Ambient Particulate Air Research Articles

Lung function is associated with short term changes in air pollution

Introduction: Exposure to ambient gaseous and particulate air pollution is a well-known public health risk. Day-to-day changes in concentrations of particulate matter, nitrogen oxides and ozone are...

Exposure to particles of different size fractions and related health effects on cardiopulmonary inflammation

Background and Aim: Cardiovascular and respiratory inflammation mediated by cytokines was considered as critical mechanisms in terms of the health effects of ambient air particles exposures. Besides, it is less clear if particles in certain detailed size fractions are more responsible for adverse health effect than others. We investigated in this panel study the exposure to particles of different size fractions and its health effects on cytokines of cardiopulmonary inflammation. Methods: 120 subjects aging from 50 to 65 were recruited through annual physical examination in Peking University Hospital. Each participant has completed 4-6 times clinical visits from Aug. 2013 to Feb. 2015. Biosamples of serum and exhaled breath condensate (EBC) collected during each visit for the measures of cytokines, including: IL-1α, IL-1β, IL2, IL-6, IL-8, TNFα, IFNγ. In total, 589 valid samplers were made for analysis. Hourly averaged number concentration of particles with the size range of 5.6 to 560 nm were measured using Fast Mobility Particle Sizer. We applied linear mixed effect model to estimate the association between biomarkers and particulate size fractions, adjusting for time variation and meteorological parameters. Results: The magnitude of association between cytokines and particle number concentrations was different by particle size, and showed different patterns in EBC and serum samples. For IL-1α, we observed significant associations with particles of all size fractions in serum samples, while in EBC samples the significance only remained for particle size of 200-560 nm. Particles of all size fractions were significantly associated with IL-2 in both EBC and serum samples. Significant adverse effect of particles on IL-6 and IL-8 were only observed in EBC samples. Conclusions: The association between cardiopulmonary inflammation with fine particle concentrations depended on particle size, and showed different patterns in respiratory and cardiovascular system.

The association between particulate air pollution and respiratory admissions among young children in Hanoi, Vietnam

While the effects of ambient air pollution on health have been studied extensively in many developed countries, few studies have been conducted in Vietnam, where the population is exposed to high levels of airborne particulate matter. The aim of our study was to examine the short-term effects of PM10, PM2.5, and PM1 on respiratory admissions among young children in Hanoi. Data on daily admissions from the Vietnam National Hospital of Paediatrics and daily records of PM10, PM2.5, PM1 and other confounding factors as NO2, SO2, CO, O3 and temperature were collected from September 2010 to September 2011. A time-stratified case-crossover design with individual lag model was applied to evaluate the associations between particulate air pollution and respiratory admissions. Significant effects on daily hospital admissions for respiratory disease were found for PM10, PM2.5 and PM1. An increase in 10μg/m3 of PM10, PM2.5 or PM1 was associated with an increase in risk of admission of 1.4%, 2.2% or 2.5% on the same day of exposure, respectively. No significant difference between the effects on males and females was found in the study. The study demonstrated that infants and young children in Hanoi are at increased risk of respiratory admissions due to the high level of airborne particles in the city's ambient air.

Annual ambient atmospheric mercury speciation measurement from Longjing, a rural site in Taiwan.

The main purpose of this study was to monitor ambient air particulates and mercury species [RGM, Hg(p), GEM and total mercury] concentrations and dry depositions over rural area at Longjing in central Taiwan during October 2014 to September 2015. In addition, passive air sampler and knife-edge surrogate surface samplers were used to collect the ambient air mercury species concentrations and dry depositions, respectively, in this study. Moreover, direct mercury analyzer was directly used to detect the mercury Hg(p) and RGM concentrations. The result indicated that: (1) The average highest RGM, Hg(p), GEM and total mercury concentrations, and dry depositions were observed in January, prevailing dust storm occurred in winter season was the possible major reason responsible for the above findings. (2) The highest average RGM, Hg(p), GEM and total mercury concentrations, dry depositions and velocities were occurred in winter. This is because that China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. (3) The results indicated that the total mercury ratios of Kaohsiung to that of this study were 5.61. This is because that Kaohsiung has the largest industry density (~60%) in Taiwan. (4) the USA showed average lower mercury species concentrations when compared to those of the other world countries. The average ratios of China/USA values were 89, 76 and 160 for total mercury, RGM and Hg(p), respectively, during the years of 2000-2012.

Chemo-Mechanical Characteristics of Mud Formed from Environmental Dust Particles in Humid Ambient Air.

Mud formed from environmental dust particles in humid ambient air significantly influences the performance of solar harvesting devices. This study examines the characterization of environmental dust particles and the chemo-mechanics of dry mud formed from dust particles. Analytical tools, including scanning electron microscopy, atomic force microscopy, energy dispersive spectroscopy, particle sizing, and X-ray diffraction, are used to characterize dry mud and dust particles. A micro/nano tribometer is used to measure the tangential force and friction coefficient while tensile tests are carried out to assess the binding forces of dry mud pellets. After dry mud is removed, mud residuals on the glass surface are examined and the optical transmittance of the glass is measured. Dust particles include alkaline compounds, which dissolve in water condensate and form a mud solution with high pH (pH = 7.5). The mud solution forms a thin liquid film at the interface of dust particles and surface. Crystals form as the mud solution dries, thus, increasing the adhesion work required to remove dry mud from the surface. Optical transmittance of the glass is reduced after dry mud is removed due to the dry mud residue on the surface.

Association between size-segregated particles in ambient air and acute respiratory inflammation

The health effects of particulate matter (PM) in ambient air are well documented. However, whether PM size plays a critical role in these effects is unclear in the population studies. This study investigated the association between the ambient concentrations of PM with varies sizes (5.6–560nm) and a biomarker of acute respiratory inflammation, the fraction of exhaled nitric oxide (FENO), in a panel of 55 elderly people in Shanghai, China. Linear mixed-effect model was fitted to estimate the association between FENO and moving average concentrations of PM, adjusting for temperature, relative humidity, day of the week, and age. Results showed that among the measured particles size range, Aitken-mode (20–100nm) particles had the strongest positive association with increased FENO when using moving average concentration of PM up to 24h prior to visits. The estimates were robust to the adjustment for gender, condition of chronic disease and use of medication, and to the sensitive analysis using different times of visits. The authors concluded that the association between acute respiratory inflammation and PM concentration of fine particulates depended on particle size, and suggested Aitken-mode particles may be the most responsible for this adverse health association.

Ambient air metallic elements (Mn, Fe, Zn, Cr, Cu, and Pb) pollutants sources study at a rural resident area near Taichung Thermal Power Plant and Industrial Park: 6-month observations

The Longjing area is located at the Taichung, in central Taiwan. And it also near the Taichung Thermal Power Plant (TTPP) and Taichung Harbor Kwan-Lien Park (THKLP). Thus, this study measured the ambient air particulates and metallic elements concentrations using total suspended particulates (TSP) at Long Cyuan Elementary School (LCYES), Lung Ching Elementary School (LCHES), and Long Shan Primary School (LSPS) sampling sites at Longjing area. Because of the unique characteristic locations, therefore, this study focused on monitor ambient air particles and metallic element [Hg(p) Mn, Fe, Zn, Cr, Cu, and Pb] concentrations, particles and metallic element dry deposition around the Longjing area. In addition, method of back trajectory analysis was used to find the pollutants parcels in this study. Moreover, Principal Component Analysis (PCA) method was also applied in the identifying the possible sources of the ambient air pollutants at Longjing area. The results indicated that the LCYES has the lowest pollutants concentrations when compared with LCHES and LSPS sampling sites. The major pollutants sources were come from China especially in January. These pollutants will come to Taiwan along with dust storm accompaning exhausted gas from TTPP and THKLP. And the highest particulates bound mercury were in January. Moreover, PCA results also show that the factor loading values >0.7 frequency for metallic elements Mn, Fe, Zn and Hg(p) were greater than the other metallic elements. Thus, we concluded that the major pollutants were mainly from vehicles emissions, transport emissions and steel factory at THKLP and TTPP sampling site. Potential significant health impacts and concern at the Longjing sampling site are needed for this study.

Causation by Diesel Exhaust Particles of Endothelial Dysfunctions in Cytotoxicity, Pro-inflammation, Permeability, and Apoptosis Induced by ROS Generation.

Epidemiological studies suggest that an increase of diesel exhaust particles (DEP) in ambient air corresponds to an increase in hospital-recorded myocardial infarctions within 48h after exposure. Among the many theories to explain this data are endothelial dysfunction and translocation of DEP into vasculature. The mechanisms for such DEP-induced vascular permeability remain unknown. One of the major mechanisms underlying the effects of DEP is suggested to be oxidative stress. Experiments have shown that DEP induce the generation of reactive oxygen species (ROS), such as superoxide anion and H2O2 in the HUVEC tube cells. Transcription factor Nrf2 is translocated to the cell nucleus, where it activates transcription of the antioxidative enzyme HO-1 and sequentially induces the release of vascular permeability factor VEGF-A. Furthermore, a recent study shows that DEP-induced intracellular ROS may cause the release of pro-inflammatory TNF-α and IL-6, which may induce endothelial permeability as well by promoting VEGF-A secretion independently of HO-1 activation. These results demonstrated that the adherens junction molecule, VE-cadherin, becomes redistributed from the membrane at cell-cell borders to the cytoplasm in response to DEP, separating the plasma membranes of adjacent cells. DEP were occasionally found in endothelial cell cytoplasm and in tube lumen. In addition, the induced ROS is cytotoxic to the endothelial tube-like HUVEC. Acute DEP exposure stimulates ATP depletion, followed by depolarization of their actin cytoskeleton, which sequentially inhibits PI3K/Akt activity and induces endothelial apoptosis. Nevertheless, high-dose DEP augments tube cell apoptosis up to 70% but disrupts the p53 negative regulator Mdm2. In summary, exposure to DEP affects parameters influencing vasculature permeability and viability, i.e., oxidative stress and its upregulated antioxidative and pro-inflammatory responses, which sequentially induce vascular permeability factor, VEGF-A release and disrupt cell-cell junction integrity. While exposure to a low dose of DEP actin triggers cytoskeleton depolarization, reduces PI3K/Akt activity, and induces a p53/Mdm2 feedback loop, a high dose causes apoptosis by depleting Mdm2. Addition of ROS scavenger N-acetyl cysteine suppresses DEP-induced oxidative stress efficiently and reduces subsequent damages by increasing endogenous glutathione.

Seasonal variations and sources study by way of back trajectories and ANOVA for ambient air pollutants (particulates and metallic elements) within a mixed area at Longjing, central Taiwan: 1-year observation.

This study measured the concentrations of particulates and metallic elements in ambient air by using PS-1 sampler (TSP) at Longjing area. And this study focuses on the collection of ambient air particulates, metallic elements, particulate-bound mercury Hg(p), concentrations. In addition, the sources of ambient pollutants by way of back trajectory analysis are found. Moreover, test mean concentration variance differences for metallic elements (PM, Hg(p), Mn, Fe, Zn, Cr, Cu, and Pb) among the four seasons (spring, summer, autumn and winter) through ANOVA are calculated. The result indicates that the average highest particulate concentration occurred in winter season, and the order was winter>spring>autumn>summer, and the mostly highest average metallic element (Mn, Fe, Zn, Cr, Cu, Pb) concentrations occurred in autumn. Moreover, the mostly average lowest metallic element concentrations occurred in summer. In addition, the above results of backward trajectories that the major particulate pollutants parcel mainly come from northeastern Taiwan. Moreover, when comparing the results of the first half year to that of the second half year, the they indicated that all metallic elements displayed significant differences in concentrations except those of Hg(p), Mn, Fe, Zn. Finally, metallic element Hg(p) is the only one which showed no significant concentration difference from either seasonal variations or half-year observations.

Annual trends in occurrence of submicron particles in ambient air and health risk posed by particle bound metals.

Risk analysis is highly important in toxicology and public health studies. Health risk related to exposure to toxic metals of PM1 was assessed. Concentrations of 13 heavy metals, adsorbed to submicron particulate matter PM1 were experimentally examined but only 12 metals were found at detectable levels inside IIT Kanpur campus in 2008-2009 for all months excluding June and October. A total of 90 samples collected for 8 h sampling time by a single stage round nozzle, grease impaction substrate based impactor type PM1 sampler were analysed by ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry). Results showed daily average PM1 concentration is 102.46 ± 35.9 μg/m(3) and metal concentration followed the trend: Ca > Fe > Mg > Zn > Pb > Cu > Cr > Ni > Se > Cd > V > As. Contamination level assessment using geo-accumulation index showed Ca, Fe and Mg exhibited non contamination whereas metals like Cr, Zn, As, Cd, Pb, Se, Ni and Cu exhibited ranges from moderate to extreme contamination. Ingestion is found to be the major exposure pathway for heavy metals. Non-carcinogenic health risk assessment for Pb, Cd and Cr (HI > 1) signified strong chances of adverse impact on children whereas adults are well under safe limit. Cancer Risk for adults and children followed the same decreasing order, Cr(VI)>Cd > Ni > As > Pb. It was found to be higher than permissible limits (10(-6)) for adults and children both.

Ambient air particle and metallic pollutant dry deposition study at a farmland sampling site during 2013–2014

ABSTRACTIn this study, the concentrations of particulate and metallic pollutants (Cu, Cd, Cr, Pb, and Zn) in ambient air and dry deposits were monitored in daytime sampling periods at a farmland sampling site in central Taiwan from August 2013 to July 2014. Ambient air dry deposition models of dry deposition from ambient air (Noll et al., 2010) were used to determine the differences between measured and modeled concentrations of pollutants in ambient air and dry deposits. The results indicate that the mean calculated/measured dry deposition flux ratios obtained using the model of Noll et al. (2010) for 2.5 µm particles and metallic elements (Cu, Cr, Cd, and Pb) in ambient air were all less than one in all seasons. The mean calculated/measured dry deposition flux ratios obtained using the model of Noll et al. (2010) for particles and metallic elements (Cu, Cr, Cd, and Pb) in ambient air were more than one in summer and autumn for particles of all sizes of interest. Finally, the mean calculated/measured dry deposition flux ratios that were obtained using the model of Noll et al. (2010) for metallic elements (Cu, Cr, Cd, Zn, and Pb) reflected the fact that all dry deposition fluxes were underestimated in the winter and spring for all particle sizes of interest.

Sources of ambient air particulates and Hg(p) pollutants at Freeway, Industrial, Thermal power plant F.I.T. characteristic sites

This study concerns the concentrations of particulates in ambient air, dry deposited particulates, particulate-bound mercury (Hg(p)), and Hg(p) that is dry deposited in both total suspended particulates and on a dry deposition plate at Long Cyuan Elementary School (LCYES), Lung Ching Elementary School (LCHES), and Long Shan Primary School (LSPS) in Longjing. The LCHES site had the highest particulate Hg(p) concentrations in October and November, and the least dry deposition of particulates in October. The LSPS site had the lowest Hg(p) dry depositions in October. The LCYES site had the lowest particulate and Hg(p) concentrations in November and October, and had the highest dry deposition of particulates and Hg(p) in November and December. These particulates originated from the northwest of Taiwan and were transported by way of mainland China in October. A back trajectory analysis supported this finding. Therefore, particulate concentrations in ambient air were highest in October and the major sources of particulate-bound mercury Hg(p) in ambient air were in mainland China, especially in October and December. Mainland China and Taichung Thermal Power Plant were the main sources of particles and Hg(p) in ambient air.

Potent In Vitro Protection Against PM₂.₅-Caused ROS Generation and Vascular Permeability by Long-Term Pretreatment with Ganoderma tsugae.

Epidemiological studies show increased particulate matter (PM[Formula: see text]) particles in ambient air are correlated with increased myocardial infarctions. Given the close association of capillaries and alveoli, the dysfunction is caused when inhaled PM[Formula: see text] particles come in close proximity to capillary endothelial cells. We previously suggested that the inhalation of PM[Formula: see text] diesel exhaust particles (DEP) induces oxidative stress and upregulates the Nrf2/HO-1 pathway, inducing vascular permeability factor VEGFA secretion, which results in cell-cell adherens junction disruption and PM[Formula: see text] transmigratation into circulation. Here, we minimized the level that PM[Formula: see text] traveled in the bloodstream by pre-supplementing with a traditional Chinese medicine (TCM) Ganoderma tsugae DMSO extract (GTDE) prior to PM[Formula: see text] exposure. Our results show that PM[Formula: see text] caused alterations in enzyme activities and cellular anti-oxidant balance. We found decreased glutathione levels, a reduced cellular redox ratio, increased ROS generation and cytotoxicity in the cellular fractions. The oxidative stress caused DNA damage and apoptosis, likely causing downstream molecular events that trigger vasculature permeabilization and, eventually, cardiovascular disorders. Our results show long-term GTDE treatment increased endogenous glutathione level, while PM[Formula: see text]-reduced glutathione levels and the cellular redox ratio. GTDE was protective against the genotoxic and apoptotic effects initiated by PM[Formula: see text] oxidative stress. Vascular permeability revealed that PM[Formula: see text] only accumulated on the surface of cells after GTDE treatment; no penetration was detected. After two weeks of GTDE treatment, VEGFA secretion was significantly reduced in human umbilical vein endothelial cells (HUVEC) and endothelial cell migration was blocked. Our results suggest GTDE prevents PM[Formula: see text] transmigration into the bloodstream, and the resultant dysfunction, by inhibiting oxidative stress production and endothelial permeability.

Perfluorinated Compounds (PFCs) in Ambient Air Particulates (PM2.5, PM10, TSP) in Beijing

Perfluorinated Compounds (PFCs) in Ambient Air Particulates (PM2.5, PM10, TSP) in Beijing

Characterization of Bioaerosols and their Relation with OC, EC and Carbonyl VOCs at a Busy Roadside Restaurants-Cluster in New Delhi

Measurement of biological particles (bioaerosols) in ambient air is of great importance as it is directly linked with the health issues. However, data on the bioaerosols characterization are scarce. Here we report on the concentration and characterization of bioaerosols (including bacterial and fungal aerosols) as well as determination of organic and elemental carbon (OC and EC) in total suspended particulate matter (TSPM) at a busy roadside restaurants-cluster site in New Delhi. In addition, 14 carbonyl volatile organic compounds (carbonyl VOCs) were also measured and their relationship with bioaerosols and OC/EC is assessed. The culturable airborne bacterial and fungal concentrations (CAB and CAF) at restaurant area varied significantly in different seasons ranging from 1.7 x 10(4)-9.8 x 10(4) (averaged 6.3 x 10(4) +/- 2.6 x 10(4) cfu m(-3)) and 3.5 x 10(2)-9.5 x 10(3) (3.9 x 10(3) +/- 3.1 x 10(3) cfu m(-3)) cfu m(-3), respectively. Major concentration peaks of TSPM, OC, EC as well as bacterial and fungal aerosols were found in winter and spring seasons. These peaks can be attributed to the low atmospheric boundary layer (ABL) height and favourable meteorological conditions for microbial growth in winter and spring seasons in New Delhi. Good correlations (R-2 > 0.5) were observed between CAB, CAF, TSPM and OC. On the other hand, CAB and CAF were not found to be correlated with carbonyl compounds (R2 < 0.2) indicative of their diverse sources. The bacterial identification was done by 16s rDNA sequencing and the identified strains were Bacillus sp., Bacillus firmus, Bacillus licheniformis, Bacillus cereus, Bacillus pumilus, Acinetobacter sp. and Acinetobactor radioresistens gene. Predominant fungal genera identified were Aspergillus, Cladosporium, Alternaria and Fusarium, which are known for adverse health effects causing numerous allergic and pathogenic inflammations.

The effect of aerobic exercise on hepatotoxicity induced by intratracheal instillation of iron oxide nanoparticles in Wistar rats.

Iron oxide nanoparticles (IONPs) can cause significant health problems due to their unique physicochemical properties and environmental characteristics. They are found as ultrafine particles in ambient air. After inhalation, these particles move from the lung to phagocytosis tissues, especially the liver. The aim of present study was to investigate the effect of concurrent aerobic exercise and IONPs on liver enzymes and histological hepatic appearance. 48 rats were divided into six groups: experimental 1 (aerobic exercise), experimental 2 (nanoparticle, anesthesia), experimental 3 (aerobic exercise, nanoparticles, anesthesia), placebo 4 (distilled water, anesthesia), placebo 5 (aerobic exercise, anesthesia), and control group. In groups 2 and 3, 40 mg/kg/b.w. of IONPs was injected via intratracheal installation every other day for 14 days. Groups 1, 3, and 5 [corrected] run on treadmill for 30 minutes with the intensity of 35-40% VO2max (maximal oxygen consumption) every day. ALT was increased in group 1 but decreased in groups 2 and 3. AST was not significant in any of the groups, while ALP was reduced significantly in groups 2 and 3 (p < 0.05). Histological examination of the liver showed that, in groups 2 and 3, hepatic cells were damaged and also the congestion, inflammation, mononuclear cell infiltration, and ballooning degeneration were occurred. Tissue injuries in group 3 were less than those of group 2. These findings indicated that hepatotoxicity was caused by iron oxide nanoparticles; however, low-intensity aerobic exercise could decrease the damage somewhat.

Effects of ambient air particles on mortality in Seoul: Have the effects changed over time?

BackgroundSeveral studies have shown that there may be temporal variation in PM short-term effect on mortality. This temporal pattern may play an important role in evaluating air quality policies. ObjectivesWe investigated temporal variation in the association between PM and mortality in Seoul, Korea, 1998–2011. MethodsWe adopted a generalized additive model and a series of time windows of five years to analyze temporal variation in associations between PM and all-cause, cardiovascular, and respiratory mortality. This time-window approach offers not only a comparison between one and the other half period but also successive variation. Time-varying associations were estimated only for days without Asian dust (dust storm blown from the Gobi desert) intrusion. ResultsAnnual average PM10 and PM2.5 total mass decreased from 70.0 to 46.9µg/m3 and 44.4 to 23.4µg/m3, respectively, during 2001–2011. A 10µg/m3 increase in PM10 was associated with 0.16% (95% CI=−0.03% to 0.35%) additional all-cause deaths in 2002–2006 and it increased to 0.26% (95% CI=0.05–0.48%) in 2007–2011. For PM2.5, the association increased from 0.35% (95% CI=−0.02% to 0.71%) to 0.48% (95% CI=0.08–0.88%). For cardiovascular and respiratory mortality, increasing trends with stronger estimates were found. ConclusionsThe present study showed temporally increasing trends in associations between PM and mortality. Current policies may not be as effective to reducing health risks attributable to PM as expected. Air quality interventions should be encouraged in terms of causal factors for time-varying association between PM and mortality.

Aerosol Analysis via Electrostatic Precipitation-Electrospray Ionization Mass Spectrometry.

Electrospray ionization (ESI) is the preferred mode of ion generation for mass analysis of many organic species, as alternative ionization techniques can lead to appreciable analyte fragmentation. For this reason, ESI is an ideal method for the analysis of species within aerosol particles. However, because of their low concentrations (∼10 μg/m(3)) in most environments, ESI has been applied sparingly in aerosol particle analysis; aerosol mass spectrometers typically employ analyte volatilization followed by electron ionization or chemical ionization, which can lead to a considerable degree of analyte fragmentation. Here, we describe an approach to apply ESI to submicrometer and nanometer scale aerosol particles, which utilizes unipolar ionization to charge particles, electrostatic precipitation to collect particles on the tip of a Tungsten rod, and subsequently, by flowing liquid over the rod, ESI and mass analysis of the species composing collected particles. This technique, which we term electrostatic precipitation-ESI-MS (EP-ESI-MS), is shown to enable analysis of nanogram quantities of collected particles (from aerosol phase concentrations as low as 10(2) ng m(-3)) composed of cesium iodide, levoglucosan, and levoglucosan within a carbon nanoparticle matrix. With EP-ESI-MS, the integrated mass spectrometric signals are found to be a monotonic function of the mass concentration of analyte in the aerosol phase. We additionally show that EP-ESI-MS has a dynamic range of close to 5 orders of magnitude in mass, making it suitable for molecular analysis of aerosol particles in laboratory settings with upstream particle size classification, as well as analysis of PM 2.5 particles in ambient air.

Fast SPH simulation for gaseous fluids

This paper presents a fast smoothed particle hydro-dynamics (SPH) simulation approach for gaseous fluids. Unlike previous SPH gas simulators, which solve the transparent air flow in a fixed simulation domain, the proposed approach directly solves the visible gas without involving the transparent air. By compensating the density and force calculation for the visible gas particles, we completely avoid the need of computational cost on ambient air particles in previous approaches. This allows the computational resources to be exclusively focused on the visible gas, leading to significant performance improvement of SPH gas simulation. The proposed approach is at least ten times faster than the standard SPH gas simulation strategy and is able to reduce the total particle number by 25–400 times in large open scenes. The proposed approach also enables fast SPH simulation of complex scenes involving liquid–gas transition, such as boiling and evaporation. A particle splitting and merging scheme is proposed to handle the degraded resolution in liquid–gas phase transition. Various examples are provided to demonstrate the effectiveness and efficiency of the proposed approach.

Ambient air particulates and particulate-bound mercury Hg(p) concentrations: dry deposition study over a Traffic, Airport, Park (T.A.P.) areas during years of 2011-2012.

The main purpose of this study was to monitor ambient air particles and particulate-bound mercury Hg(p) in total suspended particulate (TSP) concentrations and dry deposition at the Hung Kuang (Traffic), Taichung airport and Westing Park sampling sites during the daytime and nighttime, from 2011 to 2012. In addition, the calculated/measured dry deposition flux ratios of ambient air particles and particulate-bound mercury Hg(p) were also studied with Baklanov & Sorensen and the Williams models. For a particle size of 10μm, the Baklanov & Sorensen model yielded better predictions of dry deposition of ambient air particulates and particulate-bound mercury Hg(p) at the Hung Kuang (Traffic), Taichung airport and Westing Park sampling site during the daytime and nighttime sampling periods. However, for particulates with sizes 20-23μm, the results obtained in the study reveal that the Williams model provided better prediction results for ambient air particulates and particulate-bound mercury Hg(p) at all sampling sites in this study.