Radon-222 levels in New York State homes

Results are presented from a statewide survey that measured annual 222Rn concentrations in over 2000 single-family, owner-occupied homes in New York state. The participants were selected by a random-digit-dialing telephone interview approach developed by Mitofsky-Waksberg which allows inferences to be made from the sample to the statewide population. After completing a telephone questionnaire and agreeing to have their homes monitored, eligible households were mailed alpha-track detectors with instructions to place one detector in the main living area for 2 mo (during the winter heating season), a second in the main living area for 1 y, and a third in the basement (if applicable) for 1 y. The statewide median concentration for the heating-season, living-area readings was 31.6 Bq m-3, with a median of 24.0 Bq m-3 for the annual living-area readings and 51.8 for the annual basement readings. For the state, approximately 95% of the living-area concentrations and 86% of the basement concentrations were below 148 Bq m-3 (4 pCi L-1). In addition, only 1.4% of the readings in the basement were above 740 Bq m-3 (20 pCi L-1).     

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.     

室内氡的水平与控制措施

目的 验证北京市室内氡水平的分布,提出控制室内氡浓度若干途径。方法 以清华大学工程物理系室内环境质量评价中心测量的室内氡浓度数据与中国疾病预防与控制中心辐射防护核安全医学所、北京东城区卫生防疫站环卫科等单位在北京的测量数据相互印证,分析了北京市室内氡浓度的大致范围。结果 上述三家单位的氡浓度测量数据一致性比较好。结论 我国制定的"室内氡浓度行动水平"与发达国家制定的标准基本相同。在国家综合实力许可的情况下,应降低干预室内氡的行动水平,把氡致肺癌危险度降到最优化水平。加强通风、降低氡的析出率和建材控制等是室内氡的水平的有效控制措施。     

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。     

天津市部分新建楼房室内氡(222Rn)浓度水平调查

目的了解不同楼层对氡浓度的影响。方法在2002年以来对天津市部分新建楼房室内进行了验收性监测,一楼室内监测数据为130个,二楼及以上楼层室内监测数据128个。结果一楼室内平均氡浓度60.5Bq/m3,二楼及以上楼层室内平均氡浓度19.9Bq/m3,前者为后者3倍。结论楼层对氡浓度影响比较大,在今后的室内氡验收监测时,重点对一楼进行监测。     

Summertime elevation of 222Rn levels in Huntsville, Alabama

Indoor Rn concentrations and Rn in adjacent karst terrains were studied at four houses with crawlspaces in Huntsville, AL. In warm summertime weather, Rn-rich air may vent through limestone solution cavities exposed as holes at the surface of the properties. A probable interrelated-finding is that the indoor levels of 222Rn are distinctly higher in the summer than winter. The karst underlying the homes is structurally faulted and, in all probability, facilitates Rn transport from the solution cavities to the crawlspaces. Abrupt day-to-day changes in indoor Rn concentrations were recorded in addition to large seasonal changes. If the owners or residents of these particular homes had attempted to make, and interpret, short-term screening measurements for Rn during the fall season, problems, including false negatives, could have arisen because of order-of-magnitude changes in Rn concentration occurring over a few days. The best time of year to make screening measurements would be during the summer when indoor Rn concentrations are more likely to reach their maximum values.     

Relationship of 220Rn and 222Rn progeny levels in Canadian underground U mines

Radon-222 and 220Rn progeny are found in some Canadian underground U mines. Because both can contribute to lung dose, their experimental determinations are important. The relationship between 222Rn progeny Working Level [WL(Rn)] and 220Rn progeny Working Level [WL(Tn)] has been investigated in U mines. Experimental measurements extended from 1981 to 1986 and consisted of about 700 measurements of each WL(Rn) and WL(Tn). The data were analyzed by standard linear and power-function regression analysis. A power-function relationship between WL(Rn) and WL(Tn) seemed to fit the experimental data best. The relationship obtained permits the calculation of WL(Tn) from experimental values of WL(Rn). The relationship is useful for lung-dose-calculation purposes and in mine-ventilation-engineering calculations.     

Indoor 222Rn measurements in the region of Beijing, People's Republic of China

Passive integrating activated C detectors were used to study the regional distribution and temporal variation of 222Rn in indoor air in dwellings in the Beijing region. Measurements were made in 537 dwellings, which were either detached houses or multi-family apartments. The city-wide study was completed in 1985. The distributions are approximately log-normal with 90% of the dwellings having 222Rn levels less than 60 Bq m-3. The weighted average 222Rn concentration has been found to be 22.4 Bq m-3. Averages for detached houses and multi-family dwellings are 25.9 and 15.2 Bq m-3, respectively. Assuming an equilibrium factor of 0.5 and an occupancy factor of 0.8, the average equilibrium equivalent concentration of 222Rn progeny is 11.2 Bq m-3 and the annual average effective dose equivalent is 1.1 mSv.     

Radon-222 concentration in groundwater and cancer mortality in North Carolina

Summary In a geographic correlation study, we explored the possibility that residential exposure to radon in groundwater may be related to cancers other than lung cancer. Measurements of radon in groundwater and 1978–1982 cancer mortality data from North Carolina, USA were used to investigate this relationship. Counties were categorized in two levels of radon exposure according to measured radon concentration and geology. In the lower exposure group (unexposed) county mean radon concentrations ranged from 0–228 pCi/1 (0–8436 Bq/m³), and in the upper group (potentially exposed) the range of county average concentrations was 229–10892 pCi/1 (8473–403004 Bq/m³), (median 1375 pCi/1 (50875 Bq/m³)). Adjusted mortality ratios and 95% confidence intervals were calculated for selected cancers, including leukemias, gastro-intestinal tract cancers, and respiratory tract cancers excluding lung cancer. In contrast to other ecologic studies, we found no consistent association between radon level and cancer mortality.     

Indoor Rn levels in different geological areas in Switzerland

The distribution of indoor Rn concentrations in different geological areas in Switzerland was studied using passive alpha-track detectors. Measurements involving a sample of 400 single-family homes were made in the cellar, on the ground floor and the first floor, respectively. On the basis of a pilot survey, the country was divided into four zones in which the Rn distribution in houses was analyzed separately. The indoor exposure to Rn and Rn decay products is quite variable from region to region. The geology of the different areas was found to be an important factor in determining the mean value Rn levels. In the basin north of the Alps, where the population centers are located, a median Rn gas level of 47 Bq m-3 for the living area was found. The arithmetic mean value of 60 Bq m-3 in this region leads to an annual effective dose equivalent of about 1.8 mSv. For the population living in alpine areas, an arithmetic mean value exceeding 200 Bq m-3 will lead to an annual effective dose equivalent in the range of 6 mSv. The estimated exposure to Rn and Rn decay products for the upper one-percentile of the homes in the most affected alpine region even exceeds the annual limit of 50 mSv effective dose equivalent for occupational exposure.     

Indoor 222Rn measurements in Sweden with the solid-state nuclear track detector technique

Measurements of the indoor radon and radon daughter concentrations were performed in several thousand Swedish houses during the years 1979-1984 with the solid state nuclear track detector technique (SSNTD technique). The investigation focused on structures containing building materials of light-weight concrete with enhanced amounts of U. The detectors used nuclear track films exposed for 1 mo. The film basically measures total airborne alpha activity but may be calibrated in units of EER in an environment with known 222Rn and daughter concentrations. (EER is here the equilibrium equivalent concentration of Rn with the equilibrium factor F = 0.5.) The investigation was performed in various municipalities in collaboration with the local public health and environmental authorities. The investigation included 6700 individual measurements in detached (single-family) houses as well as in apartment houses. A small percentage of the dwellings exhibited Rn daughter concentrations (EER) exceeding 400 Bq m-3. It was found in detached houses that the concentrations were higher in the basement floor than in the entrance floor of a house. The Rn daughter values in the bedrooms were similar to values in any other room (mainly on the same floor) of the structure. The Rn daughter levels in apartment houses were lower than in single-family houses. The seasonal variations of the Rn daughter levels are presented and show that the levels in summertime are approximately equal to the levels in the winter.