Radon Concentration In Indoor Air Research Articles

Short- and long-term gas hazard: the release of toxic gases in the Alban Hills volcanic area (central Italy)

In the Alban Hills area, strong areally diffuse and localised spot degassing processes occur (Tivoli, Cava dei Selci, Solforata, Tor Caldara). The gas comprises a large proportion of CO 2, with minor CH 4, H 2S and Rn. These advective features are generated by fluid leakage from buried reservoirs hosted in the structural highs of the Mesozoic carbonate basement. Gas migration towards the surface is controlled by fault and fracture systems bordering the structural highs of the carbonate formations (e.g. Ciampino high). His release is triggered when the total pressure of the fluid phase exceeds the hydrostatic pressure, thus forming a free gas phase. Furthermore, both the sudden and catastrophic, and slow and continuous gas release at surface, of naturally occurring toxic species (CO 2, H 2S and Rn) poses a serious health risk to people living in this geologically active area. This paper presents data obtained from soil gas and gas flux surveys, as well as gas isotopes analyses, which suggest the presence of a deep origin gas flux enriched in carbon dioxide and minor species (CH 4 and H 2S), as well as a channelled migration of geogas mixtures having a Rn component which is not produced in situ. In regards to the health risk to local inhabitants, it was found that some anomalous areas had been zoned as parkland while others had been heavily developed for residential purposes. For example, many new houses were found to have been built on ground which has soil gas CO 2 concentrations of over 70% and a CO 2 flux of about 0.7 kg m −2 day −1, as well as radon values of more than 250 kBq/m 3. In addition, an indoor radon survey has been conducted in selected houses in the town of Cava dei Selci to search for a possible correlation between the local geology and the radon concentration in indoor air. Preliminary results indicate high indoor values at ground floor levels (up to 1000 Bq/m 3) and very high values in the cellars (up to 250.000 Bq/m 3). It is recommended that land-use planners incorporate soil gas and/or gas flux measurements in the environmental assessment of areas of possible risk (i.e. volcanic or structurally active areas).

Relationship between radon concentrations in indoor air and in soil gas

In the Ljubljana region, 53 schools were selected for measurements of radon concentrations in soil gas close to a school building, and indoor radon concentrations in one of the ground-floor classrooms of each building. The aim was to establish a relationship between radon concentrations in indoor air and in soil gas from the ground on which the building is situated. Soil gas radon concentrations between 2 and 14 kBqm–3 were found. Indoor radon concentrations ranged from 20 to 1,440 Bqm–3, with seven values exceeding 200 Bqm–3. It is concluded that good quality of the construction elements ensure low indoor radon concentration, regardless of high soil gas radon level.

Identification of sources of high radon levels in Slovenian schools.

The sources of radon were investigated in twenty selected schools with high room levels of radiation. A combination of radon measuring techniques was applied: etched track and electret detectors to obtain average indoor air radon concentration. devices to record radon concentration continuously and thus characterise its diurnal variation, and alpha scintillation cells to analyse air from potential sources of radon entry. In some cases, a single strong source was identified (e.g. sinks, sub-floor channels), while in others the poor quality of the basic concrete slab was responsible for high indoor radon concentrations. The combination of etched track and electret detectors and alpha scintillation cells was essential for locating these sources.

Correlation between Short-Term and Long-Term Radon Measurements

In selected kindergartens and schools, long-term average indoor air radon concentrations were measured by twomonth exposure of etched track detectors. Short-term average concentrations were obtained from 7–10 day continuous radon recordings during the exposure of etched track detectors. Only in about 1/3 of cases both averages did agree within ± 20%; otherwise they differ considerably. The assumption that short-term results can substitute for long-term data, which is sometimes made to correct radon exposure estimated on the basis of concentrations obtained by etched track detectors, should therefore be treated with caution.

Radon exposure levels of the staff in the drinking water supply facilities in Bavaria, Germany

Within the framework of a study covering the whole of Bavaria, water supply facilities were investigated as to radon concentrations in groundwater and indoor air and as to the radon exposure levels to which the staff working in these buildings were subjected. An inquiry sheet was sent to all drinking water supply facilities in Bavaria (Germany). Two thousand six hundred facilities were asked to provide detailed information about their facility and the duration of stay and about typical work processes. Over 500 water supply facilities were selected to take a 1-l ground water sample and to expose track-etch detectors in order to get the mean room concentration of the main working places. In addition, for a period of 2 months, the personnel had to wear a track-etch detector whilst they were in the supply facilities in order to get an estimate of their individual exposure level. In the east Bavarian crystalline region, indoor radon gas concentrations of up to 300 kBq/m 3 were observed. About 10% of the processing plant workers of this region get an annual effective dose of more than 20 mSv. The application of effective means to reduce the radon exposure levels of these persons is in progress.

Search for radon sources in buildings — kindergartens

In ten high radon level kindergartens, radon sources were sought by applying a combination of several radon measuring techniques: etched track detectors to obtain average indoor air radon concentration, continuous devices to record radon concentration and see its diurnal variation, and alpha scintillation cells to determine radon concentration in the air entering a room from cracks, holes and sinks in the floor and from under-floor channels. In three cases, a strong local radon source was identified while, in the others, the bad quality of the basic concrete slab was responsible for the high indoor radon concentration.

Radon exposure in Slovenian spas.

Radon and gamma dose rates were surveyed in five Slovenian spas, at Rogaska Slatina, Radenci, Moravci, Podcetrtek, and Catez. Due to effective ventilation systems, the indoor air radon concentration rarely exceeds 200 Bq x m(-3) and is usually lower. Uncer the present operationsal conditions and working regimes of the spas, there is no basis for concern about elevated exposure of personnel to radon.

Evaluation of Natural Radiation in Kestanbol Spa Region

Gamma background radiation measurements were made in the region of Kestanbol Spa, the outdoor and indoor air radon concentrations were measured in Kestanbol spa and in about 50 houses of Koruktasi village, which is located at 1 km from the Spa. The results were evaluated from a radiological point of view. The total annual effective dose received from natural sources by the inhabitants of the village and the workers at the Spa were calculated and compared with the total annual effective dose received by the inhabitants of Istanbul.

Survey of 222Rn concentrations in dwellings and soils in the Dutch Belgian border region.

222Rn levels in dwellings and soil gas have been investigated in the Eijsden-Visé region, located at the Dutch-Belgian border, in order to analyze the relationship between domestic radon levels and soil gas radon levels, in view of the fact that the local geology varies substantially from uranium-rich to uranium-poor rocks and soils. During February 1992, charcoal detectors were exposed for 24 h in 116 dwellings in the township of Visé, a radon prone area in Belgium. As expected, the results show a large regional variation, with an averaged indoor air radon level of 116 Bq m-3. In the nearby township of Eijsden, the Netherlands, an area with a lower radiation level, similar measurements by means of charcoal detectors in 42 dwellings during March 1993, resulted in an averaged indoor 222Rn concentration of 46 Bq m-3. Furthermore, in the same region time-integrated radon measurements were performed in 15 dwellings on different floors. These results indicate that a gradient in indoor air radon concentration exists from basement to upper floor level. In addition, a significant positive correlation has been found between radon gas levels of soils surrounding 26 houses and indoor air radon levels. The variation in indoor air radon levels in the region under study is mainly due to the variation of the radon levels in the soils. A soil gas radon survey is suitable for prescreening of the radon potential of an area taking into account the spatial heterogeneity of the local geology.

Daily variation of the radon concentration indoors and outdoors and the influence of meteorological parameters.

Series of continuous radon measurements in the open atmosphere and in a dwelling, including the parallel measurement of meteorological parameters, were performed over a period of several weeks. The radon concentration in indoor and outdoor air depends on meteorological conditions. In the open atmosphere the radon concentration varies between 1 and 100 Bq m-3, depending on weather conditions and time of day. During time periods of low turbulent air exchange (high pressure weather with clear night sky), especially in the night and early morning hours (night inversion layer), the diurnal variation of the radon concentration showed a pronounced maximum. Cloudy and windy weather conditions yield a small diurnal variation of the radon concentration. Indoors, the average level and the diurnal variation of the indoor radon concentration is also influenced by meteorological conditions. The measurements are consistent with a dependence of indoor radon concentrations on indoor-outdoor pressure differences.

Radon in Outdoor Air in Nevada

Measurements of radon at 50 sites with varying geology indicate that outdoor air in Nevada is comparable to that measured nationwide by Hopper et al. (1991). The statewide median of 15 Bq m-3 (0.4 pCi L-1) is essentially the same as the nationwide median. The range is considerable: from 2.6-52 Bq m-3 (0.07-1.40 pCi L-1). Variations in these measurements can generally be correlated with different concentrations of radon in soils and uranium and its progeny in rocks. Silica-rich igneous rocks (rhyolites and granites) appear to be the main sources of high levels of radon in outdoor air in Nevada. Concentrations of radon in outdoor air generally correlate with levels of radon in soil gas. Measurements taken from heights of 0.5, 1.0, and 2.0 m above the ground suggest that radon in outdoor air reflects the local geology throughout this range of heights. Towns for which > 20% of the homes have indoor-air radon concentrations > 48 Bq m-3 (4 pCi L-1) generally have relatively high soil-gas radon, relatively high outdoor-air radon, or both.

Preliminary Indoor Radon Investigations in Lublin Region, Poland

Indoor air radon concentrations in all kindergartens and play schools in Lublin, Poland, were determined in grab samples by using alpha scintillation cells. In addition, some public buildings and homes in Lublin and several places in Eastern Poland were surveyed for radon. For kindergartens and play schools, the geometric mean was 23 Bq m-3 with a standard deviation of 1.4 Bq m-3, while in public buildings and homes, these values were 26 and 1.6 Bq m-3, respectively.

Widespread apathy and the public's reaction to information concerning the health effects of indoor air radon concentrations

Widespread apathy and the public's reaction to information concerning the health effects of indoor air radon concentrations

Regulatory Focus: EPA's radon study results

Last winter, in cooperation with agencies in 10 states and two metropolitan area counties, EPA measured the indoor air radon concentrations of 14,000 houses, some chosen statistically at random and some by request of the homeowner. Passive measurement methodologies were used, such as exposing a charcoal canister to the air for a few days and allowing the air to migrate in to the charcoal naturally. To reduce dilution of radon by the outside air, the protocol required that the house be shut up; therefore, the study was conducted during winter. The measuring device was placed in the lowest livable area (usually the basement) of each house to maximize potential concentration. It should be noted that these procedures are generally considered to be screening tests because they result in a worst-case measurement rather than a best value. The results of these findings are presented.

A comparison of calculated indoor radiation exposure with the results of measurements

A model has been developed for the calculation of external and internal radiation exposure of the population in dwellings. The model consists of two adjacent rooms on top of a crawl-space. The indoor gamma ray exposure rates and the radon concentrations in indoor air, predicted for a variety of conditions, are compared with observations. Predictions and observations are in reasonable agreement; for the radon concentration the predictions may be around 40% too low.