Measurements of radon-daughter concentrations in and around dwellings in the northern part of The Netherlands; a search for the influences of building materials, construction and ventilation

The concentration of radon daughters has been determined in and around 80 dwellings located in the northern part of the Netherlands by using a one-filter method. Median values of 2.0 and 0.4 mWL were measured for the indoor and outdoor concentrations, respectively. The average outdoor concentration was about an order of magnitude higher for wind directions between SE and SW than for SW-NW. On the average, dwellings with double-pane windows and/or concrete floors were found to have significantly higher radon concentrations than those with single-pane windows and/or wooden floors. For the living room of a particular dwelling 18 measurements were carried out. The data for this dwelling indicate a linear relation between the concentration indoors and outdoors with a slope of 3.8 +/- 2.0. This unexpected behaviour is thought to be related to ventilation via the crawl space. Measurements of ventilation patterns and measurements of radon concentrations in the living room and the crawl space are consistent with this picture.     

Radon 222Rn in residential buildings of Swieradów Zdrój and Czerniawa Zdrój

Swieradrów Zdrój and Czerniawa Zdrój are located in Region Izera Block. A total of 789 radon passive dosimeters were distributed in 183 dwellings in these town Swieradów Zdrój and Czerniawa Zdrój to measure the indoor radon concentration in 1999. Three-five measurements were performed in each dwelling, one in the basement, and the others in the main bedroom, in the kitchen, in the bathroom, since these rooms are the most frequently occupied. In addition, the occupants of each dwelling were requested to answer a questionnaire in which a number of questions about the building, ventilation habits and other related aspects were formulated. A charcoal detectors (Pico-Rad system) were used in experiment. It is a passive short-term screening method of radon gas concentration measurements. The indoor radon level was found to range from 14.8 Bq/m3 to 5,723.9 Bq/m3. The arithmetic mean overall indoor concentration was 420.4 Bq/m3 and the geometric mean was 159.7 Bq/m3. The average concentration of indoor radon, which reflects the real risk for inhabitants, is 193.5 Bq/m3. The results hand a log-normal distribution. In Poland, an action level of 400 Bq/m3 was recommended for existing buildings and 200 Bq/m3 for newly built (after 1.01.1998) buildings. In about 23% rooms the level of Rn-222 were above the top limit of 400 Bq/m3. The highest average concentrations were present in a basement (mean 919.9 Bq/m3). A decrease of average activity were observed at the upper levels: at the ground floor (225.2 Bq/m3), at the first floor and at the higher floors (137.6 Bq/m3). The above results indicate that radon emission from the ground provides the main contribution to the radon concentration measured in dwellings indoors in Swieradów Zdrój and Czerniawa Zdrój. The effective dose to the population of the Swieradów Zdrój and Czerniawa Zdrój from indoor radon and its progeny can be derived from this data if we use an equilibrium factor of 0.4 between radon and its progeny and assuming an indoor occupation index of 0.8. Taking into account that a conversion coefficient of 1.1 mSv per mJ h m-3 is recommended in ICRP 65 for members of public, the measured average annual dose is then about 3.3 mSv per year.     

Radon in homes--a possible cause of lung cancer

An earlier case-referent study [Scand j work environ & health 5 (1979) 10-15] has indicated a possible relationship between lung cancer and exposure to radon and radon daughters in dwellings. Indoor radon concentrations seem to depend on both building material and leakage of radon from the ground. This new study, in a rural area, is a further attempt to elucidate the etiology of lung cancer, taking into consideration type of house and ground conditions, as well as smoking habits. Although the choice of a rural study population helped to eliminate various confounding exposures in the urban environment, it limited the size of the study because of the rareness of lung cancer in rural populations. Long-term residents, 30 years or more in the same houses, were studied, and again an association was found between lung cancer and estimated exposure to radon and radon daughters in homes. The data also seem to indicate the possibility of a multiplicative effect between smoking and exposure to radon and radon daughters in homes, but there was also some confounding between these factors in the data.     

Indoor radon exposure and active and passive smoking in relation to the occurrence of lung cancer

Exposure to indoor radon and radon daughters is currently attracting great interest as a possible cause of lung cancer. This concern is supported by several studies, most of them relatively small in numbers or weak in the assessment of exposure. This study encompasses 177 persons with lung cancer and 677 noncancer referents, all deceased and with 30 years or more of residency in the same house in an area with radon-leaking alum shale deposits in the central part of southern Sweden. Exposure categories based on building material, type of house, and ground conditions were created, but measurements of the indoor radon daughter concentration were also made for 142 cases and 264 referents. Active and passive smoking was ascertained through questionnaires sent to the next-of-kin. Overall, the lung cancer risk was approximately twofold with regard to the categories of assumed radon daughter exposure for the rural sector of the population but not for the same categories of the urban sector, possibly because of less precise exposure assessment and influence from other factors. Occasional and passive smokers, as well as passive smokers alone, had a particularly increased risk of lung cancer in association with the increased exposure categories.     

A study of building structural features associated with high indoor air concentrations of organochlorine termiticides

Abstract: As part of a two-year study of post-treatment residential exposure to the termiticide, aldrin, the building structural features of ten houses with crawl-space-type floors were assessed by an independent inspector. Building attributes recorded on a checklist included the age of the dwelling, room characteristics, floor details and the nature of subfloor ventilation. At the end of each inspection, the inspector, who was blinded to data on airborne aldrin concentrations, provided a rating of expected indoor air contamination. Several of the building attributes, including the age of the house, the area of exterior subfloor vents, as well as the inspector's rating, were significantly correlated with airborne aldrin values. No single building variable, however, was highly correlated with every measure of aldrin concentration over a 12-month period. The observed data are consistent with poor subfloor ventilation and a ‘leaky’ floor being important contributors to indoor air pollution. It is recommended that pest control companies advise householders about any obvious floor and ventilation deficiencies before soil treatment work is undertaken. Pesticide exposure (by analogy with geological radon exposure) may be reduced by sealing gaps in floors and/or by improving subfloor ventilation.     

Asthmatic symptoms and volatile organic compounds, formaldehyde, and carbon dioxide in dwellings.

OBJECTIVES--As a part of the worldwide European Community respiratory health survey, possible relations between symptoms of asthma, building characteristics, and indoor concentration of volatile organic compounds (VOCs) in dwellings were studied. METHODS--The study comprised 88 subjects, aged 20-45 years, from the general population in Uppsala, a mid-Swedish urban community, selected by stratified random sampling. Room temperature, air humidity, respirable dust, carbon dioxide (CO2), VOCs, formaldehyde, and house dust mites were measured in the homes of the subjects. They underwent a structured interview, spirometry, peak expiratory flow (PEF) measurements at home, methacholine provocation test for bronchial hyperresponsiveness, and skin prick tests. In addition, serum concentration of eosinophilic cationic protein (S-ECP), blood eosinophil count, and total immunoglobulin E (S-IgE) were measured. RESULTS--Symptoms related to asthma were more common in dwellings with house dust mites, and visible signs of dampness or microbial growth in the building. Significant relations were also found between nocturnal breathlessness and presence of wall to wall carpets, and indoor concentration of CO2, formaldehyde, and VOCs. The formaldehyde concentration exceeded the Swedish limit value for dwellings (100 micrograms/m3) in one building, and CO2 exceeded the recommended limit value of 1000 ppm in 26% of the dwellings, showing insufficient outdoor air supply. Bronchial hyperresponsiveness was related to indoor concentration of limonene, the most prevalent terpene. Variability in PEF was related to two other terpenes; alpha-pinen and delta-karen. CONCLUSION--Our results suggest that indoor VOCs and formaldehyde may cause asthma-like symptoms. There is a need to increase the outdoor air supply in many dwelling, and wall to wall carpeting and dampness in the building should be avoided. Improved indoor environment can also be achieved by selecting building materials, building construction, and indoor activities on the principle that the emission of volatile organic compounds should be as low as reasonably achievable, to minimise symptoms related to asthma due to indoor air pollution.     

Study of indoor radon levels in high-rise air-conditioned office buildings

A series of measurements were conducted to study the indoor radon pollution in air-conditioned high-rise office buildings. Continuous monitoring of indoor radon levels in nine air-conditioned premises located in six office buildings in Hong Kong was conducted from August 1996 to February 1998. Each of the tests lasted for at least 48 hours. The measurement covered both day time monitoring while the air-conditioning was on and night time monitoring while the air-conditioning was off. The indoor radon level followed inversely the operation pattern of the mechanical ventilation systems in the buildings. During office hours when the mechanical ventilation was on, the indoor radon level decayed and after the mechanical ventilation was off during non-office hours, the radon level increased. The average indoor radon level during office hours on the nine premises varied from 87 Bq/m3 to 296 Bq/m3, and the indoor averaged radon levels over both day time and night time periods without mechanical ventilation were about 25 percent higher. The air infiltration rate and the radon emission characteristics from the building materials were estimated from the radon build-up curves which were observed after the mechanical ventilation was off. The radon decay curve observed after the mechanical ventilation system was turned on was used to calculate the total fresh air intake rate. Average radon emanation rates of the building materials in the six buildings varied from 0.0019 to 0.0033 Bq/m2s. It has been found that building infiltration rate accounted for about 10-30 percent of the total building ventilation rate in the buildings depending on building tightness.     

A survey of 222Rn concentrations in dwellings of the town of Metsovo in north-western Greece

A radon survey has been carried out of indoor radon concentrations in dwellings located in the town of Metsovo, in north-western Greece. To measure indoor radon concentrations, CR-39 detectors were installed in randomly selected houses and were exposed for about 3 mo, during summer and winter. Gamma spectroscopy measurements of the soil's radium content also were performed. The indoor radon concentration levels varied from 17.6 to 750.4 Bq m(-3), while the radium concentration of soil varied from 4.9 to 97.1 Bq m(-3). Seasonal variation of the radon levels and the influence of house features and soil are discussed.     

The equilibrium factor F

Consideration of the equilibrium factor F between the concentration of the radon daughters and the concentration of radon is a part of the evaluation of the measurements of radon daughter concentrations in dwellings when applying limits. Measurements of radon, radon daughters and air exchange rates have been carried out in 225 dwellings in Sweden. The F-factors have been compared with the theoretical model described by Wicke, taking into account the wall effect. The parameters of the model are discussed. The situation of the dwelling and the habits of the occupants can be expected to have the greatest importance for the F-factors although the ventilation rate is usually the most important modifying factor. For low air exchange rates (l less than 0.30 hr-1) the probability that the F-factors were between 0.28 and 0.74 was 95% calculated according to the t-distribution. The arithmetical mean was found to be 0.51. For air exchange rates close to the average rate (0.30 less than l less than 0.60 hr-1), the F-factors were between 0.21 and 0.66 with a mean of 0.43, and for high air exchange rates (l greater than 0.60 hr-1) the F-factors were between 0.21 and 0.47 with a mean value of 0.33.     

Building-specific factors affecting indoor radon concentration variations in different regions in Bulgaria

The study was conducted to assess the spatiality of the building factors’ effect on air quality through evaluation of indoor radon concentration in areas with different geology and geographical position. For that matter, a survey of indoor radon concentration was carried out in 174 kindergartens of three Bulgarian cities. The time-integrated measurements were performed in 777 ground floor rooms using alpha tract detectors, exposed for 3 months in cold period of 2014. The results of indoor radon concentrations vary from 20 to 1117 Bq/m³. The differences in the mean radon concentrations measured in the different cities were related to geology. The effect of building-specific factors: elevator, basement, mechanical ventilation, type of windows, number of floors, building renovation, building materials, type of room, type of heating, construction period, and availability of foundation on radon concentration variations was examined applying univariate and multivariate analysis. Univariate analysis showed that the effects of building-specific factors on radon variation are different in different cities. The influence of building factors on radon concentration variations was more dominant in inland cities in comparison to the city situated on the sea coast. The multivariate analysis, which was applied to evaluate the impact of building factors simultaneously, confirmed this influence too.     

Use of simulink to address key factors for radon mitigation in a Fairbanks home

Hilly areas around Fairbanks, Alaska, are known to have elevated soil radon concentrations. Due to geological conditions, cold winters, and the resulting stack effect, houses in these areas are prone to higher indoor radon concentrations. Key variables with respect to radon mitigation were addressed in this paper by using a dynamic model implemented in MATLAB Simulink. These variables included the ventilation rate; the foundation flow resistance, which can be affected by sealing the foundation during the construction of a house; and the differential pressure between the subslab and the house interior, which can be affected by using a subslab depressurization system. The model was used for the scenario of a varying differential pressure and then for the scenario of a varying ventilation rate at a Fairbanks home where real-time radon concentrations were measured. The correlation coefficients between the model-predicted and measured radon concentrations were 0.96 and 0.94, for both scenarios respectively, which verified the feasibility of the model for predicting indoor radon concentrations.     

Dependence of indoor radon concentration on the year of house construction.

The dependence of indoor radon concentration on the year of house construction was studied using the results of two nationwide indoor radon surveys in Japan. The data of radon concentration in the surveys were classified into structure type as well as year of construction to obtain the current radon concentration for each structure type as a function of year of construction. The indoor radon concentration in wooden houses was found to be relatively constant with year of house construction until 1960, and then decreased, whereas the radon concentration in concrete houses increased sharply in houses constructed after 1970. The concentration in concrete houses built before 1975 was almost the same as that in contemporary wooden houses. However, the concentration in concrete houses built at present was about two times higher than that in wooden houses. The time trends found for wooden and concrete houses in the first nationwide indoor radon survey were confirmed by the second nationwide survey. In addition, these same time trends were mostly observed in the data classified into 7 districts in Japan. The increase of indoor radon concentration in concrete houses provides relatively high dose, and this increasing trend seems to continue, judging from the results of two nationwide surveys.     

Radon concentration measurements and personnel exposure levels in Bavarian water supply facilities

As part of a study covering the whole of Bavaria, the southern most of Germany's 16 states, water supply facilities were examined to determine the radon (222Rn) concentrations in ground water and indoor air and the radon exposure to the staff working in these buildings. Bavaria can be divided into ten geological regions of different geogenic radon potential. From each region, a number of water supply facilities proportional to the size of the region were selected for measurements. Over 500 of a total number of 2,600 water supply facilities were asked to take a 1-L groundwater sample and expose several track-etch detectors in order to obtain the mean room concentration of the main staff work places. In addition, for a period of 2 mo, the personnel had to wear a track-etch detector during the time they spent in the supply facilities. The resulting measurements were then used to estimate their individual effective dose of radon and its progenies. In the East Bavarian crystalline region, the region of the highest geogenic radon potential within Bavaria, indoor radon gas concentrations of up to 400 kBq m(-3) were observed. About 10% of the process controllers in this region are subjected to an annual effective dose of more than 20 mSv. In the other Bavarian regions, only 2% of staff exposure levels exceed this limit. The correlation between the radon concentration measurements of the indoor air, the ground water, and individual personnel exposure levels was determined. The average ratio of the radon indoor air to the processed groundwater concentration is 0.14. But due to the different types of ventilation in the various supply facilities, there can be great variations in this figure. Therefore, there is no clear relationship between the groundwater and the indoor air concentration of a supply facility. This study also reveals no clear relationship between radon indoor air concentrations and the personnel exposure levels of a supply facility.     

Indoor radon in Kuwait

Indoor radon measurements were carried out in 300 dwellings in Kuwait using duplicate sets of charcoal detectors. Measurements were made at three different locations in the dwellings: living rooms, bedrooms, and basements. The results show that the radon concentration in the dwellings of Kuwait was found to vary in the range of 4.0-241.8 Bq m(-3) with a mean value of 32.8 Bq m(-3), and most values are confined within the range of 10-50 Bq m(-3) for all locations with few cases above the value of 100 Bq m(-3). Overall results show that the indoor radon concentration levels in Kuwait are relatively low, which is attributed to the use of air conditioning in summer and possible natural ventilation in winter. The radon concentration in basements was found to be relatively higher when compared to other rooms of the dwellings.     

A geostatistical approach to assess the spatial association between indoor radon concentration, geological features and building characteristics: the case of Lombardy, Northern Italy

Radon is a natural gas known to be the main contributor to natural background radiation exposure and second to smoking, a major leading cause of lung cancer. The main source of radon is the soil, but the gas can enter buildings in many different ways and reach high indoor concentrations. Monitoring surveys have been promoted in many countries in order to assess the exposure of people to radon. In this paper, two complementary aspects are investigated. Firstly, we mapped indoor radon concentration in a large and inhomogeneous region using a geostatistical approach which borrows strength from the geologic nature of the soil. Secondly, knowing that geologic and anthropogenic factors, such as building characteristics, can foster the gas to flow into a building or protect against this, we evaluated these effects through a multiple regression model which takes into account the spatial correlation of the data. This allows us to rank different building typologies, identified by architectonic and geological characteristics, according to their proneness to radon. Our results suggest the opportunity to differentiate construction requirements in a large and inhomogeneous area, as the one considered in this paper, according to different places and provide a method to identify those dwellings which should be monitored more carefully.     

Indoor radon and lung cancer in France

BACKGROUND: Several case-control studies have indicated an increased risk of lung cancer linked to indoor radon exposure; others have not supported this hypothesis, partly because of a lack of statistical power. As part of a large European project, a hospital-based case-control study was carried out in 4 areas in France with relatively high radon levels. METHODS: Radon concentrations were measured in dwellings that had been occupied by the study subjects during the 5- to 30-year period before the interview. Measurements of radon concentrations were performed during a 6-month period using 2 Kodalpha LR 115 detectors (Dosirad, France), 1 in the living room and 1 in the bedroom. We examined lung cancer risk in relation to indoor radon exposure after adjustment for age, sex, region, cigarette smoking, and occupational exposure. RESULTS: We included in the analysis 486 cases and 984 controls with radon measures in at least 1 dwelling. When lung cancer risk was examined in relation to the time-weighted average radon concentration during the 5- to 30-year period, the estimated relative risks (with 95% confidence intervals) were: 0.85 (0.59-1.22), 1.19 (0.81-1.77), 1.04 (0.64-1.67), and 1.11 (0.59-2.09) for categories 50-100, 100-200, 200-400, and 400+ becquerels per cubic meter (Bq/m), respectively (reference <50 Bq/m). The estimated relative risk per 100 Bq/m was 1.04 (0.99-1.11) for all subjects and 1.07 (1.00-1.14) for subjects with complete measurements. CONCLUSIONS: Our results support the presence of a small excess lung cancer risk associated with indoor radon exposure after precise adjustment on smoking. They are in agreement with results from some other indoor radon case-control studies and with extrapolations from studies of underground miners.     

Indoor exposure to radon from the ground and bronchial cancer in women

Summary A case-referent study on the possible association between radon emanating from the ground and bronchial cancer was carried out on 292 female lung cancer cases and 584 matched population referents. Both groups had lived for at least 30 years in the city of Stockholm, Sweden. The cases were diagnosed during 1972 to 1980 with oat-cell and other types of anaplastic pulmonary carcinomas. A sample of about 10% of the dwellings where cases and referents had lived was selected for measurements of radon and radon daughters. There was a relative risk of 2.2 (P = 0.01) for lung cancer associated with living in dwellings close to the ground in areas with an increased risk of radon emanation. Smoking habits did not appear to be a major confounding factor for this association, although a detailed evaluation was not possible. The measurements indicated increased radon daughter concentrations in ground level dwellings within radon risk areas where lung cancer cases had lived, suggesting that this exposure was of etiologic importance.     

Evaluation and equity audit of the domestic radon programme in England

The UK has a radon programme to limit the radon risk to health. This involves advice on protective measures in new buildings, technical guidance on their installation, encouragement of radon measurements and remediation in existing dwellings in high radon areas. We have audited the radon programme at the level of individual homes to identify factors that influence the likelihood of remediation. 49% of the householders responded to our survey and 30% of the respondents stated that they had done some remediation to reduce the indoor radon levels. We found that householders with higher incomes and higher socio-economic status are more likely than others to remediate. Householders are less likely to remediate if they have one of the following: living in a property with a high radon concentration, current smokers in the dwelling, being unemployed or an unskilled worker, long length of time living in that property or elderly (65+ years) living by themselves. Householders appeared to be more likely to remediate if they considered the information on radon and its risk to be very clear and useful. This emphasises the importance of communication with householders.     

名古屋市室内空气222Rn、220Rn的测量及EECTn估算

目的 研究室内空气中^222Rn、^220Rn浓度以及室内平衡当量^220Rn浓度EECTn。方法 利用名古屋大学研制的新型被动累积式^222Rn、^220Rn测量杯在日本名古屋市进行了小规模的室内^222Rn、^220Rn的浓度调查，利用Deposition Rate Monitor估算了住宅室内EECTn。结果 在随机抽查的20个住宅室内^222Rn平均浓度为16．94Bqm^-3；其中5个住宅室内^220Rn平均浓度为58．09Bqm^-3，EEGTn平均值为2．75Bqm^-3。结论 本研究结果与日本全国性调查结果^222Rn浓度平均值15．5Bqm^-3相当。^220Rn的浓度在某些泥土墙壁的住房内可能达到比较高的浓度，进行进一步的研究是很有必要的。     

Quality control of mitigation methods for unusually high indoor radon concentrations

The present study's objective was to control the quality of different mitigation methods for unusually high indoor radon (222Rn) concentrations of up to 274,000 Bq m(-3) in a village (Umhausen, 2,600 inhabitants) in western Tyrol, Austria. Five years after mitigation, five different remedial actions were examined on their quality by means of measuring indoor radon concentrations with charcoal liquid scintillation radon detectors and with a continuously recording AlphaGuard detector. Mitigation method in house 1--a mechanical intake and outlet ventilation system with heat exchanger in the basement, combined with a soil depressurization system--was characterized by long-term stability. With most favorable air pressure (+100 Pa) in the basement, mean basement radon concentrations in the winter were reduced from 200,000 Bq m(-3) to 3,000 Bq m(-3) by this method 5 y after mitigation. Acting against experts' instructions, the inhabitants had switched off the ventilation system most of the time to minimize power consumption although it had been proven that ventilation reduced mean basement radon concentration by a factor of about 3 in the winter and about 15 in the summer. Mitigation method in house 2-soil depressurization with two fans and loops of drainage tubes to withdraw radon from the region below the floor and outside the basement walls, and from soil below that part of the house with no basement-had been the most successful remedial measure until the winter of 1999 (i.e., 6 y after mitigation), when micro-cracks opened and consequently mean basement radon concentration increased from 250 Bq m(-3) to 1,500 Bq m(-3). Measures to block these microcracks and to minimize soil drying are being developed. Five years after mitigation, the remedial method used in house 3--a multilayer floor construction, where a fan was used to suck radon from a layer between bottom slab and floor-reduced winter mean radon concentration from 25,000 Bq m(-3) to 1,200 Bq m(-3), with the ventilation on and the basement door open. Mitigation method in house 4--a basement sealing technique--was unsuccessful with almost identical radon concentrations during all the five years since mitigation had started. Mitigation method in house 5--a waterproof basement technique especially for future homes--reduced mean basement radon concentration below 300 Bq m(-3) and mean ground floor radon concentration below 200 Bq m(-3), which is the Austrian action level for newly constructed buildings. These findings indicate that even in areas with extremely high radon concentrations, effective mitigation of indoor radon can be achieved provided that house-specific long-term, stable mitigation techniques are applied.