Spatial and temporal indoor radon variations.

This paper examines the ability of standard radon measurement protocols to predict long-term radon concentrations in houses located in the upper Midwest. It was observed that: (1) significant radon variations can occur on a spatial scale as small as a single floor; (2) radon measurements that integrate for periods less than 3 mo are reliable only to within a factor of 2 or more; and (3) contemporary, short-term measurements within existing structures may not accurately reflect past radon concentrations. Two-hundred forty-three occupied houses located in 40 towns were monitored for at least 1 y using alpha-track detectors. If lifetime radon exposure estimates need to be determined accurately, then long-term, integrating radon detectors should be placed in several rooms of each house. In radon atmospheres that may not be stable for long periods of time, it is suggested that multiple, year-long measurements or surface alpha activity measurements in combination with year-long alpha-track measurements are needed for an accurate lifetime radon assessment.     

湛江市部分住房室内外空气中氡浓度测定

采用活性炭吸附闪烁法测定了湛江市部分住房室内、外空气中的平衡当量氡浓度。结果表明 ,住房室内、外空气中平衡当量氡浓度平均值分别为 2 5 2 7Bq/m3 和 14 6 8Bq/m3 ,室内空气中平衡当量氡浓度显著高于室外 (P <0 0 1) ;不同装饰材料的住房室内空气中平衡当量氡浓度各有差异 ,其中以花岗岩为装饰材料的住房室内平衡当量氡浓度 (31 18Bq/m3 )为最高 ,水泥地板住房 (14 71Bq/m3 )最低     

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.     

十堰市城区居民室内氡浓度调查结果与分析

目的 对十堰市城区居民室内氡浓度进行监测,分析居民室内氡浓度水平及影响因素。方法 从2019年4月到7月,采用RSKS标准型探测器对十堰市城区共计125户居民室内氡浓度进行测量并分析。结果 2019年所监测的十堰城区居民室内氡浓度结果呈偏态分布,范围为13.8～145 Bq/m³,M(P₂₅,P₇₅)为38.3(29.0,62.0) Bq/m³,居民因吸入氡及其子体产生的年均有效剂量估算值为0.52～5.50 mSv,M(P₂₅,P₇₅)为1.45(1.10,2.36) mSv,与相关文献一致;不同建筑结构(H=14.10,P<0.001)、楼层(H=24.41,P<0.001)和地区(H=8.963,P<0.05)均是居民室内氡浓度水平的影响因素,且差异均有统计学意义。结论 十堰市城区居民室内氡浓度小于国家标准限值,但在日常生活中还是需要注意采取合适的方法,尽量降低家中氡浓度。     

装修及季节因素对室内氡浓度的影响

氡致肺癌的危险度可能被低估了50·00%～100·00%〔1〕,人们约80·00%～90·00%的时间生活在室内,室内氡浓度是评价居室环境及其对健康影响的重要因素。1对象与方法1.1对象湖南省濮阳市2004年9月至2006年8月间所监测的35户装修居室和与其相临的35户非装修居室。1.2方法采用1027     

The concept of equivalent radon concentration for practical consideration of indoor exposure to thoron

To consider the total exposure to indoor radon and thoron, a concept of equivalent radon concentration for thoron is introduced, defined as the radon concentration that delivers the same annual effective dose as that resulting from the thoron concentration. The total indoor exposure to radon and thoron is then the sum of the radon concentration and the equivalent radon concentration for thoron. The total exposure should be compared to the radon guideline value, and if it exceeds the guideline value, appropriate remedial action is required. With this concept, a separate guideline for indoor thoron exposure is not necessary. For homes already tested for radon with radon detectors, Health Canada's recommendation of a 3-month radon test performed during the fall/winter heating season not only ensures a conservative estimate of the annual average radon concentration but also covers well any potentially missing contribution from thoron exposure. In addition, because the thoron concentration is much lower than the radon concentration in most homes in Canada, there is no real need to re-test homes for thoron.     

Modeling seasonal variation in indoor radon concentrations

Radon, a well-established risk factor for human lung cancer, is present at low concentrations in most homes. Consequently, many countries have established national guidelines for residential radon concentrations. In this article, we evaluate two models for describing seasonal variation in residential radon concentrations based on the data from a large case-control study conducted in Winnipeg, Canada. In this study, radon levels in homes were monitored during two successive 6-month periods, with integrated annual radon concentrations obtained using CR-39 alpha-track detectors. Significant differences were noted among measurements taken during different seasons of the year. Using the model introduced by Pinel et al. (1995) to describe temporal variation in residential radon levels in southwest England using seasonal adjustment factors, reasonable predictions of annual average radon concentrations were obtained from the 6-month integrated radon measurements. However, a simple multiplicative model was found to provide better predictions than the seasonal adjustment model. Although model coefficients vary somewhat from one geographic location to another, the concordance with respect discriminating between results above and below 150 Bq/m(3) in Winnipeg was in the range 85-90% using seasonal adjustment models with coefficients derived from data in either Winnipeg or southwest England.     

日光温室中氡浓度日变化趋势及其影响因素

目的 了解日光温室中氡浓度的本底值和变化趋势,探讨温度和相对湿度对温室氡浓度的影响规律,为温室氡污染防护和劳动者健康保护提供依据.方法 以当地普通居室为对照,使用Model 1027连续测氡仪和干湿球温度计对温室环境中的氡浓度、温度和相对湿度进行8 h连续监测.结果 在测定范围内,温室氡浓度、温湿度最大值分别为355.0 Bq/m3、30.5℃和93%,各指标最小值分别为1 1.2 Bq/m3、17.5℃和70%,均高于普通居室.结论 日光温室氡浓度明显高于普通居室,温度和相对湿度可能是影响温室中氡浓度的重要因素,可以通过自然通风或机械通风的方法降低温室氡浓度,以保护劳动者健康.     

日光温室中氡浓度日变化趋势及其影响因素

目的 了解日光温室中氡浓度的本底值和变化趋势,探讨温度和相对湿度对温室氡浓度的影响规律,为温室氡污染防护和劳动者健康保护提供依据.方法 以当地普通居室为对照,使用Model 1027连续测氡仪和干湿球温度计对温室环境中的氡浓度、温度和相对湿度进行8 h连续监测.结果 在测定范围内,温室氡浓度、温湿度最大值分别为355.0 Bq/m3、30.5℃和93%,各指标最小值分别为1 1.2 Bq/m3、17.5℃和70%,均高于普通居室.结论 日光温室氡浓度明显高于普通居室,温度和相对湿度可能是影响温室中氡浓度的重要因素,可以通过自然通风或机械通风的方法降低温室氡浓度,以保护劳动者健康.     

日光温室中氡浓度日变化趋势及其影响因素

目的 了解日光温室中氡浓度的本底值和变化趋势,探讨温度和相对湿度对温室氡浓度的影响规律,为温室氡污染防护和劳动者健康保护提供依据.方法 以当地普通居室为对照,使用Model 1027连续测氡仪和干湿球温度计对温室环境中的氡浓度、温度和相对湿度进行8 h连续监测.结果 在测定范围内,温室氡浓度、温湿度最大值分别为355.0 Bq/m3、30.5℃和93%,各指标最小值分别为1 1.2 Bq/m3、17.5℃和70%,均高于普通居室.结论 日光温室氡浓度明显高于普通居室,温度和相对湿度可能是影响温室中氡浓度的重要因素,可以通过自然通风或机械通风的方法降低温室氡浓度,以保护劳动者健康.     

Dose conversion factor for radon concentration in indoor environments using a new equation for the F-fP correlation

Since 1994 the radon studies group at the Institut de Tècniques Energètiques (INTE) of the Universitat Politècnica de Catalunya in Barcelona, Spain, has carried out a campaign of continuous measurements of the equilibrium factor (F) and the unattached fraction (f(p)) of radon decay products at four sites which are representative of different environmental characteristics on the Mediterranean littoral of Catalonia, Spain. It has been established that these parameters vary widely, F(0.03-0.87) and f(p) (0-0.72), from one site to another and with time, according to the characteristics of the site and climate. In spite of this variation, the F and f(p) parameters are log-normally or normally distributed. The measurements of F and f(p) show that f(p) is negatively correlated to F by a log-power equation, Ln(1/f(p))=1.90[Ln(1/F)](-0.68), which can be used in all the F range, instead of the commonly used power equation f(p)=aFb suggested by Stranden and Strand and other authors, which fits well for a reduced range of F. Power and log-power equations have been introduced into a simplified dosimetric model in order to estimate the effective dose per unit radon exposure as a function of F. From the log-power equation this value is quite constant and ranged from 9 nSv per Bq m(-3) h to 12 nSv per Bq m(-3) h when F is higher than 0.15. In the case of a lower F factor, a linear function that passes through 0 fits quite well. A value of 12 nSv per Bq m(-3) h is proposed for the Mediterranean littoral of Catalonia as the best estimation.     

Systematic indoor radon and gamma-ray measurements in Slovenian schools

During the winter months of 1992/93 and 1993/94, instantaneous indoor radon concentrations and gamma dose rates were measured in 890 schools in Slovenia attended in total by about 280,000 pupils. Under "closed conditions," the room to be surveyed was closed for more than 12 h prior to sampling, the air was sampled into alpha scintillation cells with a volume of 700 cm3, and alpha activity was measured. An arithmetic mean of 168 Bq m(-3) and a geometric mean of 82 Bq m(-3) were obtained. In 67% of schools, indoor radon concentrations were below 100 Bq m(-3), and in 8.7% (77 schools with about 16,000 pupils) they exceeded 400 Bq m(-3), which is the proposed Slovene action level. In the majority of cases, radon concentrations were high due to the geological characteristics of the ground. Approximately 70% of schools with high radon levels were found in the Karst region. Gamma dose rates were measured using a portable scintillation counter. An arithmetic mean of 102 nGy h(-1) and a geometric mean of 95 nGy h(-1) were obtained. No extraordinarily high values were recorded.     

Survey of indoor radon concentrations in Fukuoka and Kagoshima prefectures

It is now well established that radon and its daughter products account for nearly half of the average population exposure to ionizing radiations and that radon is the greatest single source of natural radiation to the population. Radon and its daughters are alpha-emitters, which are more biologically damaging than beta- and gamma-radiations. A nationwide survey of radon concentration was conducted by the National Institute of Radiological Sciences in order to estimate the contribution of radon and its daughters to the population dose in Japan. Authors surveyed indoor radon concentrations in Fukuoka and Kagoshima prefectures as part of this project. A passive type radon dosimeter, in which a sheet of polycarbonate film as the alpha-ray detector was mounted, was used to measure indoor radon concentrations. The resulting distribution of the average annual indoor radon concentrations in both prefectures can be characterized by an arithmetic mean of 24.4 Bq/m3 and a standard deviation of 13.1 Bq/m3, by a geometric mean of 22.2 Bq/m3, and by a median of 20.7 Bq/m3. The geometric means of the distributions for Fukuoka and Kagoshima were 25.4, and 18.4 Bq/m3, respectively. Radon concentrations were also generally high in winter and low in summer. Regarding the analysis of correlations between the concentrations and construction materials, radon concentrations were generally high in Japanese houses with earthen walls and in concrete structures. These results showed that seasons, the type of building materials, and regional differences were significant factors in the variation of indoor radon concentration.     

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.     

西宁市建筑主体材料放射性水平及氡析出率的研究

  目的  了解沈阳市改装场所室内氡污染水平,分析其可能影响因素,为制定针对性防控措施提供科学依据。  方法  选择沈阳市2017年建成的734处改装场所,检测其室内氡浓度,分析各种改装因素与氡浓度之间的关系。  结果  与住宅（n = 581）相比,办公场所室（n = 153）内氡浓度较高[（69.285 ± 7.128）vs.（75.822 ± 4.090）Bq/m³,P < 0.05];室内场所氡浓度最主要影响因素为层高;住宅室内氡浓度影响因素包括墙面使用大白、距主干道距离;办公场所室内氡浓度影响因素有墙面使用大白、使用地板、理石和地胶。  结论  应针对室内氡浓度相关影响因素制定科学防控措施,以控制其暴露水平。     

Models for retrospective quantification of indoor radon exposure in case-control studies

In epidemiologic studies on lung cancer risk due to indoor radon the quantification of individual radon exposure over a long time period is one of the main issues. Therefore, radon measurements in one or more dwellings, which in total have been inhabited by the participants for a sufficient time-period, are necessary as well as consideration of changes of building characteristics and ventilation habits, which influence radon concentration. Given data on 1-y alpha-track measurements and personal information from 6,000 participants of case-control studies in West and East Germany, an improved method is developed to assess individual radon exposure histories. Times spent in different rooms of the dwelling, which are known from a personal questionnaire, are taken into account. The time spent outside the house (average fraction 45%) varies substantially among the participants. Therefore, assuming a substantially lower radon exposure outside the dwelling, the residence time constitutes an important aspect of total radon exposure. By means of an analysis of variance, important determinants of indoor radon are identified, namely constant conditions such as type of house (one family house or multiple dwelling), type of construction (half-timbered, massive construction, lightweight construction), year of construction, floor and type of basement, and changeable conditions such as heating system, window insulation, and airing habits. A correction of measurements in former dwellings by factors derived from the analysis is applied if current living conditions differ from those of the participants at the time when they were living in the particular dwellings. In rare cases the adjustment for changes leads to a correction of the measurements with a factor of about 1.4, but a reduction of 5% on average only. Exposure assessment can be improved by considering time at home and changes of building and ventilation conditions that affect radon concentration. The major concern that changes in ventilation habits and building conditions lead to substantial errors in exposure (and therefore risk) assessment cannot be confirmed in the data analyzed.