Activity Concentrations In Air Research Articles

Radon decay products in realistic living rooms and their activity distributions in human respiratory system

In this study, the individual activity concentrations of attached short-lived radon decay products ((218)Po, (214)Pb and (214)Po) in aerosol particles were measured in ten poorly ventilated realistic living rooms. Using standard methodologies, the samples were collected using a filter holder technique connected with alpha-spectrometric. The mean value of air activity concentration of these radionuclides was found to be 5.3±0.8, 4.5±0.5 and 3.9±0.4 Bq m(-3), respectively. Based on the physical properties of the attached decay products and physiological parameters of light work activity for an adult human male recommended by ICRP 66 and considering the parameters of activity size distribution (AMD = 0.25 μm and σ(g) = 2.5) given by NRC, the total and regional deposition fractions in each airway generation could be evaluated. Moreover, the total and regional equivalent doses in the human respiratory tract could be estimated. In addition, the surface activity distribution per generation is calculated for the bronchial region (BB) and the bronchiolar region (bb) of the respiratory system. The maximum values of these activities were found in the upper bronchial airway generations.

Development of a transfer standard for the measurement of low Rn-222 activity concentration in air

A large volume transfer standard has been developed to calibrate commercial radon measurement devices in a homogeneous Rn-222 reference atmosphere. The transfer standard serves for the realization, maintenance and dissemination of the unit Bq/m3 below 1kBq/m3.The transfer standard consists of a multi-wire impulse ionization chamber, electronic measurement equipment and the corresponding software. The multi-wire impulse ionization chamber is composed of two parallel printed boards. Between the boards, 478 vertical electrode wires are soldered in to include a volume of 10L. In the dependency of the energy, the α-particles of Rn-222 and the decay products are detected in the active volume of the multi-wire impulse ionization chamber. By means of the measurement software an α-energy spectrum is produced. Via different algorithms, the activity concentration of the Rn-222 reference atmosphere is determined.

Variability of atmospheric krypton-85 activity concentrations observed close to the ITCZ in the southern hemisphere

Krypton-85 activity concentrations in surface air have been measured at Darwin, which is located in northern Australia and is influenced by seasonal monsoonal activity. Measurements between August 2007 and May 2010 covered three wet seasons. The mean activity concentration of krypton-85 measured during this period was 1.31±0.02Bqm−3. A linear model fitted to the average monthly data, using month and monsoon as predictors, shows that krypton-85 activity concentration measured during the sampling period has declined by 0.01Bqm−3 per year. Although there is no statistically significant difference in mean activity concentration of krypton-85 between wet and dry season, the model implies that activity concentration is higher by about 0.015Bqm−3 during months influenced by the monsoon when a north westerly flow prevails. Backward dispersion runs using the Lagrangian particle dispersion model Hysplit4 highlight possible source regions during an active monsoon located deep in the northern hemisphere, and include reprocessing facilities in Japan and India. However, the contribution of these facilities to krypton-85 activity concentrations in Darwin would be less than 0.003Bqm−3.

Hadley cell influence on 7Be activity concentrations at Australian mainland IMS radionuclide particulate stations

Beryllium-7 (7Be) daily data from the four International Monitoring System (IMS) radionuclide particulate stations on mainland Australia are analysed over the period 2001 to 2011. The analysis indicates that levels of 7Be in surface air at the stations follow annual cycles, with yearly peak activity concentrations occurring later at stations further south. The yearly peak migrates north–south at a rate of approximately 4.4° latitude per month. The change in phase of the 7Be annual cycle between the stations corresponds with the seasonal migration of the Southern Hemisphere Hadley cell across mainland Australia. The implication is that the changing position of the downward limb of the Southern Hemisphere Hadley cell regulates the phase of the annual cycle in 7Be activity concentrations in surface air in the Australian region.

Activity size distribution of some natural radionuclides

In this study, the results concerning the activity size distribution of the long-lived ((210)Pb) radon decay product aerosols and the thoron decay product aerosols ((212)Pb) and ((7)Be) of the outdoor atmosphere are presented. Also, the mass size distribution of the aerosol particles is determined. The low-pressure Berner cascade impactor Model 20/0.015 was used as a sampling device. The activity size distribution of these radionuclides was determined by one log-normal distribution (accumulation mode) whereas the mass size distribution was by two log-normal distributions (accumulation and coarse mode). The activity median aerodynamic diameter (AMAD) of (212)Pb was found to be 305 nm with a geometric standard deviation (σg) of 2.41. The specific air activity concentration of (212)Pb was found to be 0.14 ± 0.012 Bq m(-3). An AMAD of (210)Pb of 610 nm with σg of 1.8 was determined, whereas that of 550 nm with σg of 1.97 was determined for (7)Be. The specific air activity concentration of (210)Pb and (7)Be was found to be 0.0016±2.5×10(-4) and 0.00348 ± 4×10(-4) Bq m(-3), respectively. Using a dosimetric model, the total deposition fraction as well as the total equivalent dose has been evaluated considering the observed parameters of the activity size distribution of (212)Pb. At a total deposition fraction of ∼21 %, the total equivalent dose was found to be 0.41 µSv.

Radionuclides from Fukushima accident in Thessaloniki, Greece (40°N) and Milano, Italy (45°)

131I, 137Cs and 134Cs were observed in environmental samples in Milano (40°N), Italy and Thessaloniki (45°N), Greece, soon after the nuclear accident in Fukushima, Japan. The radionuclide concentrations were determined and studied as a function of time. In Thessaloniki the 131I in air was observed for the first time on March 24, 2011. In Milano, the first evidence of Fukushima fallout has been confirmed with 131I and 137Cs measured in wet precipitation collected 2 days later. The maximum 131I activity concentration in air of 467 ± 25 μBq m−3, observed in Milano on April 3–4, 2011, was almost similar to the highest value of 497 ± 53 μBq m−3 observed in Thessaloniki. The 134Cs/137Cs activity ratio values in air were around 1 in both regions. Soil, grass and milk samples were contaminated with 131I and 137Cs at a low level. Finally, a dose assessment for these two areas showed clearly that the detected activities in all environmental samples were far below levels of concern.

Mesoscale behavior of 7Be and 210Pb in superficial air along the Gulf of Cadiz (south of Iberian Peninsula)

210Pb and 7Be activity concentrations in surface air and in bulk deposition have been measured from November 2009 to December 2011 along the Gulf of Cadiz (Southwest of Spain). This area presents mesoscale variations in its meteorological conditions, with influence of air masses with different origins: maritime, either from the Atlantic Ocean or the Mediterranean Sea and continental, from Iberian Peninsula and north of Africa, which make possible this region to be suitable to analyse the mesoscale spatial and temporal variations of atmospheric compounds. The objective of this study is to determine if there are differences in 210Pb and 7Be activity concentrations in surface air and in bulk deposition at the mesoscale level in this complex area of southwestern Iberian Peninsula taking as reference two sites of the same geographical area but influenced by different meteorological conditions.The temporal evolution pattern of PM10 was different for each site (no correlation between both series was found), but the PM10 average concentrations were similar for both locations (differences were not found at 0.05 significance level). On the other hand, the temporal evolution of 7Be and 210Pb activity concentrations in surface air show a good correlation between both sites, indicating this fact a similar behaviour of these radionuclides in the area.Finally, for each location a strong correlation between 210Pb and 7Be depositional fluxes was also observed, showing that wet deposition plays a key role in the deposition fluxes of both radionuclides. The averages depositional fluxes for 7Be and 210Pb are 750 Bq m−2 y−1 and 60 Bq m−2 y−1 in both locations, respectively.This set of results allows to determine that both radionuclides (7Be and 210Pb) present similar atmospheric behaviours, although with mesoscale variations in the magnitude of the values along the entire southern coast of the Iberian Peninsula.

Levels of Radon Activity Concentration in Air of Coal Mines in Bosnia and Hercegovina

By coal mining and exploatation, radioactive radon gas, which is captured in natural geological structures, is reallocated from the deep coal layers. Hence it is concentrated in the depots and coal seams of the mines or being transported to the surface of the earth where it can significantly change the levels of radioactivity in the working premises and residences. This paper presents the results of a three-year research of radon activity concentration in the air in hole and surface coal mines of Bosnia and Herzegovina. Detected concentrations of radon in the coal gaseous structure, atmosphere and other ambient media are in correlation with the properties of geological structures, technology for obtaining coal and meteo-climatic changes. They were measured with Alpha GUARD PQ 2000 radon portable measuring system (instruments Genitron-Frankfurt) and RadoMeter 2000 (Radosys LTD. Budapest), using the SS-NTD method.

Assessment of environmental radiation monitoring data in Hungary following the Fukushima accident

The unusually strong earthquake in Japan on 11 March 2011 and the following extreme tsunami caused enormous damage in the buildings of Fukushima Dai-ichi Nuclear Power Plant (NPP) situated on the Pacific coastline of Japan. The accident led to the release of a large amount of radioactive material into the environment. According to the measurements of the Radiological Monitoring and Data Acquisitions Network (RAMDAN) the radioactive plume reached Hungary on 24 March 2011. The main volatile fission products – 131 I, 134 Cs, and 137 Cs radioisotopes – were measurable in aerosol and fallout samples in Hungary. Their activity concentration in air reached the maximum value in the last days of March and returned to the background level in the first half of May. As a consequence of respiration of contaminated air, a maximum of 1 Bq per capita of 131 I could be accumulated in the thyroid gland of the Hungarian population during the given period. The calculated upper limits of the committed effective dose from inhalation of 131 I were 4 nSv and 10 nSv to the Hungarian adults and infants, respectively. These values are a hundred thousand times less than the annual radiation dose from natural sources to the Hungarian population. The radiation dose from radioactive caesium isotopes originating from Fukushima was even less, around 1 nSv on average, to Hungarian residents. No health deterioration can be expected from this radiation burden.

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.

Using Animal Thyroids as Ultra-Sensitive Biomonitors for Environmental Radioiodine

In the course of the Fukushima nuclear accident large amounts of radionuclides relevant to the Comprehensive Nuclear-Test-Ban-Treaty (CTBT) were released and detected globally. We could show that the intake of environmental (131)I into the thyroids of animals can be used for verification of the CTBT. Due to continuous accumulation of (131)I, its apparent half-life in the thyroid biomonitor exceeds the physical one, thus making (131)I detectable three weeks longer than using conventional CTBT-grade high volume air samplers. The maximum (131)I activity concentrations (in Bq/kg) found in Austrian animal thyroids after the Fukushima nuclear accident could be correlated with the maximum activity concentrations found in air (Bq/m(3)) in Austria via a factor of 1.1 × 10(6). In fall 2011, a second (much smaller) release of (131)I occurred from a laboratory in Hungary, where this factor was 1.9 × 10(6). Hence thyroid biomonitors offer even some quantitative information, which allows the estimation of the (131)I activity concentrations in air. It could be shown that thyroid biomonitors can work under dry conditions, which potentially makes them the method of choice for CTBTO on-site inspections even in arid environments.

Radioecological indexes of fallout measurements from the Fukushima nuclear accident

Fallout from the Fukushima nuclear accident has been monitored for about 1 month in Thessaloniki, Northern Greece. Three different radionuclides, one short-lived, one relatively long-lived and one long-lived fission product were identified in air, grass and milk samples. The 131I, 137Cs and 134Cs activity concentrations in air reached 497, 145 and 126μBqm−3, respectively on 4 April, 2011. These radionuclides are of particular concern regarding their transfer from the environment to population through the ingestion pathways for the assessment of the Fukushima accident consequences. Radioecological indexes (eco-indexes) of fallout measurements in the air–grass–cow-milk–man pathway for 131I were determined, as they are related to radiological impact of the Fukushima derived radionuclides on the public and environment.

Meteorological factors influencing the 7Be and 210Pb concentrations in surface air from the southwestern Iberian Peninsula

During a seven-year period (April 2004–July 2011), the 210Pb and 7Be activity concentrations in surface air were determined at El Arenosillo, located on the coastline of the southwestern Iberian Peninsula. The 210Pb and 7Be activity concentrations have been classified in four ranges according to the values of percentiles, 0–P10 (lowest concentrations), P10–P50 (intermediate concentrations), P50–P90 (high concentrations), and P90–Maximum (peaks of concentrations).The computation of both backward trajectories and cluster techniques has been used for identifying the types of air masses that arrive at the sampling station for each range of 210Pb and 7Be activity concentrations. Meteorological parameters, such as the wind roses and daily cycles of specific and relative humidity, and the potential temperature have been calculated (or measured) for each one of the sampling periods and grouped according to the ranges of 210Pb and 7Be activity concentrations.The results indicate that different synoptic patterns are associated with different 210Pb and 7Be activities in this area, which indicates the differences between the arrival of maritime and continental air masses based on the 210Pb and 7Be activities. In addition, the study on the evolution of air masses from the lowest and highest ranges of 7Be/210Pb confirms that both radionuclides can be used as two independent atmospheric transport markers.

Detection of Fukushima Daiichi nuclear power plant accident radioactive traces in Monaco

Daily air monitoring of radionuclides in the Principality of Monaco (43°73′N, 7°43′E) after the Fukushima Daiichi nuclear power plant accident showed that only Iodine-131 (131I) and Caesium isotopes (134Cs and 137Cs) were detected. The peak of 131I varied and reached its maximum between March 29th and April 5th, meanwhile both peaks of 134Cs and 137Cs arrived later and attained a maximum between April 1st and 4th. Their maximum activity concentrations in air were 354, 30, and 37 μBq m−3 respectively. The 134Cs to 137Cs activity ratio was close to 1, which is different from that one observed after the Chernobyl accident (around 0.54). Up to 95% of caesium isotopes were washed out by wet scavenging during 27–28th of March, where the maximum deposition rates of 134Cs and 137Cs (13.7 and 19.1 mBq m−2 day−1, respectively) were observed. The significant input of 134Cs and 137Cs into the Mediterranean seawater column (30 m depth) was detected later, on the 24th of May. Radioisotopes of caesium and iodine were found far above the applied detection limits, but still with no concern for harmful radiation exposure and public health. The contamination gradually decreased in air and activity concentrations returned to background values after one or two months.

A theoretical approach to the re-suspension factor

The atmospheric re-suspension of radionuclides is a well-known phenomenon that consists in the re-injection into the atmosphere of previously deposited radioactivity. The process is driven by the action of wind on surfaces and can act as an additional source of radiation exposure by inhalation, after the deposition has finished. It is thus defined as the re-suspension factor, a parameter K generally considered as a time depending function and defined as the ratio of Ca ,t he volumetric air activity concentration (Bq m −3 )a ndI0 (Bq m −2 ), the radioactivity deposition at time zero. The re-suspension factor concept is very useful in radioprotection in order to estimate the inhalation of radionuclides re-suspended from contaminated surfaces when direct atmospheric measurements are lacking or difficult to perform. However, the choice of the proper values of K is usually not a simple task, being quite site-specific and related to the meteorological, geomorphologic and environmental characteristics of the area to be studied. Moreover, several investigations showed clearly that the values of K are a decreasing function of time. For that reason, K values span several orders of magnitude: typical values in the range 10 −5 –10 −10 m −1 are reported in literature for different environmental conditions and time elapsed since the deposition event. The current available models for the re-suspension factor are based on empirical formulas whose parameters are highly site dependent and cannot easily be related to some physical quantity. In this paper a simple physical model for the re-suspension factor is proposed and tested with available environmental radioactivity

Determination of Symmetrical Index for 3H in Precipitation and 137Cs in Ground Level Air

The paper presents results of a long-term investigations of tritium activity concentrations in precipitation and radiocesium activity concentrations in ground level air in Belgrade, Serbia. Samples were collected at three locations in Belgrade (Meteorological Station of Belgrade MS at Zeleno Brdo (ZB), Meteorological Station MS Usek (USEK), and Vinca Institute of Nuclear Sciences (VINS)). Presented data cover the period 1985–1997. Significantly higher tritium levels were measured in samples in VINS compared with off-site location, while the impact of research reactor for 137Cs was not detected. It was found that the value of the symmetrical index n is higher for VINS in case of tritium, compared to other locations, which is in accordance with the fact that the highest average monthly concentrations of tritium were obtained in the samples from the cited place. Although the highest value of index n in case of 137Cs was also obtained for VINS, average monthly concentrations of 137Cs in ground level air for this location were the lowest. The 137Cs concentration in the ground level air is described by a kinetic equation of the first order and provides a good description of the time changes in these concentrations.

Radiation measurements and radioecological aspects of fallout from the Fukushima nuclear accident

Fallout from the Fukushima Nuclear Accident has been monitored for about 1 month in Thessaloniki, Northern Greece. Three different radionuclides, one short-lived, one relatively long-lived and one long-lived fission product were identified in air, precipitation, soil, grass and milk samples. The 131I, 137Cs and 134Cs activity concentrations in air reached 497, 145 and 126 μBq m−3, respectively on 4 April, 2011. The external exposure dose rate to humans of the order of 14.4 pSv per day due to 137Cs deposited on the ground was very small compared to the normal background level. The accumulated dose equivalent to the adult thyroid from inhaled 131I varied from 0.4 to 3.5 nSv per day was insignificant and there was not any problem for the Greek population and no preventive measures were needed to be provided against the nuclear accident according to the Greek Atomic Energy Commission, the official agent of the Greek Government. Some special radioecological aspects in the air-grass-cow-milk-man pathway for 131I were particularly studied.

Temporal changes of 7Be, 137Cs and 210Pb activity concentrations in surface air at Monaco and their correlation with meteorological parameters

Results of analysis of 7Be, 137Cs and 210Pb on aerosol filters carried out from 1998 to 2010 in Monaco show that a weak correlation between activity concentrations of these radionuclides in the atmosphere and meteorological parameters has been found for 7Be and temperature ( r = 0.50), 210Pb and temperature and humidity ( r = 0.43 and 0.41, respectively), and 137Cs and precipitation ( r = 0.51). The minimum and maximum 7Be activity concentrations were observed during 2000 and 2009, corresponding with the maximum and minimum solar activity, respectively. The maximum 137Cs activity concentration found in May–June 1998 was due to the accident at Algeciras in Spain. The deposition velocities of 7Be, 137Cs and 210Pb depended on the precipitation rate, and attained maximum values during dry seasons. The investigated radionuclides may be used as atmospheric tracers, especially in long-term periods.

Polonium-210 and lead-210 in the terrestrial environment: a historical review

The radionuclides 210Po and 210Pb widely present in the terrestrial environment are the final long-lived radionuclides in the decay of 238U in the earth’s crust. Their presence in the atmosphere is due to the decay of 222Rn diffusing from the ground. The range of activity concentrations in ground level air for 210Po is 0.03–0.3 Bq m −3 and for 210Pb 0.2–1.5 Bq m −3. In drinking water from private wells the activity concentration of 210Po is in the order of 7–48 mBq l −1 and for 210Pb around 11–40 mBq l −1. From water works, however, the activity concentration for both 210Po and 210Pb is only in the order of 3 mBq l −1. Mosses, lichens and peat have a high efficiency in capturing 210Po and 210Pb from atmospheric fallout and exhibit an inventory of both 210Po and 210Pb in the order of 0.5–5 kBq m −2 in mosses and in lichens around 0.6 kBq m −2. The activity concentrations in lichens lies around 250 Bq kg −1, dry mass. Reindeer and caribou graze lichen which results in an activity concentration of 210Po and 210Pb of about 1–15 Bq kg −1 in meat from these animals. The food chain lichen-reindeer or caribou, and Man constitutes a unique model for studying the uptake and retention of 210Po and 210Pb in humans. The effective annual dose due to 210Po and 210Pb in people with high consumption of reindeer/caribou meat is estimated to be around 260 and 132 μSv a −1 respectively. In soils, 210Po is adsorbed to clay and organic colloids and the activity concentration varies with soil type and also correlates with the amount of atmospheric precipitation. The average activity concentration levels of 210Po in various soils are in the range of 20–240 Bq kg −1. Plants become contaminated with radioactive nuclides both by absorption from the soil (supported Po) and by deposition of radioactive fallout on the plants directly (unsupported Po). In fresh leafy plants the level of 210Po is particularly high as the result of the direct deposition of 222Rn daughters from atmospheric deposition. Tobacco is a terrestrial product with high activity concentrations of 210Po and 210Pb. The overall average activity concentration of 210Po is 13 ± 2 Bq kg −1. It is rather constant over time and by geographical origin. The average median daily dietary intakes of 210Po and 210Pb for the adult world population was estimated to 160 mBq day −1 and 110 mBq day −1, corresponding to annual effective doses of 70 μSv a −1 and 28 μSv a −1, respectively. The dietary intakes of 210Po and 210Pb from vegetarian food was estimated to only 70 mBq day −1 and 40 mBq day −1 corresponding to annual effective doses of 30.6 μSv a −1 and 10 μSv a −1, respectively. Since the activity concentration of 210Po and 210Pb in seafood is significantly higher than in vegetarian food the effective dose to populations consuming a lot of seafood might be 5–15 fold higher.

Modelling tritium flux from water to atmosphere: application to the Loire River

Tritium ( 3H or T) is one of the major radionuclides released by nuclear power plants (NPP) into rivers. However, tritiated water (HTO) flux from water to air is seldom considered when assessing health effects of such releases. The aim of this paper is to present the result of a research program, called LORA, conducted on the Loire River (France). To improve our understanding of HTO flux from surface water to air, three field campaigns were organised during the NPP’s radioactive releases to measure simultaneously the activity concentrations in air on the riverbank, using an innovative system, and in river water. The measurements showed that during radioactive releases, water vapour was enriched in 3H. These results were used to calibrate exchange velocities. The average of these estimated exchange velocities was more than one order of magnitude higher than those calculated in the literature from indoor experiments. The variability of these values was also larger, showing that outdoor studies cover a wide range of conditions influencing HTO flux. No correlation was observed between exchanges velocities and meteorological conditions. However, there was a significant difference between day and night with a higher value observed during the day. Two approaches used to calculate HTO evaporation from water (i.e. the approach based on water evaporation and the approach considering that HTO follows its own concentration gradient) were included in a hydrodynamic model, which was used to evaluate HTO air activity along the Loire River. In conclusion, only the approach considering that HTO follows its own gradient led to a good agreement between measurements and predictions. A one-year simulation was done to estimate the contribution of this process to the dose. Its contribution can be considered as negligible in this case compared to the other pathways such as ingestion of water or foodstuffs.