Increase In Radon Concentration Research Articles

Influence of temperature on the radon concentration distribution in ramp under low-speed wind field: A numerical simulation study

By introducing the parameters of radon exhalation rate and radon diffusion coefficient, the distribution of radon concentration field on ramp under the condition of superposition of temperature field and flow field is simulated. The simulation results show that the distribution of radon concentration in the ramp under the condition of low-speed ventilation is greatly affected by the temperature field and flow field, and the change of radon exhalation caused by temperature is the main factor leading to the change of radon concentration in the ramp. The change of temperature will cause the overall increase of radon concentration in the ramp. Under the condition of constant flow field, the radon concentration in the chamber is more than two times higher than the average radon concentration in the ramp. Some areas severely exceeded the limit.

The Lithosphere-Atmosphere-Ionosphere Coupling of Multiple Geophysical Parameters Approximately 3 Hours Prior to the 2022 M6.8 Luding Earthquake

Investigating various geophysical parameters from the Earth’s crust to the upper atmosphere is considered a promising approach for predicting earthquakes. Scientists have observed that changes in these parameters can occur days to months before earthquakes. Understanding and studying the impending abnormal phenomena that precede earthquakes is both urgent and challenging. On 5 September 2022, a magnitude 6.8 earthquake occurred in Sichuan, China, at 4:52:18 (Universal Time). The earthquake happened approximately 175 km away from an instrumental array established in 2021 for monitoring vibrations and perturbations in the lithosphere, atmosphere, and ionosphere (MVP-LAI). This array consisted of over 15 instruments that regularly monitor changes in various geophysical parameters from the subsurface up to an altitude of approximately 350 km in the ionosphere. Its purpose was to gain insights into the mechanisms behind the coupling of these different geospheres during natural hazards. The seven geophysical parameters from the MVP-LAI system simultaneously exhibited abnormal behaviors approximately 3 h before the Luding earthquake. These parameters include ground tilts, air pressure, radon concentration, atmospheric vertical electric field, geomagnetic field, wind field, and total electron content. The abnormal increase in radon concentration suggests that the chemical channel could be a promising mechanism for the coupling of geospheres. Furthermore, air pressure, the geomagnetic field, and total electron content exhibited abnormal characteristics with similar frequencies. Horizontal wind experienced temporary cessation or weakening, while vertical wind displayed frequent reversals. These anomalies may be attributed to atmospheric resonance before the earthquake. The results demonstrate that the coupling of geospheres, as indicated by the anomalous phenomena preceding an earthquake, could be influenced by multiple potential mechanisms. The multiple anomalies observed in this study provided approximately 3 h of warning for people to prepare for the seismic event and mitigate hazards.

On the concentration of radon in a polluted city of the Middle East: An insight into its association with PM levels, air properties, and risk assessment

This study was conducted in Ahvaz city, where the concentrations of radon and airborne particles in 10, 2.5, and 1 micrometers, along with meteorological parameters were measured. The measurements were performed in three educational and therapeutic sampling points at both ground and underground levels during cold and hot seasons. The results showed that in 3.17% of the samples, the concentration of radon exceeded the permissible limit recommended by the Environmental Protection Agency (EPA). Factors affecting the increase of radon concentration in indoor air included cold season, underground sampling points, the number of doors and windows as air dilution factor and air exchange, air pressure, and air humidity. The concentration of particles in the air did not have any effect on radon in the indoor air. The annual effective dose of exposure to radon (DR), the annual effective dose of lung (DE), and the risk of lung cancer cases (LCC) during both cold and hot seasons and at ground and underground levels were lower than the permissible values recommended by the International Committee on Radiological Protection (ICRP). We concluded that the increase of particles is neither the cause nor the source of increased indoor air radon. The findings of the present investigation recommend controlling physical indoor air parameters particularly temperature and relative humidity by proper ventilation systems to mitigate the impact of radon exposure on inhabitants.

Long-distance migration law of radon in overburden of abandoned goaf during coal spontaneous combustion

The surface isotope radon measurement method (SIRMM) is widely used in fire source detection in abandoned mines. However, studies on the long-distance migration of radon during coal spontaneous combustion are lacking, which hinders the further popularization of this technology in coal fire prevention and control. For this reason, the migration law of radon in overlying strata in fire areas was studied through experiments and numerical simulation. The radon exhalation concentration of coal was found to increase at first and then decrease in the range of 30–350 °C through experiments. The radon concentration reaches the maximum value (557.1 Bq/m3) at 150 °C, which is 6.3 times higher than that at 30 °C. Based on the radon source term obtained by fitting the experimental data, the radon migration model of coal spontaneous combustion in abandoned goaf was constructed, and the dynamic distribution characteristics of the airflow, temperature, and radon concentration fields in the overlying strata area were analyzed. The internal relationship between surface radon and underground fire source was discussed. The simulation results revealed the sharp change in the porosity of the overlying rock causes radon concentration at the interface between the caving and fissure zones to increase continually with the process of spontaneous combustion, providing material and energy support for the long-distance radon migration. When the maximum temperature of the coal pile reaches 70 °C, the concentration of radon released from the coal pile increases rapidly to 13696 Bq/m3, and the radon from the underground space appears on the surface at this temperature. In the range of 70–150 °C, with rapid increase in radon released from coal piles, the surface concentration of radon also increased rapidly to 225 Bq/m3. At the high-temperature stage exceeding 150 °C, the concentration of radon released from coal piles exhibited a downward trend, resulting in a decrease in the rate of increase of radon concentration on the surface. A close relationship between the surface radon concentration and underground fire source temperature in the process of coal spontaneous combustion was observed. In the spatial position, the peak position of radon on the surface was highly consistent with that of the fire source longitudinally, which ensures the accuracy of the SIRMM to determine the location of the hidden fire source. This suggests that the SIRMM can accurately evaluate the fire source's temperature and fire area's development trend.

Isotope radon measurement method to identify spontaneous combustion regions in coal gangue hills: case study for a coal mine in China

ABSTRACT Long-term accumulation of coal gangue hill has a high risk of spontaneous combustion, and the toxic and harmful gases emitted by spontaneous combustion seriously pollute the atmosphere. The key to managing the spontaneous combustion fire of coal gangue hill lies in the accurate measurement of fire source location. However, measuring the fire source location of surface coal gangue hill lacks experimental and empirical research. In this paper, an oxidation warming experiment was conducted on the coal gangue samples, and the law of radon gas exhalation from coal gangue under different temperatures was analyzed. At the same time, surface thermometry and isotope radon measurement were applied to measure the high-temperature areas inside the gangue hill, and the measurement results were compared. The experimental results show that as the temperature of gangue increases, the amount of radon gas exhalation in gangue shows a changing trend of rising first and then decreasing. The radon exhalation from coal gangue can be divided into three stages. In the I stage (30 ~ 100°C), the evaporation of pore water in coal gangue leads to the exhalation of radon in water, causing the increase of radon concentration; in the II stage (100 ~ 350°C), the coal gangue is pyrolyzed at high temperature, and a large amount of radon is exhalated from the closed pores; in the III stage (350 ~ 450°C), after the first two stages of radon release, the number of radon atoms in this stage decreases, leading to a rapid decrease of radon concentration. The field measurement results show that compared with the surface thermometry method, the isotope radon measurement method is less disturbed by external conditions, and the circled fire area is more accurate, which has essential theoretical significance and practical application value for the accurate measurement of fire source location in coal gangue hill.

Study on damage evolution and radon exhalation of uranium-bearing granite under high temperature.

Deep geological disposal of high-level radioactive waste is a feasible method for solving the problem of spent fuel storage in China. High-level radioactive waste releases heat during the decay process, which increases the temperature of the surrounding rock in the repository, resulting in a significant increase in radon concentration. In this study, the surrounding rock (granite) of a high-level radioactive waste repository was taken as the research object and, based on the similarity principle, an orthogonal test designed. Similar materials of uranium-containing granite were prepared in the laboratory and the physical and mechanical properties and cumulative radon concentration of granite samples assessed under different temperatures (25, 50, 100, 150, and 200°C). The results showed that, with increased temperature, the compressive and tensile strengths of samples gradually increased and their pore volume gradually decreased. After heat treatment, the longitudinal wave velocity and thermal conductivity of samples decreased linearly with increased temperature. The radon exhalation rate first increased and then decreased, with the rate reaching a maximum at 100°C. The radon exhalation rate of single-sided and double-sided samples was 0.00914 and 0.00460Bq·m-2·s-1, respectively. When the temperature was 25-100°C, the dominant stage was pore water. The radon exhalation rates of samples were positively correlated with compressive and tensile strengths and negatively correlated with pore volume, longitudinal wave velocity, and thermal conductivity. The temperature of 100-200°C was range of the dominant stage of pore structure. The conclusions obtained in this study can provide theoretical support for radon reduction and radon control of granite in high temperature environments.

Radon attenuation characteristics of compacted soil layer for uranium mill tailings pond subjected to drying-wetting cycles

Compacted soil layer (CSL) is generally designed for uranium mill tailings (UMTs) pond to form the radon seals, whereas it is usually affected by drying-wetting environmental conditions. To summarize the radon attenuation degradation performance of CSL subjected to drying-wetting cycles, an experiment with the application of meteorological data was developed. This paper focuses on the evolution of the soil apparent porosity, soil integrity and radon attenuation characteristics of CSL during continuous drying-wetting cycles. Image processing and a nonmetal acoustic wave detector were applied to analyze variations in the soil surface and internal defects, and the radon concentration was measured to reveal the radon attenuation performance of the CSL. The results reveal that with successive drying-wetting cycles, the soil apparent porosity increased, and the soil pores were enlarged. The soil integrity underwent dynamic recombination or reorganization and eventually reached a steady state. Moreover, it was observed that the saturated state of the uppermost soil led to a sharp increase in radon concentration (capping effect), and the decrease in accumulated radon concentration during the initial period resulted from the coupling effect of soil moisture, temperature and ambient pressure. The observations confirm that the drying-wetting environmental conditions markedly affect the radon migration channels and environment in the CSL, which provides a theoretical foundation for UMTs pond governance and radiation safety management.

New-designed in-situ measurement system for radon concentration in soil air and its application in vertical profile observation

ABSTRACT Radon in soil is a valuable radioactive tracer in earth science, especially for earthquake and volcanic precursors. For the purpose of continuous measurement of radon-in-soil concentration in-situ, a new-designed measurement system was developed. Calibration and experiments for humidity response correction were carried out in details, and field measurement of vertical profile with 7 radon probes at different depths was performed. Calibration results show that the sensitivity of the radon probes is 16.1 ± 1.0 cph (kBq m−3)−1, and the lower level detection limit is 231 ± 15 Bq m−3 for 1-hour measurement cycle under the absolute humidity of 32.8 g m−3. Field measurement results show that radon concentrations at different depths change with time and increase with depth in the soil. The vertical profile presents a negative exponential distribution with different diffusion length in sunny days, while rainfall can disturb the vertical distribution and lead to increase of radon concentration in the near ground surface. Radon concentration in underground deeper than 80 cm appears quite stable and hardly affected by rainfall in our observation.

Model of radon entry and accumulation in multi-flat energy-efficient buildings

Radon daughters in the atmosphere of dwellings, public buildings, and workplaces cause lung cancer. Radiation safety in a situation of indoor radon exposure is ensured by means of controlling natural radioactivity during the buildings construction and maintenance. In recent decades the energy saving has resulted in increase of radon concentration in new buildings comparing to conventional buildings. High-rise buildings where building materials are the main source of radon entry are of particular interest due to considerable influence of ventilation on the radon dynamic. To justify and optimize protection of the population against radon exposure in new energy-efficient multi-apartment buildings, a comprehensive understanding of the processes of radon transport and accumulation is required. Developed dynamic model of radon entry and accumulation in an energy-efficient multi-apartment building consists of building and room model, radon source model, ventilation model, and mass transport model. The dynamic model takes into account the basic physical properties of radon transport – diffusion and advection. Data of model experiments and observations of the radon accumulation in the real dwellings were considered to choose appropriate values of the model. Basing on simulation results, the possible range of radon concentrations under the expected concentrations of 226Ra in building materials was estimated. Simulation of indoor radon behavior approved that increased indoor radon exposure in multi-storey energy-efficient buildings can arise due to low active ventilation frequency and high 226Ra concentration.

Radon concentration in conventional and new energy efficient multi-storey apartment houses: results of survey in four Russian cities

During last decades, energy saving in new buildings became relevant within the energy efficiency strategies in various countries. Such energy efficient building characteristics as air tightening and low ventilation can compromise indoor air quality, in particular, increase radon concentration. In Russia, a significant part of the new buildings is the energy efficient multi-storey apartment houses. The aim of this study is to assess the significance of possible radon concentration increase in new energy efficient buildings in comparison with typical conventional multi-storey houses of previous periods. Radon surveys were conducted in Russian cities Ekaterinburg, Chelyabinsk, Saint-Petersburg and Krasnodar. The radon measurements were carried out in 478 flats using CR-39 nuclear track detectors. Energy efficiency index (EEI) was assigned to each house. All buildings were divided into six main categories. The smallest average radon concentration was observed in panel and brick houses built according to standard projects of 1970–1990 (four-city average 21 Bq/m3). The highest average radon concentration and EEI were observed in new energy efficient buildings (49 Bq/m3). The trend of radon increase in buildings ranked with high EEI index is observed in all cities. The potential increase of radiation exposure in energy-efficient buildings should be analyzed taking into account the principles of radiological protection.

The assessment of lining structure impact on radon behaviour inside selected underground workings under the cour d\u2019honneur of Ksi\u0105\u017c castle

The results based on 2-year long measurements 01 Jan. 2016–2031 Dec. 2017 have been used for discussing the influence of tunnel lining on the size of 222Rn activity concentration and the impact of the employed rock mass insulation on natural convective air exchange. In April, air movement started when the temperature was at least 7 °C lower than the mean inside. Between May and October, an increase to 9 °C above the underground temperature resulted in an increase of radon concentration. An unconstrained convection process did not start until November and it continued until the end of March. The reinforced concrete lining insulated the fractured and absorptive rock mass. The roof and the sidewall lining had little impact on air movement process.

Influence of some climatic elements on radon concentration in Saeva Dupka Cave, Bulgaria

This study reveals the influence of some climatic elements on radon concentration in Saeva Dupka Cave, Bulgaria. The research is based mainly on statistical methods. Radon concentration in the cave is determined by two main mechanisms. The first one is through penetration of radon from soil and rocks around the cave (present all year round, but has leading role during the warm half of the year). The second one is through thermodynamic exchange of air between inside of the cave and outside atmosphere (cold half of the year). Climatic factors that affect radon concentration in the cave are temperatures (air, surface, soil) and amount of water, expressed by precipitation or by volumetric water content in the soil. In the cold half of the year, an important factor is the duration and depth of snow cover. Statistical models and projections show that by the year 2070 CE radon concentration in the cave will increase. This increase will occur primarily in the warm half of the year due to the increase in outside air temperatures that will decrease thermodynamic exchange of air between the cave and the atmosphere. By the middle of the 21st century, it is expected that the studied area will no longer have a permanent snow cover and the temperature will remain the only factor for the increase of radon concentration in the cold half of the year. Water content in the soil and precipitation are important factors for radon concentration in the cave, but they have no significant trend and they are not expected to exert any influence in the next 50 years. The projected increase of radon concentration in Saeva Dupka Cave creates a serious risk for the health of the tour guides working there. That is why it is necessary to develop a plan to protect the health of the cave staff. On the other hand, the projected increase of radon concentration does not pose any significant health risk for the tourists visiting the cave.

Monitoring soil radon during the 2016\u20132017 central Italy sequence in light of seismicity

The radioactive nature of radon makes it a powerful tracer for fluid movements in the crust, and a potentially effective marker to study processes connected with earthquakes preparatory phase. To explore the feasibility of using soil radon variations as earthquakes precursor, we analyse the radon concentration data recorded by two stations located close to the epicentre of the strongest mainshock (Mw 6.5 on October 30, 2016) of the seismic sequence which affected central Italy from August 2016. The two stations CTTR and NRCA operate in the framework of the permanent Italian Radon monitoring Network and recorded almost continuously since 2012 and 2016, respectively, the latter being installed just after the first mainshock of the sequence (Mw 6.0 on August 24, 2016). An increase of radon emanation is clearly visible about 2 weeks before the Mw 6.5 event on both the time series, more pronounced on NRCA, nearer to the epicentre, suggesting the possibility of a direct association with the earthquake occurrence. An independently developed detection algorithm aimed at highlighting the connections between radon emission variations and major earthquakes occurrence succeeds in forecasting the Mw 6.5 mainshock on NRCA time series. The resulting time advance of the alarm is consistent with that obtained using a Bayesian approach to compute the a posteriori probability of multiple change points on the radon time series of NRCA. Moreover, it is in agreement with the delay time which maximizes the correlation between radon and seismic anomalies. Applying the detection algorithm to CTTR time series returns alarms for both the Mw 6.0 event, with epicentre closer to this station, and the stronger Mw 6.5 event, but with a higher number of false detections. Finally, we found that a preliminary correction of the bias introduced by variations of meteorological parameters does not affect our main finding of an increase in radon concentration before the major mainshocks. Our study confirms that, although much work is still needed, a monitoring approach based on a permanent dense network is crucial for making radon time series analysis an effective complement to traditional seismological tools.

Радон як можливий індикатор сейсмічності регіону Західної Антарктиди

The measurements of near-surface radon concentration have been carried out at the Ukrainian Antarctic Akademik Vernadsky station (Akademik Vernadsky station) since 2003. Abnormal concentrations of radon could serve as a possible valuable indicator of tectonic activity, along with other evidence, potential signs of an expected earthquake. The aim of the work is to find the relationship between the abnormal values of the surface radon concentration, which correlate with tectonic activity. During the measurements, dosimetric methods for detecting the decay of isotopes and daughter products were used. When analyzing the data, statistical analysis methods were used. The sequence of earthquakes that occurred during instrumental observations of radon concentration, has been analyzed. The potential seismic regions affecting the location of the Akademik Vernadsky station were determined. The distances were determined at which geophysical anomalies are likely to occur within the framework of the proposed model and the expected effect of seismicity on the radon yield at the observation site is estimated. The result of the studies shows low correlation between the concentration of radon at the observation point and tectonic activity in the region at distances up to 1100 km with a magnitude of M > 7. At shorter distances to an earthquake, radon anomalies can be expected at M > 6. In some cases, the increase in radon concentration in day–two before the earthquake has been observed. That can be used as a potential predictor, however, no stable recurrence of such events was measured. It is noted that for the correct interpretation of the radon concentration measurements, the analysis of meteorological parameters can be necessary.

Discussion on anomaly of atmospheric electrostatic field in Wenchuan Ms8.0 earthquake

On May 12, 2008, a surface wave magnitude 8.0 earthquake occurred in Wenchuan, China. In several hours to tens of days before the earthquake, a series of abnormal changes of the atmospheric vertical electrostatic field was found in Pixian and Wenjiang stations, located near the epicenter. After excluding potentially interference factors such as lightning, meteorological factors, aerosol, solar radiation and human activities, we found that the earthquake preparation process may cause abnormal synchronous changes in the atmosphere vertical electrostatic field, or equivalently, surface atmospheric potential gradient (PG), at different locations. About 40 days before the Wenchuan earthquake, the daily median of PG at Pixian and Wenjiang exhibited a synchronous downtrend, and the correlation was relatively high. With the main shock approaching, with the rapid increase of radon concentration in Guzan station, the daily mean value of PG decreased synchronously in the two stations. The PG anomaly in Wenjiang on May 9 corresponds to the ionospheric anomaly. On May 12, 6 h before the main shock, PG abnormally synchronously increased in Wenjiang and Pixian accompany with the decrease of gas radon concentration in Guzan station (PG correlation coefficient of the two stations was as high as 0.818). Two minutes after the main shock, there was a highly synchronized negative pulse lasting 225 s. These abnormal synchronous changes of PG can be explained by the mechanism of acceleration of radon emission before earthquake. The abnormal synchronic change of PG of Wenchuan earthquake was consistent with the phenomenon occurred in Japan in 2009. The results indicate that abnormal synchronous changes of atmospheric electrostatic field (or PG) may be an important earthquake precursory.

Problem of radon exposure in energy-efficient buildings: a review

The paper presents an overview of the international scientific and technical publications on a problem of radon accumulation in new energy efficient buildings and in houses reconstructed according to requirements of energy saving. Energy efficiency is an important requirement of the environmentally sustainable development. Housing and communal services have significant potential for energy saving. In Russia, the construction of highest energy efficiency classes buildings occurs at an accelerated rate and reached 75% of all multiapartment houses built in 2017. The applying of modern technologies that reduce heat loss is accompanied by a decrease in the air exchange rate, which leads to deterioration of indoor air quality, in particular, the accumulation of radon. In the international literature, there are examples of the several times growth of radon concentration after the reconstruction of the building, the average radon concentration in retrofitted buildings increased by 22–120%. In new houses built to meet energy saving requirements, there can also be a significant increase in radon concentration compared to low-energy efficiency classes houses. Excess of sanitary and hygienic norms was found in some countries, including Russia. Radon exposure of dwellers of energy-efficient buildings is largely determined by the living habits. Based on the review data, it can be assumed that the average level of Russian population exposure to radon can increase under conditions of intensive construction of energy-efficient buildings.

Absorption of the natural radioactive gas 222Rn and its progeny 210Pb by Spanish moss Tillandsia usneoides and its response to radiation

Radon is the most abundant radioactive gas in natural air and the major contributor to human exposure. However, few attempts have been made to directly measure the relationship between radon and plants. Epiphytic Tillandsia usneoides was chosen as a model to investigate whether it can absorb 222Rn and its daughter 210Pb and to determine the physiological and genetic effects of radon on plants. The results showed that T. usneoides was effective in reducing airborne radon because radon concentrations in the chamber after plant treatment decreased faster than those in the natural situation, and activity concentrations of 210Pb in the plant increased significantly with an increase in radon concentration. The changes in the parameters of genetic damage, including tail DNA, tail length, tail moment and olive tail moment in T. usneoides also increased significantly with the increase of radon concentrations, suggesting that DNA was unavoidably affected by radioactive radon. In contrast, the physiological responses of T. usneoides exposed to radon suggest that this plant can resist radon stress because there was no difference in MDA, soluble proteins and leaf relative electronic conductivity, and increasing SOD may play a role in the tolerance to oxidative stress. Therefore, parameters of genetic damage have the potential to be used as biomarkers to monitor the concentrations of airborne radon.

Genetic and physiological effects of the natural radioactive gas radon on the epiphytic plant Tillandsia brachycaulos

Radon (222Rn) is the most abundant natural radioactive gas in nature and triggers carcinogenesis. Few reports exist on whether radon can damage plants as it does animals. Therefore, we chose Tillandsia brachycaulos, a common indicator plant, as the material to detect the physiological and genetic changes caused by radon. With an increase in radon concentration, DNA indices (tail length, tail DNA, tail moment and Olive tail moment) from the comet assay and malondialdehyde (MDA) content increased significantly, suggesting that T. brachycaulos inevitably suffered from radiation damage. However, neither the leaf relative conductivity nor the soluble protein content changed significantly with radon fumigation, and no dose-dependent effect existed between the chlorophyll content and radon concentration, indicating that T. brachycaulos had resistance to radon stress. Foliar trichomes most likely excluded the pollutant from plants because DNA damage in T. brachycaulos with trichomes manually removed was considerably greater than that with trichomes. Moreover, the antioxidant enzyme system further reduced the damage of radon to plants because the activity of superoxide dismutase (SOD) increased significantly with the radon concentration.

Factors affecting atmospheric radon concentration, human health.

We studied the influence of terrain, geology and weather condition on radon concentration in the atmosphere and occurrence of radon density currents. The survey was carried out in Kowary (SW Poland) and in the spoil tip formed during uranium mining. The measurements of radon concentration were performed using SSNTD LR-115. The measurements of uranium thorium and potassium content in soil were carried out using gamma ray spectrometer Exploranium RS-230. We noticed that terrain and stability of weather condition had significant impact on atmospheric radon concentration. The seasonal variations of radon concentrations in Kowary differ from those usually registered in temperate climate. Based on our analyses, the increase of radon concentration in winter and spring was caused by inversion occurring in that area during these seasons. The observed seasonal variations of radon concentrations in the spoil tip were consistent with those characteristic for temperate climate (the highest radon concentration registered in spring and summer and the lowest in winter and autumn). The spoil tip is located above 900m a.s.l. and is not cover by grass or trees. These circumstances promoted radon exhalation. The air movement above the spoil tip area is intensive, even in winter time. The average atmospheric radon concentration in the spoil tip was 318Bqm-3. The performed research did not reveal occurrence of radon density currents and flow of radon from the spoil tip to lower lying areas in Kowary. We noticed interdependence of atmospheric radon concentration measured at the height of 1.5 above the ground and uranium content in soil and no correlation between thorium content and radon concentration. The lung cancer in residents of Kowary which is more common than in Poland can be associated with increased concentrations of radon. The average radon concentration in the atmosphere in Kowary was 79Bq m-3.

Residential radon and COPD. An ecological study in Galicia, Spain

Purpose: Radon is a human lung carcinogen but it might be linked with other respiratory diseases. We aimed to assess the relationship between residential radon exposure and COPD (chronic obstructive pulmonary disease) prevalence and hospital admissions at a municipal level.Materials and methods: We designed an ecological study where we included those municipalities with at least three radon measurements. Using mixed Poisson regression models, we calculated the relative risk (RR) for COPD for each 100 Bq/m3 of increase in radon concentration and also the relative risk for COPD using a cut-off point of 50 Bq/m3. We did not have individual data on cigarette smoking and therefore we used a proxy (bladder cancer standardized mortality rate) that has proved to account for tobacco consumption. We performed separate analyses for sex and also sensitivity analysis considering age and rurality.Results: A total of 3040 radon measurements and 49,393 COPD cases were included. The relative risk for COPD prevalence was 0.95 (95% CI: 0.92–0.97) while for hospital admissions the RR was 1.04 (95% CI: 1.00–1.10) for each 100 Bq/m3. Relative risks were higher for women compared to men. Using a categorical analysis with a cut-off point of 50 Bq/m3, the RR for COPD prevalence was 1.06 (95% CI: 1.02–1.10) and for hospital admissions it was 1.08 (95% CI: 1.00–1.17) for women living in municipalities with more than 50 Bq/m3. All risks were also higher for women. No relevant differences were observed for age, rurality or other categories for radon exposure.Conclusion: While the influence of radon on COPD prevalence is unclear depending on the approach used, it seems that residential radon might increase the risk of hospital admissions in COPD patients. Women have a higher risk than men in all situations. Since this is an ecological study, results should be interpreted cautiously.