Personal Exposure Dose Research Articles

High-resolution distributions of traffic particles and personal inhalation dose estimation at different pedestrian overpasses

While overpasses are conducive to pedestrians’ safe passage across roads, heavy road traffic can also lead to high exhaust emissions and introduce remarkable but uncertain air pollution to overpasses due to complex street environments. To clarify the pollution distribution and personal exposure dose, we collected fine-scale samples of submicron particle (PM1.0) and black carbon (BC) concentrations synchronously at two “I-shaped” overpasses with different street environments. Then, we statistically analysed the spatiotemporal particle patterns at the two overpasses and finally evaluated the pollutant inhalation doses of different pedestrians passing through the overpasses. The measurements indicated that the average particle level was higher in the open overpass crossing heavy ground traffic, and particle hotspots were distributed mostly in the upper sections of the two overpasses, while BC hotspots sometimes occurred at the entrances of the overpass stairways. Contrary to BC, PM1.0 was always high in the morning, and its fluctuations were more affected by suddenly intensified background pollution. Under a low background pollution scenario, the traffic volume and wind speed were the largest factors affecting both pollutants at the two overpasses. The inhalation exposure estimation showed that the inhaled pollutant doses of pedestrians climbing stairs were greater than those of pedestrians walking on the upper sections of the overpasses, and the maximum increment can reach 22%. Among the different groups, the inhalation dose was highest for mid-aged men but lowest for elderly women. These results highlight the importance of optimizing overpasses based on location environments and pedestrian activity levels to maximize the reduction in personal inhaled pollutant dose.

Evaluation of indoor environmental quality, personal cumulative exposure dose, and aerosol transmission risk levels inside urban buses in Dalian, China.

The transmission of pollutants in buses has an important impact on personal exposure to airborne particles and spread of the COVID-19 epidemic in enclosed spaces. We conducted the following real-time field measurements inside buses: CO2, airborne particle concentration, temperature, and relative humidity data during peak and off-peak hours in spring and autumn. Correlation analysis was adopted to evaluate the dominant factors influencing CO2 and particle mass concentrations in the vehicle. The cumulative personal exposure dose to particulate matter and reproduction number were calculated for passengers on a one-way trip. The results showed the in-cabin CO2 concentrations, with 22.11% and 21.27% of the total time exceeding 1000ppm in spring and autumn respectively. In-cabin PM2.5 mass concentration exceeded 35μm/m3 by 57.35% and 86.42% in spring and autumn, respectively. CO2 concentration and the cumulative number of passengers were approximately linearly correlated in both seasons, with R value up to 0.896. The cumulative number of passengers had the most impact on PM2.5 mass concentration among tested parameters. The cumulative personal exposure dose to PM2.5 during a one-way trip in autumn was up to 43.13μg. The average reproductive number throughout the one-way trip was 0.26; it was 0.57 under the assumed extreme environment. The results of this study provide an important basic theoretical guidance for the optimization of ventilation system design and operation strategies aimed at reducing multi-pollutant integrated health exposure and airborne particle infection (such as SARS-CoV-2) risks.

Particulate matter exposure at urban traffic intersection during haze episodes: A case study in Changsha.

Urban intersection has been identified as a major contributor to the total personal exposure and short-term high exposure of particulate matter (PM) in modern cities. The main aim of this study was to get a better understanding of the determinants of traffic-related PM temporal variations and personal exposure to PMs at a viaduct-covered intersection controlled by traffic signals during the winter haze episodes. A two-day field sampling campaign was conducted with a portable device during evening rush hour and measured the PMs in the 0.3-10 μm size range both on the surface crosswalk and underground passage. PM variations and related cumulative respiratory deposition dose (RDD) along two routes with six road crossing scenarios were estimated on a severe pollution day and a typical day for both adults and children, respectively. The PM concentration on the severe pollution day ranged 59.2-67.9 μg/m3 for PM1, 163.8-257.0 μg/m3 for PM2, and 258.2-469.1 μg/m3 for PM10, respectively, as compared to 47.9-57.9 μg/m3for PM1, 112.7-199.8 μg/m3 for PM2, and 151.0-301.0 μg/m3 for PM10 on the typical day, respectively. The variability could be explained largely by the built-up environment, traffic component, signal setting, and ventilation condition. Our data suggest that an appropriate setting of the traffic signal would help reduce the personal exposure dose on the surface crosswalk at urban intersections and the ventilation condition had a significant influence on local PM distributions inside the underground passage. Results here provide possible suggestions for the future design of a walkable city.

Current situation survey for establishing personally acceptable radiation dose limits for nuclear disaster responders.

When responding to disasters, emergency preparedness is essential to ensure that disaster activities are performed smoothly, safely and efficiently. Investigations on the Fukushima accident revealed that lack of preparedness, poor communication and unsuitable emergency measures contributed to an inadequate emergency response to the nuclear disaster. In this study, we conducted a questionnaire survey on the establishment of a personal radiation exposure dose among Disaster Medical Assistance Team (DMAT) members in Japan who might be involved in the initial response to a nuclear disaster. Establishing personal exposure doses for personnel can encourage emergency preparedness and inform decisions on appropriate role assignments during nuclear response activities. Valid responses were obtained from 178 participants, and the response distribution was as follows: ‘Already have own acceptable dose standard,’ 16 (9%); ‘Follow own institution’s standard (and know its value),’ 30 (17%); ‘Follow own institution’s standard (but do not know its value),’ 59 (33%); ‘Haven’t decided,’ 63 (35%) and ‘Don’t understand question meaning,’ 10 (6%). We also assessed intention to engage in nuclear disaster activities among respondents via engagement intent scores (EIS) and found that participants who had established personal exposure standards had significantly higher EIS scores than those who had not decided or who did not understand the question. Thus, educating potential nuclear disaster responders on personal exposure doses may contribute to a higher intention to engage in emergency responses and improve preparedness and response efficiency.

In-car particulate matter exposure across ten global cities

Cars are a commuting lifeline worldwide, despite contributing significantly to air pollution. This is the first global assessment on air pollution exposure in cars across ten cities: Dhaka (Bangladesh); Chennai (India); Guangzhou (China); Medellín (Colombia); São Paulo (Brazil); Cairo (Egypt); Sulaymaniyah (Iraq); Addis Ababa (Ethiopia); Blantyre (Malawi); and Dar-es-Salaam (Tanzania). Portable laser particle counters were used to develop a proxy of car-user exposure profiles and analyse the factors affecting particulate matter ≤2.5 μm (PM2.5; fine fraction) and ≤10 μm (PM2.5–10; coarse fraction). Measurements were carried out during morning, off- and evening-peak hours under windows-open and windows-closed (fan-on and recirculation) conditions on predefined routes. For all cities, PM2.5 and PM10 concentrations were highest during windows-open, followed by fan-on and recirculation. Compared with recirculation, PM2.5 and PM10 were higher by up to 589% (Blantyre) and 1020% (São Paulo), during windows-open and higher by up to 385% (São Paulo) and 390% (São Paulo) during fan-on, respectively. Coarse particles dominated the PM fraction during windows-open while fine particles dominated during fan-on and recirculation, indicating filter effectiveness in removing coarse particles and a need for filters that limit the ingress of fine particles. Spatial variation analysis during windows-open showed that pollution hotspots make up to a third of the total route-length. PM2.5 exposure for windows-open during off-peak hours was 91% and 40% less than morning and evening peak hours, respectively. Across cities, determinants of relatively high personal exposure doses included lower car speeds, temporally longer journeys, and higher in-car concentrations. It was also concluded that car-users in the least affluent cities experienced disproportionately higher in-car PM2.5 exposures. Cities were classified into three groups according to low, intermediate and high levels of PM exposure to car commuters, allowing to draw similarities and highlight best practices.

Identification of Potential Biomarkers of Radiation Exposure in Blood Cells by Capillary Electrophoresis Time-of-Flight Mass Spectrometry.

Biodosimetry is a useful method for estimating personal exposure doses to ionizing radiation. Studies have identified metabolites in non-cellular biofluids that can be used as markers in biodosimetry. Levels of metabolites in blood cells may reflect health status or environmental stresses differentially. Here, we report changes in the levels of murine blood cell metabolites following exposure to X-rays in vivo. Levels of blood cell metabolites were measured by capillary electrophoresis time-of-flight mass spectrometry. The levels of 100 metabolites were altered substantially following exposure. We identified 2-aminobutyric acid, 2′-deoxycytidine, and choline as potentially useful markers of radiation exposure and established a potential prediction panel of the exposure dose using stepwise regression. Levels of blood cell metabolites may be useful biomarkers in estimating exposure doses during unexpected radiation incidents.

Evaluation of Radiation Hazards Due to Mining Activities in Al Jalamid Mining Area, North Province, Saudi Arabia

Radiometric investigation has been conducted in Al Jalamid phosphate mining area, for purposes of radiation protection. A car-borne monitoring system was used for area monitoring, whereas thermoluminescence dosimeters were used for personal dose rate measurements. Natural radioactivity has been analyzed in groundwater by $$\upalpha $$ -spectrometry and liquid scintillation counting. The occupational exposure dose rate inside the open mines and the physical beneficiation site was the highest, ranging from 0.08– $$0.50\,\upmu \hbox {Sv/h}$$ , compared to the normal background values (0.04– $$0.06\,\upmu \hbox {Sv/h}$$ ) recorded on roads and undisturbed topsoil surface. The dose rate was ranging from 0.04– $$0.1\,\upmu \hbox {Sv/h}$$ inside the chemical beneficiation plant. The personal exposure dose rate measurements indicated that a worker would receive, on average, an occupational radiation dose of about $$0.214\,\upmu \hbox {Sv/h}$$ inside the mine sites. It was lowest (about $$0.06\,\upmu \hbox {Sv/h}$$ ) in the offices located outside the mining and ore beneficiation sites. Gross $$\upalpha $$ and gross $$\upbeta $$ measurements in groundwater showed activity concentrations ranging from 0.61 to 0.96 Bq/L and from 2.08 to 3.03 Bq/L, with average values of $$0.78\pm 0.08$$ and $$2.44\pm 037\,\hbox {Bq/L}$$ , respectively. All samples have activity levels exceeding the national regulation limit values. Detailed analysis showed that this water contains uranium and radium with average concentrations of $$0.12\pm 0.04$$ , $$0.33\pm 0.04$$ , $$0.14\pm 0.3$$ and $$21\pm 1.5\,\hbox {Bq/L}$$ , for $${}^{238}\hbox {U}$$ , $${}^{226}\hbox {Ra}$$ , $${}^{228}\hbox {Ra}$$ and $${}^{222}\hbox {Rn}$$ , respectively. The obtained results have been discussed in detail.

The safety assessment system based on virtual networked environment for evaluation on the hazards from human errors during decommissioning of nuclear facilities

This paper is intended to suggest a system for evaluation on the hazards from human errors during decommissioning of nuclear facilities. The system was developed under virtual networked environment. The innovative features are real-time changing direction of workers in a scenario and real-time measuring personal exposure dose and collective exposure dose. The system will be expected to be utilized as a training tool for improving familiarization of a workplace and for preventing workers from accidents.

Energy dependence measurement of small-type optically stimulated luminescence (OSL) dosimeter by means of characteristic X-rays induced with general diagnostic X-ray equipment.

For X-ray inspections by way of general X-ray equipment, it is important to measure an entrance-skin dose. Recently, a small optically stimulated luminescence (OSL) dosimeter was made commercially available by Landauer, Inc. The dosimeter does not interfere with the medical images; therefore, it is expected to be a convenient detector for measuring personal exposure doses. In an actual clinical situation, it is assumed that X-rays of different energies will be detected by a dosimeter. For evaluation of the exposure dose measured by a dosimeter, it is necessary to know the energy dependence of the dosimeter. Our aim in this study was to measure the energy dependence of the OSL dosimeter experimentally in the diagnostic X-ray region. Metal samples weighing several grams were irradiated and, in this way, characteristic X-rays having energies ranging from 8 to 85keV were generated. Using these mono-energetic X-rays, the dosimeter was irradiated. Simultaneously, the fluence of the X-rays was determined with a CdTe detector. The energy-dependent efficiency of the dosimeter was derived from the measured value of the dosimeter and the fluence. Moreover, the energy-dependent efficiency was calculated by Monte-Carlo simulation. The efficiency obtained in the experiment was in good agreement with that of the simulation. In conclusion, our proposed method, in which characteristic X-rays are used, is valuable for measurement of the energy dependence of a small OSL dosimeter in the diagnostic X-ray region.

시스템 개선을 통한 핵의학 검사실의 공간 선량률 감소방안

Objectives: This study aims at decreasing spatial dose rate through work improvement whilst spatial dose rate is the cause of increasing personal exposure dose which occurs in the process of handling radioisotope. Methods: From February 2013 until July 2013, divided into "before" and "after" the improvement, spatial dose rate in laboratory of nuclear medicine was measured in gamma image room, PET/CT-1 image room, and PET/CT-2 image room as its locations. The measurement time was 08:00, 12:00 and 17:00, and SPSS 21.0 USA was opted for its statistical analysis. Result: The spatial dose rate at distribution worktable, injection table, the entrance to the distribution room, and radioisotope storage box, which had showed high spatial dose rate, decreased by more than 43.7% a monthly average. The distribution worktable, that had showed the highest spatial dose rate in PET/CT-1 image room, dropped the rate to 42.3% as of July. The injection table and distribution worktable in the PET/CT-2 image room also showed the decline of spatial dose rate to 89% and 64.4%, respectively. Conclusion: By improving distribution process and introducing proper radiation shielding material, we were able to drop the spatial dose rate substantially at distribution worktable, injection table, and nuclide storage box. However, taking into account of steadily increasing amount of radioisotope used, strengthening radiation related regulations, and safe utilization of radioisotope, the process of system improvement needs to be maintained through continuous monitoring.

Study on the angular dependence of personal exposure dosimeter – Focus on thermoluminescent dosimeter and photoluminescent dosimeter

Radiation management departments place more emphasis on the accuracy of measurements than on the increase in the average dose and personal exposure dose from the use of radiation equipment and radioactive isotopes. Although current measurements are taken using devices, such as film badge dosimeters, pocket dosimeters and thermoluminescent dosimeters (TLDs), this study compared the angular dependence between the widely used TLDs and photoluminescent dosimeter (PLDs) in order to present primary data and evaluate the utility of PLD as a new dosimeter device. For X-ray fluoroscopy, a whole body phantom was placed on a table with a setting for the G-I technical factors fixed at a range of approximately 40 cm with a range of ±90° at an interval scale of 15° from the center location of an average radiological worker for PLDs (GD-450) and TLDs (Carot). This process was repeated 10 times, and at each time, the cumulative dosage was interpreted from 130 dosimeters using TLDs (UD-710R, Panasonic) and PLDs (FGD-650). The TLD and PLD showed a 52% and 23% decrease in the depth dosage from 0° to −90°, respectively. Therefore, PLDs have a lower angular dependence than TLDs.

ＩＶＲに従事する看護師の被ばく形態の把握と管理手法の検討

Although a large number of studies have been done on exposure to operators and doctors during interventional radiology(IVR), there have been very few reports on nurses. This study was carried out to clarify the situation regarding exposure for nurses, and provides examples of how to estimate and manage. We measured space dose-rate distributions with an ionization survey meter, and personal exposure dose by a small fluorescent grass dosimeter(Dose Ace). The experimental results disclosed that there tended to be two types of exposure depending on the task performed. Head and neck(collar level)were associated with the highest exposure dose, which was observed in nurses assisting operators. Alternatively, knees showed the highest exposure dose, which was observed in nurses observing and assisting the patient. When estimation of skin equivalent exposure at the knees is needed, it can be calculated by using the value measured at the collar level. Furthermore, in estimating exposure dose, the directional and energy characteristics of personal dosimeters should be considered adequate. For radiation management, a circular protective sheet can be placed around the patient's lower area and a protective screen near the patient's head, and basic and practical education can be given. We concluded that these are highly useful for the personal monitoring of nurses engaged in IVR.

Can Urinary OH-PAHs Be Used to Predict Cancer Risk Associated with Personal Exposure to PAHs?

P-140 Abstract: Polycyclic aromatic hydrocarbons (PAHs), a group of known or suspected carcinogenic compounds, are produced during pyrolysis or incomplete combustion of organic materials. PAHs are ubiquitously present in multiple environmental media such as air, food, cigarette smoke and certain products. Although a number of biomarker studies have been carried out for assessing PAH exposures, so far the biomarker-based studies have not contributed to the identification and quantification of cancer risk. One of the biomarkers widely studied is urinary 1-hydroxyl-pyrene (1-OH-Py), a metabolite of pyrene. Pyrene is a relatively abundant but noncarcinogenic compound in the PAHs family. To date few studies have focused on urinary 3-OH-BaP, a direct metabolite of carcinogenic benzo(a)pyrene. The purpose of this paper is to study the feasibility of using 1-OH-Py or/and 3-OH-BaP to predict human exposure dose to PAHs and associated cancer risk. In this study, 100 non-smoking adults were selected as subjects. Among them, 50 were coke oven workers in various jobsites, 25 were administrators in a steal factory, and 25 were non-factory employees in offices far away from factory. Their 24-hr personal air samples, 24-hr dietary samples and every void of urine samples during this 24-hr study time were collected. Fourteen individual PAHs in air and food samples as well as 1-OH-Py and 3-OH-BaP in urine samples were respectively analyzed using HPLC-fluorescence techniques. The results showed that the total daily exposure dose to PAHs in coke oven workers was 17.94 ± 30.10(mean ± SD)μg/day, significantly higher than 1.27 ± 2.23 ug/day in the general group. The concentration of urinary 1-OH-Py in coke oven workers was 3.19 ± 4.10 μmol per mol creatinine, significantly higher than 0.19 ± 0.27 μmol/mol. in the general group. We found positive quantitative relationships between urinary 1-OH-Py and personal exposure dose to PAHs. Thus urinary 1-OH-Py concentrations can be used to estimate PAH cancer risks. On the contrary, the concentration of urinary 3-OH-BaP in coke oven workers was 0.04 ± 0.02 μmol/mol, significantly lower than 0.09 ± 0.07 in the general group. This may reflect reduced PAH-detoxification capability, due to long-term exposure to high levels of PAHs, of the coke oven workers. Therefore, the PAH body burden may be better predicted using both 1-OH-Py and 3-OH-BaP than solely using 1-OH-Py. We propose a cancer risk assessment model based on the ratio of urinary 1-OH-Py to 3-OH-BaP. Key Words: Polycyclic aromatic hydrocarbons(PAHs); Biomarker; Urinary 1-OH-Py; Urinary 3-OH-BaP.

Contributions of Chinese-style cooking and incense burning to personal exposure and residential PM concentrations in Taiwan region

We investigated the effect of indoor sources including Chinese-style cooking, incense burning, cleaning, and people's moving on indoor particle size distributions and concentrations and calculated the personal exposure dose rates in the human respiratory tract (HRT) using time-activity and indoor and outdoor particle size distribution data collected from a traditional Taiwanese residence in central Taiwan region. We applied a simple size-dependent indoor air quality model associated with a compartmental lung model to determine the source emission rates and exposure dose. Cooking and incense burning had size-integrated source emission rates of 0.042 ± 0.024 (mean ± S.D.) and 0.038 ± 0.026 particles s − 1 , respectively. Cooking and incense burning were significant contributors to indoor particle levels for particle sizes from 0.5 to 5 μm in that the percent contributions to indoor concentrations were 0.334 ± 0.02 and 0.267 ± 0.035, respectively. Our results demonstrated that extrathoracic (ET) region had higher average PM mass lung/indoor ratio (0.77) than that of bronchial (BB) (0.52), bronchiolar (bb) (0.27) and alveolar-interstitial (AI) (0.14) regions from both cooking and incense burning events. The average integrated deposition dose rates (particles cm − 2 h − 1 ) of 24.11 in ET, 4.68 in BB, and 7.89 in bb were higher than that of 0.011 in AI for both cooking and incense burning events. This research illustrates that exposure assessment based on time-activity and real-time behavior of particle data can provide valuable information on the fate of indoor particles and hazard to human health.

101. パーソナルコンピュータを用いた個人被ばく情報管理システム (第 2 報)(被曝・装置管理)

101. パーソナルコンピュータを用いた個人被ばく情報管理システム (第 2 報)(被曝・装置管理)

101. パーソナルコンピュータを用いた個人被ばく情報管理システム (第 2 報)

101. パーソナルコンピュータを用いた個人被ばく情報管理システム (第 2 報)

A simple method for monitoring ozone exposure (author's transl)

A simple passive type sampling device has been developed for personal monitoring of ozone exposure in the workshop of welding. Atmospheric ozone is collected on a filter paper soaked in 1,2-di-(4-pyridyl)-ethylene. Pyridine-4-aldehyde is produced by the ozonolysis reaction. Analysis of the results showed the time-weighted (TWA) exposure concentration of ozone. The relationship showed a good linearity between the pyridine-4-aldehyde produced and the ozone concentration. Coefficient of variation of the data of measurement after exposure was less than 10%. and the range of the data was from 0.05 to above 1.42 ppm hr. Promising results have been obtained in the data of controlled exposures to nitrogen dioxide, and excellent stability for delayed analysis after sampling. According to these results, we believe that the simple sampling device can be used for the evaluation of personal exposure dose for ozone.

Effects of the Relative Humidity on Track Fading and Prevention of Fading of the Personal Neutron Monitoring Film

In JAERI, Kodak Personal Neutron Monitoring Film, Type A-NTA film-has been used to estimate personal exposure dose due to fast neutrons. Track fading, spectrum of track after fading and prevention of track fading of the NTA film were investigated at various relative humidities of the atomosphere.The phenomenon of track fading of the NTA film was remarkable at higher relative humidity and the fading curves consist of two components of exponential function. Relationship of lineality between dose and number of track was found to be still maintained in the advance of fading. In addition, dose dependence of fading was not observed. As relative humidity and storage time increases, track length became shorter and grain density of track decreased. Track fading is prevented by wrapping the NTA film with vinylidene chloride film and putting in the badge case.

緊急時における中性子被曝線量の推定

In the case of a nuclear accident, it is important to quickly know personal exposure doses. In spite of the recent advances in physical dosimetry, the detection of neutron exposure dose is not always possible, because of the absence of an adequate system of physical dosimetry. The object of this study is to obtain information concerning personal neutron exposure doses on human hair, nails, and blood, with the view to determining a convenient method of detecting unexpected exposure.The most easily detectable nuclides in the hair were 24Na, 56Mn, 64Cu and 32P. In case of serum, 24Na was the element easily detected, while 24Na, 56Mn, 64Cu and 32P were also found in the nails. The production of 32P is the result of 32S (n, p) 32P reaction with fast neutrons, while the other nuclides have been mainly produced with thermal neutrons. The effect of competing reactions was found to be negligibly small. In order to know the content of each element in the human hair, nails and blood, neutron activation analyses of 24Na, 56Mn, 64Cu, 38Cl and 32P were carried out. The detectable limits for 1 g of hair were 5 rem for thermal neutron exposure and 60 rem for fast neutron exposure. The result of this study shows that the hair is a useful detector for estimating the fast and thermal neutron exposure doses in the case of nuclear accident.