Earthquake precursory studies in Kangra valley of North West Himalayas, India, with special emphasis on radon emission

The continuous soil gas radon monitoring is carried out at Palampur and the daily monitoring of radon concentration in water is carried out at Dharamshala region of Kangra valley of North West Himalayas, India, a seismic zone V, to study the correlation of radon anomalies in relation to seismic activities. In this study, radon monitoring in soil was carried out by using barasol probe manufactured by Algade France, whereas the radon content in water was recorded using RAD 7 radon monitoring system of Durridge Company USA. The effect of meteorological parameters viz. temperature, pressure, wind velocity, rainfall, and humidity on radon emission has been studied. The seasonal average value and standard deviation of radon in soil and water is calculated to find the radon anomaly to minimize the effect of meteorological parameters on radon emission. The radon anomalies observed in the region have been correlated with the seismic events of M≥2 reported by Wadia Institute of Himalayas Geology Dehradoon and Indian Meteorological Department, New Delhi in NW Himalayas within 250 km distance from the monitoring stations.     

Public exposure to radon in drinking water in SERBIA

Radon is the main source of natural radiation that is received by population. The results of radon activity measurements in water from public drinking fountain, from bottled drinking water and from tap water in the city of Novi Sad, Serbia, are presented in this paper. The measurements were performed by RAD 7 radon detector manufactured by DURRIDGE COMPANY Inc. The corrected value of radon concentration in one sample exceeded the European Commission recommendation reference level for radon in drinking water of 100 Bq l⁻¹. In order to make the correlation between radon and radium concentrations in the tap water and in the water from public drinking fountain, the gamma-spectrometric measurements were performed. The results of ²²²Rn activity concentration measurements from soil in the city of Novi Sad using RAD 7 detector are presented.     

The influence of uncertainties of radon exposure on the results of case-control epidemiological study

Abstract

Purpose: Simulation of large-scale epidemiological study to identify the influence of uncertainties of radon exposure assessment on the excess relative risk of lung cancer.

Materials and methods: Analysis of sources of uncertainties arising during radon epidemiologic case-control studies. Assessment of the uncertainties due to influence of long-term variations of radon concentration, exposure to radon in other places of human presence, except dwellings, quality of radon concentration measurements etc. Simulation by Monte Carlo technique of radon epidemiologic study, comparable to the pooled European radon case-control study, and assessment of uncertainties, which affect the evaluation of dose-effect dependence.

Results: The uncertainties of personal exposure to radon are generally caused by the combined effect of long-term variations of radon concentration and the differences in the levels of radon concentration in homes and other places of human presence. The logarithmic standard deviation of this uncertainty is from 0.70 to 0.90. This value is ～2 times higher than the uncertainty, applied for correction of the results in the pooled European radon case-control study. It is shown that for σ_err?<?1.0 regression calibration technique allows to make full correction of the uncertainty. The error in assessment of uncertainties of the exposure to radon concentration in the pooled European radon case-control study has led to an underestimation of excess relative risk of lung cancer incidence at least by 1.5 times.

Conclusion: The error in an assessment of uncertainties of radon exposure in the pooled European radon case-control study has led to an underestimation of relative risk of lung cancer incidence at least by 1.5 times.     

北京地区室外氡及氡子体浓度水平及变化规律研究

目的 了解北京地区室外环境空气中氡及氡子体浓度水平,分析其变化规律及影响因素。方法 采用氡及氡子体浓度在线连续测量装置,测量周期为60 min,在北京地区不同方位的3个观测点,进行为期1年的长期连续测量。结果 北京地区室外空气中氡浓度年平均值为（10.9±4.9）Bq/m³,氡子体浓度（平衡当量氡浓度）年平均值为（5.8±3.4）Bq/m³、平衡因子年均值为0.52±0.19;观测到氡及氡子体浓度有类似的日变化规律,最高值出现在清晨时段,最低值出现在下午黄昏时段、没有观测到平衡因子有日变化规律;氡及氡子体浓度月平均值在4~5月份较低,在11、12月和次年1月份相对较高。结论 为期1年的在线连续测量结果表明,北京地区室外空气中氡及氡子体浓度年均值与世界均值水平接近,低于抓取式采样测量给出的我国典型值;氡及氡子体浓度日变化规律与国内外类似测量研究结果相同,季节变化规律具有北京地区局地气候影响特征。     

土壤物理性质对土壤氡浓度及地表氡析出率的影响

目的探讨土壤性质对土壤氡浓度及地表氡析出率的影响。方法在北京、贵阳、呼和浩特的31个测量点进行土壤氡浓度及析出率的现场实测。采集土壤样品，在实验室进行土壤镭含量、含水量、孔隙度和粒径分布等物理性质测量。用线性拟合方法分析了实测土壤氡、析出率数据之间的相关性，以及它们与土壤镭含量的关系。结果地表氡析出率与土壤氡浓度和土壤镭含量有正相关关系；土壤含水饱和度过高或过低均会使析出率和土壤氡浓度降低；贵阳地区土壤镭含量较高，但其粉砂黏土壤的特性使土壤氡浓度很难准确采样，导致结果偏低。结论地表氡析出率和土壤氡浓度虽然与土壤镭含量有正相关关系，但在实际环境中易受含水量等多因素影响，而且土壤氡浓度的准确测量受土壤特性限制较大。     

南宁市某办公室内氡平衡因子变化规律研究

目的 研究室内环境中氡平衡因子数值水平和变化范围。方法 在南宁市某室内工作场所中，开展了为期1年的氡浓度和平衡当量氡浓度同地点同时连续测量，氡气体和氡子体有效数据获取率分别为99.9%和86.7%。结果 测量结果表明，该室内环境中，氡年平均活度浓度和平衡当量氡浓度分别为（50.9±20.7）和（15.5±10.1） Bq/m³，二者均观测到了一致的日变化和季节性变化规律；平衡因子年均值为0.30±0.12，没有观测到日变化规律，但发现平衡因子月均值的年分布同氡浓度及氡子体浓度分布趋势类似，最高值和最低值出现在11月和6月，分别为0.47±0.24和0.19±0.06。结论 平衡因子月均值的波动，推测是不同季节室内通风状态不同导致。该结果提示，基于氡气体浓度估算氡暴露年有效剂量时，平衡因子取值有可能带来较大的不确定度，应该谨慎。     

Quantification of the dependency of radon emanation power on soil temperature

A study on the quantification of the dependency of the radon emanation power on soil temperature has been made using the accumulation method. The emanation from dry soil was studied at temperatures between −20°C and 45°C. A formula to calculate the radon emanation power as a function of the temperatures has been developed. The formula would contribute to the modeling of radon transport in soils and building materials.     

土壤氡析出率影响因素及估算模型

目的通过对某定点处土壤氡析出率的长期测量观察,分析并总结环境因素对氡析出率的影响规律。方法使用ERS-2静电收集式氡采样测量仪,每次采样累积时间40min,每10分钟测量一次氡浓度,通过线性拟和求算出土壤表面氡析出率;利用已有的数学模型对测量结果进行估算和评价;同时测量环境空气的湿度、温度、土壤含水量和土壤氡浓度。结果春季土壤氡析出率平均值为(24·9±5·6)mBq/(m2·s),夏季平均值为(11·9±3·4)mBq/(m2·s)。结论在影响土壤氡析出率的诸因素中,湿度非常重要,而环境温度对氡析出率的影响相对较小;测量期间环境气压变化不明显,没有观测到气压对析出率的影响。开展土壤射气系数的研究,将有助于阐明多种环境因素对土壤表面氡析出率的影响。     

Application of decision trees to the analysis of soil radon data for earthquake prediction

Different regression methods have been used to predict radon concentration in soil gas on the basis of environmental data, i.e. barometric pressure, soil temperature, air temperature and rainfall. Analyses of the radon data from three stations in the Kr ko basin, Slovenia, have shown that model trees outperform other regression methods. A model has been built which predicts radon concentration with a correlation of 0.8, provided it is influenced only by the environmental parameters. In periods with seismic activity this correlation is much lower. This decrease in predictive accuracy appears 1–7 days before earthquakes with local magnitude 0.8–3.3.     

Uncertainty evaluation in radon concentration measurement using charcoal canister

Active charcoal detectors are used for testing the concentration of radon in dwellings. The method of measurement is based on radon adsorption on coal and measurement of gamma radiation of radon daughters. The contributions to the final measurement uncertainty are identified, based on the equation for radon activity concentration calculation. Different methods for setting the region of interest for gamma spectrometry of canisters were discussed and evaluated. The obtained radon activity concentration and uncertainties do not depend on peak area determination method.     

International intercomparisons of integrating radon detectors in the NIRS radon chamber

An international intercomparison of integrating detectors was conducted at NIRS (National Institute of Radiological Science, Japan) with a 24.4 m³ inner volume walk-in radon chamber that has systems to control radon concentration, temperature and humidity.During the first intercomparison (05.2007) four groups participated from four countries and for the second intercomparison (10.2007) 17 participants were involved from 11 countries.Most of detectors are in good agreement with each other when compared to the radon level provided by the radon chamber. It appeared that the 70% of detectors are unified within the 20% margin of uncertainty.     

某市两座地下水处理厂氡浓度初步调查与分析

目的 通过对水和空气中氡浓度的测量,初步调查水氡释放对水厂空气氡的影响.方法 选取某市的两座地下水处理厂,采集水厂的水源水、出厂水和末梢水.利用连续测氡仪快速水氡测量方法,测量水中氡浓度;采用固体径迹探测器,累积测量水厂不同区域空气氡浓度.结果 两座水处理厂水源水、出厂水和末梢水中氡浓度分别为:(7.59±1.36)、(3.56±0.86)和(3.68±0.81)Bq/L与(12.19±0.57)、(7.87±1.12)和(9.50±1.12)Bq/L.水源水最高,出厂水与末梢水相近.跌水曝气和开放式过滤工艺能明显降低水中氡含量.曝气室和过滤车间氡浓度分别高达4 218和1 937 Bq/m³,明显高于我国工作场所氡浓度限值1 000 Bq/m³.结论 地下水处理厂曝气车间和开放式过滤车间氡浓度受到水氡释放的影响,我国地下水处理厂氡的问题应该引起重视.     

中国室内氡行动水平的研究

目的　通过研究我国各类房屋中氡浓度的水平和分布 ,探讨适合我国国情的室内氡浓度的行动水平。方法　应用累积测量技术进行室内氡浓度的测量。结果　我国 18个城市普通房屋 (n =2 117)中氡浓度的算术平均值为 44 1Bq·m- 3 ,其中超过 10 0Bq·m- 3 、2 0 0Bq·m- 3 和 40 0Bq·m- 3 的房屋分别占测量总数的 6 5%、1 0 %和 0 1%。煤渣砖建筑物、窑洞和地下建筑物分别有14 1%、16 7%、2 7 3 %和 2 3 %、3 0 %、4 0 %的房间中氡浓度超过 2 0 0Bq·m- 3 和 40 0Bq·m- 3 。我国2 0个省市实测的平衡因子均值为 0 49。结论　建议氡行动水平的单位由平衡等效浓度改为氡的实测浓度 ;取消新建住房和已有住房的划分 ;在未进行国家氡水平调查前 ,我国室内氡的行动水平可继续沿用GB T 1614 6 1995给出的已有住房 40 0Bq·m- 3 的控制水平     

深圳新建住宅室内氡水平及分布特征

目的 初步调查深圳市新建住宅室内氡水平及分布特征。方法 选择深圳市低层、多层、中高层和高层结构住宅108户,采用固体径迹法累积测量室内氡浓度。结果 深圳市居室内氡浓度算数均值为64 Bq/m³,几何均值为58 Bq/m³,范围15~155 Bq/m³;宝安区室内氡浓度均值最低,为50 Bq/m³,坪山新区室内氡浓度均值最高,为87 Bq/m³。深圳室内氡浓度 > 100 Bq/m³的测量点有12个,占总数的11.1%。Shapiro-Wilk检验表明,深圳室内氡浓度频数分布呈对数正态分布（P > 0.05）。建筑年代为1990—2015年的房屋,室内氡浓度随建筑年代呈降低趋势。除10层及以上,室内氡浓度随楼层的升高呈降低趋势。结论 本次调查比以往调查深圳市室内氡浓度相比升高了35%。建议继续加强完善建材放射性标准,加强高层住宅的自然通风,降低室内氡的辐射危害。     

Health effects of radon: A review of the literature

Purpose:?Radon is natural radioactive noble gas that can be found in soil, water, outdoor and indoor air. Exposure to radon accounts for more that 50% of the annual effective dose of natural radioactivity. The purpose of the current review is to summarize recent literature and evaluate the weight of evidence on the adverse health effects of radon.

Conclusions:?Radon is an established human lung carcinogen based on human epidemiological data supported by experimental evidence of mutagenesis studies in cell culture and laboratory animals. Extrapolation from cohort studies on miners suggested that radon is the second leading cause of lung cancer death after tobacco smoke. The majority of studies on the relationship between radon and other types of cancers showed weak or no association. Low levels of radon can be found in drinking water; however, radon released during water usage adds small quantities to indoor radon concentration. Studies showed that the risk of stomach cancer and other gastrointestinal malignancies from radon in drinking water is small. Studies of the genetic and cytogenetic effects of indoor radon yielded equivocal results; while radon exposure in miners induces gene mutations and chromosomal aberrations. Numerous in vitro cytogenetic studies demonstrated that radon induces different types of genetic and cytogenetic damage that is likely to play a role in radon lung carcinogenesis.     

过滤室内空气对降低居民室内氡照射的效果研究

目的 研究空气净化器过滤室内空气对室内氡子体行为的影响,探讨该方法对降低居民室内氡照射的效果。方法 构建理论模型计算室内空气过滤前后室内氡子体的浓度,基于结合态和未结合态氡子体的剂量转换系数,评估过滤室内空气对居民氡照射剂量的降低效果,并在密闭房间内进行部分实验验证。结果 室内空气的过滤速率越大,氡子体的去除效率越明显。在一个气溶胶初始浓度为10 000 cm^-3的密闭室内,当过滤速率>10 h^-1时,氡子体总浓度可下降90%以上。但不同过滤速率下,未结合态氡子体浓度均有所增高。室内氡子体浓度变化和居民氡照射剂量下降与净化器的过滤速率密切相关,过滤速率越大,降低剂量的效果越快越好。当过滤速率>5 h^-1时,净化器可降低居民内照射剂量70%以上。结论 空气净化器过滤室内空气虽然会导致未结合态氡子体浓度上升,但仍能有效地降低氡子体所致居民的暴露剂量。     

基于EPA/BEIR-VI模型的我国居室内氡致肺癌风险估计

目的:估计我国居室内氡导致的居民肺癌归因份额。方法:利用较为权威且适用的EPA/BEIR-VI风险模型,基于我国2015年肺癌死亡率、全死因死亡率以及有代表性的吸烟率和居室内氡平均浓度,预测我国居室内氡浓度水平致肺癌死亡风险。结果:非吸烟男性人群居室内氡致肺癌死亡超额相对危险(ERR)高于吸烟人群,且达到年龄为50岁时...     

Two year evolution of radon emission and tectonic movements in Tuzla Fault,Seferihisar-İzmir

Previous studies showed that tectonic movement and meteorological events are accompanied with radon release. In this study soil gas radon and tectonic movements were investigated with meteorological factors taking into account. Soil gas radon measurements were collected over a-two year period (2008–2010) at the Tuzla Fault in Turkey. The relationship between radon anomalies and seismic activities was evaluated using Dobrovolsky's form. It is shown that not only magnitude of earthquake but also distance from the measurement site should be used for identifying radon anomalies.     

我国部分地区土壤氡析出率的理论模型

目的 本研究旨在通过理论研究和实验验证初步建立我国部分地区土壤氡析出率的理论模型。方法 通过对氡在土壤中扩散理论的分析，建立土壤氡析出率数学模型，该模型考虑了土壤的镭含量、射气系数、孔隙度和含水饱和度等因素对氡析出率的影响。为验证此模型，我们在北京、贵阳和内蒙古3个不同土壤类型的地区，共30处进行了氡析出率及土壤相关物理性质的实际测量。结果 有近1／3的样品理论值与实测值吻合比较好。结论 实测结果初步显示出模型的有效性。笔者对误差分布规律及产生原因进行了分析，提出了今后土壤氡析出率模型的改进方向。     

Natural radioactivity and radon exhalation rate of soil in southern Egypt

The level of natural radioactivity in soil of 30 mining samples collected from six locations in southern Egypt was measured. Concentrations of radionuclides in samples were determined by γ-ray spectrometer using HPGe detector with a specially designed shield. The obtained results of uranium and thorium series as well as potassium (K-40) are discussed. The present data were compared with data obtained from different areas in Egypt.

Also, a solid state nuclear track detector SSNTD (Cr-39) was used to measure the radon concentration as well as exhalation rate for these samples. The radon concentrations were found to vary from 1.54 to 5.37 Bq/kg. The exhalation rates were found to vary from 338.81 to 1426.47 Bq/m²d. The values of the radon exhalation rate are found to correspond with the uranium concentration values measured by the germanium detector in the corresponding soil samples.