Radon levels assessment in some Northern Romanian salt mines

Due to their low radioactivity background, underground salt mines spaces offer a unique possibility for speleotherapy use. The knowledge of radon concentration levels in such underground environments is essential for therapeutic purposes of different respiratory and rheumatic diseases. In order to develop speleotherapy in Romania, this paper presents the results of an indoor radon concentration levels survey in some salt mines in Romania. The survey was carried out using radon monitor Pylon AB-5 system methodology validated by a CIS-P5M system. In order to investigate whether differences in depth and microclimate parameters translate into significant differences in salt mine indoor radon concentrations, have been chosen three salts mine test sites placed in the Northern part of Romania (Turda, Cacica and Ocna Dej) in stable areas of the mining field at 32?C120?m depth. Environmental microclimate conditions (mean values of air temperature 10?C14.5?°C, air humidity 65?C80%, air velocity 0.2?m/s saline aerosols and low microbial factors) have anti-bacterial, anti-microbial, and anti-inflammatory properties and recognized therapeutically effects on human body??s health. Air temperature is one of the most important factors which need to be considered when carrying out a survey of indoor radon concentrations in salt mines because temperature largely determines close spaces ventilation rates, and ventilation habits are known to have significant effects on indoor radon concentrations. The analyzed environmental conditions and recorded low levels of indoor mean radon concentration (6.9?±?0.39 and 96.5?±?4.76?Bq/m³) demonstrated the best suitability of the investigated three salt mines in Romania for speleotherapeutic applications.     

成都市某人口密集区室内氡水平及其影响因素

分析了成都市某人口密集区室内氡水平的调查结果及其影响因素。结果表明,室内氡水平主要取决于通风条件;不同的楼层高度、气候条件也会影响氡的水平;室内氡水平分布还呈现日变化规律。     

Superheavy nuclei and hypernuclei: extending the limits of the nuclear chart

In this study, a tubular radon removal device and a movable one were prepared and investigated. The tubular radon removal device in an air conditioning return air system reduced the radon progeny by more than 84%. The radon progeny concentration reached equilibrium after 4 h when it was used only for a ventilation at the rate of 10 h⁻¹. Radon progeny removal efficiency was above 95% for the movable radon removal device, when the ventilation rate was 17 h⁻¹. The results showed that the radon removal devices can effectively remove the radon progeny in the air.

     

Investigation of radon and thoron concentrations in a landmark skyscraper in Tokyo

The temporal variation of the radon concentration, and the radon and thoron concentrations every 3 months for a year were measured using two types of devices in a landmark skyscraper, the Tokyo Metropolitan Government Daiichi Building. In the measurement of temporal variation of the radon concentration using a pulse type ionization chamber, the average radon concentration was 21 ± 13 Bq m^?3 (2–68 Bq m^?3). The measured indoor radon concentration had a strong relationship with the operation of the mechanical ventilation system and the activities of the office workers. The radon concentration also increased together with temperature. Other environmental parameters, such as air pressure and relative humidity, were not related to the radon concentration. In the long-term measurements using a passive radon and thoron discriminative monitor, no seasonal variation was observed. The annual average concentrations of radon and thoron were 16 ± 8 and 16 ± 7 Bq m^?3, respectively. There was also no relationship between the two concentrations. The annual average effective dose for office workers in this skyscraper was estimated to be 0.08 mSv y^?1 for 2000 working hours per year. When considering the indoor radon exposure received from their residential dwellings using the annual mean radon concentration indoors in Japan (15.5 Bq m^?3), the annual average effective dose was estimated to be 0.37 mSv y^?1. This value was 31 % of the worldwide average annual effective dose.     

Radon survey in office room and effective dose estimation for staff

This study aims to: (1) Acquire the radon level in closed office rooms, providing radon exposure data for preliminary health risk assessment of office-working population. (2) Pre-analyze the relationship between radon concentration and indoor temperature, relative humidity. (3) Estimate seasonal, annual and total radon effective dose for ordinary office-working population. The results show that the 24-h or 8-h average radon concentrations in closed office rooms were about 32.0 Bq/m³ and 29.5 Bq/m³ during detection period, and the estimated effective doses in office rooms calculated by using 24-h and 8-h average radon concentrations were all far below that in residential environment.

     

A case study on the effect of water from groundwater sources on indoor radon levels

Indoor airborne radon concentration released from water was estimated over several months based on experimental measurements. When heated water including radon was used, the radon level became high in the entire house. Filling the bathtub with hot water had a strong effect on the indoor radon level. In winter, the indoor radon concentration was high due to windows being closed. The radon transfer coefficient was estimated 2.5·10⁻⁴ in this test house. This is 2.5 times higher than the average radon transfer efficiency estimated by UNSCEAR.     

222Rn determination in drinkable waters of a central eastern Italian area: Comparison between liquid scintillation and gamma-spectrometry

Summary It is well known that the interest in radon concentration indoor as a pollutant emerged during the energy crisis of seventies which led to reduce ventilation in dwellings. Recently the Euratom Recommendation 2001/928 suggested the necessity of performing frequent ²²²Rn checks on tap waters. As a consequence of this Recommendation, Urbino and Perugia Universities carried out a preliminary ²²²Rn determination on tap waters of the Pesaro-Urbino province. Samplings were carried out in twenty-eight sites and radon concentration was determined by liquid scintillation counting and gamma-spectrometry. The results obtained by the two techniques were comparable (the deviation from the mean is lower than 10% for 54.5% of the samples). The resulted ²²²Rn concentration was very low (5 Bq ^. l^-1 for 43% of the samples) and, therefore, radon in waters cannot be considered as a direct radiological risk for the local population.     

Effects of negative ion generators on radon- and thoron-progeny concentrations in an occupied residence

Operation of negative ion generators in three rooms of an occupied residence caused decreases in indoor concentrations of the radon decay products²¹⁸Po,²¹⁴Pb and²¹⁴Bi, and of the thoron progeny²¹²Pb. Activity levels of²¹²Pb were lowered more than those of²¹⁴Pb, resulting in a decrease in the potential alpha energy concentration ratio, PAEC(Tn:Rn). The change in PAEC(Tn:Rn) is a function of the halflives of²¹⁴Pb and²¹²Pb and their respective precursors and is similar to the effect brought about by increased room ventilation. Decay products are also removed from indoor air by plateout of charged particles on room walls. Plateout rates calculated for²¹⁴Pb suggest that even in well-ventilated houses, the potential alpha energy concentration of radon is affected as much by wall plateout as by infiltration of outside air.     

Influence of ventilation on the reduction of the radon concentration in an underground research facility

The concentration of radon in an underground research facility (URF) was measured by setting up 12 sampling points in the URF and with 3 different measurement methods. All the methods were calibrated in the radon laboratory of the No. 6 Institute of Nuclear Industry. The accumulation of radon in the URF was observed before a ventilation system was applied. The reduction of radon concentration in the URF by 1-hour ventilation was also observed. Experimental result indicates that the concentration of radon in the URF increased from 15 to 50 Bq·m⁻³ in 5 days without ventilation, and decreased to less than 10 Bq·m⁻³ with 1-hour ventilation. Applying the average working time of 4 hours per day of the workers in the URF, the additional effective dose is 0.75 msv·y⁻¹ when 1 hour ventilation is applied before entering the URF and 13 mSv·y⁻¹ without ventilation. These figures strongly suggest that for the health of the workers, ventilation in such underground research facilities is needed.     

Radon and thoron concentrations in offices and dwellings of the Gunma prefecture, Japan

Summary Aone year survey of indoor radon and thoron concentrations was carried out in offices and dwellings of the Gunma prefecture, Japan. A passive integrating radon and thoron discriminative monitor was used in the survey. The annual mean radon concentration was 22±14 Bq ^. m^-3, and ranged from 12 to 93 Bq ^. m^-3 among the 56 surveyed rooms. Radon concentration in offices was generally higher than that in the dwellings, with the arithmetic averages of 29 and 17 Bq ^. m^-3, respectively. Radon concentrations were generally lower in the traditional Japanese wooden houses than those houses built with other building materials. Seasonal variation of indoor radon was also observed in this survey. Compared to summer and autumn, radon concentrations were generally higher in spring and winter. The mean value of thoron to radon ratio was estimated to be 1.3, higher values were observed in the dwellings than in the offices. The annual effective dose from the exposure to indoor radon was estimated to be 0.47 mSv after taking the occupancy factors of offices and dwellings into account.     

Indoor radon concentration survey in Mexico

Indoor radon evaluations in specific regions of the country have been performed in an effort to assess the magnitude of the radon problem and its public health consequences. The survey of this paper covers four large non-tropical regions of north and central Mexico, and reports the results of measurements of indoor radon concentrations in houses of towns with between 100,001 and 500,000 inhabitants. The measurements were done by using passive detectors, namely, the closed-end-cup system with CR-39 polycarbonate chips as detector material. The measurements were performed throughout the two coldest seasons (between 5 and 20°C), winter and spring, in integration periods of 28 days covering the six month cycle. The results show a moderate average radon concentration below 200 Bq·m⁻³ with occasional higher values. This is very probably due to the climate conditions and the traditional habits of open door and window ventilation. The IFUNAM (Instituto de Física, Universidad Nacional Autónoma de México) Laboratory, where the closed-end cup system for radon was developed, has gained experience though this survey and is willing to share it for future surveys at regional or national levels.     

Calibration coefficient of the SSNTD and equilibrium factor for radon

Disintegration, ventilation and deposition were considered as removal processes of the radon and its short-lived daughters in air and the respective concentration equations were applied. Calibration coefficient (K_F) of the solid state nuclear track detector (SSNTD) LR-115 for radon and the equilibrium factor (F) were related to track densities of the bare detector (D) and the filtered one (D_o). A useful relationship between K_F, F and detector sensitivity coefficient (k) was derived. Using the calibrated value k=3.29×10^–3 m, the exposed detectors gave the average values of the equilibrium factor, calibration coefficient and indoor radon concentration of a single house living room in Osijek 0.46, 142.3 m^–1 and 37.8 Bq m^–3, respectively.     

Field measurement of the <Superscript>218</Superscript>Po, <Superscript>214</Superscript>Pb and <Superscript>214</Superscript>Bi concentrations in typical indoor and outdoor environments in Beijing

The activity concentrations of ²¹⁸Po, ²¹⁴Pb and ²¹⁴Bi [i.e. C(²¹⁸Po), C(²¹⁴Pb), and C(²¹⁴Bi)] and the calculated concentration ratios [i.e. 1:C(²¹⁴Pb)/C(²¹⁸Po):C(²¹⁴Bi)/C(²¹⁸Po)] are necessary for assessing radon and its progenies exposure. In this study, a measurement method of radon progenies concentrations with both high sensitivity and low uncertainty, was developed based on the Kerr method. The field measurement results of radon progeny concentrations and calculated concentration ratios in both typical indoor and outdoor environments in Beijing, China, were reported. The effects of air exchange rate on concentration ratios of radon progenies in indoor environments were discussed.     

Industrial commercial respirator filter as indoor radon monitor

This paper presents a method for measuring indoor radon concentrations using a commercially available air-purifying respirator filter as a component of the radon monitor. The filter used was Survivair’s NIOSH (National Institute for Occupational Health and Safety)-approved 100800 model. The method is based on the diffusion of radon gas into the activated carbon of the filter and the measurement of the radioactive daughters resulting from the radon decay. The photopeaks of the ²¹⁴Bi daughter gamma rays (0.609 MeV) were analyzed with a Hyper-Pure Germanium (HPGe) detector and a multichannel system. A monotonically increasing and very close to linear response relation between the integrated area under the ²¹⁴Bi photopeak and the radon concentration of the activated carbon was found. A well-defined relation held for radon levels ranging from 15 to 4,700 Bq/m³. This procedure results in highly reproducible and reliable measurements of indoor radon levels. Interesting applications include the investigation of radiological accidents involving radon and the retrospective measuring of indoor radon concentrations by analyzing the filters of the respirators worn by personnel working during the relevant period.     

The fluctuations of indoor radon measurements from the building materials in a real situation

In this study, we have investigated the fluctuations of radon levels in two experimental rooms constructed for secondary standard dosimetric calibration. The values over the short-term (the first two weeks) were in the range of 10–14 pCi/L of radon in air, while those of the long-term were between 6–14 pCi/L of radon. Even though the temperature and humidity was relatively constant during the second half of the rainy season, there was a trend towards lower radon values. It is concluded that ventilation is an important factor in indoor radon levels.     

Radon and thoron progeny levels in air samples at Udagamandalam region of Nilgiris in India

Measurement of concentration of radon and thoron daughter products in various indoor environment covering four seasons of a year in Udagamandalam Taluk of Nilgiris biosphere has been carried out using a high volume air sampler to asses the inhalation dose to the population which delivers higher dose than the radon and thoron gas alone. The potential alpha-energy concentrations of the radon and thoron progeny ranged from 0.97 to 12.72 mWL and from 1.63 to 15.83 mWL with a geometric mean of 6.02 and 7.89 mWL, respectively, taking all seasons into account. These measurements have yielded a wealth of data on the variation among the indoor radon and thoron progeny in various places during different seasons. The radon and thoron progeny levels are higher in winter seasons and are less in summer season with autumn and spring data lie in between winter and summer. Using the dose conversion factor for indoor exposures given in UNSCEAR 93 report the internal equivalent dose to the inhalation of radon progeny is evaluated to be 1357 mSv^.y^–1 and the corresponding annual effective dose equivalent value has been found to be 2.13 mSv^.y^–1. It can be observed that the mean value of radon is higher than the Indian average. Also it is found the radon and thoron progeny levels are higher in the case of houses built with rock and granite and in tiled type houses of nearly 100 years old. The levels are less in the case of houses built with brick and cement. The observed results for different types of houses and seasons are discussed in this paper.     

Gamma radiation and radon levels in Mexico City dwellings

Gamma exposure rate and radon levels were measured in 75 single-family dwellings in Mexico City in order to correlate them with local environment. Radon monitoring was performed both indoors and outdoors using a continuous working level monitor for short-lived radon decay products; the gamma exposure rate was measured using CaSO₄: Dy+PTFE. The results obtained show a log-normal distribution. The mean indoor radon concentration is lower than 45 Bq/m³ and the mean indoor gamma exposure rate was 11.29 R/h.     

Indoor radon measurement in Izmir Province,Turkey

In 2013, an extensive study was performed in a total of 117 locations in Izmir province and indoor radon levels were measured using the alpha track etch integrated method with LR-115 detectors. As the maps are more practical to interpret the results of radiological survey, the distributions of indoor ²²²Rn activities in four most densely populated districts of Izmir were mapped in detail. It is seen that the estimated average radon concentration level (210 Bq m^?3) determined in Izmir province was almost three times higher than the mean value for Turkey (81 Bq m^?3). Exposed annual effective dose equivalents for Izmir province were estimated in the range of 0.7 to 12.3 mSv year^?1 with a mean of 5.3 mSv year^?1. In this study, it is pointed out that indoor radon concentration was affected by the age of the building and height above the ground.     

Radon concentration in drinking water in villages nearby Rafsanjan fault and evaluation the annual effective dose

Abnormal amount of radon in water results in increasing health risks. Concentrations of ²²²Rn in 56 samples of drinking water resources, in villages surrounding “Rafsanjan fault” were measured in the fall of 2013. Range radon concentration is 0 and 18.480 BqL^?1, respectively. The maximum annual effective dose for adults and children were 181.5 and 248.95 μSvY^?1, respectively, and the lowest was zero for both groups. Radon concentration is higher on the right side of the fault than the left side. In order to reduce the radon concentration, water ventilation is recommended before use.     

Enhanced indoor radon concentration by using radon-rich well water in a Japanese wooden house in Fukuoka, Japan

Summary Radon measurements were carried out in a Japanese wooden house built on granitic geology, where radon-rich well water is used. Atmospheric radon concentrations were measured over one year with passive integrated radon monitors. The monitors were distributed at several locations in the house and were replaced every two months. In order to confirm the diurnal variation and heterogeneous distribution of radon, short-term measurements were carried out accordingly. Radon, its decay products and terrestrial gamma-radiations were measured in this survey. From the long-term measurement, the radon concentration in the house ranged from 14 to 184 Bq^. m^-3with an arithmetic mean of 45 Bq^. m^-3. A radon concentration of 184 Bq^. m^-3was observed in the bathroom in spring (March-May) though the radon level was normal in the living room and bedroom. In order to characterize the house, similar measurements were conducted in several surrounding houses. There was a significant difference in radon concentration between the investigated houses. There was a spatial distribution of the radon concentration and the highest value was found in the bathroom. Radon and its decay products concentrations varied with time, which increased from midnight to morning whereas they decreased during daytime. Although the radon concentration in tap water was 1 Bq^. l^-1, a high level of 353 Bq^. l^-1was found in the well water.While well water was being used, the indoor radon concentration near the bathroom increased rapidly with a maximum value of 964 Bq^. m^-3. It is clear that the use of well water enhanced the radon level around the bathroom.