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PubMed1984

Natural radioactivity in and radon exhalation from Finnish building materials.

A total of 369 samples of Finnish building materials were tested for their 226Ra, 232Th and 40K concentrations. The rate of radon exhalation was measured from 19 samples of material and 34 dwellings were tested for their room air ventilation rate and radon concentration. The mean values of 226Ra, 232Th and 40K concentrations in ballast materials for concrete production were 34.2 Bq X kg-1, 39.0 Bq X kg-1 and 964 Bq X kg-1, with standard deviations of 18.7 Bq X kg-1, 19.5 Bq X kg-1 and 265 Bq X kg-1, respectively. The activity concentrations were higher in clay bricks than in concrete, the mean values being 79.8 Bq X kg-1, 61.6 Bq X kg-1 and 986 Bq X kg-1 for 226Ra, 232Th and 40K, respectively. The normalized radon exhalation rates from 15-cm-thick concrete, slag-aggregate concrete and by-product gypsum were 0.38 (Bq X m-2 X h-1)/(Bq X kg-1), 0.15 (Bq X m-2 X h-1)/(Bq X kg-1), and 0.06 (Bq X m-2 X h-1)/(Bq X kg-1), respectively. The ventilation rates in dwellings varied between 0.27 and 1.99 air changes per h, the mean value being 0.60 h-1, and the corresponding steady state radon concentrations in room air varied from 17.0 to 149 Bq X m-3 in blocks of flats made of concrete and from 11.2 to 61.9 Bq X m-3 in blocks of flats made of brick.

Air Pollutants, Radioactive↗
PubMed1991

An evaluation of radiation and dust hazards at a mineral sand processing plant.

This three-part article discusses the results of a 2-y study on radiation and dust hazards in a mineral sand processing plant involving: (1) evaluation of external gamma radiation levels and determination of isotopic composition of the different sand products; (2) evaluation of radiation carried in long-lived radioactive dust (LLRD) particles; (3) evaluation of Rn gas concentrations within the working environs of the plant. Gamma radiation levels had a mean value of approximately 40 nSv h-1, and monazite sand returned the highest activity concentrations of 0.16% and 3.4% for 238U and 232Th, respectively. Low volume gross respirable dust sampling revealed an average long-lived airborne alpha activity concentration of 0.07 +/- 0.02 Bq m-3 and an average dust mass concentration of 3.3 +/- 2 mg m-3. Gamma spectroscopy applied to high-volume air samples showed average airborne 232Th and 238U activities of 0.012 +/- 0.004 Bq m-3 and 0.005 +/- 0.002 Bq m-3, respectively, giving an airborne 232Th: 238U ratio of 2.4:1. Air sampling using a high volume, five-stage cascade impactor indicated an average activity median aerodynamic diameter (AMAD) of 3.2 microns with an associated average geometric standard deviation (GSD) of 2.8. Average radiation dose arising from the inhalation of LLRD was estimated to be 7 mSv per annum. CR-39 (polycarbonate plastic) nuclear track detectors indicated that Rn gas concentrations in the environs of the processing plant dry mill and main product warehouse ranged from 30 Bq m-3 to 220 Bq m-3, with an average value of 100 Bq m-3, which presents a possible inhaled dose from Rn daughters of 1.5 mSv y-1 (assuming an equilibrium ratio of 0.5).

Air Pollutants, Radioactive↗
PubMed1992

Iodine-131 contamination from thyroid cancer patients.

High-dose radioactive iodine therapy using 131I is the treatment of choice for patients with thyroid cancer following thyroidectomy. Because of the large amount of activity which is excreted during hospitalization, contamination hazard from 131I excretion via perspiration, saliva, breath and urine may arise. In eight patients treated with doses of 131I ranging from 3.7 to 14.8 GBq (100-400 mCi), activity levels were measured in room air, from room surfaces, the toilet, the patients' exhaled breath, skin, saliva and toothbrushes, and the gloves used by medical staff. Thyroid bioassays were also performed on medical staff personnel caring for these patients both before and two days after administration of the treatment dose. Removable activity from the skin was positively correlated with treatment dose and reached a maximum at 24 hr post-therapy. Removable activity from room surfaces exceeded the level of contamination which requires clean-up in a restricted area during the patient's hospitalization. Thyroid bioassays on medical staff showed no significant uptake 2 days after treatment. The relatively high activities present in the saliva, urine and on the skin of these patients emphasizes the need for all individuals coming in contact with these patients to be made aware of the contamination hazard present.

Adolescent↗
PubMedDate not supplied

[Estimation of rate constant for dissolution of radioactive fuel particles].

Some theoretical of the experimental investigation of solubility of radioactive aerosols were examined. Filters, which were exposed during October-November 1987 in Pripyat town, were studied. Measurements on 22 November 1987 showed that an activity in the air was 12.1-20.8 mBq/m3 for 137Cs, 34.9-89.3 mBq/m-3 for 144Ce, 24.3-30.5 mBq/m-3 for 106Ru. Disperse structure of aerosol hot particles and the number of hot particles on each filter fragment was estimated by radiography. To determine a dissolution rate constant a static system with two 0.14 micron pore size membrane MFE filters (Dubna, Russia) enclosing fragments of Petryanov filters was selected. The composition was held in Gamble's solution lung fluid anf then in 0.1 mol/l HCl as dastic juice simulation. The activity of 90Sr, 238Pu, 239 + 240Pu, 241Am and 244Cm in aerosol filters and solutions was measured by radiochemical methods. It was shown that leaching of radionuclides from aerosol hot particles in lung fluid simulation decreases in line 137Cs > 90Sr >> 239 + 240Pu > or = 241Am, depending om particle diameter and time. Dissolution constants were presented. Dissolution of aerosol particles in 0.1 mol/l HCl is also shown (dissolution time was 3 days). A radionuclide transition to HCl solution decreases in line 90Am 241Am >> 137Cs > 239 + 240Pu. A transition degree reached 21% for 90Sr and extraction of 241Am was 3-17%.

Aerosols↗
PubMed1996

Uncertainty of historical measurements of 131I in Hanford-area vegetation.

The Hanford Environmental Dose Reconstruction (HEDR) Project was conducted to estimate the radiation dose that individuals could have received as a result of emissions to the air and water from Hanford Site operations since 1944. The largest doses were to the human thyroid gland from 131I released into the atmosphere from Hanford facilities in the 1945-1947 time period. In support of the dose reconstruction effort, a database of historical environmental radioactivity measurements was constructed. This database includes measurements of total radioactivity for vegetation samples collected from 1945-1948 and counted using a Geiger-Mueller (GM) detector system. Because the factors used at that time to convert the GM counts to 131I activity did not take all parameters into account, and because some parameter values were inaccurate, more accurate conversion factors were developed as part of the HEDR Project. These factors can be used to estimate the actual historical activity levels. This paper summarizes the Monte Carlo uncertainty and sensitivity analysis methods used to assess the uncertainty of the newly reconstructed historical vegetation 131I activities and to identify the parameters that contributed the most uncertainty to these reconstructed activities. Based on the study of two vegetation (sagebrush) samples collected in the mid-1940's, it appears that the true 131I activity of the historical vegetation samples should be within a factor of three of the reconstructed activity. Also, the uncertainty in the parameter Icf (the fraction of the background-corrected GM measurement of a vegetation sample that resulted from 131I) was found to contribute the most uncertainty to the reconstructed 131I activities when the uncertainty in Icf was large.

Air Pollutants, Radioactive↗
PubMed2006

Radiation dose from cigarette tobacco.

The radioactivity in tobacco leaves collected from 15 different regions of Greece before cigarette production was studied in order to estimate the effective dose from cigarette tobacco due to the naturally occurring primordial radionuclides, such as (226)Ra and (210)Pb of the uranium series and (228)Ra of the thorium series and or man-made radionuclides, such as (137)Cs of Chernobyl origin. Gamma-ray spectrometry was applied using Ge planar and coaxial type detectors of high resolution and high efficiency. It was concluded that the annual effective dose due to inhalation for adults (smokers) for (226)Ra varied from 42.5 to 178.6 microSv y(-1) (average 79.7 microSv y(-1)), while for (228)Ra from 19.3 to 116.0 microSv y(-1) (average 67.1 microSv y(-1)) and for (210)Pb from 47.0 to 134.9 microSv y(-1) (average 104.7 microSv y(-1)), that is the same order of magnitude for each radionuclide. The sum of the effective doses of the three natural radionuclides varied from 151.9 to 401.3 microSv y(-1) (average 251.5 microSv y(-1)). The annual effective dose from (137)Cs of Chernobyl origin was three orders of magnitude lower as it varied from 70.4 to 410.4 nSv y(-1) (average 199.3 nSv y(-1)).

Administration, Inhalation↗
PubMed1996

Radiation doses from Hanford Site releases to the atmosphere and the Columbia River.

Radiation doses to individuals were estimated for the years 1944-1992 as part of the Hanford Dose Reconstruction Project (HEDR). The dose estimates were based on the radioactive releases to the atmosphere and Columbia River from the Hanford Site in southcentral Washington State. Conceptual models, computer codes, and previously published dose estimates were used to reconstruct doses. The most significant exposure pathway was found to be the consumption of cow's milk containing 131I. The median cumulative dose estimates to the thyroid of children ranged from < 0.7 mGy to 2.3 Gy throughout the study area, depending upon residence location. The highest estimated cumulative dose to a child ranged from 0.6-8.4 Gy (5th and 95th percentiles) with a median of 2.3 Gy based on 100 Monte Carlo realizations. The geographic distribution of the dose levels was directly related to the pattern of 131I deposition and was affected by the distribution of commercial milk and leafy vegetables. For the atmospheric pathway, the highest cumulative effective dose equivalent to an adult was estimated to be 12 mSv at Ringold, Washington, for the period 1944-1992. For the Columbia River pathway, cumulative effective dose equivalent estimates ranged from < 5 mSv to 15 mSv cumulative dose to maximally exposed adults downriver from the Hanford Site for the years 1944-1992. The most significant river exposure pathway was consumption of resident fish containing 32P and 65Zn.

Adult↗
PubMed1999

Assessment of need for transport tubes when continuously monitoring for radioactive aerosols.

Aerosol transport tubes are often used to draw aerosol from desirable sampling locations to nearby air sampling equipment that cannot be placed at that location. In many plutonium laboratories at Los Alamos National Laboratory, aerosol transport tubes are used to transport aerosol from the front of room ventilation exhaust registers to continuous air monitors (CAMs) that are mounted on nearby walls. Transport tubes are used because past guidance suggests that extraction of aerosol samples from exhaust locations provides the most sensitive and reliable detection under conditions where the rooms have unpredictable release locations and significant spatial variability in aerosol concentrations after releases, and where CAMs cannot be located in front of exhaust registers without blocking worker walkways. Despite designs to minimize particle loss in tubes, aerosol transport model predictions suggest losses occur lowering the sensitivity of CAMs to accidentally released plutonium aerosol. The goal of this study was to test the hypotheses that the reliability, speed, and sensitivity of aerosol detection would be equal whether the sample was extracted from the front of the exhaust register or from the wall location of CAMs. Polydisperse oil aerosols were released from multiple locations in two plutonium laboratories to simulate plutonium aerosol releases. Networked laser particle counters (LPCs) were positioned to simultaneously measure time-resolved aerosol concentrations at each exhaust register (representative of sampling with transport tubes) and at each wall-mounted CAM location (representative of sampling without transport tubes). Results showed no significant differences in detection reliability, speed, or sensitivity for LPCs positioned at exhaust locations when compared to LPCs positioned at the CAM wall location. Therefore, elimination of transport tubes would likely improve CAM performance.

Aerosols↗
PubMed2006

Assessment of environmental radon hazard using human respiratory tract models.

Radon is a natural radioactive gas derived from geological materials. It has been estimated that about half of the total effective dose received by human beings from all sources of ionizing radiation is attributed to 222Rn and its short-lived progeny. In this paper, the use of human respiratory tract models to assess the health hazard from environmental radon is reviewed. A short history of dosimetric models for the human respiratory tract from the International Commission on Radiological Protection (ICRP) is first presented. The most important features of the newest model published by ICRP in 1994 (as ICRP Publication 66) are then described, including the morphometric model, physiological parameters, radiation biology, deposition of aerosols, clearance model and dose weighting. Comparison between different morphometric models and comparison between different deposition models are then given. Finally, the significance of various parameters in the lung model is discussed, including aerosol parameters, subject related parameters, target and cell related parameters, and parameters that define the absorption of radon from the lungs to blood. Dosimetric calculations gave a dose conversion coefficient of 15 mSv/WLM, which is higher than the value 5 mSv/WLM derived from epidemiological studies. ICRP stated that dosimetric models should only be used for comparison of doses in the human lungs resulted from different exposure conditions.

Aerosols↗
PubMed1982

Parameters for modelling the interception and retention of deposits from atmosphere by grain and leafy vegetables.

The Normalised Specific Activity (NSA), a quantity which relates the concentration of a contaminant per unit mass of vegetation to its daily rate of ground deposition, has been used as the basis for determining interception factors and retention half-lives for radioactive contaminants deposited on grain and leafy vegetables. The values are for use in assessing contamination levels on crops at harvest during conditions of continuous deposition. The approach implicitly takes account of other processes which influence foliar contamination, namely, translocation and dilution due to plant growth. The respective NSA values for grain and prepared leafy vegetables determined from several separate experimental studies are fairly constant and are of about the same level for fall-out strontium and caesium. There is evidence from previous studies on herbage to suggest that similar NSA values might be expected for other contaminants on grain and leafy vegetables. Plutonium is an exception in that NSA values for grain and prepared leafy vegetables are lower than those for the fission products by factors of between 5 and 10 depending upon the source of the contaminant. Consideration has been given to determining the most appropriate value of the fraction of activity transferred from grain to flour during refining. This is an element dependent parameter and the values estimated for strontium, caesium and plutonium are respectively 0.15, 0.5 and 0.1. The study has indicated the need for data in several areas in order to improve the capability to model interception and retention on field crops in continuous and acute release conditions.

Air Pollutants↗
PubMed2005

Calculation of immersion doses from external exposure to a plume of radioactive material.

The immersion doses from external exposure to a Gaussian plume of noble gases accidentally released into the atmosphere have been calculated. A numerical integration procedure employing Gauss-Legendre of 64th order has been used. The numerical procedure allows calculating the dose rate at any downwind horizontal or vertical distance. The dose rates were calculated using various forms of gamma dose build-up factors, including Linear, Berger and Geometric Progression (GP). The GP form, having an extraordinarily precise formulation, is a favored choice because the build-up factor levels off for large distances and does not increase exponentially as does the Berger form. The Linear form much under predicts the build-up and subsequently the dose rates for large distances from the source. The dose predictions using a simple uniform cloud model (that does not use any form of build-up factor) is also presented for comparison purposes. The comparison of dose rates with the already reported results indicated that the numerical procedure could be used for dose calculations from a Gaussian plume for all downwind and crosswind distances. The comparison of dose rates obtained using different forms of the build-up factors indicated that the Geometric Progression form was a favored choice and has a wider range of applicability as compared to the Linear or Berger form. The simple uniform cloud model for dose calculations is only suitable for plume centerline doses and should be used with caution for off-center distances.

Air Pollutants, Radioactive↗
PubMed2003

Modeling of the dispersion of depleted uranium aerosol.

Depleted uranium is a low-cost radioactive material that, in addition to other applications, is used by the military in kinetic energy weapons against armored vehicles. During the Gulf and Balkan conflicts concern has been raised about the potential health hazards arising from the toxic and radioactive material released. The aerosol produced during impact and combustion of depleted uranium munitions can potentially contaminate wide areas around the impact sites or can be inhaled by civilians and military personnel. Attempts to estimate the extent and magnitude of the dispersion were until now performed by complex modeling tools employing unclear assumptions and input parameters of high uncertainty. An analytical puff model accommodating diffusion with simultaneous deposition is developed, which can provide a reasonable estimation of the dispersion of the released depleted uranium aerosol. Furthermore, the period of the exposure for a given point downwind from the release can be estimated (as opposed to when using a plume model). The main result is that the depleted uranium mass is deposited very close to the release point. The deposition flux at a couple of kilometers from the release point is more than one order of magnitude lower than the one a few meters near the release point. The effects due to uncertainties in the key input variables are addressed. The most influential parameters are found to be atmospheric stability, height of release, and wind speed, whereas aerosol size distribution is less significant. The output from the analytical model developed was tested against the numerical model RPM-AERO. Results display satisfactory agreement between the two models.

Aerosols↗
PubMed2000

CGH analysis of radon-induced rat lung tumors indicates similarities with human lung cancers.

Epidemiological studies have shown that inhalation of radon, a radioactive gas, is associated with an increased risk for lung cancer. We have developed a model of radon-induced rat lung tumors to characterize cytogenetic and molecular events involved in radon-induced lung tumorigenesis. Using comparative genomic hybridization (CGH), gains and losses of genetic material were investigated in a series of 13 carcinomas and four adenomas of the lung. Frequent losses occurred at 4q12-21, 5q11-33, and 15q, which are homologous to human chromosome (HSA) bands 7q21-36, 1p31-36/9p21-31, and 13q14.1-14.3/3p14.2, respectively. These regions are frequently (30-80%) deleted in human lung cancer and contain tumor suppressor genes or proto-oncogenes such as MET, CDKN2A/p16/MTS1, CDKN2B/p15/MTS2, FHIT, and RB1 or yet to be identified genes. Frequent gains involved 6, 7q34-qter, and 19q; chromosomes 6 and 7 being homologous to human 2p21-25 and 8q21-24 where the MYCN and MYC oncogenes are located. The genetic similarities between rat and human lung cancer suggest common underlying mechanisms for tumor evolution in both species. Moreover, cytogenetic and molecular genetic analyses of radon-induced rat lung tumors could help to better understand the development and progression of radon-induced lung cancer in man.

Adenoma↗
PubMed2000

Environmental releases of radioactivity and the incidence of thyroid disease at the Ignalina Nuclear Power Plant.

The Ignalina Nuclear Power Plant consists of two Russian-made RBMK-1500 reactors. The plant uses Lake Druksiai as a natural reservoir for cooling water. Within the framework of the revised radiation dose limitation system, site-specific routine release conversion factors and maximum annual effective doses for the dominant radionuclides and pathways were evaluated for both atmospheric and aquatic releases. Using calculated release conversion factors, the locations of the highest predicted activity concentrations were determined for air and for the dilution zone of heated effluent water during the period 1984-1998. Committed effective doses for critical group members were less than 0.001 mSv for Ignalina Nuclear Power Plant airborne releases and less than 0.05 mSv for aquatic releases. These dose estimates are lower than the 1 mSv dose limit for the adjacent population. In the case of Ignalina Nuclear Power Plant, taking into account the uncertainties, a recommendation for the administrative dose constraint is 0.25 mSv y(-1). This dose level may scarcely affect human health. Interestingly, during screening for thyroid disorders, endocrinologists and pediatric-endocrinologists determined a dominance of abnormal thyroids (up to 60%) among school children in the vicinity of Ignalina NPP. The data on neonatal screening for congenital hypothyroidism and transient hyperthyrotropinemia, however, suggested a possibility that the majority of abnormal thyroid cases were related to stable iodine deficiency. Thus, the influence of Ignalina Nuclear Power Plant on thyroid disorders is highly conjectural and unlikely to be associated with the observed levels of childhood thyroid disease.

Adult↗
PubMed1998

Indoor radon.

The naturally radioactive but chemically inert gas, radon, is formed from the radioactive decay of radium which is part of the uranium series. Radon gas, which has a half life of 3.8 days, must escape from soil particles through air-filled pores in order to enter the atmosphere following the decay of radium. The concentration of radon in the atmosphere varies, depending on the place, time, height above the ground and meteorological conditions. It is thus an inescapable source of radiation exposure, both at home and at work. The potential hazards posed by exposure to radiation from indoor radon gas and its daughter products are of great concern worldwide. Noting of an excessive lung cancer risk among several groups of underground miners exposed to radon and its daughter products, studies on radon concentrations in the workplace and in dwellings have been conducted in many countries. The results have shown that the distribution of radon concentrations are approximately lognormal from which population weighted; the arithmetic mean of radon concentration of 40 Bq.m-3 has been adopted worldwide for dwellings and workplaces. The principal methods for reducing a high indoor radon concentration are: reducing the radon supply by reversing the pressure difference between the building and the soil; raising the resistance of the foundations to soil gas entry; removing the radon sources such as water or underlying soil; diluting the concentration by increasing the ventilation rate; and reducing the concentration of radon progeny by filtering and increasing the circulation of indoor air. Buildings which have a radon concentration higher than 200 Bq.m-3 should be investigated by the national authorities concerned; meanwhile, householders should be advised to take simple temporary precautions, such as increasing ventilation, until a permanent remedy can be effected.

Air Pollution, Indoor↗
PubMed2004

[Indoor radon exposure and lung cancer risk: a review of case-control studies].

BACKGROUND: Radon is a radioactive gas that tends to accumulate in indoor environment. A causal relationship between lung cancer and radon exposure has been demonstrated in epidemiologic studies of miners. The objective of this paper is to present the results of case-control studies of lung cancer risk associated with indoor radon exposure. METHODS: Case-control studies published since 1990 are included in this review. This type of protocol is particularly well suited for studying the relationship between indoor radon exposure and lung cancer risk, taking into account possible confounding factors such as tobacco smoking. The characteristics and results of these studies are summarized. The limitations associated with each of these studies are also discussed. RESULTS: The results of available studies are relatively concordant and suggest a positive association between lung cancer risk and indoor radon exposure with an estimated excess relative risk of about 6 to 9% per 100Bq/m3 increase in the observed time-weighted average radon concentration. The order of magnitude of this estimation agrees with extrapolations from miners but some studies may suffer from inadequate statistical power. CONCLUSION: At present, efforts are underway to pool together the data from the existing studies of indoor radon. This pooling analysis with thousands of cases and controls will provide a more precise estimate of the lung cancer risk from indoor radon exposure and explore the effect of modifying factors, such as smoking.

Air Pollution, Indoor↗
PubMed2006

Testing of high-volume sampler inlets for the sampling of atmospheric radionuclides.

Sampling of air for radioactive particles is one of the most important techniques used to determine the nuclear debris from a nuclear weapon test in the Earth's atmosphere or those particles vented from underground or underwater tests. Massive-flow air samplers are used to sample air for any indication of radionuclides that are a signature of nuclear tests. The International Monitoring System of the Comprehensive Nuclear Test Ban Treaty Organization includes seismic, hydroacoustic, infrasound, and gaseous xenon isotopes sampling technologies, in addition to radionuclide sampling, to monitor for any violation of the treaty. Lovelace Respiratory Research Institute has developed a large wind tunnel to test the outdoor radionuclide samplers for the International Monitoring System. The inlets for these samplers are tested for their collection efficiencies for different particle sizes at various wind speeds. This paper describes the results from the testing of two radionuclide sampling units used in the International Monitoring System. The possible areas of depositional wall losses are identified and the losses in these areas are determined. Sampling inlet type 1 was tested at 2.2 m s wind speed for 5, 10, and 20-microm aerodynamic diameter particles. The global collection efficiency was about 87.6% for 10-microm particles for sampling inlet type 1. Sampling inlet type 2 was tested for three wind speeds at 0.56, 2.2, and 6.6 m s for 5, 10, and 20-microm aerodynamic diameter particles in two different configurations (sampling head lowered and raised). The global collection efficiencies for these configurations for 10-microm particles at 2.2 m s wind speed were 77.4% and 82.5%, respectively. The sampling flow rate was 600 m h for both sampling inlets.

Aerosols↗
PubMed2005

Measurements of activity concentrations of naturally occurring radionuclides in soil samples from Punjab province of Pakistan and assessment of radiological hazards.

The natural level of radioactivity in soil is one of the major causes of external gamma rays exposure. It was considered imperative to measure gamma-ray activity concentrations due to naturally occurring, potentially hazardous radionuclides from 232Th, 226Ra and 40K in soil samples from Punjab, the most populated province of Pakistan. The activity concentrations were measured in soil samples collected from all 34 district headquarters of Punjab province using a P-type coaxial high purity germanium (HPGe)-based gamma-ray spectrometer having a relative efficiency of 60%. The mean activity concentrations for 232Th, 226Ra and 40K were found to be 41 +/- 8, 35 +/- 7 and 615 +/- 143 Bq kg(-1), respectively in soil samples from all 34 district headquarters of Punjab. The mean values of radium equivalent index (Ra(eq)) and total annual external gamma radiation dose were found to be 141 +/- 27 Bq kg(-1)and 0.38 mSv, respectively. Since these estimated radiological impact assessment factors are lower than the recommended values there seems to be no potential radiological health hazard associated with the soils from the district headquarters in the Punjab province of Pakistan. Geological studies show that most of the soils in Punjab have developed on the extensive fluviatile deposits of five rivers and a stable ratio of natural activity concentrations is observed in soil samples of the areas under study.

Air Pollution, Radioactive↗