浙江省居室内氡浓度和γ辐射水平的初步调查

目的 初步了解浙江省居室内的氡浓度和γ辐射水平及其分布特性,估算这两类辐射所致居民的受照剂量。方法 采用固体核径迹方法和热释光剂量方法测量氡浓度和γ辐射水平;根据地级市行政区域划分,随机抽取共490个卧室或客厅开展3个月以上的累积测量;在其中75个房间开展6个月以上测量以观察两类辐射水平的季节性变化;在开展调查过程中记录建筑物的结构、建筑年代、通风情况和楼层等信息。结果 全省居室内氡浓度和γ辐射水平均值为29.3 Bq·m^-3和105.8 nSv·h^-1,所致公众的平均年有效剂量分别为0.77和0.74 mSv;新建居室内的氡浓度较高,别墅内氡浓度明显高于其他类型的建筑物,居室内氡浓度水平随通风时间减少而升高;室内氡浓度和γ辐射水平没有明显的相关性,且随季节变化也不明显。结论 当前浙江省居室内的平均氡浓度和γ辐射水平虽然不高,但室内氡浓度已有增高的趋势,值得关注与控制。     

我国东北地区室内氡浓度水平与变化趋势分析

目的 初步调查我国东北地区居室氡浓度水平和变化趋势。方法 选择东北地区的沈阳、长春、哈尔滨、黑河和伊春5个城市的多层和高层住宅共261户，采用固体核径迹法累积测量室内氡浓度，测量时间3个月以上。长春进行了为期1年的测量，分析季节变化。结果 5个城市室内氡浓度均值为88 Bq/m³，范围为12～558 Bq/m³。室内氡浓度≤100 Bq/m³的房屋占75.1%，室内氡浓度≤300 Bq/m³的房屋占97.7%。室内氡浓度随建筑年代增加呈现增长趋势。冬季室内氡浓度明显高于其他季节；夏季氡浓度明显高于秋季和春季；结论 我国东北室内氡浓度比上世纪八九十年代的调查结果相比，呈现明显升高趋势，冬季取暖季节氡浓度明显偏高，夏季氡浓度明显高于秋季和春季，室内氡污染值得关注。     

河北平山温泉氡水平与剂量贡献

目的 了解平山温塘镇温泉水和自来水中氡的水平,用水过程室内氡浓度的变化,为开展含氡温泉氡水平调查与剂量评价提供有效方案。方法 选取典型住宅和宾馆,采集温泉水和自来水样品,用连续测氡仪(RAD7)进行现场测量水中氡浓度。采用α径迹探测器(ATDs)、氡气测量仪(EQF3120)和工作水平测量仪(WLx)测量大气氡和氡子体浓度。结果 温塘镇温泉水和自来水中氡的浓度分别是(102±11.4)Bq/l和(8.2±9.6)Bq/L;室内氡浓度6个月均值为41.9±18.6 Bq/m³,平衡因子的典型值为0.61。结论 平山温塘镇温泉含有较高水平的氡浓度,一些场所的泉水已达到医疗温泉和氡泉规定的水平。用水过程浴室里的氡浓度有所增加,所造成的附加年有效剂量约为0.09mSv,尚未造成明显污染。     

西藏居室内氡浓度调查及所致居民剂量估算

目的 在国内城市室内氡呈上升趋势的背景下,为了获取现阶段西藏地区室内氡浓度水平,开展本次西藏地区室内氡浓度调查工作。方法 采用KF606B型固体核径迹氡累积探测器,对西藏自治区居室氡浓度进行测量,测量周期6～12个月。结果 西藏地区138间居室内氡浓度范围为14～119 Bq·m^-3,均值为（47.8 ±23.0） Bq·m^-3。氡浓度大于100 Bq·m^-3房间有5个,占总调查房间数的4%。居室内氡所致西藏地区居民有效剂量范围为0.46～3.89 mSv·a^-1,均值为1.56 mSv·a^-1。文章还对不同调查地区、城镇/农村、不同建筑类型和不同建筑年代居室内氡浓度进行了比较分析。结论 本次居室内氡浓度调查结果比上世纪八九十年代西藏地区测量结果有显著增高。     

石家庄市办公场所室内氡浓度及所致剂量估算

目的 通过对石家庄市区不同楼层、不同建筑材料、不同建筑年代等办公场所室内氡浓度水平及其影响因素的调查分析,估算所致工作人员受照剂量。方法 采用固体核径迹法测量累积剂量。结果 石家庄市办公场所室内氡浓度平均值为(32.12 ±13.74)Bq·m^-3,最高值为钢筋混凝土结构的平房。所致工作人员平均有效剂量为0.58mSv/a。结论 石家庄市办公场所室内氡所致工作人员受照剂量属正常天然本底辐射水平;建筑材料及通风设施是影响办公场所氡浓度的主要因素,选择恰当的建筑材料、有效通风可以降低工作人员受照剂量,减低其对人类健康的影响。     

广州某地下人防工事空气氡浓度监测分析

目的 了解广州某地下人防工事空气氡浓度水平及其变化规律。方法 采用RAD7型测氡仪对指挥中心、通道等场所进行瞬时氡浓度测量与分析,并粗略估算氡及其子体所致工作人员年有效剂量。结果 指挥中心、无线通讯室、中央主通道和仓库区通道这4个有人员停留的主要工作场所的日间氡浓度均值分别为106.7、98.4、129.0、111.1 Bq/m³,总体平均为111.0 Bq/m³。²²²Rn子体所致工作人员的年有效剂量当量为0.400 mSv/a。结论 不同场所的氡浓度不尽相同,且其受通风、排水等人为活动的影响呈不同的变化规律。     

广东省居民住宅室内氡浓度检测与评价

目的 了解广东省居民室内氡浓度水平与相关影响因素。方法 采用被动式活性炭室内氡探测器进行测量。结果 本次调查的广东省室内氡浓度总算术平均值为46.1 Bq/m³(卧室)和38.8 Bq/m³(客厅)。室内不同建材类型地面氡浓度均值为:花岗岩(53.5 ±19.2)Bq/m³、瓷砖(45.4 ±32.0)Bq/m³、木地板(29.7 ±21.20)Bq/m³。冬季氡浓度比夏季多一倍多。结论 广东省居民室内氡浓度总算术平均值基本与世界平均值40.0 Bq/m³相接近,其中中山、博罗室内氡浓度均值较世界均值约高1倍。     

北京新镇地区室外氡子体水平调查

目的 调查北京新镇地区室外氡子体浓度水平及其变化规律,并估算其所致当地居民有效剂量。方法 运用德国BWLM-Plus-s、南华NR-200A和北大RPMD-SF01氡子体连续测量仪测量空气中氡子体浓度。结果 测量时间内新镇地区的室外平衡当量氡浓度平均值为9.1 Bq/m³,范围值为0.4~27.5 Bq/m³;室外氡子体致居民有效剂量为149 μSv,其中霾天附加剂量为9 μSv。结论 大气氡子体浓度受天气和气象因素影响,呈现上午高下午低的日变化规律;秋冬季较高,春夏季较低的季节变化规律。大气氡子体浓度霾天高于非霾天;霾可增加当地居民所受室外氡子体照射的有效剂量约6%。     

北京市生活饮用水放射性水平调查分析

目的调查北京市生活饮用水的放射性水平,以更好地开展本地区饮用水放射卫生监测与评价。方法抽查北京市9个区县55个生活饮用水水样,包括井水29个、自来水21个和地面水5个,使用BH1217B双路弱α、β测量仪测量水中的总α和总β放射性,使用RTM2200连续氡测量仪测量水中放射性氡浓度。结果 55个水样中总α浓度最高值为0.325 Bq/L,总β浓度最高值为0.331 Bq/L,均低于我国《生活饮用水卫生标准》GB 5749—2006规定的指导值;地表水氡浓度均值仅为0.62 Bq/L,远低于地下井水中氡浓度的均值(15.95 Bq/L),地下水源井水中氡浓度和总α无直接关系。结论生活饮用水中放射性水平受多种因素影响,应进行持续监测以及时发现和控制水中的意外污染。     

银川市室内氡浓度调查及公众剂量估算

目的 初步调查银川市城乡住宅室内氡浓度水平及估算有效剂量。方法 采用固体核迹径法，选择银川市城市49户、农村18户，共计67间居室累积测量3个月以上。结果 银川市城乡室内氡浓度算术平均值为64 Bq/m³，几何均值为59 Bq/m³，中位数为57 Bq/m³，范围为25～172 Bq/m³，室内氡浓度大于100 Bq/m³的测量点占7.5%。农村室内氡浓度高于城市。室内氡浓度呈冬季最高，夏季最低的特点。室内氡所致银川市居民有效剂量为1.86 mSv/a。结论 本次银川市室内氡浓度调查结果比上世纪九十年代测量结果有显著上升，年有效剂量高于世界及全国平均水平。     

Measurements of airborne 212Pb and 220Rn at varied indoor locations within the United States

Measurements have been made at varied locations within the United States comparing the concentration of 212Pb in air with that of the progeny of 222Rn to see if 212Pb is typically a significant contributor to indoor radioactivity. Auxiliary measurements were made comparing 220Rn with 222Rn. In terms of potential alpha-particle energy, 212Pb is significant (the ratio of its contribution to the combined contribution of 218Po, 214Pb, and 214Bi averaged about 0.6) and may warrant greater consideration as a component of indoor radioactivity. Correlations were found between the concentration of 220Rn progeny and 222Rn progeny, and the concentration of 220Rn and 222Rn. Environmental factors such as transport pathways and ventilation rates which exert a common influence on the concentrations of airborne isotopes provide a possible explanation for these correlations.     

Continuous measurements of outdoor 222Rn concentrations for three years at one location in Colorado

Measurements were made of 222Rn concentrations outdoors in Ft. Collins, Colorado, using a continuously sampling scintillation flask between January 1993 and December 1995. These data were analyzed for hourly, daily, and seasonal variations. The average 222Rn concentration at 1 m above the ground was 18 +/- 10 Bq m(-3) with a geometric mean of 15 Bq m(-3) and a geometric standard deviation of 1.7. Hourly averaged data indicated a diurnal pattern with the outdoor 222Rn concentration reaching a maximum in the early morning between 4:00 a.m. and 6:00 a.m. and a broad minimum between 1:00 p.m. and 4:00 p.m. in the afternoon. An analysis also indicated that the outdoor 222Rn concentrations were consistently lowest during the spring (March and April) and highest during the late summer (July-September).     

Radon-222, 222Rn progeny, and 220Rn progeny levels in 70 houses

A year-long, multipollutant, indoor air quality study involving 70 occupied houses in four states was completed in 1987. All of the houses included in the study had a partial or complete basement with a concrete slab floor and block walls. On an approximately quarterly schedule, integrating monitors for short-lived Rn progeny, nitrogen dioxide, formaldehyde, and water vapor were exposed for 1 wk in each house on both the basement and main floors. At the beginning of the study, a pair of alpha-track detectors were placed on top of the refrigerator in the kitchen (or some other sampling location on the main floor) and at a location in the basement. One detector at each location was left in place for a year while the other detector was retrieved and replaced once every 3-mo period. In addition, short-term measurements of Rn and 222Rn progeny were made at all sampling locations once per quarter. In this study, comparisons were made between: (1) seasonal and annual averages, (2) summer and winter averages, (3) living-area and basement results, (4) 222Rn and 220Rn progeny, and (5) short- and long-term measurements. The Rn and Rn progeny concentrations in houses near Huntsville, AL were found to be well above recommended action levels (150 Bq m-3). For houses near Birmingham, AL, summer Rn concentrations were found to exceed winter concentrations, whereas for the other houses in the study, winter concentrations exceeded summer concentrations. Potential alpha energy concentrations (PAEC) from 220Rn progeny were found to be generally less than PAEC from 222Rn.     

崇明县空气中氡浓度水平调查与评价

目的 了解崇明县室内外氡浓度水平并估算其所致公众的受照剂量。方法 根据2010年全国人口普查崇明县乡镇人口比例、房屋建筑类型、建筑年代和主体建筑材料等对测量样本进行分类选择。使用美国Durridge公司制造RAD7型电子氡气检测仪对室内外氡进行测量,数据采用SPSS 17.0软件进行统计分析。结果 本次调查的室内²²²Rn浓度范围为5.75~195.29 Bq/m³,平均浓度为(25.76±2.07) Bq/m³。约有73.89%的房屋内氡浓度低于40 Bq/m³。室外²²²Rn浓度的范围为5.70~19.32 Bq/m³,平均浓度为(9.92±1.43) Bq/m³。结论 本次调查的崇明县室内氡浓度均未超过国家推荐的控制限值。崇明县居民吸入氡所致人年均有效剂量为0.74 mSv。     

Radon-222 concentrations and decay-product equilibrium in dwellings and in the open air

Results are presented of measurements of the activity concentrations of 222Rn and its short-lived decay products and the 212Pb/212Bi concentrations in more than 200 dwellings in West Germany and in the open air. For more than 130 measurements of the equilibrium factor F in dwellings the median value was found to be 0.3. Measurements of F in the open air under various conditions resulted in a mean value of about 0.4. The results of the investigations showed that indoors F depends only slightly on ventilation, indoor 222Rn concentration and other parameters. The equilibrium factor F in the open air, however, was found to depend on meteorological conditions. Empirical correlations from the data obtained for the daughter/222Rn concentration ratios were derived to provide relations for the prediction of the individual daughter product concentrations at a measured 222Rn level. It was established that the daughter/222Rn concentration ratios for indoor air do not change within the range of 222Rn concentrations investigated (1-370 Bq X m-3). These relations, however, are not valid for the daughter/222Rn concentration ratios in outdoor air. The correlations derived further suggest that the individual daughter product concentrations may be assessed with sufficient accuracy by only measuring the 222Rn concentrations. Thus the daughter ratios obtained in this way should enable good estimates of the lung dose for members of the public due to inhalation of the short-lived 222Rn daughters and the dose contribution of the individual 222Rn-daughter products.     

Spatial variation of waterborne radon and temporal variation of radon in water at nine Maine schools

Nine elementary schools in Maine were examined to track the release of 222Rn and to determine the transfer coefficient from water into air. Water-use simulations were performed by running sinks and sprayers for 1 h in a kitchen. The 222Rn in air was measured over 24 h throughout the school. The subsequent release of 222Rn into the kitchen air was measured to be greater than the EPA action level of 0.15 Bq L-1 (4 pCi L-1), but negligible concentrations of 222Rn were found in adjacent classrooms. In two schools, more than 10 222Rn-in-air detectors were placed throughout the kitchen and showed a three-fold spatial concentration variation. During the hour-long simulations, the 222Rn in water concentration was measured periodically, and many of the schools showed an increase in the 222Rn concentration in water before remaining constant. These measured variations suggest that multiple detectors are needed to accurately measure waterborne 222Rn in air, and multiple delayed measurements of 222Rn dissolved in water are needed to obtain a representative groundwater sample.     

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。     

Radon entry into houses having a crawl space

The transport of 222Rn from soil, through a vented crawl space, and into the living space of single-family residences was studied. Two houses were monitored in detail for periods of 5 and 7 weeks. With crawl space vents open, the average indoor 222Rn concentrations were 1.2 and 0.6 pCi 1.-1 (44 and 22 Bq m-3); with the vents sealed the averages rose to 2.2 and 1.0 pCi 1.-1 (81 and 37 Bq m-3). The data suggest that, of the Rn released into the crawl space from the soil beneath the house, a significant fraction, perhaps 50% or more, enters the living space. The effect of 3 meteorological parameters--wind speed, indoor-outdoor temperature difference, and rate of barometric pressure change--on Rn concentration and entry rate were examined. In 1 of the houses a higher temperature difference corresponded to a higher indoor concentration, suggesting that the increased infiltration rate is more than compensated by an increase in the Rn entry rate. On the other hand, a high wind speed tended to reduce the indoor concentration, presumably by increasing both cross-ventilation of the crawl space and the infiltration rate of the living space. Results suggest that Rn transport into the crawl space of at least 1 of the houses occurred by pressure-driven flow, rather than solely by molecular diffusion. The diffusion coefficient of 222Rn through polyethylene sheeting, such as was present on the ground beneath this house, was measured in the laboratory and found to range from 0.65 X 10(-7) cm2 s-1 at 11 degrees C to 1.6 X 10(-7) cm2 s-1 at 25 degrees C, implying that the maximum diffusive flux through the sheet was many times smaller than that necessary to account for the rate of Rn entry into the house. A third house was studied using a tracer gas injected into the crawl space at a controlled rate. The fraction of air leaving the crawl space that entered the living space ranged from 0.3 to 0.65, in good agreement with results for Rn transmission in the other 2 houses, assuming that the 222Rn flux into the crawl space was comparable to that which would have resulted from molecular diffusion from soil having a 222Rn diffusion length of 1.0 m. By sealing leaks in the floor of this house, the average infiltration rate was reduced by 25%, but the indoor concentration of the tracer gas remained constant.     

Estimation of the radiological risk related to the presence of radon 222 in a hydrotherapy centre in Tunisia.

The (222)Rn concentration in air was measured in a thermal water spa used as a hydrotherapy centre in Tunisia. The associated health risk for employees and patients due to the inhalation of (222)Rn and its progeny was estimated. A protection scheme for the employees of the spas has been designed. Results show that the (222)Rn concentration varies in the range 33-589 Bq m(-3). The (222)Rn concentrations measured in the present study show lower values in comparison to those reported for thermal spas in other countries. The (222)Rn concentration in different rooms of the spa depends mainly on the ventilation rate. A model based on a dosimetric approach was adopted to estimate the radon risk considering the (222)Rn concentration, the time spent in the spa, and the radioactive equilibrium factor F. The annual effective dose was found to vary between 0.2 and 1.7 mSv for workers while the range for patients was from 2.8 x 10(-4) to 1.1 x 10(-4) mSv. These values are within the ICRP recommended values.     

Radon and thoron in cave dwellings (Yan'an, China)

222Rn and 220Rn concentrations were measured in cave dwellings and brick houses in the region of Yan'an (China) during summer 1997. The underground dwellings are built into Quaternary loess, and all investigated houses are founded on it. The median values of indoor 222Rn and 220Rn concentrations are 42 (n = 18) and 77 Bq m(-3) (n = 15) for brick houses and 92 (n = 23) and 215 (n = 17) Bq m(-3) for cave dwellings. To classify the dwellings in respect to their "cave-character," the fraction of walls having a direct contact to the loses is calculated for each dwelling. While the 222Rn concentrations are increasing with higher fractions, the 220Rn concentrations are not correlated with this fraction. On the other hand, due to the short half-life of 220Rn the distance from the measuring point to the walls is negatively correlated with the 220Rn concentration, while there is no correlation with the 222Rn concentration. Therefore, concentric isolines of 220Rn concentrations showing a strong gradient were detected in cave dwellings. An influence of the ventilation rate is distinct for 222Rn but weak for 220Rn. The effective dose rates for 222Rn and 220Rn and their progenies are calculated for brick houses (2.7 mSv y(-1)), cave dwellings (7.1 mSv y(-1)), and for traditional cave dwellings with a bed foundation built with loess (16.7 mSv y(-1)). These calculations are based on summer measurements only. It is expected that the true effective dose rates will be significantly higher.