Indoor radon risk potential of Hawaii

Summary A comprehensive evaluation of radon risk potential in the State of Hawaii indicates that the potential for Hawaii is low. Using a combination of factors including geology, soils, source-rock type, soil-gas radon concentrations, and indoor measurements throughout the state, a general model was developed that permits prediction for various regions in Hawaii. For the nearly 3,100 counties in the coterminous U.S., National Uranium Resource Evaluation (NURE) aerorad data was the primary input factor. However, NURE aerorad data was not collected in Hawaii, therefore, this study used geology and soil type as the primary and secondary components of potential prediction. Although the radon potential of some Hawaiian soils suggests moderate risk, most houses are built above ground level and the radon soil potential is effectively decoupled from the house. Only underground facilities or those with closed or recirculating ventilation systems might have elevated radon potential.     

Measurement of radon exhalation rate from soil samples of Garhwal Himalaya, India

Laboratory experiment was performed for the measurement of radon exhalation rate from the soil samples collected from Garhwal Himalayas. This study is accompanied by the measurement of soil-gas radon concentration in the same area. Both results were compared with the geological formation and structure of the area. No correlation was observed between soil-gas radon concentration and radon exhalation rate. However, it was found to be controlled by the lithology, geological structure and uranium mineralization in the area. The relationship between radon emanation, geological formation and occurrence of high indoor radon concentration is discussed.     

Methodology for rapid assessment of the radon potential of soils

A technique using a small diameter probe and a portable alpha-particle scintillometer for sample collection and analysis has been developed. It is fast, efficient, cost-effective, and can be modified to accommodate a wide spectrum of sampling conditions. When soil-gas sampling for radon is combined with geophysical gamma-ray measurements, pedological characteristics of surficial materials, and geologic knowledge of bedrock, the combination forms a powerful technological basis for estimating radon potential of soils. The method can help provide information on a short time-frame so that local governments, land developers, and builders can take appropriate measures when planning new construction.     

Long-term radon investigation in four selected kindergartens in different geological and climate regions of Slovenia

During a one year-and-a-half period in 1993 and 1994 indoor radon concentrations were measured with complementary measurement techniques in four selected kindergartens in different geological and climate regions in Slovenia. This study was performed to obtain more information how local geology, climate, building materials and occupational patterns affect radon concentration in a kindergarten. In addition, the advantages and disadvantages of different measurement techniques were critically appraised. It was found that average working hours radon concentrations, calculated on the basis of continuous radon measurements, are significantly lower than whole day averages obtained by track-etch detectors. The ratio might be as large as two.     

Development and distribution of radon risk maps in New York State

Radon maps for each county in New York State have been developed onthe township level indicating the percent of homes with .148 Bq/m 3 (4 pCi/l)in the indoor air of the basement and living area. Estimates are based ona combination of nearly 45,000 basement-screening measurements and correlationsto surficial geology. Many of the towns and cities in the State with the highestaverage indoor radon concentrations are located on highly-permeable gravellysoils formed during the retreat of the Wisconsinan Glaciation. As many towns(32% of total) had .5 measurements, a project to obtain additional measurementsin high-risk towns produced results comparable to estimates based on correlationsto surficial geology. Radon risk maps for each county have been distributedto municipal governments, schools, and professionals in activities relatedto homes, buildings, and indoor air quality.     

Simple and rapid methods for on-site determination of radon and thoron in soil-gases for seismic studies

The determination of soil-gas anomalies especially ²²²Rn anomalies, are important to precisely locate fault traces, as well as to investigate earthquake precursors. In this paper, we have studied and compared new rapid methods for on site determinations of radon (²²²Rn), thoron (²²⁰Rn) and total radon (²²²Rn+²²⁰Rn) in soil-gas. These new techniques pump the soil-gas continuously from the soil through a simple sampling tube to the counting cell for one-minute with discarding the excess. Then, either four one-minute counting periods (5-minute technique) or nine one-minute counting intervals (10-minute technique) are followed immediately. In all the methods, conversely to Morse"s method, the first counting period (C1) was not employed for calculations. Three calculation methods for the five-minute technique, two for the ten-minute technique and a modified Morse"s method are compared with theoretical values and different real soil-gases with different radon/thoron ratios. The affect of different flow rates of soil-gases into the counting cell was also investigated. Finally, the ten-minute technique seems to be a little more accurate, but the 5-minute technique is much more suitable for seismic field studies when a much larger number of determinations are required in a short time.     

Industrial commercial respirator filter as indoor radon monitor

This paper presents a method for measuring indoor radon concentrations using a commercially available air-purifying respirator filter as a component of the radon monitor. The filter used was Survivair’s NIOSH (National Institute for Occupational Health and Safety)-approved 100800 model. The method is based on the diffusion of radon gas into the activated carbon of the filter and the measurement of the radioactive daughters resulting from the radon decay. The photopeaks of the ²¹⁴Bi daughter gamma rays (0.609 MeV) were analyzed with a Hyper-Pure Germanium (HPGe) detector and a multichannel system. A monotonically increasing and very close to linear response relation between the integrated area under the ²¹⁴Bi photopeak and the radon concentration of the activated carbon was found. A well-defined relation held for radon levels ranging from 15 to 4,700 Bq/m³. This procedure results in highly reproducible and reliable measurements of indoor radon levels. Interesting applications include the investigation of radiological accidents involving radon and the retrospective measuring of indoor radon concentrations by analyzing the filters of the respirators worn by personnel working during the relevant period.     

Indoor radon measurement methodology by solid state nuclear track detectors

The measurement of radon using solid state nuclear track detectors is presented. The importance of radon in environmental radiation and to human health is well known and thus the measurement and evaluation of indoor radon is important not only for dosimetry purposes but also for evaluation of public health impacts. In this work we discuss the detection and calibration systems and the etching method of solid state detectors. Some considerations regarding potential problems that can be encountered in measuring indoor radon in an underdeveloped country, and how can they be solved are discussed.     

Measurements of indoor radon concentration levels in Kilis,Osmaniye and Antakya,Turkey during spring season

The fact that 50% of the natural radiation dose to which humans are exposed is caused by radon gas makes indoor radon measurements important. In this study, levels of indoor radon gas were measured in 204 houses in Kilis, Osmaniye and Antakya using passive nuclear track detectors. Cr-39 radon detectors were left in the living rooms of participants’ houses, then analyzed at the Radon Laboratory of Health Physics Department in Çekmece Nuclear Research and Training Center (ÇANEM) of Atomic Energy Agency of Turkey (TAEK). Average indoor radon activity concentrations for Kilis, Osmaniye and Antakya were 50 Bq/m³ (1.26 mSv/y), 51 Bq/m³ (1.29 mSv/y) and 40 Bq/m³ (1.01 mSv/y), respectively.     

Evidence for radon transport by carrier gas through faulted clays in Italy

Extensive soil-gas surveys in sedimentary basins in Italy were performed to study the potential of some naturally occurring gases as indicators for concealed fracture zones, hydrocarbon and geothermal fluids. One conclusive result is a positive correlation between anomalously high values of radon and carbon dioxide in the soil-air over faults. The correlation coefficient for 1173 gas samples is 0.41. Statistically derived contourlines of Rn and CO₂ anomalies show similar locations, shapes and directions. Fairly good Rn–CO₂ coupling evidence appears even on a point-to-point analysis. Furthermore, it was recognized that the highest Rn values are in contrast to the low Ra content of the underlying clayey rocks and that conventional Rn transportation mechanisms seem to be inadequate for the clay sequences. All these facts strongly suggest that Rn is transported from the subsoil, through fault-linked pathways, by carrier gases of which CO₂ could be one of the major components. The theory of geogas microbubbles is a possible explanation of the observed results. The carrier effect of ascending microbubbles can explain both the origin of soil-gas Rn anomaly and the Rn–CO₂ coupling phenomenon.     

Indoor radon measurement in Izmir Province,Turkey

In 2013, an extensive study was performed in a total of 117 locations in Izmir province and indoor radon levels were measured using the alpha track etch integrated method with LR-115 detectors. As the maps are more practical to interpret the results of radiological survey, the distributions of indoor ²²²Rn activities in four most densely populated districts of Izmir were mapped in detail. It is seen that the estimated average radon concentration level (210 Bq m^?3) determined in Izmir province was almost three times higher than the mean value for Turkey (81 Bq m^?3). Exposed annual effective dose equivalents for Izmir province were estimated in the range of 0.7 to 12.3 mSv year^?1 with a mean of 5.3 mSv year^?1. In this study, it is pointed out that indoor radon concentration was affected by the age of the building and height above the ground.     

Long term and equilibrium factor indoor radon measurements

This paper presents the annual radon gas concentrations obtained during the 1994–1995 monitoring campaign using passive electret system (type E-PERM). Radon levels were measured in 154 single family dwellings, in normal occupancy conditions (open house condition) in the metropolitan zone of Mexico City. At the same time radon monitoring was performed outdoors. The results show the general log-normal distribution of integrated indoor radon concentration with an annual indoor mean of 3.8 pCi·l⁻¹. The seasonal variations show the minimum mean values in the summer season which are 39% lower than that in autumn. Equilibrium factors (F) were measured in 12 typical houses both in autumn and winter using a continuous working level monitor for short-lived radon decay products and H-chamber loaded with a short term electret (HST, E-PERM) for radon gas. The obtained total mean equilibrium factors are:F=0.41±0.17 andF=0.29±0.04 for indoor and outdoor, respectively. A quality program was also improved.     

Characterization of airborne radon released by domestic showering and the use of a washing machine

Water originated from groundwater systems can have relatively high concentration of radon. In many situations, radon is released from the water and mixes with the indoor air. In the present study, laboratory experiments were conducted to characterize the airborne radon released by showering and the use of a washing machine. The followings were discussed: (1) a comparison between the loss of waterborne radon and the increase of airborne radon, (2) time-related changes in airborne radon after the water use, (3) changes in the equilibrium factor, and (4) the relationship between radon concentration and the distance from the source of radon release.     

The fluctuations of indoor radon measurements from the building materials in a real situation

In this study, we have investigated the fluctuations of radon levels in two experimental rooms constructed for secondary standard dosimetric calibration. The values over the short-term (the first two weeks) were in the range of 10–14 pCi/L of radon in air, while those of the long-term were between 6–14 pCi/L of radon. Even though the temperature and humidity was relatively constant during the second half of the rainy season, there was a trend towards lower radon values. It is concluded that ventilation is an important factor in indoor radon levels.     

Spatial and vertical distribution of radon and thoron in a typical Indian dwelling

Radon and thoron have been identified as potential radiological health hazard and the dose estimation due to their exposure is an important task. Understanding their behavior in indoor environment helps in calculating the inhalation doses due to them. Present study aims at the distribution of radon and thoron concentrations in a typical Indian dwelling. Solid state nuclear track detectors are employed in the study. The concentration of radon is found to be invariant in indoor environment. The thoron concentration is found to decrease exponentially as a function of distance from the source (wall/floor). Solution of one dimensional diffusion equation is used for regression fittings for thoron variation, from which the diffusion constants and the exhalation rates were calculated. The diffusion constants varied from 0.00195 to 0.00540 m² s⁻¹.     

Effects of residential radon on cancer incidence

Radon activity concentrations of 1077 homes were surveyed in two villages of Northern Hungary to obtain the yearly averages. The distribution of indoor radon activity concentrations covered a wide range. Cancer incidences of all the 2680 inhabitants for the last 30 years were also studied in these villages in order to establish a possible correlation with radon exposure. The methods applied in the analysis allow to draw up statistically supported statements concerning the relative cancer risks of different radon level groups. The results show that among non-smoking middle-aged women the frequency of cancer, regardless to tumor types, is lower for those who live in residential radon activity concentrations of a level between 110 and 185 Bq^.m^-3 compared to those living in radon levels outside this range. A minimum value in the cancer frequency exists at a level of significance p<0.008 (determined with the help of Fisher's test). In general, the present study corroborates the outcome of other studies demonstrating the existence of a biopositive effect, and suggests a wider concept of radon health effects.     

A case study on the effect of water from groundwater sources on indoor radon levels

Indoor airborne radon concentration released from water was estimated over several months based on experimental measurements. When heated water including radon was used, the radon level became high in the entire house. Filling the bathtub with hot water had a strong effect on the indoor radon level. In winter, the indoor radon concentration was high due to windows being closed. The radon transfer coefficient was estimated 2.5·10⁻⁴ in this test house. This is 2.5 times higher than the average radon transfer efficiency estimated by UNSCEAR.     

Measurements of radon,thoron and their progeny in Gifu prefecture,Japan

Summary Due to the rocky neighborhood, consisting of mostly granite with high radium content, an elevated radon concentration was found in a territory of Gifu prefecture situated in the middle of Japan. Radon concentrations in water were measured and were found to be considerably high. Since indoor radon and radon progeny concentrations might be relatively high, their concentrations were also analyzed. Besides the radon and radon progeny, thoron and thoron progeny concentrations were also investigated. Dose estimations for radon and thoron in indoor air are discussed.     

Peculiar radon spot in Hungary

For the public, indoor radon is the main source of exposure from ionizing radiation. Radon gas originates from the radioactive decay chain of uranium deposited in rocks or in building materials. In the reviews mostly a rather steady radon exhalation has been assumed. In a village of North-East Hungary, however, high radon concentrations have been measured, differing strongly in neighbouring houses and varying in time, due to the interplay of several geochemical phenomena.     

Short-term variations of indoor and outdoor radon concentrations in a typical semi-arid city of Northwest China

Journal of Radioanalytical and Nuclear Chemistry - To obtain basic data for adverse effects of radon (Rn) on human health, indoor and outdoor Rn concentrations were measured using a RAD7 Rn...