Table 3 - uploaded by Hardev Singh Virk
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Distribution of radon/thoron in different types of houses
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It is well established that some areas of Himachal Pradesh (H.P.) state of India situated in the environs of the Himalayan mountains are relatively rich in uranium-bearing minerals. Some earlier studies by our group have indicated high levels of radon (>200 Bq m(-3)) in the dwellings. It is in this context that an indoor radon/thoron survey has bee...
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Igarapés são ecossistemas que sofrem intervenções em suas paisagens decorrentes de ações antropogênicas, devido aos processos de urbanização. Por meio da avaliação rápida de diversidade de habitats é possível identificar o estado de conservação desses ambientes. Os protocolos de avaliação rápida (PAR), podem ser utilizados como instrumentos no moni...
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... Further the dwellings are also analyzed based on the floor and walls of the dwellings and the measured average radon and thoron levels are given in Table 2. It is inference that the radon and thoron levels are found to be higher in the dwellings constructed either floor or walls with mud and this findings are consistent with the earlier results 6,32,33 . The difference of the thoron levels between the mud and cement floor, mud and cement wall are relatively higher than radon levels of identical floor and wall, this may be due to the concealing effect of thoron emanation by the cement because of its shot half-life. ...
Elevated levels of radon and thoron in the indoor atmosphere may cause the deleterious effects on the mankind. Mining sites and their environs attract a special interest in radon studies as higher levels are frequently reported in the habitats. In the present study, radon and thoron levels were measured in the dwellings of Buddonithanda, a village in the environs of proposed uranium mining site, with pin-hole (SSNTDs) dosimeters for the period of a year. The measured radon and thoron levels were found to vary widely from 14 to 675 Bq m −3 (geometric mean = 94 Bq m −3) and from 21 to 704 Bq m −3 (geometric mean = 121 Bq m −3), respectively. An attempt was made to understand the large spatial variation of these levels. The seasonal and diurnal variation studies were used in unraveling the behavior of the radioactive isotopes in indoor environment and the same was explained with the help of a simplified mathematical model. Quantification of inhalation dose due to radon and thoron was done with suitable occupancy factors. Radon, being inert gas and radioactive in all of its isotopes, attracts much importance from radiological pollution point of view. The investigations across the globe indicate that half of the average annual natural background radiation dose comes from radon and its isotopes. Out of the various isotopes, the isotopes which are practically significant to the inhalation radiation dose are 222 Rn and 220 Rn, called as radon and thoron. The first one is more abundant, has half-life of 3.8 days and comes from the decay of 226 Ra. The latter has a very short half-life of 55.6 s and comes from the decay of 224 Ra 1. Radon and thoron can enter human body by inhalation and most of the inhaled will be exhaled. However, a small fraction of the concentration of the gases might stuck in the lungs/ respiratory tract and these trapped radioactive elements on successive disintegration emit alpha particles that possibly ionize the lung tissues and results in the lung damage 2,3. Epidemiological studies have confirmed that the exposure to radon in work places and dwellings increase the risk of developing lung cancer. Exposure to indoor radon and its isotopes have been determined to be the second leading cause of lung cancer after tobacco smoking 3. The studies on uranium miners proved to be a positive risk coefficient on health and the measurements of radon and thoron levels are made inevitable in the indoor environment. This attention has been picked up the pace during last few decades and has become a global observable fact. The concentration of radon and thoron gases in the indoors is largely influenced by the materials used for construction, life style of dwellers, geology and meteorological conditions of the study area 4. Generally, the exposure to 222 Rn and its daughter products contribute more to radiation dose than that of 220 Rn 5. However this perception has been changed, due to many systematic investigations across the world during the last few decades suggesting that, the 220 Rn is also significantly contributes to the inhalation dose if the thorium content is rich in materials used for construction and local geology 6-8 .
... Indoor radon investigations have been carried out by several groups [10][11][12][13][14][15][16][17][18] throughout the world to evaluate the source of radon in the indoor environment, to estimate the volumetric radon concentration in living rooms of the residential buildings and workplaces, and to study health hazards due to high exposure to indoor radon. Author's group [19,20] carried out indoor radon survey in the dwellings of Punjab and Himachal Pradesh (India) under a Department of Atomic Energy (DAE) sponsored national project. ...
Indoor radon concentration activity measurement has been considered as a useful parameter in evaluation of health hazards due to radon. The major health hazard is lung cancer attributable to radon in Canada which causes 16% of total lung cancer deaths. The purpose of this study is to determine indoor radon concentration (Bq/m 3) and effective annual dose (mSv/yr) in a residential building. Plastic detector LR-115 Type II has been used for recording alpha tracks emanated by Radon and its progenies. To determine track density, tracks were counted using optical microscope, after etching detector foils of 1.5 cm 2 with 2.5 N NaOH at 55°C for 120 minutes. Radon concentration was estimated using a calibration factor, 0.0344 track.cm-2. d-1 /Bq.m-3. The time interval for indoor radon recording was 45 days and 30 days, respectively. The highest value of radon activity (106.0 ± 7.4 Bq.m-3) was recorded in the basement of our house and the lowest (24.2 ± 2.4 Bq.m-3) on the first floor. The corresponding average annual doses are estimated to be2.05 ± 0.14 and 0.44 ± 0.04 mSv/yr, respectively. These values are within the safe limit proposed by WHO.
... Further the dwellings are also analyzed based on the floor and walls of the dwellings and the measured average radon and thoron levels are given in Table 2. It is inference that the radon and thoron levels are found to be higher in the dwellings constructed either floor or walls with mud and this findings are consistent with the earlier results 6,32,33 . The difference of the thoron levels between the mud and cement floor, mud and cement wall are relatively higher than radon levels of identical floor and wall, this may be due to the concealing effect of thoron emanation by the cement because of its shot half-life. ...
Elevated levels of radon and thoron in the indoor atmosphere may cause the deleterious effects on the mankind. Mining sites and their environs attract a special interest in radon studies as higher levels are frequently reported in the habitats. In the present study, radon and thoron levels were measured in the dwellings of Buddonithanda, a village in the environs of proposed uranium mining site, with pin-hole (SSNTDs) dosimeters for the period of a year. The measured radon and thoron levels were found to vary widely from 14 to 675 Bq m−3 (geometric mean = 94 Bq m−3) and from 21 to 704 Bq m−3 (geometric mean = 121 Bq m−3), respectively. An attempt was made to understand the large spatial variation of these levels. The seasonal and diurnal variation studies were used in unraveling the behavior of the radioactive isotopes in indoor environment and the same was explained with the help of a simplified mathematical model. Quantification of inhalation dose due to radon and thoron was done with suitable occupancy factors.
... where AED ing is the effective dose of ingestion (μSv a -1 ), W in is the ingestion intake rate (230, 330 and 730 L a -1 for infants, children and adults respectively [54]), DCF ing is the ingestion dose conversion factor (23, 5.9 and 3.5 × 10 -9 Sv Bq -1 for infants, children and adults respectively [23]), AED inh is the effective dose of inhalation (μSv a -1 ), R aw is the ratio of Rn in air to Rn in water (10 -4 ) [55], F is the equilibrium factor between Rn and its decay products (0.4) [23,56,57], O is the average indoor occupancy time per person (7000 h y −1 ) [29,58,59] and DCF inh is the inhalation dose conversion factor (9 nSv h) −1 (Bq m -3 ) −1 [23,58]. ...
A comprehensive study was conducted to understand the radon (222Rn) distribution and associated radiation doses to the public in a small tropical river basin partly set in the western slope of the Southern Western Ghats of Kerala, India. Radon, though detected in all the 71 monitored wells (0.17–68.3 Bq L–1), exceeded the maximum contamination level (MCL) of 11.1 Bq L–1 for drinking water recommended by United States Environmental Protection Agency (USEPA) in eight samples from isolated pockets of highland, midland and lowland of the Karamana River Basin (KRB) and found to be well within 100 Bq L–1, the parametric value suggested by the World Health Organization (WHO) and the European Union (EU). The age-wise total annual effective doses (AEDs) of groundwater radon activity ranged from 0.5–208.4 μSv a–1 for infants, 0.4–172.2 for children and 0.5–189.7 μSv a–1 for adults. The results reveal that effective doses due to groundwater radon pose no potential public health risk in the study region. Since there is no previous background information on radon-induced radiation dose in the KRB, this work is a newfangled attempt from a public health point of view.
... The study of indoor radon/thoron levels and inhalation dose to some population of Himachal Pradesh, India was carried out by various workers. Virk and Sharma [2] have observed radon and thoron levels in some villages of Himachal Pradesh in the range 17.4 -140.3 Bq.m -3 } and 5.2 -131.9 ...
Radon and Thoron and their progenies cause potential health hazard to human population. As such a study was conducted in some selected places in the Brahmaputra valley of Assam. The result of indoor radon concentration varies from 39.76 Bq.m-3 to 196.49 Bq.m-3 with an average value 108.53 Bq.m-3. Similar result for thoron varies from 5.55 Bq.m-3 to 111.11 Bq.m-3 with an average value 41.98 Bq.m-3. Progeny concentration for radon varies from 0.14 mWL to 2.34 mWL with an average value 0.41 mWL and that for thoron varies from 0.01 mWL to 0.27 mWL with an average value 0.09 mWL. In the present study we have tried to explore individual influence of each of these components on overall dose. It is observed that compared to radon and its progeny, thoron and its progeny has strong linear dependence on overall dose. Based on multivariate regression analysis with gradient descent, we have modelled to predict the indoor inhalation dose based on input features like-indoor radon concentration, indoor thoron concentration, indoor radon progeny concentration and indoor thoron progeny concentration.
... Radon accumulates in houses, buildings, and workplaces. 2,3 Radon exhalation rate is crucial in the estimation of radiation risk from various materials. [4][5][6][7] Radon exhalation rate can be measured in open loop arrangement with a ventilation-type accumulation chamber. ...
Generally, 88% of the freshly generated 218Po ions decayed from 222Rn are positively charged. These positive ions become neutralized by recombination with negative ions, and the main source of the negative ions is the OH− ions formed by radiolysis of water vapor. However, the neutralization rate of positively charged 218Po versus the square root of the concentration of H2O will be a constant when the concentration
of H2O is sufficiently high. Since the electron affinity of the hydroxyl radical formed by water vapor is high, the authors propose that the hydroxyl radical can grab an electron to become OH−. Because the average period of collision with other positively charged ions and the average life of the OH− are much longer than those of the electron, the average concentration of negative ions will grow when the water vapor concentration increases. The authors obtained a model to describe the growth of OH− ions. From this model, it was found that the maximum value of the OH− ion concentration is limited by the square root of the radon concentration. If the radon concentration is invariant, the OH− ion concentration should be approximately a constant when the water vapor concentration is higher than a certain value. The phenomenon that the neutralization rate of positively charged 218Po versus the square root of the water vapor concentration will be saturated when the water vapor concentration is sufficiently high can be explained by this mechanism.
This mechanism can be used also to explain the phenomenon that the detection efficiency of a radon monitor based on the electrostatic collection method seems to be constant when the water vapor concentration is high.
... The twin cup dosimeters (Fig. 2) employed for mixed radon, thoron, and their progeny measurements have been developed and standardized at BARC and reported elsewhere (Mayya et al. 1998; Virk and Sharma 2002; Eappen and Mayya 2004). It consists of two chambers; each chamber has a length of 4.5 cm and a radius of 3.1 cm. ...
... The concentrations of radon and thoron gases were calculated using the following modified equations reported elsewhere (Mayya et al. 1998; Virk and Sharma 2002; Khan and Azam 2012): The detector 3 exposed externally (i.e., bare mode exposure) registers the tracks of radon, thoron, and their a-emitting progenies present in the ambient air. The cup detector sensitivity for radon is close to that of the bare detector. ...
Radon, thoron, and their progeny are largest
contributors to the radiation dose received by human
beings present in the natural environment. The indoor
radon depends upon many factors such as building materials,
meteorology, ventilation, and occupant’s behavior.
This paper presents the measurements of indoor radon,
thoron, and their progeny in four villages in rural area of
district Kanshiram Nagar (Kasganj) in the state of Uttar
Pradesh in Northern India. The concentration of indoor
radon and thoron varies from 10.32 to 72.24 and 11.61 to
84.49 Bq m-3 with a geometric mean (GM) of 29.49 and
31.20 Bq m-3, respectively. The concentration of radon
and thoron daughters was found to vary from 1.11 to 7.80
and 0.31 to 2.28 mWL, respectively. The annual exposure
due to radon and thoron mainly vary from 0.05 to
0.30 WLM. The preliminary results (i.e., bare mode
exposure of the LR-115 detectors fixed on cards) of this
study have been separately published and compared this
recent data with those results.
... Radon accumulates in houses, buildings, and workplaces. 2,3 Radon exhalation rate is crucial in the estimation of radiation risk from various materials. [4][5][6][7] Radon exhalation rate can be measured in open loop arrangement with a ventilation-type accumulation chamber. ...
A novel method was proposed to measure the radon exhalation rate in only one measurement cycle. We obtain the radon concentration variety regulation in the internal cell of the RAD7 by analyzing the work principle of RAD7 and the radon concentration variety regulation in the ventilation-type accumulation chamber when the effects of leakage and back diffusion are neglected. This method uses the measured value before the radon concentration in the ventilation-type accumulation chamber reaches a steady state. Several radon exhalation rate measurements of the medium surface have been performed in the Radon Laboratory of the University of South China. The radon exhalation rates obtained by verification experiments are in good agreement with the reference value. This simple, accurate and fast method can be applied to develop and improve the instruments for measuring radon exhalation rates.
... Moreover, there are several reports of radioactive mineralization (not ore deposits) within (Parvati Valley) the study area as well as in similar geotectonic setup elsewhere in Lesser Himalaya ( Das et al. 1972Das et al. , 1979Nashine et al. 1982;Sharma et al. 1983). Radon exposure studies have been carried out in several parts of the Himachal Himalaya in a variety of medium like indoor air, soil and water (Singh et al. 2002;Virk and Sharma 2002;Walia et al. 2003), with special emphasis on its environmental aspects. However, very little attention was given on its geological controls. ...
Radon measurements in soil and groundwater (springs, thermal springs and handpumps) were made in a variety of lithological
units including major thrusts between Mandi and Manali in Himachal Himalaya. Analysis of radon data in light of lithological
controls and influence of deep-seated thrusts has been made to elucidate the causative factors for anomalous emanation of
radon. The lithological types include banded gneisses, schists, quartzite, granite, phyllites, volcanics and mylonites. The
low-grade metasedimentries of Shali and Dharamsala generally show low and narrow range of radon concentration in water (5.6–13.4Bq/l)
as well as in soil (1.8–3.2kBq/m3) except for the samples related to thrusts. On the other hand, sheared and deformed rocks of Chail and Jutogh show moderate
radon content (average 5.03kBq/m3, range 2.9–11.1kBq/m3) in soil. However, the groundwater radon concentration shows wide variation in different types of sources (2.1–80.8Bq/l).
The quartzite and volcanic rocks of Rampur formation in this area present as a window separated by Chail thrust. Radon emanations
on these rock types are relatively high (6.3–68.1Bq/l in water and 5.5–15.9kBq/m3 in soil) and are exceptionally high in samples that are related to uranium mineralization, deep-seated thrusts and hot springs
(13.5–653.5Bq/l). It is generally observed that anomalous high radon content is associated with mineralization, deeper source
and tectonic discontinuities. Whereas it is obvious that subsurface radioactive mineralization would facilitate enhanced radon
production, however, thrust plains provide easy pathways for escape of gases from the deeper sources. Shallow and deep sources
of the groundwater have contrasting radon content particularly in the deformed and metamorphosed rocks of Jutogh and Chail.
Shallow groundwater sources, mainly handpumps, have lower radon concentration due to limited superficial water circulation,
whereas deeper sources, mainly perennial springs, show higher radon content because of larger opportunity for water–rock interaction.
Study compares radon and thoron levels in dwellings near Kasimpur Thermal Power Plant, Aligarh. In First Rampur Village (RP-1–RP-12), radon ranges from 3.2 to 13.2 Bq m−3, thoron from 1.4 to 11.2 Bq m−3, with inhalation doses from 0.13 to 0.53 mSv y−1. In Talib Nagar (TN-13–TN-20), radon varies from 4.5 to 35.8 Bq m−3, thoron from 3.1 to 6.1 Bq m−3, with doses from 0.21 to 1.00 mSv y−1. Satha Village (ST-21–ST-31) shows radon from 2.2 to 13.7 Bq m−3, thoron from 3.1 to 12.3 Bq m−3, with doses from 0.13 to 0.55 mSv y−1, all within WHO’s 100 Bqm−3 safety limit.
