Mean Radon Activity Research Articles

Preliminary studies on soil radon activity at geothermal hotspot of Bakreswar-Tantloi

Bakreswar-Tantloi region of India, besides being a geothermally active region, also harbours a high amount of Radon in soil-gas and groundwater of the region. Measurement of Radon-content across the region is an active area of research aimed to properly understand the geothermal potential of the region, the study of local geology and to determine the risks of Radon exposure in the area. In an aim to evaluate the Radon potential of this important geothermal hub, we have done a pilot study on the region by doing spot measurements of Soil-Radon activity in 41 specific geographic locations spread out across the region of interest which will act as groundwork for further in-depth analysis. The measurements showed that Radon activity varies widely in the region with the Radon activity ranging from 1 to 52 across the measured locations. Mean Radon activity across the measured locations was found to be 16 with standard deviation of the sample set of 14 Seven locations recorded Radon activity to be greater than standard deviation from average while four locations recorded Radon activity greater than twice the standard deviation from average.

Radon Activity in Volcanic Gases of Mt. Etna by Passive Dosimetry

AbstractRadon (222Rn) activity in air was measured for about 6 months at the summit of Mt. Etna Central Crater (Sicily) by integrative radon dosimetry at two different heights above ground level (5 cm and 1 m). This technique for air radon monitoring proved operational in the harsh volcanic environment of Mt. Etna summit with a 94% recovery rate of dosimeters. In the southeast sector exposed to the main gas plume, mean radon activity in free air (height 1 m) is significantly higher than the local background and the ground level activity (height 5 cm). The results strongly suggest that the plume is enriched in radon by ≈550 Bq/m3, which has never been evidenced before. Radon activities also reflect soil degassing occurring in the proximity of the crater, with increased ground level activities in zones of enhanced soil fracturing and degassing. Radon measurements also revealed a hot spot in front of the Voragine vent with extraordinary high levels of air activities (26 kBq/m3 at ground level and 8 kBq/m3 in free air). The temporal variation of radon activity was investigated by replacing a few stations half way through the exposure period. The only significant increase was associated with the site located under the main gas plume and correlated with eruptive unrest within the crater. Finally, air radon levels higher than the recommended threshold of 300 Bq/m3 were detected in several zones on the rim and could generate a nonnegligible radiologic dose for workers on the volcano.

Occurrence of radon contamination in ground water samples of Amritsar city, Punjab, India

In the current examination, the ingestion and inhalation dose measurements for the particular body organs in light of the intake of radon through ground water used by the inhabitants have been surveyed in the various locations of Amritsar province, India, using an electrostatic collection type radon monitor (RAD7) analyzer with RAD-H2O accessory. The mean radon activity level in water was seen to be 5.93 ± 2.34 BqL-1. However, the radiation dose received by all different body organs significantly less than the UNSCEAR and WHO suggested a level of 100 μSvY-1. The annual effective dose for the diverse body organs in view of the intake of radon was additionally ascertained and found the maximum dose for lungs than other organs. The radiation dose received by bronchial epithelium by the means of inhalation was likewise high when contrasted with that by stomach walls through ingestion.

INGESTION AND INHALATION DOSES DUE TO INTAKE OF RADON IN DRINKING WATER SAMPLES OF AMRITSAR PROVINCE, PUNJAB, INDIA.

In the present investigation, the ingestion and inhalation dosage for the particular body organs in light of the intake of radon through ground water utilised by the occupants have been assessed in the different villages of the Upper Bari Doab region of Amritsar province, India using an electrostatic collection type radon monitor (RAD7) analyzer with RAD-H2O accessory. The mean radon activity level in water was seen to be 8.34 ± 2.99 Bql-1. The newborn children have higher radiation dosage than the other age groups because of their high dosage transformation factors. However, the radiation dosage received by all different age groups significantly less than the UNSCEAR and WHO suggested a level of 100 μSv y-1. The annual effective dosage for the diverse body organs because of the intake of radon was moreover ascertained and found the maximum dosage for lungs than other organs. The radiation dosage received by bronchial epithelium by the means of inhalation was likewise high when contrasted with that by stomach walls through ingestion.

Characterising fifteen years of continuous atmospheric radon activity observations at Cape Point (South Africa)

This paper describes and discusses fifteen years (1999–2013) of continuous hourly atmospheric radon (222Rn) monitoring at the coastal low-altitude Southern Hemisphere Cape Point Station in South Africa. A strong seasonal cycle is evident in the observed radon concentrations, with maxima during the winter months, when air masses arriving at the Cape Point station from over the African continental surface are more frequently observed, and minima during the summer months, when an oceanic fetch is predominant. An atmospheric mean radon activity concentration of 676 ± 2 mBq/m3 is found over the 15-year record, having a strongly skewed distribution that exhibits a large number of events falling into a compact range of low values (corresponding to oceanic air masses), and a smaller number of events with high radon values spread over a wide range (corresponding to continental air masses). The mean radon concentration from continental air masses (1 004 ± 6 mBq/m3) is about two times higher compared to oceanic air masses (479 ± 3 mBq/m3). The number of atmospheric radon events observed is strongly dependent on the wind direction. A power spectral Fast Fourier Transform analysis of the 15-year radon time series reveals prominent peaks at semi-diurnal, diurnal and annual timescales. Two inter-annual radon periodicities have been established, the diurnal 0.98 ± 0.04 day−1 and half-diurnal 2.07 ± 0.15 day−1. The annual peak reflects major seasonal changes in the patterns of offshore versus onshore flow associated with regional/hemispheric circulation patterns, whereas the diurnal and semi-diurnal peaks together reflect the influence of local nocturnal radon build-up over land, and the interplay between mesoscale sea/land breezes. The winter-time diurnal radon concentration had a significant decrease of about 200 mBq/m3 (17%) while the summer-time diurnal radon concentration revealed nearly no changes. A slow decline in the higher radon percentiles (75th and 95th) for the winter and spring seasons is found over the 15-year data set, with most of the change occurring in the first 9 years (1999–2007). This observed inter-annual decline appears to be associated with changes in the frequency of air masses having originated from over the African continental surfaces, and no significant trend is found in the lower radon percentiles associated with oceanic air masses. The general decrease of atmospheric radon-associated with continental air-masses at Cape Point could be attributed to changing meteorological conditions, possibly driven by climate change.

Natural radioactivity levels in the soils and human risk assessment in Tiruchirappalli district (Tamil Nadu, India)

The activity concentrations of 226Ra, 232Th and 40K in 91 soil samples collected from proposed housing sites in Tiruchirappalli district were measured using gamma ray spectrometer, 222Rn activity using SSNTD technique and ambient absorbed gamma dose employing hand held scintillometer. The mean activity concentrations of 226Ra, 232Th and 40K were found to be 6.5, 61.7 and 379.8 Bq kg−1, respectively. The mean ambient gamma dose rate was 66.7 nGy h−1 and the mean radon activity 210.8 Bq m−3. The study identified two stations in which Raeq levels exceeded the permissible limit (370 Bq kg−1).

Spatio-temporal Variation in Radon Concentration in Groundwater with Respect to Rock Types: A Case Study from Chitradurga District, Karnataka

Abstract: An attempt was made in the present study to delineate how the radon concentrations vary with respect to different geological formations and to evaluate annual effective dose exposure due to ingestion of radon. A total of 60 groundwater samples were collected from layered sequential aquifers in Chitradurga district having major rock types such as Bababudan Group, Charnockite, Chitradurga Group, Closepet granite, migmatites and granodiorite – tonalitic gneisses and Sargur Schist complex during pre-monsoon and post-season of the year 2011. Radon measurement was made using Durridge RAD-7 radon-in-air monitor, connected to RAD H2O accessory with closed loop aeration concept. In the present study, the radon activity ranged from 0 to 186.6 Bq/L and 0 to 150.6 Bq/L during pre- and post-monsoon seasons of the year 2011, with 56.67 % (17 samples) of samples during both the seasons exceeding the EPA’s MCL value of 11.1 Bq/L. The annual mean radon activity in the groundwater was higher in the area having Chitradurga rock group formations (78.1 Bq/L) followed by Sargur-Satyamangalam schist complex group (56.8 bq/L), migmatites and granodiorite – tonalitic Gneisses group (56.3 Bq/L), Closepet granite (42.7 Bq/L), Charnonkite (29.1 Bq/L) and Bababudan Group (22.2 Bq/L). It is inferred that radon concentration found to depend on the tectonic structure, geology of the area and on the presence of uranium minerals in these rocks. The annual effective dose resulting from radon in groundwater in the Chitradurga district were significantly lower than UNSCEAR and WHO recommended limit of 1 mSv/y.

Indoor radon levels in workplaces of Adapazarı, north-western Turkey

The main objective of this study is to assess the health hazards due to radon gas accumulation and to compare the concentrations in different kinds of workplaces, in the city of Adapazarı, one of the most important industrial cities of Turkey. For this purpose, radon activity concentration measurements were carried out in schools, factories, offices and outdoors using CR-39 solid state nuclear track detectors (SSNTD). Results show that the mean radon activity concentrations (RAC) in schools, offices and factories were found to be 66, 76 and 27 Bq/m3, respectively, with an outdoor concentration of 14 Bq/m3. The average concentrations were found to decrease as follows for different types of industries: automotive > electronic > metal > textile. Because the maximum measured radon concentrations are 151 Bq/m3 in the schools, 173 Bq/m3 in the offices and 52 Bq/m3 in the factories, the limits of ICRP are not exceeded in any of the buildings in the region. In addition, the estimated mean annual effective doses to the people in the workplace, students, office workers and factory workers have been calculated as 0.27, 0.63 and 0.20 mSv/y, respectively for the region.

Determination of the radiation dose due to radon ingestion and inhalation

The distribution of radon in ground and surface water samples in Sankey Tank and Mallathahalli Lake areas was determined using Durridge RAD-7 analyzer with RAD H2O accessory. The radiation dose received by an individual falling under different age groups (viz., 3 months; 1, 5, 10, 15 years and adult) depending upon their average annual water consumption rate was attempted. The mean radon activity in surface water of Sankey Tank and Mallathahalli Lake was 7.24 ± 1.48 and 11.43 ± 1.11 Bq/L, respectively. The average radon activities ranged from 11.6 ± 1.7 to 381.2 ± 2.0 Bq/L and 1.50 ± 0.83 to 18.9 ± 1.59 Bq/L, respectively, in 12 groundwater samples each around Sankey Tank and Mallathahalli Lake areas. Majority of the measured groundwater samples (viz., 100 % in Sankey Tank area and 75 % in Mallathahalli Lake area) showed mean radon values above the EPA’s maximum contaminant level of 11.1 Bq/L and only 66.67 % of samples in Sankey Tank area showed radon above the WHO and EU’s reference level of 100 Bq/L. The overall radiation dose due to radon emanating from water in the study area was increasing with increase in age and water consumption rates, but significantly lower than UNSCEAR and WHO recommended limit of 1 mSv/year except for few groundwater samples in Sankey Tank area (i.e., 0.92, 0.99 and 1.39 mSv/year). The radiation dose rate received by bronchial epithelium via inhalation was very high compared to that by stomach walls via ingestion.

Assessment of activity and effective dose rate of222Rn in several dwellings in Bamako, Mali

We used CR-39 detectors to evaluate radon activity concentrations in several habitations of Bamako. The calibration factor of the dosimeters was determined experimentally with known radon activity concentrations inside a radon chamber, and was also simulated with MCNPX. The experimental and simulated calibration factorsare,respectively,kexp=0.119 ± 0.017andksim=0.126±0.007tr.cm -2 .d -1 .Bq -1 .m 3 . Indoor radon activity concentrations in Bamako were found to vary from 70 ± 18 to 154 ± 35 Bq.m -3 . No significant differences were observed in the mean radon activity concentrations compared with five other African countries. Taking into account an occupancy factor of 0.8 and an equilibrium factor of 0.4 for radon indoors, the effective dose rate ranges from 1.77 to 2.35 mSv.y -1 . In all cases the radon activity

Experimental study on the effect of high humidity environments on the response of long-term exposed nuclear track detectors

Abstract In Spain, a recent modification in the regulations of protection against ionizing radiation obligates to determine radon levels in particular workplaces like spas, mines and caves. Most of these workplaces may present extreme measurement conditions like high aerosol content, temperature, and humidity that can affect the radon detector response. In our laboratory we use to determine mean radon activity concentration in air with the nuclear track detector Makrofol DE covered with an aluminized Mylar foil and placed within the FzK FN diffusion chamber with a glass fibre filter. We have compared detector response using different filter configurations in common laboratory ambient conditions. The configuration with a better response (polyethylene filter) and our reference configuration took part in a study of the effect of different temperature and humidity on our detector response carried out in the INTE radon chamber. Results obtained did not show a significant difference between detector responses with both filters. However, when we exposed them for long periods to real environmental conditions at underground sites we could observe Mylar deterioration. To look in detail into a possible effect of long-term high-humidity exposures we exposed nine sets of detectors with three different polyethylene bags, first five sets under controlled conditions in the INTE radon chamber and then four sets in long-term exposures at high humidity environments. We have seen that the Mylar foil can be damaged depending on the duration of exposure. In a radon chamber exposure time is normally limited to a few days for practical and financial reasons; therefore, results do not show if humidity affects the glass fibre filter and detectors response. To analyse it we exposed detectors in a real humid environment up to a month where we already observed Mylar deterioration due to humidity but the possible impact on track density is hidden by the scattering of the results found, so a clear conclusion cannot be stated.

Assessment of Radiological Levels at Schools in Trabzon, Turkey

In this study, a survey on environmental radioactivity in 16 high schools located in north eastern region of Turkey (the black sea region, province of Trabzon) was carried out. Indoor air radon (222Rn) concentrations were measured in spring and autumn 2008 seasons using LR115 solid state nuclear track detectors and gamma radioactivity levels were measured using an HPGe gamma ray detector. It was seen that mean radon activity concentrations in schools ranged from 31 to 157 Bq/m3 for spring season and from 38 to 114 Bq/m3 for autumn season. The mean gamma activity concentrations in located areas of schools are between 18–52, 21–59, 11–97 and 265–759 Bq/kg for 226Ra, 232Th, 137Cs and 40K, respectively. The annual effective doses of students and staff received due to radon and locations’ gamma radioactivity levels are calculated.

Radon in Drinking Water

Firstly, we wish to express to the authors our appreciation of and thanks for their article. They showed the risk for lung cancer while focusing in their discussion mainly on inhaled radon, which penetrates into buildings and residential spaces from underground. We wish to point out a further source of cancer risk, which we think has not received enough attention in the public discussion—namely, the release of radon that is dissolved in drinking water. In Germany, the mean radon activity in drinking water is about 6 Bq/L, although regionally it may exceed 100 Bq/L and even 1000 Bq/L. What happens if the gas is released from the water into the shower cubicle during a warm shower and then inhaled? For a concentration of 100 Bq/L, activity in the shower cubicle will rise by 100 Bq per liter of water used if the radon is fully released (activity describes the number of radioactive breakdowns per second [1 Bq=1 breakdown/second]. For the purposes of describing exposures, using Bq/L or Bq/m3 as the unit of measurement seems appropriate [2]). A few years ago, an American brochure caused shockwaves by reporting values of several kBq/m3 that had been measured in shower cubicles after 15 minutes—a value that is entirely plausible according to the calculation in our example. Is the risk posed by radon inhaled during a shower really negligible, as is often claimed, especially as ventilating the cubicle or cabin during the shower is usually difficult? In the kitchen, the evaporation of steam and the radon concentrated in natural gas constitute an additional radon exposure. Opening the windows is a useful counter-measure in this context. In modern residences with tightly sealed windows, however, thorough ventilation is more problematic. We would welcome a short comment from the authors, outlining their views on the problems of “radon in shower cubicles” and “lacking ventilation in modern residential buildings.” As a result of insufficient ventilation, several other causes of health risks have made the newspaper headlines, including pathogenic indoor climates, concentration of allergens, or fungal (mould) overgrowth.

Radon Survey and Exposure Assessment in Karaca and Çal Caves, Turkey

Radon concentration and gamma activity concentration of naturally occurring radionuclides were determined and presented for two tourist caves (Karaca and Cal caves) in this study. These caves are reported to receive about 77,000 visitors during the summer season in 2007. It was seen that mean radon activity concentrations for the winter and summer seasons for the Karaca cave is 1,023 and 823 Bq/m3 and for the Cal cave is 264 and 473 Bq/m3. Mean 226Ra, 232Th, and 40K activity concentrations are found to be 43, 19, and 262 Bq/kg for the Karaca cave and 31, 27, and 460 Bq/kg for the Cal cave. Doses received by the cave guides due to radon were estimated to be 2.9 mSv/year for the winter season and 2.3 mSv/year for the summer season for the Karaca cave. Same values were estimated for the Cal cave, and the results were found to be 0.6 mSv/year for the winter season and 1.1 mSv/year for the summer season. Annual effective doses received by the visitors in both caves were estimated to be in the order of μSv/year because of the short exposure time comparing the cave guides. Although the reported values are below the recommended values, both groups are exposed to possible radiological risk during their stay inside the cave, since prolonged exposure to high radon concentration has been linked to lung cancer.

Groundwater inflow to a shallow, poorly-mixed wetland estimated from a mass balance of radon

Summary Radon activity within a shallow wetland in southern Australia has been measured on three occasions between May and October 2006. Measured activities within the surface water display a similar pattern of spatial variability on each occasion, suggesting that it is related to the locations of groundwater inflow and mixing processes. The mean groundwater inflow rate has been estimated from the mean radon activity using a mass balance approach. The components of the radon budget are (i) contribution from groundwater inflow, (ii) diffusive flux from wetland bottom sediments (iii) loss due to gas exchange, (iv) loss due to radioactive decay, (v) loss due to groundwater or surface water outflow. Also required to complete the water balance are the surface water inflow rate, direct precipitation on the wetland, and evaporation rate. The radon diffusive flux has been estimated from measurements of radon production within the sediments and a diffusive transport model, calibrated by measurements of radon activity in sealed chambers that can receive radon only from diffusion and lose it only by radioactive decay. Radon loss due to gas exchange is inferred from the loss rate of SF6, following its injection into isolated areas of the wetland, while the rate of radioactive decay is known. The radon activity in groundwater inflow is measured from sampling piezometers surrounding the wetland. Steady state and transient mass balance approaches yield similar results, with groundwater inflow rates varying between 12 and 18 m3/day. Estimated groundwater inflow rates are most sensitive to the radon activity of groundwater inflow, the gas exchange velocity, surface water area and the accuracy with which the mean radon activity in the wetland can be measured. Importantly, it is relatively insensitive to the surface water inflow rate, which is poorly known.

Radon activity concentrations and effective doses in ancient Egyptian tombs of the Valley of the Kings

Radon concentrations and equilibrium factors were measured in three pharaonic tombs during the year 1998. The tombs, which are open to the public are located in a limestone wadi on the West Bank of the River Nile at Luxor, 650 km south of Cairo. The radon activity concentration and equilibrium factor were measured monthly by two-integral nuclear track detectors (bare and diffusion detectors). Seasonal variation of radon concentrations, with summer maximum and winter minimum were observed in all tombs investigated. The yearly mean radon activity concentrations inside the tombs ranged from 540 to 3115 Bq m −3. The mean equilibrium factor over a year was found to be 0.25 and 0.32 inside and at the entrance, respectively. Estimated annual effective doses to tour guides ranged from 0.33 to 1.90 mSv, visitors receive doses from 0.65 to 3.80 μSv per visit. The effective dose to tomb workers did not exceed the 20 mSv yr −1 limit.