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This study aims to assess the particulate matter (PM1, PM2.5, PM10) and black carbon (BC) in the Korea Train eXpress (KTX) cabin during train running, and the personal exposure of PM2.5 for the female/male passengers who use the KTX 20 days a month to commute. Intensive measurements were made on the day when the outside ambient PM concentration was much higher than usual. To compare with the PM concentration in the subway cabin, a measurement was also performed in some sections of the Seoul Metro subway (from Namyoung Station (hereafter referred to as the "Sta.") to Jonggak Sta.). The amount of PM2.5 exposure (Exposure PM2.5 (µg)) was calculated for the male/female passengers who regularly board the KTX. The Car-exposure PM2.5 (µg), which is the amount of PM2.5 exposure when moving by car in the same section, was also calculated. The PM concentration in the KTX cabin elevated and fallen off at train staying and train running, respectively. The PM2.5 concentrations inside KTX cabin at the stop station exhibited a remarkable positive correlation with those of outdoor. Compared to the PM concentration measured in the cabin of Seoul Metro subway, PM1, PM2.5, and PM10 in the KTX passenger cabin were 74.9%, 73.3%, and 62.7% of those in the cabin of Seoul Metro subway, respectively. The PM2.5 exposure amount (exposure PM2.5 (µg)) when moving the same section using the KTX and passenger cars was calculated, and as a result, the exposure PM2.5 (µg) for both male and female were 5.7 times lower in the KTX than that in car. The mapping result of BC concentration drawn on the KTX line from Iksan Sta. to Gwangmyeong Sta. shows that it fluctuated greatly for each service section or stop station. [ABSTRACT FROM AUTHOR]

A thick foggy weather and worst visibility in Fukuoka, Japan and Busan, South Korea occurred from the late July to early August 2020 due to the Nishinoshima volcanic eruption. In this study, an intensive measurement was made to clarify the chemical nature of the ambient particulate matter (PM) and rain water collected in Fukuoka and Busan during the Nishinoshima volcanic eruption (episode period) and non-eruption (non-episode period). In this study, one week after volcanic eruption, which recorded the usual PM concentration, was defined as the non-episode period. Compared to non-episode period, the PM2.5 concentration during the episode period increased 4.32 times in Busan and 6.03 times in Fukuoka. The sulfur and chlorine concentrations in the total suspended particles (TSP) and rainwater of episode period were particularly higher than those of non-episode period. The sulfate concentration in PM2.5 was 1.81 and 27.98 µg/m³ in non-episode and episode periods, respectively. The sulfate concentration during the episode period accounted for 55.4% of PM2.5 (50.45 µg/m³). Strong correlation between trace elements in TSP and those in rainwater during the episode period indicates that the volcanic ashes could be incorporated into raindrops. [ABSTRACT FROM AUTHOR]

In order to provide a better knowledge of visibility degradation during the PM2.5 event day (episodic high PM2.5 level, hereafter called as "event day"), the relationship between visibility and the chemical species of PM2.5 measured in Gwangju, Korea was estimated. Moreover, a visibility forecasting model was constructed by a statistical approach. The diurnal variation of visibility and PM2.5 concentration on the event day indicated that as the concentration of PM2.5 increased, more light was absorbed and scattered, resulting in visibility deterioration. The averaged visibility during the event day was 7.9 km, which was almost three times lower than that observed during a non-event day. Although the hygroscopic growth of aerosol was not considered in this study, it has been proved that NH4NO3 and organics dominantly contributed to the light scattering during the PM2.5 event day in Gwangju, Korea. The visibility determined in this study had also a negative correlation with PM10, nitrate, relative humidity, EC, OC, and sulfate. Meanwhile, visibility was positively linked with wind speed and temperature. The results of interrelationship and a multiple regression model suggest that among the meteorological variables, temperature was the main variable that influenced visibility. [ABSTRACT FROM AUTHOR]

Coronavirus disease 2019 (COVID-19), first reported in Wuhan, China, became pandemic in less than two months, and Korea was no exception. Daegu Metropolitan City, in particular, has become the center of the explosive outbreak in Korea. In this study, we evaluated how the air quality of Daegu Metropolitan City varied when people were fighting the spread of COVID-19. In concretely, we tried to estimate the air quality variation with the trend of COVID-19 in Daegu Metropolitan City based on the measured data at hourly intervals from two air quality monitoring stations (AQMSs) (see Fig. 2). In addition, we quantitatively assessed the positive health effects of improved air quality from fighting against COVID-19. Compared to the concentration in the same period of 2019, the PM2.5 measured at the ambient AQMS decreased by 36.7, 22.5, and 37.6% respectively in January, February, and March. Meanwhile, those at the road side AQMS were 39.9, 23.7, and 40.3% in January, February, and March, respectively. The decreasing trend was not shown in April. Along with the floating population, the concentration of NO2 at the road side AQMS decreased from 49.9 ppb to 32.7 ppb, indicating that the reduction rate was 34.5%. The summed concentration of seven hazardous metals decreased by 27.4% in February 2020 compared to 2019. Among them, lead showed the biggest drop to 43.4% in 2002 compared to 2019. The exposure of PM2.5, DosePM2.5 (µg), during 60 days of self-reflection for 10-year-old children has decreased by 29.6% compared to that in the same period of 2019. The results of adult females and males also show 27, 8% and 29.5% decrease, respectively. [ABSTRACT FROM AUTHOR]

The current study aims to characterize the PM2.5 and the equivalent black carbon (eBC) inside/outside vehicles (hereafter called "in/out-cabin") and near roadway, and to estimate their personal exposure to the driver himself as well as the school-aged children. Based on the DoseDEP of a mouse reaching the 90% polymorphonuclear leukocytes (PMNs90%) (Stoeger et al., 2006), the time (day) to reaching the PMNs90% in the blood of a male resident who lives around the roadway was newly calculated. Five independent measurements of PM2.5 and eBC were intensively taken in May 2019 using the monitors attached to the interior and exterior of the vehicle, respectively. In-cabin and out-cabin PM2.5 on the course of driving measurement ranged from 29.4-47.4 µg/m3 with an average of 34.4 µg/m3 and 32.5-56.0 µg/m3 with an average of 45.6 µg/m3, respectively. The eBC in/out-cabin ratio during idling on a busy road ranged from 22% to 86% depending on the windows open/close and ventilation on/off. The in-cabin DosePM2.5 (ng) for 30 seconds on the test driving route ranged from 166-240 ng with an average of 190.4 ng. The average in-school DosePM2.5 (µg) for the schoolchild attending the school near a bus stop is 1.2 times higher than that of schoolchild attending the school away from a bus stop. The time (day) to reaching the PMNs90% due to DEP inhalation for the male resident who lives around the roadway was estimated as 113 days. [ABSTRACT FROM AUTHOR]

It is meaningful to estimate the chalk dust behavior and its exposure for school-aged children and teachers who spend a lot of time in the classroom. In the present study, model classes were designed to characterize temporal and spatial variations of chalk dust in a classroom and indoor exposure dose to children and teachers. For about 20% of the entire class time, the PM2.5 level greatly exceeded that of ambient PM2.5 daily standard (35 μg m-3). Meanwhile, there was no apparent elevation of PM2.5 during the control experiment carried out using a whiteboard and a dry erase marker with the same teaching behavior. The largest quantity of chalk dust was deposited in the front of the classroom when a cleaner of the blackboard eraser was operated. A SEM image revealed that chalk particles have random shape in a broad range (mainly in the diameter range of 2.0 to 5.0 μm) of their size. The calculated chalk PM2.5 deposition dose, DosePM2.5 (μg), in the alveolar interstitial region revealed the highest level during the period from operating a cleaner of the chalkboard eraser to the end of the class. The DosePM2.5 (μg) in that period was 3.86, 18.95, and 15.79 μg for 10y male/female students, male teacher, and female teacher, respectively. [ABSTRACT FROM AUTHOR]

It is crucial for understanding the characteristics of fly ash, emitted from the incinerator of municipal solid waste, to properly diagnose its impact on air quality and human health. In this study, to precisely describe the chemical property of the fly ash and its effects on near ambient particles, an intensive measurement was conducted. Fly ash was collected in dry condition from the downstream of a bag filter dust collector which is installed at an incinerator located in Iksan City, Korea. Sampling of ambient particles was carried out at both near and far away sites from an incinerator. Elemental analyses of the pretreated samples were subsequently performed by a Particle Induced X-ray Emission (PIXE) and a Scanning Electron Microscope (SEM) equipped with an Energy Dispersive X-ray Detector (EDX). Moreover, in order to estimate the residents' exposure to the fly ash and the effect of fly ash on the near ambient particles, Gaussian plume model was carried out. The high content of soluble S, Cl, K, and Ca in fly ash were detected. Small quantities of heavy elements including Zn, Br, and Pb were also detected in the water-soluble fraction. The scattering plots drawn by the ratios of Z/Zn (i.e., the ratio of mass concentration of each element (Z) to that of zinc) of ambient PM2.5 and that of fly ash reveal a good relationship regardless of the distance from an incinerator. A ternary plot drawn by the wt% concentrations of Na, K, and Cl in the individual ambient particles and fly ash powders indicates that a small portion of the fine and coarse ambient particles was directly influenced by the fly ashes. Modeling evaluation of fly ash diffusion suggests that the air quality at the incinerator nearby areas, especially 1.5 km points, was strongly influenced by the air pollution materials emitted from an incinerator. [ABSTRACT FROM AUTHOR]

Although it is well known that nasal hair keeps particles from entering our body, its quantitative evaluation has not been done. In this study, the particle blocking efficiency by nasal hair was studied both experimentally and numerically. The results of laboratory experiments performed with the successfully reconstructed artificial nose indicate that nasal breathing is effective in blocking particle (especially the giant particle lager than 5 µm), especially during the exercise respiration mode. At the exercise respiration pattern, two kinds of coarse particles (i.e., particles of 2-5 µm and >5 µm) showed a continuous decrease in particle blocking efficiency (Epb (%)) with increasing breathing duration. All curves drown by the theoretically calculated particle cut-off efficiency of nasal hairs (Einteg.) with three different thicknesses (i.e., 50, 75, and 100 µm) show a minimum (nearly zero) for the particle ranged from 0.004 to 0.4 µm. In the Einteg. curves, the thinner nasal hair can block particles more efficiently through a whole particle size range. [ABSTRACT FROM AUTHOR]

Although it is well known that rain plays an important role in capturing air pollutants, its quantitative evaluation has not been done enough. In this study, the effect of raindrop size on pollutant scavenging was investigated by clarifying the chemical nature of individual size-resolved raindrops and their residual particles. Raindrops as a function of their size were collected using the raindrop collector devised by our oneself in previous study (Ma et al., 2000) during high atmospheric loading for PM2.5. Elemental analyses of solid residues and individual residual particles in raindrops were subsequently analyzed by Particle Induced X-ray Emission (PIXE) and Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Analysis (EDX), respectively. The raindrop number concentration (m-2 h-1) tended to drastically decrease as the drop size goes up. Particle scavenging rate, Rsca. (%), based on the actual measurement values were 38.7, 69.5, and 80.8% for the particles with 0.3-0.5, 0.5-1.0, and 1.0-2.0 μm diameter, respectively. S, Ca, Si, and Al ranked relatively high concentration in raindrops, especially small ones. Most of the element showed a continuous decrease in concentration with increasing raindrop diameter. The source profile by factor analysis for the components of residual particles indicated that the rainfall plays a valuable role in scavenging natural as well as artificial particles from the dirty atmosphere. [ABSTRACT FROM AUTHOR]

The main purpose of the study was to clarify the properties of individual particles collected at each behavior space of a factory worker. The samplings of size-segregated (PM2.1-1.1 and PM4.7-3.3) indoor particles were conducted at three different behavior spaces of a factory worker who is engaged in an auto parts manufacturing plant (i.e., his home, his work place in factory, and his favorite restaurant). Elemental specification (i.e., relative elemental content and distribution in and/or on individual particles) was performed by a micro-PIXE system. Every element detected from the coarse particulate matters of home was classified into three groups, i.e., a group of high net-counts (Na, Al, and Si), a group of intermediate net-counts (Mg, S, Cl, K, and Ca), and a group of minor trace elements (P, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb). The results of EF for PM4.7-3.3 in home indicated that several heavy metals were generated from the sources within the house itself. An exceptional feature shown in the individual particles in workplace is that Cr, Mn, and Co were clearly detected in both fine and coarse particles. Cluster analysis suggested that the individual coarse particles (PM4.7-3.3) collected at the indoor of factory were chemically heterogeneous and they modified with sea-salt, mineral, and artificially derived elements. The principal components in individual coarse particles collected at restaurant were sea-salt and mineral without mixing with harmful trace elements like chromium and manganese. Compared to the indoor fine particles of home and restaurant, many elements, especially, Cl, Na, Cr, Mn, Pb, and Zn showed overwhelmingly high net-counts in those of factory. [ABSTRACT FROM AUTHOR]

Quantifying the trace elements in infinitesimal ambient liquid samples (e.g., single raindrop, cloud/fog water, and the soluble fraction extracted from the particles collected for a short time) is an important task for understanding formation processes, heating/cooling rates, and their health hazards. The purpose of this study is to employ an in-air micro PIXE system for quantitative analysis of the trace elements in a thimbleful of reference liquid sample. The bag type liquid sample holder originally designed with 10 µm thick Mylar® film retained the original shape without any film perforation and apparent peaks of film blank by the end of the analysis. As one of tasks to be solved, the homogeneity of the elemental distribution in liquid reference species was verified by the X-ray line profiles for several references. It was possible to resolve the significant peaks for whole target elements corresponding to the channel number of micro-PIXE spectrum. The calibration curves for the six target elements (Si, S, Cl, Fe, Ni, and Zn) in standard solutions were successfully plotted by concentration (ppm) and ROI of interest net counts/dose (nC). [ABSTRACT FROM AUTHOR]

In order to remove fog often causes various troubles in our daily lives, the novel defog blower equipped the roller brush made of recycled horse's mane hair was developed. This work presents the overview of new defog devices and the experimental data obtained at two different kinds of defogging experiments. In the model experiment carried out at the enclosed cleanroom (W 5.9 m×L 5.1 m×H 2.4 m) targeted a vinyl house, fog was dissipated in less than 30 seconds in case with wind entrainment and two minutes 45 seconds in case without wind entrainment after running of the newly designed defog blower. When the demisting blower was run in a duct, it has an excellent mist sweeping qualities as well as a great removal effect for the background particles (89.5% and 65.4% scavenging rates for fine and coarse particles, respectively). It can be therefore said that the mist eliminator presented in this paper is ideal for use in the sealing space like a vinyl house and the industrial sites where required to remove both harmful mist and particle. [ABSTRACT FROM AUTHOR]

In order to deal with current environmental issues and their backgrounds, further development of current teaching methods and tools are essential. The result of questionnaire performed in this study indicates that the effect and the change of the perception of power generation in Japan after the great disaster of East Japan have caused many students (both high school and college students) to become interested in the energy situation. In the present study, we made an attempt to develop a model instrument of a thermal power plant that can be applied as a teaching tool for understanding of air pollutant forming as well as power generation. Our novel model tool consists of a body (30 cm width, 21 cm depth, and 41 cm height), a combustion chamber, two motors, a boiler, a voltmeter, and a chimney for measurement of exhaust gas. Using our novel hand-made power plant, we carried out some model experiments with learners (i.e. high school and college students). Through model experiments, students can be experienced not only about power generation but also about generation of air pollutants. In order to estimate the applicability of our novel instrument as an educational tool, we carried out the questionnaires before and after model experiments. More than 80% of educatees reported that it was very useful as a teaching tool for energy and environmental education. The results of questionnaires indicated that learners achieved a very deep understanding of the principles of power generation and the forming of air pollutants. [ABSTRACT FROM AUTHOR]

A change in chemical compositions of Asian dust (AD) particles can dramatically alter their optical properties, cloud-forming properties, and health effects. The present study was undertaken to evaluate this aging of AD particles by means of two complementary methods (i.e., the traditional spot test and the most advanced micro-PIXE analytical technique) for single particle analysis. Size-classified particles were sampled at the rural peninsula of Korea (Byunsan, 35.37N; 126.27E) during AD event and non-AD period in 2004. Sulfate was principally enriched on the particles in the size range of 7.65-10.85 µm collected during AD event. The average number fraction of coarse particles (>2.05 µm) containing chloride was 16.2% during AD event. Relatively low particles containing nitrate compared to those containing sulfate and chloride were found in AD event. Micro-PIXE elemental maps indicated that a large number of AD particles were internally mixed with man-made zinc. The highest peaks of EC and OC concentrations were appeared at 0.01-0.43 µm particle aerodynamic diameter. High EC concentration in PM1 was might be caused by the Saemangeum Seawall Project that was being conducted during our field measurement. [ABSTRACT FROM AUTHOR]

The high time-resolution monitoring data are essential to estimate rapid changes in chemical compositions, concentrations, formation mechanisms, and likely sources of atmospheric particulate matter (PM). In this study, PM2.5 sulfate, PM2.5, PM10, and the number concentration of size-resolved PMs were monitored in Fukuoka, Japan by good time-resolved methods during the springtime. The highest monthly average PM2.5 sulfate was found in May (8.85 µg m-3), followed by April (8.36 µg m-3), March (8.13 µg m-3), and June (7.22 µg m-3). The cases exceed the Japanese central government's safety standard for PM2.5 (35 µg m-3) reached 10.11% during four months campaign. The fraction of PM2.5 sulfate to PM2.5 varied from 12.05% to 68.11% with average value of 35.49% throughout the entire period of monitoring. This high proportion of sulfate in PM2.5 is an obvious characteristic of the ambient PM2.5 in Fukuoka during the springtime. However, the average fraction of PM2.5 sulfate to PM2.5 in three rain events occurred during our intensive campaign fell right down to 15.53%. Unusually high PM2.5 sulfate (>30 µg m-3) marked on three days were probably affected by the air parcels coming from the Chinese continent, the natural sulfur in the remote marine atmosphere, and a large number of ships sailing on the nearby sea. The theoretical number concentration of (NH4)2SO4 in PM0.5-0.3 was originally calculated and then compared to PM2.5 sulfate. A close resemblance between the diurnal variations of the theoretically calculated number concentration of (NH4)2SO4 in PM0.5-0.3 and PM2.5 sulfate concentration indicates that the secondary formed (NH4)2SO4 was the primary form of sulfate in PM2.5 during our monitoring period. [ABSTRACT FROM AUTHOR]

The information about the dispersion and scavenging of traffic-related pollutants at the locations near busy expressways is very helpful to highway planners for developing better plans to reduce exposures to air pollution for people living as well as children attending schools and child care centers near roadways. The objective of the current study was to give information in the dispersion and scavenging of vehiclederived pollutants at the region near a busy urban expressway by a combination of two different model calculations. The modified Gaussian dispersion model and the Lagrange type below-cloud scavenging model were applied to evaluate NOx dispersion and DEP (Diesel exhaust particles) wet removal, respectively. The highest NOx was marked 53.17 ppb within 20-30 meters from the target urban expressway during the heaviest traffic hours (08:00AM-09:00AM) and it was 2.8 times higher than that of really measured at a nearby ambient measuring station. The calculated DEP concentration in size-resolved raindrops showed a continuous decreasing with increasing raindrop size. Especially, a noticeable decrease was found between 0.2 mm and 1.0 mm raindrop diameter. [ABSTRACT FROM AUTHOR]

In order to clarify the thermal and hygroscopic properties of indoor particulate matter (PM) in a semiclosed subway space, which is critically important for understanding of the distinctive particle formation processes as well as the assessment of their health effects, the size-resolved PMs (i.e., PM2.5 and PM10-2.5) were intensively collected on the platform of Miasageori station on the Seoul Subway Line-4. The elemental concentrations in soluble and insoluble fractions were determined by PIXE from the bulkily pretreated PM2.5. The thermal and hygroscopic characteristics of individual particles were investigated via a combination of the unique pretreatment techniques (i.e., the high-temperature rapid thermal process and the water dialysis) and SEM-EDX analysis. Iron and calcium were unequaled in insoluble and soluble PM2.5 fractions, respectively, with overwhelming concentration. The SEM-EDX's elemental net-counts for the pre- and post-pyrolyzed PMs newly suggest that magnesium and several elements (i.e., silica, aluminum, and calcium) may be readily involved in the newly generated subway fine PM by a high-temperature thermal processing when trains are breaking and starting. Through the water dialysis technique, it turned out that calcium has meaningful amount of water soluble fraction. Furthermore, the concentrations of the counter-ions associated with the calcium in subway PM10-2.5 were theoretically estimated. [ABSTRACT FROM AUTHOR]

The environmental education with ideal teaching tools (e.g., a small-scaled experimental kit) is essential for raising the public's, especially student's, awareness of many environmental issues. This study was undertaken to develop a do-it-yourself model instrument of acid rain and estimating its applicability to the environmental education. Our novel model tool consists of a body (17 cm width, 6 cm depth, and 17 cm height), an acid gas injector, acid four rain reservoirs, and a drop supply pump. An alternative model instrument that can be more readily assembled was also suggested. Based on our novel approach, we carried out several model experiments with educatees (i.e., high school and college students, and adults). The results of questionnaires indicated that educatees achieved a very deep understanding of acid rain through an experienced model experiment. A 77 to 89% of educatees experienced the reappearance experiment of acid rain by our model instrument felt that it was very useful as a teaching tool of environmental education. [ABSTRACT FROM AUTHOR]

The objective of the current study was to assess the comparative risk associated with exposure to particulate matter (PM) while commuting via different public transport modes in Fukuoka, Japan. For the given routes and measuring days, a trip-maker carried a lightweight portable bag loaded the real-time measurement devices which take simultaneous measurement for size-fractioned particle number concentration, PM2.5 mass concentration, and total suspended particle (TSP) collection. The results of the present study have shown significant differences between public transports as commuting modes in Fukuoka. The PM exposure levels on subway platform and inside subway train were overwhelmingly higher than those of other points on commuting route. The relative ratio between modes (i.e., the ratio of PM2.5 inside subway to that inside bus) provides an idea for choosing a right commuting mode for our health. This study clearly provided evidence of the extremely high levels of iron exposure by subway uses compared to bus uses. The result of theoretically reconstructed mass concentration of PM2.0-0.3 collected on subway platform suggests that the PM of underground subway will be associated with PM both generated in subway system and inleakaged from outdoor environment. [ABSTRACT FROM AUTHOR]

Under a very tough situation that there has been increasing concern to the air quality in underground subway spaces, this study set sights on the thorough estimation of the chemical properties and source apportionment of particulate matter (PM) collected on an underground subway platform by a cooperative approach of semi-bulk and single particle analyses. The size-resolved PMs were intensively collected on the platform of Miasageori station on the Seoul Subway Line-4, and then, they were semibulkily analyzed by a PIXE and the TOR ® method, and individually analyzed by a SEM-EDX. Overwhelmingly enriched iron was a notable feature of elemental concentration of PM2.5. Source classification of iron in PM10-2.5 and PM2.5 performed along with their elemental concentrations, indicates that the railway originated iron accounts for 95.71% and 66.39% of total iron in PM10-2.5 and PM2.5, respectively. Via a stoichiometric categorization, Fe2O3, CaAl2Si2O8, Al2O3, and CaCO3 show more than 85% abundance ratio in individual coarse particles. The result of theoretical estimation of the subway derived organic carbon (OCSubway) suggests that OCSubway in PM1 and PM2.5-1 account for 75.86% and 51.88% of total organic carbon, respectively. [ABSTRACT FROM AUTHOR]

Due to the heightened ambient PM2.5 levels, the whole citizen of Japan, especially dwellers in Fukuoka Prefecture, start to make attention to the particulate matter (PM) of indoor environments. This study was aimed to thoroughly estimate the characteristics of indoor PM collected in five Japanese homes located in Fukuoka Prefecture. Simultaneous indoor measurements of PM were intensively made at five homes using filter-pack samplers, particle counters, and PM2.5 monitors for a day in springtime, 2012. Major ionic and carbonaceous components were also analyzed. The time series fluctuation of PM number concentration was gradually decreased by 6 AM and then it was rapidly increased by 8 AM in all indoor sites. The maximum level of PM2.5 was measured at the morning time (8 AM-9 AM) when the resident's behavior was fast and strenuous. The Indoor/Outdoor (I/O) ratio for the giant PM larger than 5.0 μm was 1.16. It was possible to identify PM types and estimate the resident's behavior through the comparison the theoretically calculated and the measured retention times for several types of PM in an indoor site. The theoretically reconstructed mass concentration of PM2.0-0.3 suggested that the portion of PM2.5 in indoor was quietly occupied by PM0.3 or the PM inherently originated from indoor environment. [ABSTRACT FROM AUTHOR]

To visually and chemically verify the rainout of soot particles, a model experiment was carried out with the cylindrical chamber (0.2 m (D) and 4 m (H)) installing a cloud drop generator, a hydrotherometer, a particle counter, a drop collector, a diffusing drier, and an artificial soot particle distributer. The processes of the model experiment were as follows; generating artificial cloud droplets (major drop size : 12- 14 μm) until supersaturation reach at 0.52%-nebulizing of soot particles (JIS Z 8901) with an average size of 0.5 μm-counting cloud condensation nuclei (CCN) particles and droplets by OPC and the fixation method (Ma et al., 2011; Carter and Hasegawa, 1975), respectively - collecting of individual cloud drops - observation of individual cloud drops by SEM - chemical identifying of residual particle in each individual droplet by SEM-EDX. After 10 minutes of the completion of soot particle inject, the number concentrations of PM of all sizes (>0.3 μm) dramatically decreased. The time required to return to the initial conditions, i.e., the time needed to CCN activation for the fed soot particles was about 40 minutes for the PM sized from 0.3-2.0 μm. The EDX spectra of residual particles left at the center of individual droplet after evaporation suggest that the soot particles seeded into our experimental chamber obviously acted as CCN. The coexistence of soot and mineral particle in single droplet was probably due to the coalescence of droplets (i.e., two droplets embodying different particles (in here, soot and background mineral particles) were coalesced) or the particle capture by a droplet in our CCN chamber. [ABSTRACT FROM AUTHOR]

The present study was undertaken to evaluate the chemical characteristics of Asian dust (hereafter called "AD") particles with the aid of the most advanced micro-PIXE (Particle-induced X-ray emission) analytical technique. To this end, size-selected particles were sampled on a rural peninsula of Korea (Byunsan, 35.37N; 126.27E) during AD and non-AD periods in 2004. The coarse particle (>2 µm) number density during an AD event were 170 times higher than those of the non-AD counterpart. The average net-count of silica in individual particles collected on AD event was roughly 11 times higher than that of non-AD counterpart. The X-ray net-counts of trace elements (Zn, Co, Mn, and V) were also considerably high in AD relative to the non-AD day. Particle classification based on the inter ratio analysis of elemental net-count suggests that a large portion of the coarse particles collected during AD event underwent chemical transformation to a certain degree. The visual interpretation of micro-PIXE elemental maps and elemental localization data in and/or on individual AD particles clarified the internal mixture of AD particles with sea-salt and artificial metallic particles. [ABSTRACT FROM AUTHOR]

This study focused on a comprehensive and detailed interpretation for the springtime air quality influenced by both artificial (particulate matter (PM) and asbestos) and biological (pollen) sources in Fukuoka Prefecture, Japan. An intensive measurement of PM was conducted at four characteristic sites (i.e., a heavy traffic area, a residential area, an industrial area, and a desolate area) in the Fukuoka Prefecture during spring of 2007. Analysis of major ionic species in PM2.5 was performed by an Ion Chromatography, and asbestos and pollen were identified by Scanning Electron Microscopy with an energy dispersive X-ray spectrometer (EDX). PM2.5 concentration (65.3 µg m-3) measured in an industrial area (site C) was extraordinarily high compared to those monitored in other areas; it greatly exceeded the Japan's PM2.5 criteria (a daily average of 35 µg m ). NOAA's HYSPLIT dispersion model suggests that this high level of PM2.5 monitored at site C is unlikely to affect the Asian continent. The ambient concentrations of PM2.5-related anions (NH4 +, NO3 -, and SO4 2+) and their relative contributions to PM2.5 were also investigated in four study areas. The concentrations of these major water-soluble ions exhibit not only strong spatial dependence but also different ratios to each other. Asbestos fiber (crocidolite and amosite) concentration values changed in the range of 2.5 to 14.4 f per liter of air. The number of pollen grains showed that Cedar ranked higher in concentration than other types of pollen, with the maximum concentration at site A. [ABSTRACT FROM AUTHOR]

In this study, an investigation was conducted to assess the washout mechanism of Asian dust particles through both laboratory-scale experiment and model calculation. To artificially simulate Asian dust particle, CaCO3 particles were generated inside an experimental chamber. They were then scavenged by the artificial rain drops. The abundant CaCO3 particles scavenged on a rain drop were successively identified by SEM observation. The concentrations of Ca in residual CaCO3 particles on individual droplet were quantified by PIXE analysis. There was a tendency toward a high accumulation of Ca on a relatively small drop (e.g., <1.0 mm diameter). It is thus suggested that smaller rain drops can effectively scavenge a significant amount of Asian dust particles in ambient atmosphere. The numerical estimation can account for 92.1% and 83.2% of Ca that were measured in small (<1.0 mm diameter) and large (>2.0 mm diameter) size drops, respectively. [ABSTRACT FROM AUTHOR]

The wintertime high loading for atmospheric pollutants is certainly expected in the Byunsan Peninsula of Korea because of a great-scale reclamation project having construction of 33 km tidal sea dike impounding an area of over 40,000 ha and long-range transport. The goal of this study is to trace the origin of this wintertime burden for ambient particulate matter (hereafter called "PM") in the Byunsan Peninsula of Korea. The size-segregated (i.e., cutoff size from 0.01 µm to 4.7 µm) PM sampling was conducted at a ground-based site of Byunsan Peninsula located in the west coast of Korean Peninsula during the height of dike constructing. Data archived in this study are the mass concentrations of ionic, elemental, and carbonic components in size-fractioned PM. The elemental mass of individual submicrometer particles was also analyzed. The sum of 5-source (i.e., elemental carbon, organic materials, inorganic secondary pollutants, crustal matter, and sea-salts) concentrations shows the bimodal distribution (major and minor peaks formed around Dp, 0.65 µm and Dp, 4.7 µm, respectively) by border with 0.19 µm of cut-off size. The concentrations of EC in PM1.1-0.01 in winter and spring times were 4.62 µg m-3 and 3.74 µg m-3, respectively. Elemental masses of submicron individual particles are classified into two groups, i.e., the major elements (Cl, Al, Si, S, and P) and the minor trace elements. Cluster analysis differentiated the elements in submicron individual particles into 4-cluster. Among them, three clusters are in agreement with the major (Al, Si, S, and P), minor (Fe, Ca, and K), and trace compositions of coal burning. Meanwhile, Cl classified as an independent cluster has different source profile which was mainly due to the Saemangeum seawall project. Some highly toxic elements (e.g., Cr, Mn, and As (and/or Pb)) were also detected in some part of submicron individual PM. As a consequence, the combination of the Saemangeum project and winter monsoon played a considerable part in the double aggravation of winter-time air pollution in the Byunsan Peninsular. [ABSTRACT FROM AUTHOR]

This study was aimed to thoroughly estimate the characteristics of indoor particulate matter (PM) collected on subway platforms by the cooperative approach of semi-bulk and single particle analyses. The size-resolved PM and its number concentration were measured on the platform in a heavily traveled subway station in Fukuoka, Japan. Particle Induced X-ray Emission (PIXE) and micro-PIXE techniques were applied to the chemical analyses of semi-bulk and single particle, respectively. There was the close resemblance of timely fluctuation between PM number concentration and train service on the third basement floor (B3F) platform compared to the second basement floor (B2F) and its maximum level was marked in rush hour. Higher number counts in large particles (>1 μm) and lower number counts in fine particles (<1 μm) were shown on the platform compared to an above ground. PM2.5 accounted for 58.2% and 38.2% of TSP on B3F and on B2F, respectively. The elements that were ranked at high concentration in size- resolved semi-bulk PM were Fe, Si, Ca, S, and Na. The major elements tending to have more elevated levels on B3F than B2F were Fe (4.4 times), Ca (17.3 times), and Si (46.4 times). Although concentrations were very low, Cr (11.9 ng m-3 on B3F, 2.4 ng m-3 on B2F), Mn (3.4 ng m-3 on B3F, 0.9 ng m-3 on B2F), and Pb (0.6 ng m-3 on B3F, 1.6 ng m-3 on B2F) were detected from PM2.5. Individual PM was nearly all enriched in Fe with Si and Ca. Classifying and source profiling of the individual particles by elemental maps and particle morphology were tried and particles were presumably divided into four groups (i.e., train/rail friction, train-rail sparking, ballast/abrasive, and cement). [ABSTRACT FROM AUTHOR]

This paper is focused on the comprehensive and detailed interpretation for the chemical transformation of individual Asian dust (hereafter called "AD") particles during long-range transport from source regions to receptor area. A multi-stage particle sampler was operated at a ground-based site in Taean, Korea directly exposed to the outflow of air masses from China during AD period in April 2003. Both quantitative and qualitative analyses for size-classified individual particles were carried out by a microbeam X-ray fluorescence (XRF) method and a microbeam Particle Induced X-ray Emission (micro-PIXE), respectively. Among major characteristic elements, the elemental masses of soil derived components, sulfur, and chloride varied as a function of particle size showing the monomodal maximum with a steeply increasing at 3.3-4.7 μm particle size. Although the details on chemical composition of AD particle collected on a straight line from source area to our ground-based site are needed, a large amount of Cl coexisted in and/or on AD particles suggests that AD particles collected in the present study might be actively engaged in chemical transformation by sea-salt and other Cl containing pollutants emitted from the China's domestic sources. Through the statistical analyses it was possible to classify individual AD particles into six distinct groups. The internally mixed AD particles with Cl, which has various sources (e.g., sea-salt, coal combustion origin HCl, gaseous HCl derived from the adsorption of acids to sea-salt, and Cl containing man-made particles) were thoroughly fractionated by the elemental spectra drivened by the double detector system of micro-PIXE. [ABSTRACT FROM AUTHOR]