A comparative study of indoor radon level measurements in the dwellings of Punjab and Himachal Pradesh, India

The LR-115 type-II plastic track detector has been used for measuring the indoor radon levels in the dwellings of some villages of Punjab and Himachal Pradesh. In Punjab, the villages surveyed are Rampura Phul, Lehra Mahabat and Pitho (villages in Bathinda district), and Amritsar city. The average indoor radon levels in these areas are found to vary from 64 to 152 Bq/m³, which are quite within the safe limits recommended by International Commission on Radiological Protection (Ann. ICRP 23(2)). The indoor radon levels have also been measured in the dwellings of Hamirpur district of Himachal Pradesh. The villages surveyed in this area are Nukhel, Badarn, Galore-Khas, Har-Upper, Tikker Brahamana and Awah-Lower where radon concentration has been found to vary from 261 to 724 Bq/m³. These values are higher than the recommended limit.     

Airborne radioactivity levels in dwellings of Khammam district, Andhra Pradesh, India

Radon/thoron levels are estimated in Khammam district as a part of “Radon/thoron mapping” program in Andhra Pradesh, India. About 100 dwellings were chosen at random covering most parts of Khammam district. Twin chamber cup dosimeters consisting of solid-state nuclear track detectors (SSNTDs, LR-115, Type-II) were used to evaluate the radiation levels at quarterly intervals for a period of one calendar year. The average radon and thoron concentrations were found to be 39.1±13.3 and 19.4±14.9 Bq/m³, respectively. Seasonal variations of radon/thoron levels were also studied. Variations of radon/thoron concentration levels with different types of dwellings have been studied. In the bare flooring dwellings thoron levels were found to be highest in comparison to concrete, limestone and marble floorings.     

Measurement of radon and thoron concentration by using LR-115 type-II plastic track detectors in the environ of Brahmaputra Valley, Assam, India

Radon/thoron and their progeny concentrations were measured in different types of dwellings at different locations around industrial areas, cities and rural areas of Brahmaputra Valley of Assam by using LR-115 (type-II) plastic detector. Radon levels of different dwellings were analysed with reference to the nature of building materials, ventilation patterns and the types of underlying soil. The results were discussed under the light of exposure limits set by ICRP. The average concentrations of indoor radon and thoron varied from 39.5 to 215.2 Bqm⁻³ and 12.9 to 37.6 Bqm⁻³, respectively. The estimated inhalation dose due to radon, thoron and their daughter products in the study areas varied from 0.53 to 1.00 μSvh⁻¹.     

Inter-comparison of three techniques for radon activity measurements

In this paper the results of an inter-comparison employing three distinct techniques for measuring indoor radon activities are discussed: (i) NRPB–SSI dosimeter, a diffusion chamber, CR-39 based, calibrated in a controlled radon chamber; (ii) a diffusion chamber, CR-39 based, calibrated via nuclear emulsion; (iii) canister with activated charcoal. Totally 39 dwellings of Poços de Caldas city (Minas Gerais State, Brazil), located in a high natural radioactivity region, have been monitored during a six months period.

Dosimeters (i) and (ii) were exposed continuously in all of 39 dwellings and dosimeter (iii) was exposed in 10 of them, randomly chosen. In this case the individual exposures lasted around 5 days and 4 equally time spaced exposures were made in each dwelling. Results produced by techniques (i) and (ii) show a great level of concordance. Individual results of technique (iii) for each residence show great fluctuations, but their mean results statistically agree with the other techniques. So our results indicate that active charcoal technique can be used to study average term radon variation (in few days), but its individual results cannot reflect long-term indoor radon activity.     

Zur Entdeckungsgeschichte des Radons

The radioactivity of the noble gas radon and its short-life daughter products as the essential part of natural radioactivity have gained in topically in the last years. For this reason the history of discovery of radon has been summed up. This history is one part of the early research about radioactivity. From the appearance of induced radioactivity the way leads to the discovery of thorium emanation by Rutherford and of radium emanation by Dorn. Finally, the article deals with the detection of radon in the air by Elster and Qeitel and of the radon in well water and springivaler by Thomson because only these results have opened the way for the therapeutical usage of radon.     

Baseline studies of radon/thoron concentration levels in and around the Lambapur and Peddagattu areas in Nalgonda district, Andhra Pradesh, India

Studies conducted by Atomic Minerals Directorate of Exploration and Research (AMD) of Hyderabad, India had established the presence of higher concentrations of uranium in Lambapur and Peddagattu areas of Nalgonda district, AP, India and it was estimated that it could be a viable source for commercial extraction. The envisaged extraction process involves dispersion of radioactive particulate matter into atmosphere. Environmental radioactive studies in and around proposed mining areas at this point of time will be extremely useful for establishing base line data before a large scale uranium extraction process comes into existence. To this end, Solid State Nuclear Track Detectors were installed to evaluate indoor radon and thoron concentration levels in the dwellings of the area. The geometric means of radon and thoron concentration levels were found to be (7.1±0.2)×10¹ and (6.7±0.3)×10¹ Bq/m³, respectively. Simultaneously, natural background radiation measurements were also made and these levels are found to vary from 770 to 3995 μGy/y in the spatial distribution.     

A comparative study of indoor radon levels and inhalation dose in some areas of Punjab and Haryana, India

Indoor radon concentrations have been measured for two consecutive half-year periods in a wide range of dwellings of some regions of Punjab and Haryana states. The objective was to find correlation between the variations of indoor radon levels with the sub-soil, local geology, type of building materials, etc. of the two regions. So keeping this in view the indoor radon measurements have been carried out in the dwellings of different villages around the Tusham ring complex, Bhiwani District, Haryana, known to be composed of acidic volcanics and the associated granites along with some villages of Amritsar District, Punjab. The indoor radon concentration in the dwellings around Tusham (Haryana) have been found to be varying from 120.5±95 to 915.2±233 Bq m⁻³, whereas it ranges from 60.0±37 to 235.6±96 Bq m⁻³ for the dwellings of Punjab. The ²²²Rn concentration observed at most of locations particularly around Tusham ring complex region is higher than that of all the villages studied in Punjab region. Local geology including embedded granitic rocks, sub-soil, etc. as well as building materials having higher radioactive content are the major contributors for the higher indoor radon levels observed in the dwelling around Tusham, where few dwellings have higher radon concentrations than the ICRP, 1993 recommendations. The annual effective dose equivalent has also been estimated for each location of the both regions, which has been found to be varying from 1.0 to 17.2 mSv/y.     

Indoor radon survey in Eastern Sicily

Inhalation of radon (Rn-222) and its progeny is one of the most significant sources of natural radiation exposure of the population. Nowadays, high radon exposures have been shown to cause lung cancer and many governments all over the world have therefore recommended that radon exposures in dwellings and indoor workplaces should be limited. Radon levels in buildings vary widely from area to area depending on local geology. This paper presents the results of a long-term survey of radon concentrations carried out from 2005 till 2010 in schools and dwellings of Eastern Sicily, using the solid-state nuclear track detector (SSNTD) technique. The investigated area shows medium-high indoor radon concentrations, higher than the Italian average of about 70 Bq/m³, with peaks of 500 Bq/m³ or more in buildings near active faults. Fortunately, only a small fraction of the measurements, about 1.5% of total, was found greater than EU and Italian action limits for indoor and workplaces.     

Seasonal variation of radon-222 concentrations in specific locations in Jordan

Previously calibrated passive detectors (CR-39) and an active radon device (Radon Monitor RM3) were used to study seasonal variation of radon-222 concentration levels inside and outside specific locations in Jordan. The study sites were located in an area that used to be an old phosphate mine. We found that the maximum value of radon concentration in air inside the dwellings, as measured by the passive dosimeters, was 1532.9 Bq/m³ during the winter season, and the minimum one was 46.3 Bq/m³ during fall season. While the highest and lowest readings of the active monitor were 892 and 4 Bq/m³ during fall and summer seasons, respectively. The radon concentration in soil ranges from 0.2 kBq/m³ in spring to 37.8 kBq/m³ in fall.     

Studies on radon/thoron and their decay products in granite quarries around Bangalore city, India

The radon survey was performed in granite quarries around Bangalore rural district and Bangalore city as part of a lung cancer epidemiological study. Long duration measurements of indoor and outdoor radon, thoron and their progenies concentrations were made around granite quarries of Bangalore rural district by using Solid State Nuclear Track Detector (SSNTD, LR-115, Type-II Plastic track detector) during summer and winter period (2006–07). The increase of radioactivity in granite quarries and inhalation dose to workers and populations near the quarries have been summarized. The higher concentrations of radon and thoron in granite quarries suggest radiation health effects on workers and public around the quarries is higher than permissible levels. The results are presented and analyzed with reference to ICRP limits.     

Study of indoor radon and thoron progeny levels in surrounding areas of Nalbari, Assam, India

With the growing understanding of the role of radon and its daughter products as major sources of radiation exposure, the importance of large number of estimation of radon concentration in various parts of the country is realized. Inhalation of radon, thoron and their decay products is the major source of the total radioactive dose received by the human population from natural radiation. The indoor radon and thoron progeny levels in Nalbari area of Assam are studied by using the LR-115 (type II) Solid State Nuclear Track Detector in Plastic Twin Chamber dosimeter. Radon and thoron progeny levels in different types of dwellings for one full calendar year are presented in this paper. For Assam Type (A.T.) houses, indoor radon progeny concentrations vary from 0.17 to 0.64 mWL with an annual geometric mean of 0.27 mWL and that for Reinforced Cement Concrete (R.C.C.) houses vary from 0.22 mWL to 0.60 mWL with the annual geometric mean of 0.37 mWL. The thoron progeny levels in A.T. houses also vary from 0.01 to of 0.05 mWL with an annual geometric mean of 0.02 mWL and that for R.C.C. houses vary from 0.02 to 0.08 mWL with the annual geometric mean of 0.04 mWL.      

Comparison of radon exposure assessment results: Po surface activity on glass objects vs. contemporary air radon concentration

Radon exposure assessment in case–control studies on radon and lung cancer is generally based on contemporary radon concentration measurements, which can be affected by significant changes in the building structures or in living habits. Another method to estimate the radon exposure of the subjects is the recently developed retrospective dosimetry technique based on the ²¹⁰Po surface activity from glass objects. In order to compare the results obtained by the two methods, a study has been carried out in a sample of 26 dwellings in Rome, with radon concentration values ranging from 28 to 623 Bqm⁻³. Retrospective detectors based on CR-39 and LR 115 were exposed on 50 glass objects in bedrooms and living rooms. The correlation factor between the two sets of data, after removing six extreme values, is 0.67, which is similar to results obtained in other validation studies of similar sample size. The correlation increases to 0.83 if the 21 objects exposed in non-smoky dwellings are selected, while it vanishes to −0.01 for the 23 objects exposed in smoky dwellings, suggesting quite larger variations of plate-out in presence of environmental tobacco smoke.     

Radon levels in the volcanic region of La Garrotxa, Spain

A preliminary survey in the city of Olot, the main town of the volcanic region of La Garrotxa, showed that dwellings built on volcanic formations present higher indoor radon levels than dwellings on non-volcanic materials. The soil of the area is not especially rich in radium. However, some of the volcanic materials present very high permeability and therefore radon entering the houses might have travelled over long distances. In this paper we present indoor radon values measured in a larger survey carried out during April–July 2004. The influence of the volcanic materials found in the preliminary survey has been confirmed. The results obtained suggest the possibility that radon comes from the degassification of mantle through active faults. The values obtained in working places do not constitute a relevant radiological risk for workers.     

Indoor radon measurements in a Greek city located in the vicinity of lignite-fired power plants

This work presents indoor radon measurements in 42 dwellings in the city of Megalopolis, Southern Greece, located in the vicinity of 2 lignite-fired power plants and examines the effect of season, floor level and age of the dwellings on indoor radon concentration. The radon measurements have been carried out using the LR-115, type II and CR-39 alpha track detectors in “closed-can” geometry. The average annual indoor radon concentration (GM) was found to be 52 Bq m^?3, which is well below the recommended action level of the European Union. This value corresponds to an annual effective dose to the population of 1.3 ± 0.4 mSv. Season and age of the examined dwellings represent factors that affected significantly the indoor radon in Megalopolis, while the effect of floor level appeared to be not significant. Radium activity concentration values, measured by γ-ray spectrometry in 20 sub-samples of six soil cores (60–135 cm depth), collected from the surrounding area of the city, were found to be consistent with the Greek and world average values. Based on the results of this study, it is concluded that the effect of the lignite-fired power plants on indoor radon concentration in Megalopolis’ dwellings was not significant.     

Natural radiation background in the ancient city of Palmyra

Natural radiation background has been determined for the Ancient City of Palmyra and its surrounding areas. Car-borne gamma spectrometry, indoor radon gas concentration and natural radionuclides levels in environmental samples (soil, water and plants) have been determined. Two types of dwelling were involved in this study, one with cancer cases, and the others without. The results showed that indoor radon gas concentrations and radiation exposure rates are within reported mean background levels in Syria (45 Bq m^?3 and less than 0.1 μSv h^?1, respectively); no differences were noticed between the dwelling groups. In addition, the results did not indicate any relation between recorded cancers and measured natural radioactivity.     

Indoor radon survey in dwellings of some regions in Yemen

Indoor radon survey in a total of 241 dwellings, distributed in some regions of Yemen was performed, using CR-39 based radon monitors. The objective of this radon survey is to get representative indoor radon data of three regions, namely Dhamar, Taiz and Hodeidah, situated at different altitudes above sea level. The radon concentrations varied from 3 to 270 Bqm⁻³ with an average of 42 Bqm⁻³. It was found that the average radon concentration in the surveyed areas increases with altitudes. The highest average radon concentration of 59 Bqm⁻³ was found in Dhamar city while the lowest average concentration of 8 Bqm⁻³ was found in Hodeidah city.     

Emanation power of radon and its concentration in soil and rocks

Experiments were carried out to determine emanation power and radon levels in different kinds of soil and bedrocks. Seven stations were selected in the investigated district, which covers an area of about 2300 km² in the northern and western part of Jordan. Five holes were dug in each station at different depths. Two to three passive dosimeters using plastic detectors (CR-39) were put in each hole. Two weeks later, the dosimeters were collected and chemically etched. Some soil and rock samples from the study area were collected and analyzed for radioactive nuclides using γ-ray spectroscopy. The correspondence between radon levels in the soil gas and its precursor concentrations is not clear. However, the study confirms the exponential increase in radon level with depth. In general, Al-Hisa phosphate limestone showed the highest radon concentration while Amman silicified limestone showed the lowest concentration.     

Radioactivity measurements in the environment of the Udhampur area,Jammu and Kashmir Himalayas,India

LR-115 plastic track detectors have been used for the measurement of radon exhalation rate and radium concentration in soil samples collected from some villages of the Udhampur district, Jammu and Kashmir, India. Uranium concentration has also been determined in these soil samples using the fission track registration technique. Radium concentration in soil samples varies from 5.46 to 19.17 Bqkg^?1, whereas uranium concentration varies from 2.53 to 3.65 ppm. The radon exhalation rate in these samples has been found to vary from 6.42 to 22.47 mB kg^?1 hr^?1. The work is undertaken for health risk assessments due to uranium and radium in the study area. A positive correlation has been observed between uranium and radium, as well as uranium and radon exhalation rate in soil samples.     

Quantitative evaluation of the lung cancer deaths attributable to residential radon: A simple method and results for all the 21 Italian Regions

Pooled analyses of epidemiological case--control studies on lung cancer and residential radon have shown that radon exposure in dwellings increases lung cancer risk, and that the increase is statistically significant also for prolonged exposures to low-medium level of radon concentration, i.e. levels commonly found in many dwellings. In this paper, a simple method to evaluate the health burden due to the presence of radon in homes (i.e. the number of lung cancer deaths attributable to radon exposure in dwellings) was presented. This method is based on the following parameters: i) the excess relative risk per unit of exposure evaluated in case-control studies; ii) the average radon concentration that can be considered representative of population exposure in dwellings; iii) the total number of lung cancer deaths occurring each year. Moreover, the interaction between radon and cigarette smoking is needed to be taken into account: in fact, although most of the persons are non-smokers, most of the lung cancer deaths attributed to radon are actually due to the multiplicative effect of radon and cigarette smoking. To show this effect, the number of radon related lung cancer deaths estimated to occur among current, former and never smokers was calculated separately for males and females, taking into account the relative risk of lung cancer for the different smoking categories and the prevalence of smoking habits. The methodology described in this work was applied to all the 21 Italian Regions in order to illustrate it. The overall fraction of lung cancer deaths attributable to radon in Italy is about 10%, with values in individual Regions ranging from 4% to 16%. The greater part of the lung cancers attributable to radon is estimated to occur among current smokers for both males and females (72% and 60%, respectively, at national level). This is due to the synergistic effects of radon and cigarette smoking, which should therefore be taken into account in policies aimed to reduce the health burden from radon.