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.     

Indoor radon in the region of Brussels

The indoor radon (222Rn) concentration has been measured by charcoal detectors in 278 buildings in the region of Brussels, Belgium. The correlation with the nature of the subsoil can be studied in detail thanks to the available geotechnical map. With a geometrical mean indoor radon concentration of 19 Bq m(-3), Brussels can be considered as generally unaffected by the radon problem. No value higher than 400 Bq m(-3) (the EU reference level for existing houses) was measured in an occupied room. However, two factors that may enhance the risk are identified: the absence of a basement or a ventilated crawl space, and the presence of loess, under the house. About one third of the houses without basements or ventilated crawl spaces built on loess show an indoor radon concentration above 200 Bq m(-3) (the EU reference level for new houses).     

Seasonal variation in indoor radon concentrations in dwellings in six districts of the Punjab province, Pakistan

An indoor radon measurement survey has been carried out in six districts of the Punjab province. These included Gujranwala, Gujrat, Hafizabad, Sialkot, Narowal and Mandibahauddin districts. In each district, 40 representative houses were chosen and indoor radon levels were measured in these dwellings in autumn, winter, spring and summer seasons using CR-39 based NRPB radon dosimeters. After exposure to radon, the CR-39 detectors were etched in 25% NaOH at 80 degrees C and track densities were related to radon concentration levels. From the observed data, average radon concentration levels and a seasonal correction factor were calculated. The average 222Rn concentration level was found to vary from 40 +/- 15 to 160 +/- 32 Bq m(-3) and 38 +/- 17 to 141 +/- 26 Bq m(-3) in the bedrooms and living rooms of the houses surveyed, respectively. The annual mean effective dose received by the occupants has been calculated using ICRP (1993 Ann. ICRP 23) and UNSCEAR (2000 Sources and Effects of Ionizing Radiation (New York: United Nations)); it varied from 1.2 to 1.7 mSv and from 1.8 to 2.4 mSv, respectively.     

Radon concentrations in elementary schools in Kuwait

Measurements of indoor radon concentrations were performed in 25 classrooms in the capital city of Kuwait from September 2003 to March 2004 using track etch detectors. The investigation was focused on area, ventilation, windows, air conditioners, fans, and floor number. All the schools have nearly the same design. Mean indoor radon concentration was higher for case subjects (classrooms) than for control subjects (locations in inert gas, p < 0.001). The mean alpha dose equivalent rate for case subjects, 0.97 +/- 0.25 mSv y, was higher than the radiation dose equivalent rate value of control subjects, 0.43 +/- 0.11 mSv y. The average radon concentrations were found to be 16 +/- 4 Bq m for the first floor and 19 +/- 4.8 Bq m for the second floor after subtraction of the control. These values lead to average effective dose equivalent rates of 0.40 +/- 0.10 and 0.48 +/- 0.12 mSv y, respectively. The equilibrium factor between radon and its progeny was found to be 0.6 +/- 0.2.     

Study of radon concentrations in oil refinery premises and city dwellings.

Radon and its progeny concentrations were measured in several dwellings at an oil refinery premises and these concentrations were compared with those found in dwellings in Mathura and Agra cities. Radon progeny concentrations were measured using LR-115 type II nuclear track etch detectors. The radon concentrations were estimated by using a value of 0.42 for the equilibrium factor. The geometric means (GM) of radon concentrations in the refinery dwellings, Mathura city and Agra city dwellings were 97, 91 and 75 Bq m(-3) with geometric standard deviations of 1.7, 1.8 and 1.8 respectively. The average lifetime risk of lung cancer for an adjusted annual average chronic radon exposure of 69 Bq m(-3) (7.8 mWL; WL = working level) with an occupancy factor of 0.7 comes out to be 5.4 x 10(-3).     

The effectiveness of radon remediation in Irish schools

An advisory reference level of 200 Bq m(-3) and a statutory reference level of 400 Bq m(-3) apply to radon exposure in Irish schools. Following the results of a national survey of radon in Irish schools, several hundred classrooms were identified in which the reference levels were exceeded and a remediation program was put in place. This paper provides an initial analysis of the effectiveness of that remediation program. All remediation techniques proved successful in reducing radon concentrations. Active systems such as radon sumps and fan assisted under-floor ventilation were generally applied in rooms with radon concentrations above 400 Bq m(-3). These proved most effective with average radon reduction factors of 9 to 34 being achieved for radon sumps and 13 to 57 for fan assisted under-floor ventilation. Both of these techniques achieved maximum radon reduction factors in excess of 100. The highest average reduction factors were associated with the highest initial radon concentrations. Passive remediation systems such as wall and window vents were used to increase background ventilation in rooms with radon concentrations below 400 Bq m(-3) and achieved average radon reductions of approximately 55%. Following the installation of active remediation systems, the radon concentration in adjacent rooms, i.e., rooms in which the radon concentration was already below 200 Bq m(-3) and therefore did not require remediation, was further reduced by an average of 25%. The long-term effectiveness of a number of radon sump systems with at least three years operation showed no evidence of fan failures. This study showed an apparent increase in sump effectiveness with time as indicated by an increase in radon reduction factors during this period.     

Radon concentrations in some dwellings of Tunisia

Indoor air radon concentrations are still unknown in Tunisia. For the first time, they have been determined in several regions of the country using open alpha track dosimeters containing LR-115 film. Measurements were taken in 69 dwellings located around greater Tunis during 1 y, changing dosimeters every 2 mo. In 12 other locations, devices were placed during 2 winter months. The median of 1,217 measurements was 40 Bq m(-3) and 93.4% of them were less than 100 Bq m(-3). The highest concentration was 392 Bq m(-3). In Tunis, concentrations were higher during winter. Indoor air radon figures varied with geographic location: the highest values were found in Jendouba, Gafsa, Beja, and Tataouine government districts where phosphate and lead mines and deposits are present. This first study showed that indoor air radon concentrations are low in Tunisia, but further studies should be performed in localized areas, taking into consideration the geology, the climatic variations, and the building material.     

Indoor radon determination in dwellings located at Dikili geothermal area in Western Turkey

This paper presents the indoor radon concentrations in dwellings located in the Dikili geothermal area in western Turkey. Indoor radon monitoring was performed for 3 mo using 121 detectors installed in the living rooms and bedrooms of 62 houses selected from the region. A passive time-integrating radon measuring technique was applied by using CR-39 solid-state nuclear track detectors. Average indoor radon levels for the houses varied from 31 to 280 Bq m(-3). Corresponding annual effective doses were calculated, and risks for lung cancer due to inhalation of indoor radon were estimated.     

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.     

Radon in Tunisian buildings

Radon is a natural radioactive gas produced by decay of uranium and radium present in soils. Diluted in air, in confined atmospheres, it may accumulate in high concentrations. Inhalation of radon and its progeny is thought to increase lung cancer risk. For the first time, air radon concentrations were determined in 1151 dwellings situated in all the inhabited regions of Tunisia, using open alpha-track dosimeters exposed during two months. The median of 1864 measurements was 36 Bq m(-3) (with a maximum of 512 Bq m(-3), most of them being less than 100 Bq m(-3). All results were under the International Instances recommended range.     

Do the UK workplace Radon Action Levels reflect the radiation dose received by the occupants?

In the UK, Action Levels for radon have been established at 400 Bq m(-3) for the workplace and 200 Bq m(-3) for the home. We have estimated the dose received by occupants of rooms with radon levels near or above the Action Level, using hourly radon readings, and a questionnaire to record occupancy. In the workplace, results for 73 staff suggest that doses are lower than expected, partly due to part-time working and partly due to the mobility of staff. The 75% quantile for the series, corrected to a 37 hour week, is 5.2 mSv at 400 Bq m(-3). Compared to the current annual limit for radiation workers, the Action Level could be increased, but the current Action Level is compatible with the recent EEC Directive requiring a lower dose limit. However, when raised radon levels in the workplace were reduced by remediation in the series we studied, the dose reduction to staff was consistently around half of the radon level reduction. Although it would be appropriate to study more locations, this suggests an Action Level for remediated workplaces of 200 Bq m(-3). Finally, in a limited series of dose assessments in domestic properties, we found that doses could considerably exceed 5 mSv at the 200 Bq m(-3) Action Level, primarily because the sample included an example of high occupancy, in our case several Asian wives in purdah, whose occupancy was almost total.     

The measurement of radon working levels at a mineral separation pilot plant in Cox''s Bazar,Bangladesh

Beach Sand Exploitation Centre at Cox's Bazar, Bangladesh, produces commercial grade concentrations of magnetite, ilmenite, zircon, etc., from the high-grade accumulations available along the beach and foredune of Cox's Bazar. Solid state nuclear track detectors (CR-39 foils) were used to determine indoor radon concentration of radioactive mineral sands and the technologically enhanced radiation level inside the pilot plant of the Centre. It is found that the concentrations at processed mineral stock areas are high, and the maximum concentration was found to be 2,103 +/- 331 Bq m(-3) (0.23 +/- 0.03 WL). The indoor concentration of radon and its decay products in the raw sand stock area and at other locations was in the range of 116 +/- 27 Bq m(-3) (0.03 +/- 0.003 WL) to 2,042 +/- 233 Bq m(-3) (0.22 +/- 0.03 WL).     

Radon in Irish schools: the results of a national survey.

This paper presents the results of a survey of radon concentrations in Irish primary and post-primary schools. The objective of this survey was to assess the distribution of radon in Irish schools and to identify those requiring remedial work to reduce radon exposure to children and staff. All primary and post-primary schools were invited to participate in the survey. Indoor radon concentrations were measured during the academic year using integrating passive alpha track-etch detectors with a measurement period from three to nine months. The survey was carried out on a phased basis from 1998 to 2004 and is one of the most comprehensive of its kind undertaken in Europe. Measurements were completed in 38 531 ground floor classrooms and offices in 3826 schools, representing over 95% of the approximate 4000 primary and post-primary schools in Ireland. Of these, 984 schools had radon concentrations greater than 200 Bq m(-3) in 3028 rooms and 329 schools had radon concentrations in excess of 400 Bq m(-3) in 800 rooms. The average radon concentration in schools was 93 Bq m(-3). This results in an annual average effective dose to an Irish child from exposure to radon of 0.3 mSv per year, assuming that the long-term radon concentration is equal to the radon concentration present during the working hours and that the annual average occupancy is 1000 h per year. A programme of remediation of schools with radon concentrations above 200 Bq m(-3) has been put in place.     

Anomalously high radon concentrations in dwellings located on permeable glacial sediments.

Indoor radon concentrations were measured in different seasons in 104 dwellings located on a highly permeable ice-marginal moraine in Kinsarvik, Western Norway. The measurements revealed the highest indoor radon levels ever detected in Norway and extreme variations in seasonal and short-term indoor radon levels. Annual average indoor radon concentrations up to 56 000 Bq m(-3) and a mean value of 4340 Bq m(-3) for the whole residential area are reported. By using the ICRP conversion factors to effective dose, these indoor radon values correspond to a total annual effective dose of 930 mSv and 72 mSv, respectively. By using the conversion as recommended by UNSCEAR, the effective doses would be about 50% higher. The indoor radon concentrations are found to be strongly influenced by thermally induced flows of radon-bearing soil air directed towards the upper part of the ice-marginal deposit in winter and towards the area of lowest elevation in summer. The pattern of seasonal variations observed suggests that in areas where thermal convection may occur, annual average indoor radon levels should be derived from measurements performed both in summer and in winter.     

Radon in a self-selected sample of Israeli homes, schools, and workplaces.

Some 1,100 residences and places of work and 400 schoolrooms in Israel were tested for ambient air radon activity concentration in response to requests by the owners, tenants, or local authorities. A polyethylene vial containing activated charcoal was exposed to room air in each of these structures for 7 days, sealed, and transported to the laboratory. Adsorbed radon was extracted with a toluene-based cocktail which was then subjected to liquid scintillation counting. Mean radon activity concentrations were found to vary from city to city by more than an order of magnitude, indicating strong regional differences. The countrywide geometric mean was found to be 38 Bq/m3; the median, 37. The range for these means was 6-77 Bq/m3; for the medians, 11-100 Bq/m3. The highest reading was 9,100 Bq/m3. Our results are basically in line with those from the United States and much of Europe, but apparently higher than those found in the United Kingdom and Japan. It may be fairly said that mass testing for radon (222Rn) inside buildings in the United States began in the wake of the finding of a radon activity concentration in excess of 100,000 Bq/m3 in the home of the Watras family in Boyertown, PA in December 1984. To date, literally millions of American buildings have been tested, and mandatory testing of schoolrooms has begun in some states. In Israel, by contrast, where such a dramatically high measurement has not (yet) occurred, only 5 structures had been checked for radon by 1989.(ABSTRACT TRUNCATED AT 250 WORDS)     

Glass-based radon-exposure assessment and lung cancer risk

Lung cancer risk estimation in relation to residential radon exposure remains uncertain, partly as a result of imprecision in air-based retrospective radon-exposure assessment in epidemiological studies. A recently developed methodology provides estimates for past radon concentrations and involves measurement of the surface activity of a glass object that has been in a subject's dwellings through the period for exposure assessment. Such glass measurements were performed for 110 lung cancer subjects, diagnosed 1985 to 1995, and for 231 control subjects, recruited in a case-control study of residential radon and lung cancer among never-smokers in Sweden. The relative risks (with 95% confidence intervals) of lung cancer in relation to categories of surface-based average domestic radon concentration during three decades, delimited by cutpoints at 50, 80, and 140 Bq m(-3), were 1.60 (0.8 to 3.4), 1.96 (0.9 to 4.2), and 2.20 (0.9 to 5.6), respectively, with average radon concentrations below 50 Bq m(-3) used as reference category, and with adjustment for other risk factors. These relative risks, and the excess relative risk (ERR) of 75% (-4% to 430%) per 100 Bq m(-3) obtained when using a continuous variable for surface-based average radon concentration estimates, were about twice the size of the corresponding relative risks obtained among these subjects when using air-based average radon concentration estimates. This suggests that surface-based estimates may provide a more relevant exposure proxy than air-based estimates for relating past radon exposure to lung cancer risk.     

Radon action level for high-rise buildings

Radon and its progeny are the major contributors to the natural radiation dose received by human beings. Many countries and radiological authorities have recommended radon action levels to limit the indoor radon concentrations and, hence, the annual doses to the general public. Since the sources of indoor radon and the methods for reducing its concentration are different for different types of buildings, social and economic factors have to be considered when setting the action level. But so far no action levels are specifically recommended for cities that have dwellings and offices all housed in high-rise buildings. In this study, an optimization approach was used to determine an action level for high-rise buildings based on data obtained through previous territory-wide radon surveys. A protection cost of HK$0.044 per unit fresh air change rate per unit volume and a detriment cost of HK$120,000 per person-Sv were used, which gave a minimum total cost at an action level of 200 Bq m(-3). The optimization analyses were repeated for different simulated radon distributions and living environment, which resulted in quite significantly different action levels. Finally, an action level of 200 Bq m(-3) was recommended for existing buildings and 150 Bq m(-3) for newly built buildings.     

Current status of programmes to measure and reduce radon exposure in Irish workplaces.

National legislation, which implements European Council Directive 96/29/EURATOM in Ireland, sets a reference level of 400 Bq m(-3) averaged over any 3 month period for radon exposure in the workplace and also empowers the Radiological Protection Institute of Ireland to direct employers to have radon measurements carried out. This legislation came into effect in May 2000. Radon measurements have already been completed in show caves and other underground workplaces. Between 1998 and 2001, over 33 800 individual radon measurements were carried out in all ground floor offices and classrooms in 3444 schools nationwide as part of a programme undertaken jointly with the Department of Education and Science. Where the average indoor radon concentration in one or more rooms exceeded 200 Bq m(-3), remedial measures were implemented. For concentrations up to 400 Bq m(-3) this involved increased ventilation while for higher concentrations an active sump was normally installed. The results of the survey, as well as the effectiveness of the different remedial strategies, are discussed. In the case of other above ground workplaces, different approaches have been adopted. As a first step, workplaces in two known high radon areas were directed to have radon measurements carried out. This programme had limited success because of problems in obtaining accurate workplace databases and a general lack of awareness on the part of employers of the issues involved. From a sample of 2610 employers directed to measure radon, only 408 actually completed measurements and 37 workplaces were identified as having average 3 month average radon concentrations above 400 Bq m(-3). A total of 1356 employers ignored all correspondence, some of which was sent by registered post and signed for on receipt. Current initiatives are focused on the provision of information and include newspaper advertising as well as publications aimed specifically at both employer and employee representative groups. The ability to provide accurate information that encourages both measurement and remediation is seen as central to an effective radon workplace programme.     

地热田高氡建筑治理与效果评价

目的 探讨地热田高氡房屋氡的来源与治理.方法 α径迹探测器(ATD)分冬夏两个季节测量室内和土壤中的氡浓度.采用γ能谱法测量房屋主体建材放射性核素含量;采用6150 AD/6HX-γ剂量率仪测量房屋主体建材的外照射剂量率;对其中一栋房屋实施土壤减压技术的降氡改造.结果 夏冬季32个房间氡浓度均值分别为(106.4±63...     

The Castleisland Radon Survey-follow--up to the discovery of a house with extremely high radon concentrations in County Kerry (SW Ireland).

In July 2003, a house with a seasonally adjusted annual average radon concentration of 49 000 Bq m(-3) was identified near Castleisland in County Kerry (SW Ireland). The possibility that other houses with similar extreme radon concentrations could be present in the surrounding area triggered the setting up of a localised radon survey, the so-called 'Castleisland Radon Survey' (CRS). To this end, approximately 2500 householders living in four 10 x 10 km2 grid squares from the Irish grid closest to the town of Castleisland were invited to participate. Four hundred and eighteen householders responded to the invitation (17% response rate) and 383 home results were used for further analysis. In the 400 km2 encompassing the four studied grid squares, 14% of the homes were found to have a seasonally adjusted annual average radon concentration above the national reference level of 200 Bq m(-3) while 2% above 800 Bq m(-3). An average radon concentration of 147 Bq m(-3) was calculated. This can be compared with the average radon concentration of 98 Bq m(-3) calculated for the same four grid squares on the basis of 80 measurements carried out during the Irish National Radon Survey (NRS) which was conducted between 1992 and 1997. The fourth highest radon concentration (6184 Bq m(-3)) and three of the ten highest ever measured in Ireland were all identified during the CRS. This shows that localised and targeted radon surveys are an invaluable tool for the identification of homes at highest risk from high radon concentrations. Two of the four grid squares investigated during the CRS are currently designated as high radon areas (defined as areas where 10% or more of all houses are predicted to exceed 200 Bq m(-3)) as predicted by the NRS. A thorough statistical analysis of the CRS and NRS data was carried out and indicated that both datasets could be merged and used to refine the original NRS predictions. The results indicate that two of the four studied grid squares could potentially be redesignated. The practical feasibility and overall benefit of updating the Irish radon map in light of this analysis is described.