Outdoor Radon Concentrations Research Articles

Indoor and outdoor Radon concentration measurements in Sivas, Turkey, in comparison with geological setting

Indoor and soil gas Radon ( 222Rn) concentration measurements were accomplished in two stages in Sivas, a central eastern city in Turkey. In the first stage, CR-39 passive nuclear track detectors supplied by the Turkish Atomic Energy Authority (TAEA) were placed in the selected houses throughout Sivas centrum in two seasons; summer and winter. Before the setup of detectors, a detailed questionnaire form was distributed to the inhabitants of selected houses to investigate construction parameters and properties of the houses, and living conditions of inhabitants. Detectors were collected back two months later and analysed at TAEA laboratories to obtain indoor 222Rn gas concentration values. In the second stage, soil gas 222Rn measurements were performed using an alphameter near the selected houses for the indoor measurements. Although 222Rn concentrations in Sivas were quite low in relation with the allowable limits, they are higher than the average of Turkey. Indoor and soil gas 222Rn concentration distribution maps were prepared seperately and these maps were applied onto the surface geological map. In this way, both surveys were correlated with the each other and they were interpreted in comparison with the answers of questionnaire and the geological setting of the Sivas centrum and the vicinity.

Outdoor radon concentration measurements: some correlation with major urban pollutants

Air pollutants concentration in the urban air strongly depends on the properties of the planetary boundary layer (the lower region of the atmosphere), roughly up to 1 km from Earth's surface. Radioactive radon gas has been recognised by various authors as a valuable natural tracer of transport and dispersion within this layer. To achieve a better comprehension of the urban pollution dynamic in the town of Alessandria, situated in the Po Valley in the north-west of Italy, a system for continuous measurement of radon concentration in outdoor air was experimented. This paper presents the first results obtained: the hourly trend of radon concentration in the diurnal course during different seasons and its correlation with the concentration of the major urban pollutants.

Assessing exposure to granite countertops—part 2: Radon

Radon gas ((222)Rn) is a natural constituent of the environment and a risk factor for lung cancer that we are exposed to as a result of radioactive decay of radium ((226)Ra) in stone and soil. Granite countertops, in particular, have received recent media attention regarding their potential to emit radon. Radon flux was measured on 39 full slabs of granite from 27 different varieties to evaluate the potential for exposure and examine determinants of radon flux. Flux was measured at up to six pre-selected locations on each slab and also at areas identified as potentially enriched after a full-slab scan using a Geiger-Muller detector. Predicted indoor radon concentrations were estimated from the measured radon flux using the CONTAM indoor air quality model. Whole-slab average emissions ranged from less than limit of detection to 79.4 Bq/m(2)/h (median 3.9 Bq/m(2)/h), similar to the range reported in the literature for convenience samples of small granite pieces. Modeled indoor radon concentrations were less than the average outdoor radon concentration (14.8 Bq/m(3); 0.4 pCi/l) and average indoor radon concentrations (48 Bq/m(3); 1.3 pCi/l) found in the United States. Significant within-slab variability was observed for stones on the higher end of whole slab radon emissions, underscoring the limitations of drawing conclusions from discrete samples.

Mapping terrestrial [formula omitted]-dose rate in Europe based on routine monitoring data

After the nuclear reactor accident in Chernobyl in 1986, most countries of the European Union (EU) established monitoring networks measuring outdoor γ -dose rates for early warning. The data are composite values γ -dose rate due to terrestrial, cosmic and artificial radiation sources, and in most cases also include some instrument background. While EURDEP is mainly designed for exchanging and stocking data during radiological emergencies, the data it is storing in its database may potentially contain valuable information about spatio-temporal variations of the Rn 222 source term which can be used for the validation of atmospheric transport models and other atmospheric tracer applications. The use of γ -dose rates as a proxy for outdoor radon concentrations is indeed possible if one can extract the terrestrial γ -dose rate contribution from the values reported in EURDEP. It is the purpose of this paper to discuss the preparation of the terrestrial γ -dose rates using EURDEP data and to present seasonal maps of terrestrial γ -dose rates in Europe. Such maps could be used for the preparation of Rn 222 source term which can be used for the validation of atmospheric transport models as well as for exploring variations in soil moisture content, an important parameter in flood prediction. These applications are the focus of the ongoing studies, but beyond the scope of this paper. In this paper, we show how the terrestrial γ -dose rate can be derived from the emergency monitoring data and two seasonal maps of γ -dose rates at the European scale are produced using geostatistics.

Radon survey related to construction materials and soils in Zacatecas, México using LR-115

Indoor radon gas ( Rn 222 ), present in the air inside buildings, is one of the most important sources of radiation exposure to the population. This gas originates in the U 238 radioactive decay chain, which is contained in rock and solid soil particles. Radon accumulation in confined spaces, inside buildings, depends on several factors such as the type of soils, type of constructions, building materials, and ventilation. The aim of this work is to present indoor and outdoor radon concentrations for 202 dwellings and indoor concentrations for 148 public clinics; and the radon concentrations relate to the type of predominant soils, the construction years; and building materials used in the ceilings, walls and floors, for cities and towns of the 57 municipalities in the State of Zacatecas, Mexico. The Rn 222 concentrations were measured with a passive-type radon monitor, with LR-115 as detector material; and the radon survey was made during four stages of three months each throughout Zacatecas from 2001 to 2002. The indoor and outdoor radon concentration averages in dwellings were 55.6 ± 4.9 Bq m - 3 and 46.5 ± 5.3 Bq m - 3 , respectively. The indoor radon concentration average in public clinics was 57.8 ± 5.4 Bq m - 3 . These values were lower than the US EPA action limit of 148 Bq m - 3 .

Radon survey in the high natural radiation region of Niška Banja, Serbia

A radon survey has been carried out around the town of Niška Banja (Serbia) in a region partly located over travertine formations, showing an enhanced level of natural radioactivity. Outdoor and indoor radon concentrations were measured seasonally over the whole year, using CR-39 diffusion type radon detectors. Outdoor measurements were performed at 56 points distributed over both travertine and alluvium sediment formations. Indoor radon concentrations were measured in 102 living rooms and bedrooms of 65 family houses. In about 50% of all measurement sites, radon concentration was measured over each season separately, making it possible to estimate seasonal variations, which were then used to correct values measured over different periods, and to estimate annual values. The average annual indoor radon concentration was estimated at over 1500 Bq/m 3 and at about 650 Bq/m 3 in parts of Niška Banja located over travertine and alluvium sediment formations, respectively, with maximum values exceeding 6000 Bq/m 3. The average value of outdoor annual radon concentration was 57 Bq/m 3, with a maximum value of 168 Bq/m 3. The high values of indoor and outdoor radon concentrations found at Niška Banja make this region a high natural background radiation area. Statistical analysis of our data confirms that the level of indoor radon concentration depends primarily on the underlying soil and building characteristics.

Methodology for determination of radon-222 production rate of residential building and experimental verification

Indoor radon concentration is mainly associated with the radon production rate of building material, ventilation rate, and the outdoor radon concentrations. Radon production rate of a room is defined as the sum of the products of the radon emanation rates and the exposed areas of the materials. Since the selection of the building materials and the exposed areas are different from room to room, it makes the radon production rate of homes fall in a wide range. Here, the radon production rate of a room is suggested to be quantified by a sealing method, in which the systematic radon growth curve is obtained. The radon production rate of the room can be determined from the initial slope of the growth curve. Three rooms at different homes in Hong Kong were selected in the study for verifying the methodology. The uncertainty characterized by data scatter arisen from the coupling effect of the leakage rate and outdoor radon was also included in the discussion. During the measurements, no occupant was allowed into the home. No mechanical ventilation was involved in the measurement. The indoor and outdoor radon concentrations of the sampled homes were monitored simultaneously and lasted for more than three days. The radon production rates and the uncertainties of three rooms at Homes 1, 2, and 3 were found to be 232.8, 46.0, 414.6, and 20.3, 9.4, 59.2 Bq h - 1 , respectively. The approach is valid when the air leakage rate of the room is controlled below 0.1 h - 1 .

Soil radon flux and outdoor radon concentrations in East Asia

Soil 222Rn flux and outdoor 222Rn concentrations were continuously measured at 20 sites in China, Japan and Korea. Annual averaged 222Rn flux and outdoor 222Rn concentrations ranged from 6.9 to 59.6 mBq m −2 s −1 and 5.3 to 17.0 Bq m −3 among those sites. Seasonal variations of both 222Rn flux and outdoor 222Rn were observed at most of the sites. A significant positive correlation exists between the soil 222Rn flux and outdoor 222Rn concentrations.

Improvement of the radon situation at former uranium mining and milling sites in East Germany

Uranium mining in East Germany was accompanied by piling up of more than 300 Mio m 3 of radioactive waste rock material, often adjacent to settlements. This resulted at some places in mean outdoor radon concentrations of 1000 Bq/m 3 and more. In 1991, the national corporation WISMUT was charged with rehabilitation of the sites. For waste rock piles, WISMUT developed the concept of in situ remediation involving reshaping and covering of the piles. The optimised 1 m thick cover allows to reduce the radon exhalation rate by a factor greater than 10. Reshaping and covering of the piles guarantees that the remediation target of 1 mSv of annual effective dose for the local population will be met.

Outdoor Radon Concentration at a Uranium Tailings Site and Its Occupational Radiation Dose

Outdoor Radon Concentration at a Uranium Tailings Site and Its Occupational Radiation Dose

Nationwide survey of radon levels in Korea.

A nationwide radon survey was conducted to provide data on the annual average indoor radon concentration in Korean homes. This survey also provided data on the variation of radon concentration with season, house type, and building age. The arithmetic mean (AM) of annual radon concentration in Korean homes was 53.4 +/- 57.5 Bq m(-3). The indoor radon concentration showed a lognormal distribution with a geometric mean (GM) and its standard deviation (GSD) of 43.3 +/- 1.8 Bq m(-3). The radon concentrations in the traditional Korean-style houses were about two times higher than those in apartments and row houses. The average annual outdoor radon concentration was 23.3 Bq m(-3). The average annual effective dose to the general public from radon was 1.63 mSv y(-1).

Indoor Radon Radioactivity at the University of Brunei Darussalam

Indoor radon radioactivity in the rooms on the ground floor and first floor of the Physics Department, Faculty of Science, Universiti Brunei Darussalam was measured using a system that consists of an air filter pump, ZnS detector, photomultiplier tube and counter. Ground floor rooms’ radon radioactivity was found to be about three times higher than that of the first floor. The maximum ground floor indoor radioactivity is only 0.39 Bqm3a value relatively low and safe compared to the mean outdoor radon concentration of 1.41 Bqm3measured (Hu and TAN, 2000). The main source of radon emanation originates from the ground soil rather than the building materials.

A nationwide survey of outdoor radon concentration in Japan

Nationwide outdoor radon ( 222Rn) concentrations in Japan were measured to survey the environmental outdoor 222Rn level and to estimate the effective dose to the general public from 222Rn and its progeny. The 222Rn concentration was measured with a passive-type radon monitor. The 222Rn monitors were installed at about 700 points throughout Japan from 1997 to 1999. The annual mean 222Rn concentration in Japan was estimated from four quarters measurements of 47 prefectures in Japan. Nationwide outdoor mean 222Rn concentration was 6.1 Bq m –3. This was about 40% of the indoor 222Rn concentration in Japan. The 222Rn concentration in Japan ranged from 3.3 Bq m –3 in the Okinawa region to 9.8 Bq m –3 in the Chugoku region, reflecting geological characteristics. Seasonal variation of outdoor 222Rn concentration was also found to be lowest in July to September, and highest in October to December. From the results of this 222Rn survey and previous indoor 222Rn survey program, the effective dose to the general public from 222Rn and its progeny was estimated to be 0.45 mSv y –1.

Long period study of outdoor radon concentration in Milan and correlation between its temporal variations and dispersion properties of atmosphere

The results of a survey of outdoor radon concentrations in Milan are reported. Measurements were performed hourly over a continuous four year period from January 1997 to December 2000. Radon concentration was obtained by two means: both direct measurement of radon; and measurement of its decay products. The average daily pattern of radon concentration featured a minimum in the late afternoon and a maximum in the early hours of the morning. A seasonal pattern with higher concentrations in winter than in summer (from around 15 Bq m −3 in winter to around 5 Bq m −3 in summer) was also observed. Similar average annual values of around 10 Bq m −3 were obtained. The annual effective outdoor radon dose was found to be 0.12 mSv. The variation from minimum in the afternoon to maximum the following morning was found to be a good indicator of the height of the nocturnal mixing layer. The variation between maximum and minimum levels on the same day is an index of the maximum height of the mixing layer. Furthermore, our long term measurements of radon have permitted us to examine the dispersion characteristics of the atmosphere over Milan, and to establish the frequency of conditions unfavourable to the dispersion of atmospheric pollutants.

KSB HELPS TO FIGHT THE FLOODS

In the German Federal States of Saxony, Saxony-Anhalt and Thuringia, centuries of mining and milling activities resulted in numerous residues with increased levels of natural radioactivity such as waste rock dumps and tailings ponds. These may have altered potential radiation exposures of the population significantly. Especially waste rock dumps from old mining activities as well as 20th century uranium mining may, due to their radon (222Rn) exhalation capacity, lead to significant radiation exposures. They often lie close to or within residential areas. In order to study the impact on the natural radon level, the Federal Office for Radiation Protection (BfS) has run networks of radon measurement points in 16 former mining areas, together with 2 networks in regions not influenced by mining for comparison purposes.Representative overviews of the long-term outdoor radon concentrations could be established including estimates of regional background concentrations. Former mining and milling activities did not result in large-area impacts on the outdoor radon level. However, significantly increased radon concentrations were observed in close vicinity of shafts and large waste rock dumps. They are partly located in residential areas and need to be considered under radiation protection aspects. Examples are given that illustrate the consequences of the Wismut Ltd. Company's reclamation activities on the radon situation.

Radon Levels in China

This paper reviewed and summarized the results and problems of a nation-wide environmental radon survey which was carried out from 1984 to 1990 in China. Indoor radon concentrations were measured in 10,811 dwellings, and which covered 26 provinces and cities all over China. The range of indoor radon concentrations was <LLD-386.8Bq·m−3, the average was 22.5 Bq·m−3 and 19.6 Bq·m−3 for arithmetic mean and geometric mean, respectively. Both outdoor radon concentrations and indoor radon progeny concentrations were also reported. Even though the grab sampling was taken as the main method of the survey, it was still a valuable reference.

The Iowa radon lung cancer study — phase I: residential radon gas exposure and lung cancer

Exposure to high concentrations of radon ( 222Rn) progeny produces lung cancer in both underground miners and experimentally-exposed laboratory animals. The goal of the study was to determine whether or not residential radon exposure exhibits a statistically significant association with lung cancer in a state with high residential radon concentrations. A population-based, case-control epidemiologic study was conducted examining the relationship between residential radon gas exposure and lung cancer in Iowa females who occupied their current home for at least 20 years. The study included 413 incident lung cancer cases and 614 age-frequency-matched controls. Participant information was obtained by a mailed-out questionnaire with face-to-face follow-up. Radon dosimetry assessment consisted of five components: (1) on-site residential assessment survey; (2) on-site radon measurements; (3) regional outdoor radon measurements; (4) assessment of subjects’ exposure when in another building; and (5) linkage of historic subject mobility with residential, outdoor, and other building radon concentrations. Histologic review was performed for 96% of the cases. Approximately 60% of the basement radon concentrations and 30% of the first floor radon concentrations of study participants’ homes exceeded the US Environmental Protection Agency action level of 150 Bq m −3 (4 pCi l −1). Large areas of western Iowa had outdoor radon concentrations comparable to the national average indoor value of 55 Bq m −3 (1.5 pCi l −1). Excess odds of 0.24 (95% CI=−0.05–0.92) and 0.49 (95% CI=0.03–1.84) per 11 WLM 5-19 were calculated using the continuous radon exposure estimates for all cases and live cases, respectively. Slightly higher excess odds of 0.50 (95% CI=0.004–1.80) and 0.83 (CI=0.11–3.34) per 11 WLM 5-19 were noted for the categorical radon exposure estimates for all cases and the live cases. A positive association between cumulative radon gas exposure and lung cancer was demonstrated using both categorical and continuous analyses. The risk estimates obtained in this study indicate that cumulative radon exposure presents an important environmental health hazard.

Population dose due to natural radiation in Hong Kong.

In densely populated cities such as Hong Kong where people live and work in high-rise buildings that are all built with concrete, the indoor gamma dose rate and indoor radon concentration are not wide ranging. Indoor gamma dose rates (including cosmic rays) follow a normal distribution with an arithmetic mean of 0.22 +/- 0.04 microGy h(-1), whereas indoor radon concentrations follow a log-normal distribution with geometric means of 48 +/- 2 Bq m(-3) and 90 +/- 2 Bq m(-3) for the two main categories of buildings: residential and non-residential. Since different occupations result in different occupancy in different categories of buildings, the annual total dose [indoor and outdoor radon effective dose + indoor and outdoor gamma absorbed dose (including cosmic ray)] to the population in Hong Kong was estimated based on the number of people for each occupation; the occupancy of each occupation; indoor radon concentration distribution and indoor gamma dose rate distribution for each category of buildings; outdoor radon concentration and gamma dose rate; and indoor and outdoor cosmic ray dose rates. The result shows that the annual doses for every occupation follow a log-normal distribution. This is expected since the total dose is dominated by radon effective dose, which has a log-normal distribution. The annual dose to the population of Hong Kong is characterized by a log-normal distribution with a geometric mean of 2.4 mSv and a geometric standard deviation of 1.3 mSv.

Determination of Ambient Gamma Radiation Levels using Electret Ion Chambers

Electret ion chambers are widely used for the measurements of indoor and outdoor radon concentrations as well as gamma radiation levels. Long-term electrets and standard ion chambers constituting the electret-passive environmental radon monitor system were mounted in a plastic analysis jar to investigate the ambient gamma exposure rates in some research laboratories. Control measurements were simultaneously performed by means of a high pressure ionisation chamber. The mean ratio of electret ion chamber measurements was 1.07. The agreement between the two methods can be considered as good. The agreement was of the order of 7%. The gamma radiation levels recorded over a one year span are presented. The significance of the results is discussed together with comments on the comparison of the figures obtained through the two methods.

Evidence for and implications of self-background of radon dosimeters with glass-fiber filters.

The first national radon survey in The Netherlands was conducted in 1984 with passive radon dosimeters that contain glass-fiber diffusion filters. During the last few years, measurements of outdoor-radon concentrations and information in the literature suggested to us that these dosimeters may give falsely elevated readings. A systematic contribution would be present due to alpha particles from natural radionuclides in the glass-fiber filter producing tracks on the track-etch foil. In the framework of the quality assurance of our laboratories, the origin of this offset was systematically assessed by means of measurements of alpha and gamma radiation from the glass-fiber filters and by intercomparisons between different types of detectors at low radon concentrations. It was found that alpha particles from the decay of 214Po in the glass-fiber filter are the main cause of the extra tracks (only 12% originates from decay of 212Po), leading, for this type of filter, to an offset in concentration of approximately 8 Bq m(-3). The implications of this offset are discussed.