the touristic exploitation of La Cueva del Viento is safe for both tourists and guides. However, based on our results, La Cueva del Viento had to be classified as a "Monitoring zone" and a regular monitoring program should be implemented.

Temporal Variation in Indoor Radon Concentrations Using Environmental Public Health Tracking Data.

Indoor radon is the second leading cause of lung cancer in the United States (US) after smoking and the number one for lung cancer in non-smokers. Understanding how indoor radon varies during the year reveals the best time to test to avoid underestimating exposure. This study looks at the temporal variation in 13 years of radon concentrations in buildings located in 46 US states and the District of Columbia (DC). In the dataset, radon concentration varies from 3.7 Bq m -3 (Becquerels per cubic meter) to 52,958.1 Bq m -3 , with an overall mean of 181.4 Bq m -3 . About 35.4% of tests have a radon concentration level equal to or greater than the US Environmental Protection Agency (US EPA) action level 4.0 pCi L -1 (148 Bq m -3 ). 3 Temporal variation in radon concentrations was assessed using the overall monthly mean radon concentration. The highest concentrations were found in January (203.8 Bq m -3 ) and the lowest in July (129.5 Bq m -3 ). Higher monthly mean indoor radon concentrations were found in January, February, and October, and lower in July, August, and June. This result is consistent with findings from other studies and suggests continuing to encourage radon testing throughout the year with an emphasis on testing during the colder months.

DETERMINATION OF SEASONAL CHANGES IN CONCENTRATIONS OF RADON ISOTOPES WITHIN KURCHATOV TOWN

The article presents findings on the content of radon isotopes in the air of buildings maintained in Kurchatov t., the dependence of concentrations of radon isotopes in residential and administrative buildings on a season assessed as well as on the type of premises and their purpose. Seasonal variations in radon concentrations in the air were studied by measuring the equivalent equilibrium volumetric activity (EEVA) and the volumetric activity (VA) of radon. For the first time, volumetric activities of radon isotopes in premises of residential and industrial buildings have been determined. Data showed that EEVA and VA values of radon in the air of residential and administrative premises surveyed increase from winter toward summer in the following descending series: summer > autumn > spring > winter, which, is perhaps related to soil freezing and the presence of the snow cover at the winter time. Radon concentration was also proved to decrease in the indoor air with a storey.

Radon Exposure in the Underground Tourist Route–Historic Silver Mine in Tarnowskie Góry, Poland

An assessment of the exposure of workers and tourists to radon in the underground tourist route of the Historic Silver Mine in Tarnowskie Góry was carried out. The study was conducted over a one-year period to capture seasonal variations in radon concentrations. CR-39 track detectors were used to measure radon concentrations, which were exposed in the mine during the following periods: 9 February 2021-19 May 2021, 19 May 2021-26 August 2021, 26 August 2021-25 November 2021 and 25 November 2021-3 March 2022. The annual average radon concentration along the tourist route was 1021 Bq m-3. The highest measured concentration was 2280 Bq m-3 and the lowest concentration was 80 Bq m-3. Based on the measured concentrations, effective doses were calculated, assuming that employees spend 1350 h a year in underground areas and that the time of visiting the mine by tourists is ca. 1 h. The average annual effective dose a worker would receive is approximately 2.5 mSv, and a tourist below 2 μSv. The dose limit expressed as the annual effective dose is 1 mSv for members of the general public and 20 mSv for occupational exposure.

Assessment of soil-gas radon concentration over lithologies: a case study from district Karak, Khyber Pakhtunkhwa, Pakistan.

The current study is aimed to determine the variation of soil-gas radon concentrations over different rock formations representing diverse lithologies in the district of Karak, Khyber Pakhtunkhwa, Pakistan. The stratigraphic units were grouped on the basis of lithological contents into four categories, i.e., limestone, evaporites, claystone/mudstone, and sandstone. The highest average soil-gas 222Rn concentration (544Bq/L) was found in the uranium-bearing Dhok Pathan Formation of the Pliocene age, while the lowest radon levels (0.15Bq/L) were observed in the salt-bearing strata of Bahadurkhel Salt of Eocene age showing the non-uraniferous nature of the salt. High radon potential associated with the Dhok Pathan Formation is likely to be related to the high degree of uranium mineralization which is contributing to the elevated soil-gas radon levels. The study revealed that the soil-gas radon concentration in all lithologies is varying in the order of RnSandstone > RnLimestone > RnClaystone/Mudstone > RnEvaporites with the highest radon levels in the sandstone unit of uranium-bearing Dhok Pathan Formation. High fluctuations of soil-gas radon levels observed in this study evidently show that lithology and uranium mineralization have strong control over the 222Rn concentrations.

Radon concentration variations at the Yangyang underground laboratory

The concentration of222Rn in the air has been measured in the 700 m-deep Yangyang underground laboratory between October 2004 and May 2022. The average concentrations (spreads) in two experimental areas, called A6 and A5, were measured to be 53.4 Bq/m3(13.9 Bq/m3) and 33.5 Bq/m3(7.9 Bq/m3), respectively. The lower value in the A5 area reflects the presence of better ventilation. The radon concentrations sampled within the two A5 experimental rooms’ air are found to be correlated to the local tunnel temperature outside of the rooms, with correlation coefficientsr= 0.22 andr= 0.70. Therefore, the radon concentrations display a seasonal variation, because the local temperature driven by the overground season influences air ventilation in the experimental areas. A sinusoidal function with a period of 1 year was used to fit the radon concentration data of both underground areas finding a maximum amplitude on August, 31 ± 6 days.

Diurnal, monthly, and seasonal variations of indoor radon concentrations concerning meteorological parameters.

As reported by the Turkish Atomic Energy Agency (formerly TAEK, newly TENMAK), Izmir province has higher indoor radon concentrations compared to other cities in Turkey. Since modern people spend 92% of their daily time indoors, it is important to know indoor radon levels and long-term variation. However, our knowledge of indoor radon levels of Izmir and its surrounding are limited. Moreover, there is no information about this area's large-term variation of indoor radon. In this study, which was carried out with this motivation, indoor radon concentrations and meteorological parameters were measured in an office of the teaching staff in a university building. Data were collected hourly over 25months (762days). Raw data, diurnal, monthly, and seasonal variations of parameters were investigated separately. The results show that the average indoor radon concentration (18Bqm-3) is relatively lower than national and international reference values. Indoor radon concentrations showed an increasing and decreasing trend throughout the day. Radon concentrations are slightly higher in the morning (downtime and early hours of the day) and then reduced in the afternoon. This can be related to the daily routine usage of the office, which is affected by ventilation of the room, air temperature variations, etc.

Radiological risk estimation from indoor radon, thoron, and their progeny concentrations using nuclear track detectors.

In this paper, we report the results of seasonal variations of indoor radon and thoron concentrations, equilibrium factors for gas progeny, and radiological risks to dwellers in the hilly area of Guwahati City, Assam, India. Twin-cup dosemeters with LR-115 (II) nuclear track detectors were used in this study. The findings show that values vary significantly, with winter having the highest values and summer having the lowest, with spring and autumn having moderate values. In winter, radon concentrations range from 61.6 ± 11.2Bqm-3 (Mud) to 115.3 ± 34.3Bqm-3 (AT), with geometric mean values of 69.2 ± 13.8Bqm-3 and 109.4 ± 27.9Bqm-3, and in summer, they range from 21.1 ± 5.9Bqm-3 (Mud) to 28.4 ± 8.3Bqm-3 (AT), with geometric mean values of 22.7 ± 6.3Bqm-3 and 26.1 ± 7.1Bqm-3, whereas thoron concentrations range from 13.1 ± 5.1Bqm-3 (Mud) to 58.8 ± 12.6Bqm-3 (AT), with geometric mean values of 27.6 ± 7.0Bqm-3 and 52.9 ± 10.1Bqm-3 in winter, respectively, and in summer, from 8.8 ± 2.3Bqm-3 (Mud) to 13.0 ± 5.5Bqm-3 (Mud), with a geometric mean value of 1.87 ± 1.29Bqm-3. Radon and thoron progeny levels are reported to vary from 4.1 ± 0.3 mWL (Mud) to 15.1 ± 4.3 mWL (AT) and 2.6 ± 0.9 mWL (Mud) to 14.3 ± 4.2 mWL (AT) in winter and from 1.5 ± 0.7 mWL (AT) to 3.0 ± 2.5 mWL (Mud) and 0.9 ± 0.3 mWL (AT) to 2.7 ± 0.5 mWL (Mud) in summer, respectively. The equilibrium factors for radon and its progeny have been reported to range from 0.23 ± 0.1 (Mud) to 0.51 ± 0.3 (AT) in winter, whereas from 0.23 ± 0.1 (AT) to 0.48 ± 0.4 (Mud) in summer, respectively. The equilibrium factors for thoron and its progeny have been estimated in the range of 0.02 ± 0.01 (Mud) to 0.09 ± 0.06 (AT) in winter, whereas 0.02 ± 0.02 (AT) to 0.07 ± 0.05 (Mud) in summer, respectively. The inhalation dose rates differed from house to house, having values in the range of 1.2 ± 0.2mSvyear-1 (Mud) to 4.6 ± 1.3mSvyear-1 (AT) in winter, whereas 0.5 ± 0.3mSvyear-1 (AT) to 0.9 ± 0.5mSvyear-1 (Mud) in summer, respectively. The effective doses (EDs) due to the exposure of radon and thoron in the study area have been found to range from 2.5 ± 0.3mSv (Mud) to 9.1 ± 2.7mSv (AT) in winter and 0.9 ± 0.4mSv (AT) to 1.8 ± 1.3mSv (Mud) in summer, respectively. The levels of radon and thoron in similar types of construction were found to be significantly different from one house to another. The estimated radon and thoron concentrations in the houses of that region during winter are found to be substantially higher than the global averages as reported by UNSCEAR.