Annual Radon Research Articles

Prediction of long-term indoor radon concentration based on short-term measurements

We present a method for the estimation of annual radon concentration based on short-term (three months) measurements. The study involves results from two independent sets of indoor radon concentration measurements performed in 16 cities of the Republic of Macedonia. The first data set contains winter and annual radon concentration obtained during the National survey in 2010 and the second, contains only the radon concentration measured during the winter of 2013. Both data sets pertain to radon concentration from the same cities and have been measured applying the same methodology in ground floor dwellings. The results appeared to be consistent and the dispersion of radon concentration was low. Linear regression analysis of the radon concentration measured in winter of 2010 and of the 2010 annual radon concentration revealed a high coefficient of determination R2 = 0.92, with a relative uncertainty of 3%. Furthermore, this model was used to estimate the annual radon concentration solely from winter-term measurements performed in 2013. The geometrical mean of the estimated annual radon concentration of the 2013: radon concentration (A-2013) =98 Bqm-3 was almost equal to the geometrical mean of the annual radon concentration from the 2010, radon concentration (A-2010) = 99 Bqm-3. Analysis of the influence of building characteristics, such as presence/absence of a basement in the building, or the dominant building material on the estimated annual radon concentration is also reported. Our results show that a low number of relatively short-term radon measurements may produce a reasonable insight into a gross average obtained in a larger survey.

Study on Characteristics of Radon Concentration and Effective Dose at Public Buildings in Korea

The purpose of this study was to survey radon concentration and to evaluate radon annual effective dose in public buildings. We investigated 351 public buildings using alpha-track detector between January 2008 and May 2009. The concentration of indoor radon concentration for public building was 52.6±33.1 Bq/m³ (GM: 46.6 Bq/m³), and the range (min-max) was 15.2 to 317.7 Bq/m³. The indoor radon concentration for all public buildings were far below the recommended standards of IAQ Guideline, Ministry of Environment Korea. Indoor radon concentration of the C.B Province (AM: 70.0±53.2, GM: 58.7 Bq/m³) is higher than other Province. Also, Except for J.J Province, radon concentration at winter-season higher than that of the other seasons (spring, summer, autumn), respectively (p0.01). The annual effective indoor radon dose was 0.37mSv/y, this values not exceed recommended standards of ICKL. This study will provide useful data for the determination of radon management and reduction at the public buildings.

Significant annual and sub-annual cycles in indoor radon concentrations: seasonal variation and correction

Abstract The majority of radon measurements in the built environment are made over sub-year periods and are then generally seasonally corrected (i.e. scaled by an appropriate seasonal correction factor (SCF)) to estimate the annual average radon concentration. SCFs are statistically derived and assume an underlying annual cycle, reflecting the widely observed seasonal variation in indoor radon concentrations. In the UK, Public Health England has pioneered the calculation and use of a national SCF set using an annual sinusoidal model for variations in radon concentration and averaging across the entire country. To test the validity of that model, a 4 year record of weekly radon data from four houses in Brixworth (Northamptonshire, UK) was analysed in conjunction with corresponding weather data for the period from a nearby weather station. The radon data showed a statistically significant annual cycle comprising both annual sinusoidal and second harmonic (i.e. 6 month period) terms. Two sets of SCFs were calculated: first, using a conventional annual sinusoidal model that explained 21.2% of the variance in the radon data; and, secondly, a second harmonic term was included in the model that explained 24.6% of the variance. This represents an improvement of 3.4 percentage points (15.9%) and, thus, will result in better SCFs.

In-field evaluation of the impact of ageing and fading effects on annual radon concentration measurements for two different techniques

Measurements covering a 1 year period are often used and required by legislation to assess the average radon concentration within a house or a workplace. This kind of long-term measurement—generally carried out with techniques based on nuclear track detectors—can be affected by a reduction in sensitivity due to ageing and fading of latent tracks during the exposure period, thus resulting in an underestimation of the actual average concentration.In order to evaluate in field conditions the ageing and fading effects on annual radon concentration measurements, two different studies in a large sample of rooms in dwellings (162) and in workplaces (432) were conducted using two different techniques (detector and track read-out system): (i) CR-39 plastics readout with a fully automated image analysis system, and (ii) LR 115 films with a spark-counter for track counting.Study design and data analysis aimed to evaluate both the average and the variability of ageing and fading effects in real conditions, and to reduce and separate the contribution of measurement uncertainty to the observed variability.For the CR-39 based technique, the results show that radon concentration measurements over a 12month period are on average about 16% lower than those evaluated with measurements of two consecutive 6 month periods, implying the need for a correction factor to avoid measurement bias (i.e. underestimation) due to ageing and fading effects. The observed variability of ageing and fading effects among the sampled rooms is not negligible (coefficient of variation about 18%), although a considerable fraction is attributable to measurement uncertainty, which is presumably not related to ageing and fading. For the technique based on LR 115 spark counting, ageing and fading do not significantly affect the results of radon concentration measurement.

New Correction Factors Based on Seasonal Variability of Outdoor Temperature for Estimating Annual Radon Concentrations in UK.

Indoor radon concentrations generally vary with season. Radon gas enters buildings from beneath due to a small air pressure difference between the inside of a house and outdoors. This underpressure which draws soil gas including radon into the house depends on the difference between the indoor and outdoor temperatures. The variation in a typical house in UK showed that the mean indoor radon concentration reaches a maximum in January and a minimum in July. Sine functions were used to model the indoor radon data and monthly average outdoor temperatures, covering the period between 2005 and 2014. The analysis showed a strong negative correlation between the modelled indoor radon data and outdoor temperature. This correlation was used to calculate new correction factors that could be used for estimation of annual radon concentration in UK homes. The comparison between the results obtained with the new correction factors and the previously published correction factors showed that the new correction factors perform consistently better on the selected data sets.

Outdoor radon concentration in China

Abstract A nationwide survey was conducted in 2014 to investigate environmental outdoor radon level in 33 provincial cities across China. The radon detector used was a passive-type solid-state nuclear track detector, CR-39. Measurements were conducted under the same condition following the quality control programme. Outdoor radon concentrations in China ranged from 3 to 30.0 Bq·m−3. The annual arithmetic and geometric mean radon concentration were 14 and 13.2 Bq·m−3, respectively. The radon concentrations in the locations near or along coastline were lower than the average value, while those located in the inland area were higher. As a whole, the result showed no big difference from the data measured during the period 1983–1998. It demonstrated that the outdoor radon concentration level in China has not been changing remarkably for 20 years.

Distribution of indoor radon concentrations between selected Hungarian thermal baths

Abstract Owing to the high potential of radon to increase the risk of lung cancer, health organizations are enforced to update their regulations and recommendations regarding indoor radon levels each year. In this study, the indoor radon concentrations of three randomly selected thermal baths in Hungary using CR-39 and an AlphaGUARD radon monitor were measured with regard to the new updated standards of the European Basic Safety Standard (EU BSS, Council Directive 2013/59/Euratom, 2014). The annual average of indoor radon concentrations in Parad Medical Bath, Igal Health Spa and Eger Turkish Bath were measured as 159 ± 19, 176 ± 27 and 301 ± 30 Bq/m3, respectively. Indoor radon concentration in all measurement locations were determined to be below the reference level, with the exception of the main pool, small pool and sparkling bath areas in the Eger Turkish Bath that were measured as 403 ± 42, 315 ± 32 and 354 ± 36 Bq/m3, respectively. In light of the results, the estimated annual average radon concentration in the thermal baths was below the EU BSS reference level of 300 Bq/m3. Personal dosimetry is required to estimate the annual effective dose from inhaled radon by the workers at the Eger Turkish Bath. This procedure is required in order to justify the application of the mitigation process of decreasing working hours, improving the ventilation rate or increasing the number of classified employees in response to the official radiation surveillance programme.

Results of radon CR-39 detectors exposed in schools due two different long-term periods

Abstract The paper deals with the recent survey of indoor radon (Rn) results in schools, where paired CR-39 detectors were simultaneously exposed to different long-term periods, i.e., one detector was exposed during the whole year and the other one in the period of the school year duration. To be able to compare the results obtained, for its analysis, the relative bias and U tests were used. It was found that there are no systematic differences between the results, which points that the exposure of the detector during summer vacations did not affect the estimated average annual radon concentration. The paired results were modelled by a linear function, giving an extremely high coefficient of determination R 2 = 0.99.

Development of Predictive Model for Annual Mean Radon Concentration for Assessment of Annual Effective dose of Radon Exposure

Development of Predictive Model for Annual Mean Radon Concentration for Assessment of Annual Effective dose of Radon Exposure

Variability of Atmospheric Radon‐222 and Secondary Aerosol Components in Accordance with Air Mass Transport Pathways at Jeju Island, Korea, during 2011–2014

Real‐time monitoring of hourly atmospheric Radon‐222 concentration and three daily monitoring of the secondary aerosol components of PM10 were performed throughout 2011–2014 at Gosan station, Jeju Island, in order to characterize their background levels and temporal variation. The annual mean radon and PM10 mass concentrations were 2326 ± 1198 mBq/m3 and 37.1 ± 19.5 µg/m3, respectively. Based on cluster analyses of air mass back trajectories, the frequencies of air masses originating from continental China, the Korean Peninsula, and North Pacific Ocean routes were 53, 28, and 19%, respectively. When the air masses were transported to Jeju Island from continental China, the concentrations of radon and secondary aerosol components (nss‐SO4 2 −, NO3 −, NH4 +) were relatively high: 2577 mBq/m3 and 14.4 µg/m3, respectively. In cases when the air masses have moved from the Korean Peninsula, the corresponding concentrations were 2247 mBq/m3 and 11.4 µg/m3, respectively. On the other hand, when the air masses came from the North Pacific Ocean, their radon and secondary aerosol concentrations decreased much further, 1372 mBq/m3 and 10.5 µg/m3, respectively. Consequently, the variability of atmospheric radon concentrations at Gosan station might be characterized by synoptic changes in air mass fetch as well as diurnal changes in atmospheric mixing depth.

Indoor radon concentration and gamma dose rate in dwellings of the Province of Naples, South Italy, and estimation of the effective dose to the inhabitants

The indoor radon concentration was measured in 471 dwellings in the Province of Naples. Radon concentration measurements were carried out using LR-115 passive alpha track detectors (SSNTDs) that were exposed for two consecutive semesters. The annual average radon concentration in the dwellings was found to vary from 21 to 722 Bq m -3 with an average value of 107 ± 75 Bq m -3 . In about 93% of the dwellings the radon concentrations were found to be below 200 Bq m -3 , which is the recommended level by Italian law for new buildings. Simultaneously with the radon concentration measurements, indoor gamma dose rates were measured in 388 dwellings. Indoor gamma dose rates were measured using Thermoluminescent Dosimeters (TLDs) exposed in each dwelling for six months. The arithmetic mean value was found to be 327 ± 102 nGy h -1 , after the subtraction of the cosmic ray contribution. A weak correlation between the indoor radon concentration and gamma dose rate was found. The correlation between indoor radon measurements and gamma dose rates and the same building characteristics was also studied.

Indoor radon concentrations and radon doses at three districts of Ankara, Turkey and raising public awareness on the issue

Indoor radon concentrations at METU, CIGDEM and DOSTLAR in Ankara were measured using electrets. The statistical analysis of the data indicated a lognormal distribution of radon concentrations, with no significant difference between CIGDEM and DOSTLAR with geometric means of GM = 87.5 and 54.5 Bq m−3, respectively. Radon concentrations did not change seasonally at CIGDEM which contain modern buildings, but at the slum district DOSTLAR, with poor insulation of houses a seasonal variation was observed. Annual effective radon doses were estimated (0.4–8.4 mSv). Public awareness about indoor radon was raised.

Radon concentration Measurements in Qaysare of Erbil City

In this study the assessment of indoor radon concentration in the air of Qaysare in Erbil city have been studied by using CR-39 Solid–State Nuclear Track Detector Technique. A total of 18 selected zones inside the suq have been selected to place the dosimeters. The average radon concentration was found to be 21.54 ± 8.017 Bq/m3 ,which is fortunately lower than the standard international limit from 200-600 Bq/m3 as recommended by ICRP, IAEA. The potential alpha energy concentration and annual effective dose have been calculated. A proportional relationship between the annual effective dose and radon concentration within the studied region has been certified.

A follow-up study on indoor 222Rn, 220Rn their decay product concentrations in a mineralised zone of Himachal Pradesh, India.

A follow-up study was taken up in a mineralised zone situated in Hamirpur district, Himachal Pradesh, India, to investigate high values of radon concentrations reported in past studies as well to update the old radon data based on bare SSNTD technique. In the present investigation, the concentrations of indoor radon, thoron and their decay products have been measured using the newly developed radon/thoron discriminating diffusion chamber with single entry face, direct radon and thoron progeny sensors (DRPS/DTPS), respectively. The measurements have been carried out in 75 dwellings of 14 different villages where the previous studies were carried out using bare SSNTD technique. It was observed that high values of earlier reported radon concentrations were mainly due to thoron interference in the Solid State Nuclear Track Detector (LR-115 type II) exposed in bare mode. Now, the average concentration values and the estimated annual inhalation dose in these villages have been found to be within the reference level as recommended by the ICRP. The annual average indoor radon and thoron concentrations observed in these dwellings have been found to vary from 44±12 to 157±73 Bq m(-3) and 44±11 to 240±125 Bq m(-3), respectively. The equilibrium equivalent concentrations of radon and thoron decay products have been observed to be in the range of 10 to 63 and 1 to 5 Bq m(-3), respectively.

Indoor exposure assessment of radon in the elementary schools, Palestine

Background: Many public health agencies rank residenal radon exposure as the second leading cause of lung cancer aer cigaree smoking. It has been shown that the risk coefficient for lung cancer is higher for children than that for adults. Therefore, indoor radon measurements were carried out in the elementary schools of Tulkarem province, West Bank, Palesne. Materials and Methods: Two hundred and thirty solid state nuclear track detectors (SSNTDs) type CR-39 were distributed in the classrooms of 20 elementary schools in Tulkarem province area. About thirty of them were used for quality assurance purposes. The CR-39 detectors were exposed in the schools for three months during the school summer holiday from May 2012 to August 2012 and then collected and etched in Sodium Hydroxide (NaOH) 6.25 N soluon at 75 °C for 6 h. The tracks were counted manually at the digital microscope. Results: The indoor radon levels were generally low, ranging from 3.48 to 210.51 Bq/m 3 (Becquerel per cubic meter), with a mean radon concentraon (mean±SE; standard error) of 40.42± 2.49 Bq/m 3 . The average annual radon effecve dose was assessed to be (mean±SE) 0.17 ± 0.01 mSv/y (milliSievert per year) while the excess lifeme lung cancer risk was approximately 0.09%. The results obtained indicate that the indoor radon concentraon was signif icantly af fected by the fl oor level of the classroom (negavely correlated) and the school building age (posively correlated). Conclusion: The radon concentraon and the resulng dose in the schools were within the reference levels of the Internaonal Commission on Radiological Protecon (ICRP). Beer venlaon is recommended to decrease the risk to the minimum.

A critical analysis of climatic influences on indoor radon concentrations: Implications for seasonal correction

Although statistically-derived national Seasonal Correction Factors (SCFs) are conventionally used to convert sub-year radon concentration measurements to an annual mean, it has recently been suggested that external temperature could be used to derive local SCFs for short-term domestic measurements. To validate this approach, hitherto unanalysed radon and temperature data from an environmentally-stable location were analysed. Radon concentration and internal temperature were measured over periods totalling 1025 days during an overall period of 1762 days, the greatest continuous sampling period being 334 days, with corresponding meteorological data collected at a weather station 10 km distant. Mean daily, monthly and annual radon concentrations and internal temperatures were calculated.SCFs derived using monthly mean radon concentration, external temperature and internal-external temperature-difference were cross-correlated with each other and with published UK domestic SCF sets. Relatively good correlation exists between SCFs derived from radon concentration and internal-external temperature difference but correlation with external temperature, was markedly poorer. SCFs derived from external temperature correlate very well with published SCF tabulations, confirming that the complexity of deriving SCFs from temperature data may be outweighed by the convenience of using either of the existing domestic SCF tabulations.Mean monthly radon data fitted to a 12-month sinusoid showed reasonable correlation with many of the annual climatic parameter profiles, exceptions being atmospheric pressure, rainfall and internal temperature. Introducing an additional 6-month sinusoid enhanced correlation with these three parameters, the other correlations remaining essentially unchanged. Radon latency of the order of months in moisture-related parameters suggests that the principal driver for radon is total atmospheric moisture content rather than relative humidity.

Occupational exposure assessment and radiation dose estimation of vegetable-plant farmers to 222Rn in greenhouses of Shouguang county, China

This study aims to: (1) assess exposure levels of radon and explore seasonal variations of radon concentrations in greenhouses in Shouguang county. (2) Estimate annual radon radiation dose level for vegetable-plant farmers working in greenhouses. During detection period, the annual mean radon concentration was approximately 286 Bq m−3. The annual radon radiation dose of farmers is 3.3 mSv a−1. Both obvious seasonal variations in average radon concentrations and radon radiation dose in greenhouses are observed. Both levels are much higher in winter and spring than in summer and autumn.

Effect of soil moisture on seasonal variation in indoor radon concentration: modelling and measurements in 326 Finnish houses.

The effect of soil moisture on seasonal variation in soil air and indoor radon is studied. A brief review of the theory of the effect of soil moisture on soil air radon has been presented. The theoretical estimates, together with soil moisture measurements over a period of 10 y, indicate that variation in soil moisture evidently is an important factor affecting the seasonal variation in soil air radon concentration. Partitioning of radon gas between the water and air fractions of soil pores is the main factor increasing soil air radon concentration. On two example test sites, the relative standard deviation of the calculated monthly average soil air radon concentration was 17 and 26%. Increased soil moisture in autumn and spring, after the snowmelt, increases soil gas radon concentrations by 10-20 %. In February and March, the soil gas radon concentration is in its minimum. Soil temperature is also an important factor. High soil temperature in summer increased the calculated soil gas radon concentration by 14%, compared with winter values. The monthly indoor radon measurements over period of 1 y in 326 Finnish houses are presented and compared with the modelling results. The model takes into account radon entry, climate and air exchange. The measured radon concentrations in autumn and spring were higher than expected and it can be explained by the seasonal variation in the soil moisture. The variation in soil moisture is a potential factor affecting markedly to the high year-to-year variation in the annual or seasonal average radon concentrations, observed in many radon studies.

The results of integration measurements of indoor radon activity concentration in houses in Ružomberok town (Northern Slovakia)

Abstract Integration measurements of indoor radon in houses were performed within the framework of the project “Harmonization of determining the radiation dose of the population originating from radon in V4 countries”. In Slovakia, the survey was performed in three localities: Záhorská Bystrica, Mochovce and Ružomberok. Monitoring started in March 2012 and lasted for one year. In Ružomberok ten houses were selected for monitoring purposes. The houses built before 1990 were predominantly chosen for the investigation. In selected houses in Ružomberok, radon activity concentration rarely exceeded 400 Bq/m3 in a three month period, in this case the inhabitants were advised how to lower radon exposure. No house was found with an annual radon activity concentration of more than 400 Bq/m3.

Radon levels in underground workplaces: a map of the Italian regions.

The indoor radon exposition is a widely recognised health hazard, so specific laws and regulations have been produced in many countries and so-called radon-risk maps have consequently been produced. In Italy the regulation applies to general workplaces and a national survey was carried out in the 1990s to evaluate the exposure to radon in dwellings. Failing a national coordinated mapping programme, some Italian regions performed a survey to identify radon-prone areas, nevertheless with different methodologies. In this work a national map of the average annual radon concentration levels in underground workplaces, obtained from the results of 8695 annual indoor radon measurements carried out by U-Series laboratory between 2003 and 2010, was presented. Due to underground locations, the mean radon concentration is higher than that from previous map elaborated for dwellings and a significant radon concentration was also found in Regions traditionally considered as low-risk areas.