Predicting New Hampshire indoor radon concentrations from geologic information and other covariates

 Generalized geologic province information and data on house construction were used to predict indoor radon concentrations in New Hampshire (NH). A mixed-effects regression model was used to predict the geometric mean (GM) short-term radon concentrations in 259 NH towns. Bayesian methods were used to avoid over-fitting and to minimize the effects of small sample variation within towns. Data from a random survey of short-term radon measurements, individual residence building characteristics, along with geologic unit information, and average surface radium concentration by town, were variables used in the model. Predicted town GM short-term indoor radon concentrations for detached houses with usable basements range from 34 Bq/m³ (1 pCi/l) to 558 Bq/m³ (15 pCi/l), with uncertainties of about 30%. A geologic province consisting of glacial deposits and marine sediments was associated with significantly elevated radon levels, after adjustment for radium concentration and building type. Validation and interpretation of results are discussed. Received: 20 October 1997 · Accepted: 18 May 1998     

Regional levels of indoor radon in Virginia and Maryland

The levels of Rn-222 in homes located in Fairfax County, Virginia, and Montgomery County, Maryland, are currently being measured during four consecutive three-month seasonal intervals using alpha-track detectors. Significant variations occur between parts of northern Virginia and southern Maryland because the area is part of three very different geologic provinces. Results from the winter period in these three provinces show that the indoor radon levels were about twice as high as anticipated. Approximately 45 percent of the homes had winter indoor radon levels above 4 pCi/l, the EPA’s recommended action level, and in the spring period, more than 30 percent of the homes still had indoor levels above 4 pCi/l. Indoor radon variations due to seasonal control were about as significant as geological control. Worst-case combinations developed over some rock units in the winter, producing areas in which about 70 percent of the homes exceeded 4 pCi/l.     

Geological and geochemical factors affecting radon concentrations in dwellings located on permeable glacial sediments—a case study from Kinsarvik,Norway

In 1996–1997, indoor radon values of more than 40,000 Bq/m³ and large seasonal and geographical variations in indoor air radon were reported from a residential area located on a highly permeable ice-marginal deposit. Geochemical analyses of bedrock, groundwater and sediments and comparisons between indoor radon values and soil radon values indicate that the indoor radon concentrations in this area are strongly affected by subterranean airflows caused by temperature differences between soil air and atmospheric air. The airflows concentrate the radon-laden soil air towards the topographic highest part of the deposit in winter and towards the topographic lowest part in summer. In areas where subterranean airflows are likely to occur, radon measurements performed both in summer and in winter provide the best estimate of annual average indoor radon concentrations, and assessments of indoor radon concentrations based on single soil gas measurements are not recommended.     

The indoor radon problem: Studies in the Albuquerque,New Mexico area

Radon buildup in homes is now recognized throughout the world as a potentially major health hazard. The U.S. Nuclear Regulatory Commission and the U.S. Environmental Protection Agency estimate 8,000–30,000 fatalities per year in the United States due to indoor radon. The Albuquerque, New Mexico area was chosen for study because it is representative of metropolitan areas in the southwestern United States where slightly uraniferous source rocks (Sandia granite) have provided the very immature soil for much of the area. The granite contains 4.7 ppm U, and limestone capping the granite 5.7 ppm U. Soils in the area average 4.24 ppm U, and Th/U ratios average 3.2. These data suggest some removal of U from the source rocks, but fixation of the U in the soils (that is, as opposed to widespread removal of the U by solution), thus providing a ready source for soil radon. A pilot study of soil radon in the area in winter of 1983–1984 shows high values, 180 pCi/l, relative to the U.S. average (about 100 pCi/l). In the winter of 1986–1987, 180 dwellings were surveyed for their indoor radon levels, including 20 that had been surveyed in summer of 1986. Twenty-eight percent of those in the winter study yielded indoor radon above the EPA suggested maximum permissible level of 4 pCi/l air, well above the EPA estimate of 10–15 dwellings for the U.S. The indoor radon levels show positive correlation with closeness to the Sandia Mountains, to soil radon, to excess insulation, to homes with solar capacities, and other factors. Building materials may provide a very minor source of some indoor radon. Summer readings are lower than winter readings except when the houses possess refrigerated air conditioning.     

Radon soil–gas as a geological mapping tool: case study from basement complex of Nigeria

In an effort to quantify the geogenic radon soil–gas potential and appraise the use of radon technique as a geological mapping tool in a crystalline basement rock terrain of Ile–Ife Nigeria, radon measurement concentration were made using a radon detector instrument (EDA RD-200) that measures radon isotopes by a scintillator cell coupled to a photomultiplier tube. The data were collected from soils derived from three different lithologic rock units. The observed values were then correlated with the geology of the area. Significant differences in the radon soil–gas concentrations among the three geologic units were observed. Granite gneiss has the highest concentration, followed by grey gneiss and mica schist in that order. The geometric mean (GM) concentration of radon-222 measured in soils directly overlying the three different rock types were 301.4 pCi/l for granite gneiss, 202.8 pCi/l for the grey gneiss, and 199.4 pCi/l for mica schist. Conversely, the average values for radon-220 averaged 1510.0, 815.4, and 733.0 pCi/l for granite gneiss, grey gneiss, and mica schist rocks, respectively. Statistical t test (α=0.05) results indicated that there was no significant difference in the geometric mean of radon soil–gas measured between low and medium potential zones. However, significant differences were found between the low and high radon potential zones, and between the medium and high zones. The low concentrations of radon soil–gas emission observed in this study is explained in terms of the seasonal variation due to thermal convection fluid movement, while the radon concentrations were found to be controlled by the lithology and geochemistry of the underlying bedrock.     

An evaluation of residential air radon concentrations and related variables in southeast Michigan,USA

Analysis of 153 residential air radon (Rn-222) screening measurements from southeast Michigan indicates that basements host Rn levels two to three times higher than upper-level rooms. Compared to unfinished basements, finished (e.g., paneled walls, tiled floors) basements apparently reduce indoor air Rn levels while partially finished basements may not. Factor analysis of residence questionnaire data explains 59 percent of the Rn data variance. The volume of pathways (e.g., foundation cracks/holes, uncapped sumps) allowing Rn seepage into the dwelling controls the largest portion, 23 percent, of the explained data variance. The residence water source explains 11 percent of the Rn data variance. Groundwater Rn levels contribute to the air Rn data variability, but the study data cannot quantitatively assess this contribution. Seven percent of the Rn data variance is likely controlled by house depressurization facilitated by residence structural properties. Residences with foundation cracks or poorly sealed joints and low-volume indoor-outdoor air exchange are more prone to this effect. Eighteen percent of the explained Rn data variance correlates with the residence's primary heat source. Evidently, operating combustion sources also induce house depressurization and allow Rn to be drawn into the house through entry paths. Twenty-four percent of the analyses equal or exceed 4 pCi/1 Rn. In residences occupied 5 years by the same individuals, 17 percent of the Rn data are 4 pCi/l; here the arithmetic mean air Rn level is 8.3 pCi/l and the average occupancy period 17.4 years.     

From radon hazard to risk prediction-based on geological maps,soil gas and indoor measurements in Germany

Mapped geological units can be regarded as proxies standing for a complex series of subsoil geochemical and physical properties including the assigned radon activity concentration in soil gas, which is taken as best estimator of the regional geogenic radon potential. Areal distribution of measuring sites for soil gas in Germany is adapted to spatial variation of geology. A grid-based and distance-weighted interpolation procedure is applied, following geologically defined neighbourhood relations of measuring sites and accounting for isolated outcrops of known geology but without measurements. To investigate the statistical relationship between indoor radon, house type and building ground specifications, measurements of the indoor radon concentration have been carried out in more than 10,000 dwellings in different regions of Germany. Multiple regression analyses of variance reveal that besides region-specific geological properties and building characteristics, various house type and living style variables significantly contribute to the explained variance for ground floor radon concentrations. These parameters are also dominant in controlling the radon transfer relation from soil gas to indoor air. Risk prediction maps for radon in houses indicating the probability to exceed certain indoor threshold values can be useful especially for regions with no or only a few measurements of indoor radon.     

Correlation of soil radon and uranium with indoor radon in the Albuquerque,New Mexico area

High indoor radon in approximately 30 percent of private dwellings in the Albuquerque, New Mexico area has been reported previously. The present study explains the areas of high indoor radon as a function of different soil and/or bedrock in the area. Soils were sampled during summer and winter periods using alpha track radon detectors. The values range from 40 to 890 pCi/I air at a depth of 38 cm. The gross mean average is 360 pCi/I for the area for summer readings and 200 pCi/I for winter readings; both values are well over the average U.S. soil radon values of approximately 100 pCi/I. Analyses of soil uranium show a range in values of 1–6 ppm, with a mean of 3.1 ppm. Thorium values range from 3.3 to 28.8 ppm, and Th/U ratios range from 2.9 to 4.6.These values for U, Th, and Th/U suggest that soil U and Th are close to the values reported for the Sandia granite, the source of most of the pediment on which Albuquerque is built. Soil infiltration rates range from ~6 × 10^–4 to 4.5 × 10^–3 cm/sec for the samples, and soil moisture content ranges from 1.4 to 7.2 percent. A fair correlation of summer soil radon with infiltration rate is noted. Correlation of soil radon with moisture content and/or with percent silt, silt + clay, clay size fraction material is not established by this study. Soil radon values do correlate with regions in the Albuquerque area where high indoor radon is common. A better correlation of high indoor radon values with soils developed immediately over bedrock is observed. Furthermore, all values of average soil and indoor radon increase significantly with proximity of the stations to the Sandia Mountains. Soil uranium also shows this trend. The data argue that regions of potentially high radon can thus be identified.     

Reliability of inexpensive charcoal and alpha-track radon monitors

A comparison between single short-term radon measurements and annual radon measurements in basements shows that significant uncertainties should be associated with the short-term measurements. Activated charcoal radon monitors which measure radon over a 3 to 7 day interval yield measurements that should carry a ± 90% uncertainty in terms of estimating annual radon concentration. Alpha-track radon monitors which measure radon over a 3 month interval should carry a ± 30% uncertainty. Decisions about home purchases, home remediation and the development of risk characterizations may often be incorrect if currently popular but unrealistically low estimates of uncertainty are applied to short-term radon measurements. Optimal results are obtained from year-long alpha-track measurements.     

Radon distributions in the Hail Region of Northern Saudi Arabia

Indoor radon measurements were carried out in a total of 420 dwellings and 17 schools in Hail region of Saudi Arabia, using NTDs based radon dosimeters. The duration of the measurements was one year, from April 2008 to April 2009. The indoor radon concentrations varied from 4 to 513 Bq/m³ with an overall average of 45 Bq/m³ for all surveyed dwellings. These passive measurements were confirmed by the active measurements. The anomalous concentrations above 200 Bq/m³ were observed in 13 dwellings, representing 3.1 % of the total surveyed dwellings. In Inbowan village alone, it was found that 7.6 % of the dwellings have indoor radon concentration above 200 Bq/m³. The highest average indoor radon concentration of 64 Bq/m³ was found in Inbowan village while the lowest average of 24 Bq/m³ was found in Majasah village. The city of Hail showed an average indoor radon concentration of 49 Bq/m³. The average indoor radon concentration in one area located at the edge of the Aja Mountain in Hail city was 111 Bq/m³. The elevated indoor radon concentrations in many dwellings in the Hail region, prompted us to measure outdoor ground radon in such locations using gas monitor. It was found that radon concentrations at a depth of 0.5 m varied significantly from place to place ranging from 1.2 to 177 kBq/m³. The outdoor radon concentrations are generally correlated with the indoor radon measurements. Radon exhalations from construction materials and soil samples from the Hail region were also measured. It was found that radon exhalations from soil samples are higher than that of construction materials by a factor of at least 3 and reaching up to 11. These results indicate that soil is the main source of indoor radon. Geological interpretations of the results are also given.     

Reconnaissance soil-gas radon survey over the faulted crystalline area of Ile-Ife, Nigeria

Tropical rain forest areas are well known for problems with geological mapping because of the dense vegetation and thick overburden. The application of soil-gas radon measurements was carried out over known and suspected fault zones in the basement terrains of Ile-Ife, southwestern Nigeria. Radon concentration in the area ranged from 25.6 to 6,227.8 pCi/l, with distinct contrasts and overlap in concentrations among soil groups derived from various rock types. Radon concentrations in the soil exhibit a strong dependence on the local geology and reflect the bedrock geochemistry. Relatively high radon soil-gas concentrations of between 4,000 and 6,227.8 pCi/l were found directly on the axis of the known and suspected strike slip faults. The use of the radon-222 technique confirms its application as a useful tool in geological and structural mapping in basement terrains largely covered by relatively thick overburdens.     

Distribution of indoor radon concentrations and uranium-bearing rocks in Texas

 The purpose of this study was to compare regional patterns of indoor radon concentration with uranium-bearing rock zones and county populations in Texas. Zones yielding radon concentrations that are relatively high for Texas include shale and sandstone in northwest Texas; red beds in north-central Texas; felsic volcanic rocks in west Texas; and sandstone, limestone, and igneous rocks in central Texas. Located in northwest Texas, only five of the 202 counties evaluated have mean indoor radon concentrations above 4.0 pCi l^–1. Two of those counties have populations above the state median of 20 115. The highest county mean concentration is 8.8 pCi l^–1. Results of this study suggest that (1) regional geology influences indoor radon concentrations in Texas, (2) statewide, the radon concentrations are relatively low, (3) highly populated counties do not coincide with regions of high indoor radon concentration, and (4) regions that may warrant further monitoring include northwest Texas and, to a lesser degree, west and central Texas. Received: 8 August 1995 · Accepted: 6 September 1995     

Measurements of indoor radon, thoron, and their progeny using twin cup dosimeters in rural areas of Northern India

Radon, thoron, and their progeny are largest contributors to the radiation dose received by human beings present in the natural environment. The indoor radon depends upon many factors such as building materials, meteorology, ventilation, and occupant’s behavior. This paper presents the measurements of indoor radon, thoron, and their progeny in four villages in rural area of district Kanshiram Nagar (Kasganj) in the state of Uttar Pradesh in Northern India. The concentration of indoor radon and thoron varies from 10.32 to 72.24 and 11.61 to 84.49 Bq m^?3 with a geometric mean (GM) of 29.49 and 31.20 Bq m^?3, respectively. The concentration of radon and thoron daughters was found to vary from 1.11 to 7.80 and 0.31 to 2.28 mWL, respectively. The annual exposure due to radon and thoron mainly vary from 0.05 to 0.30 WLM. The preliminary results (i.e., bare mode exposure of the LR-115 detectors fixed on cards) of this study have been separately published and compared this recent data with those results.     

Indoor radon mapping and its relation to geology in Hungary

Indoor radon mapping may show stronger dependence on geological formations if the measured homes are one-storied houses with no basement. In Hungary, 17,244 homes were investigated on the yearly average of indoor radon concentrations; among these homes, there were 6,154, one-storied, no-basement houses. In Hungary, 21 geological units were created relevant for indoor radon index characterized by lithology, the position of the ground water table, and the gas permeability. Maps were drawn of different topography (counties, grid, geological units) and different values (maximum, mean, indoor radon indexes). A kind of standardization of houses was that only the one-storied, no-basement ones were chosen, but from geological point of view some more information was gained when the wall materials (bricks or adobe) were also taken into account. (“Adobe” is made of clay and straw in Hungary, and not burned as brick, just dried on sunshine). Enhanced indoor radon values can be observed on the bedrock of Cenozoic volcanic rocks and their eroded materials deposited on the local alluvial valleys. Another group with relatively increased indoor radon values can be connected to granite bodies. The grid method is useful for covering large state or even continental areas. For practical public use and detailed radon risk mapping geological or administrative unit-systems could yield more reasonable and useful results.     

Radon in groundwater as a tracer to assess flow velocities: two test cases from Israel

 Two test cases from Israel are presented herein employing the decay rate of radon along the flow path to assess groundwater flow velocities. Groundwater flow reaching the fault zone emerges in several places along the rift fault zone as thermal springs because of deep water confinement. The high water temperature of the surface is indicative of high vertical flow velocities, which maintains the original high temperatures. Knowing the Rn content at a source point and at a given down-gradient, and assuming no Rn addition from the water itself or along the flow path, one can calculate the flow velocity based on the Rn half-life time. The decay of Rn in western Galilee was found to be ∼570–150 pCi/l, and in the Dead Sea area from 5000–2000 pCi/l along a respective flow path of 1000 and 200 m, Based on the above, the calculated flow velocities were compared with those obtained from pumping tests in the study area. The method is applicable, because of the short Rn half-life, to cases of high Rn contents, short distances and high flow velocities. Received: 18 January 2000 · Accepted: 21 March 2000     

Geochemistry and ground permeability as determinants of indoor radon concentrations in southernmost Sweden

A study of the indoor radon gas levels was performed in 935 homes in Scania, southernmost Sweden, located on geologically different ground with regard to uranium (U) content. In one of these two areas the bedrock consists of alum shale with U contents exceeding 200 ppm. In the other area there is no U-rich bedrock. Indoor radon levels are influenced by U content and permeability as shown below.For maam nancy for table, please place here. Thanx!The results show that the indoor radon levels were highest in homes located on bedrock with medium to high U content combined with a highly permeable drift covering the bedrock. The difference was statistically significant(P < 0.0001). Other results of the investigation are: 14 homes built from aerated concrete made from U-rich alum shale had higher levels than 767 homes with walls from other material (312 vs 106 Bq/m³;P = 0.0011); 242 homes with a cellar had lower radon levels than 563 without (62 vs 138 Bq/m³;P <0.0001); further, 418 homes with private well had higher levels than 360 with public water supply (140 vs 82 Bq/m³;P <0.0001). The results of the investigation show a profound effect of a combination of high bedrock U content and high cover permeability. The effect of the uraniferous drift on the indoor radon levels is evident. Thus, the geological conditions should be carefully considered when screening for high-risk buildings, as well as when planning for new ones. Also, the construction of the building and its water supply have some influence.     

广东温泉水-汽转化过程对室内氡浓度的影响

研究了广东省四家温泉宾馆室内温泉水及其使用过程中对氡浓度的影响。利用RAD-7测氡仪和NR667A测氡义连续测量室内外氡浓度和水氡浓度,发现室内氡浓度受地基土壤、建筑物类型、利用方式(是否洗浴、洗浴时间长短等)、通风状况等诸多因素的影响。无人入住时宾馆室内氡浓度的变化说明土壤氡的渗入是底层房间室内氡的重要影响因素。当在浴室内使用温泉水洗浴时,浴室内平均氡浓度比没有用温泉水时高出1～8．3倍,客房内氡浓度比没有用温泉水洗浴时高出1．2～8．3倍。在使用温泉水时,某些宾馆室内氡浓度超标,可能对宾馆工作人员造成潜在的健康危害,应采取管理措施或技术手段降低其暴露水平。     

Correlation between geology and radon levels in groundwater, soil and indoor air in Bhilangana Valley, Garhwal Himalaya, India

 Radon concentrations were measured in soil, air and groundwater in Bhilangana Valley, Garhwal Himalaya, India by using an LR-115 plastic track detector and radon emanometer. Radon concentrations were found to vary from 1 KBq/m³ to 57 KBq/m³ in soil , 5 Bq/l to 887 Bq/l in water and 95 Bq/m³ to 208 Bq/m³ in air. The recorded values are quite high due to associated uranium mineralization in the area. Radon concentration was also found to depend on the tectonic structure and geology of the area. Received: 22 July 1996 · Accepted: 8 January 1997     

Study of the radon concentrations in drinking water from three main cities of Shaanxi Province,China

This paper presents the results of radon concentration measurements in the drinking water from the municipal water supply system and private wells of Xian, Xianyang and Baoji city of Shaanxi province of China. The measurements were carried out on 38 samples. Radon levels in drinking water in Xian, Xianyang and Baoji were found to be 5.78, 13.04 and 15.01 k Bq m^–3, respectively. The AM radon concentration of private well water from Xianyang and Baoji is 28.84 k Bq m^–3 and 38.85 k Bq m^–3, respectively, which is 2.56 times and 3.14 times as high as that of tap water radon, respectively. The radiation risk of radon in water would be due to degassing and not due to drinking water. The domestic use of showers, humidifiers, and cooking, washing up, laundering, etc. may lead to an additional increase of the radon concentration in the indoor air. The observed radon concentration in drinking water from three main cities of Shaanxi Province can contribute to a 4.86 to 32.63% increase in indoor radon concentration and can cause 0.068±0.016 mSv y^–1 to 0.177±0.045 mSv y^–1 extra annual effective dose to males, 0.060±0.014 mSv y^–1 to 0.155±0.039 mSv y^–1 to females. The mean annual effective dose equivalents to males and females of Xianyang and Baoji from well water account for 25.94 to 39.75% of environmental radon and radon daughters annual effective dose equivalents. The radon concentrations in the well water from Xianyang and Baoji will bring a definite additional risk to the population.     

Radon variations in an active landslide zone along the Pindar River, in Chamoli District, Garhwal Lesser Himalaya, India

Radon measurements were made in the soil and spring/seepage water in and around an active landslide located along the Pindar river in the Chamoli District of Uttaranchal in Garhwal Lesser Himalaya, to understand the application of radon in geological disasters. The landslide is a compound slide i.e. a slump in the crown portion, and debris slide and fall in the lower part. The bedrock consists of gneisses and schists of the Saryu Formation of the Almora Group of Precambrian age. The presence of several small slump scars and debris slide/fall scars along the length of the slide indicates continuous downward movement. The radon concentrations in the present study are much lower in comparison to values reported from other regions. However, the present radon data show relative variation in the slide zone. The concentration of radon measured in landslide zones varies from 3.1 Bq/l to 18.4 Bq/l in spring water and from 2.3 kBq/m³ to 12.2 kBq/m³ in the soil gas of the debris. Along the section of the slide, the radon values in water and soil are slightly higher in the upper slopes i.e. toward the crown portion of the landslide as compared to the distal portion. The relatively low concentration of radon both in soil gas and water in the toe portion of the landslide may be due to the high porosity of the debris, which does not allow radon to accumulate in the soil and water, whereas, towards the crown portion, the high frequency of fractures increases the surface area due to particle size reduction, and the near absence of debris enhances the radon emanation in soil.