Analysis of microparticle deposition in the human lung by taguchi method and response surface methodology.

The deposition phenomenon of microparticle and SAR-CoV-2 laced bioaerosol in human airways is studied by Taguchi methods and response surface methodology (RSM). The data used herein is obtained from simulations of airflow dynamics and deposition fractions of drug particle aerosols in the downstream airways of asthma patients using computational fluid dynamics (CFD) and discrete particle motion (DPM). Three main parameters, including airflow rate, drug dose, and particle size, affecting aerosol deposition in the lungs of asthma patients are examined. The highest deposition fraction (DF) is obtained at the flow rate of 45 L min-1, the drug dose of 200 µg·puff-1, and the particle diameter of 5 µm. The optimized combination of levels for the three parameters for maximum drug deposition is performed via the Taguchi method. The importance of the influencing factors rank as particle size > drug dose > flow rate. RSM reveals that the combination of 30 L min-1, 5 µm, 200 µg·puff- has the highest deposition fraction. In part, this research also studied the deposition of bioaerosols contaminated with the SAR-CoV-2 virus, and their lowest DF is 1.15%. The low DF of bioaerosols reduces the probability of the SAR-CoV-2 virus transmission.

An investigation for airflow and deposition of PM2.5 contaminated with SAR-CoV-2 virus in healthy and diseased human airway.

This study is motivated by the amplified transmission rates of the SAR-CoV-2 virus in areas with high concentrations of fine particulates (PM2.5) as reported in northern Italy and Mexico. To develop a deeper understanding of the contribution of PM2.5 in the propagation of the SAR-CoV-2 virus in the population, the deposition patterns and efficiencies (DEs) of PM2.5 laced with the virus in healthy and asthmatic airways are studied. Physiologically correct 3-D models for generations 10-12 of the human airways are applied to carry out a numerical analysis of two-phase flow for full breathing cycles. Two concentrations of PM2.5 are applied for the simulation, i.e., 30 µg⋅m-3 and 80 µg⋅m-3 for three breathing statuses, i.e., rest, light exercise, and moderate activity. All the PM2.5 injected into the control volume is assumed to be 100% contaminated with the SAR-CoV-2 virus. Skewed air-flow phenomena at the bifurcations are proportional to the Reynolds number at the inlet, and their intensity in the asthmatic airway exceeded that of the healthy one. Upon exhalation, two peak air-flow vectors from daughter branches combine to form one big vector in the parent generation. Asthmatic airway models has higher deposition efficiencies (DEs) for contaminated PM2.5 as compared to the healthy one. Higher DEs arise in the asthmatic airway model due to complex secondary flows which increase the impaction of contaminated PM2.5 on airways' walls.

Reducing emissions of persistent organic pollutants from a diesel engine by fueling with water-containing butanol diesel blends.

The manufacture of water-containing butanol diesel blends requires no excess dehydration and surfactant addition. Therefore, compared with the manufacture of conventional bio-alcohols, the energy consumption for the manufacture of water-containing butanol diesel blends is reduced, and the costs are lowered. In this study, we verified that using water-containing butanol diesel blends not only solves the tradeoff problem between nitrogen oxides (NOx) and particulate matter emissions from diesel engines, but it also reduces the emissions of persistent organic pollutants (POPs), including polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls, polychlorinated diphenyl ethers, polybrominated dibenzo-p-dioxins and dibenzofurans, polybrominated biphenyls and polybrominated diphenyl ethers. After using blends of B2 with 10% and 20% water-containing butanol, the POP emission factors were decreased by amounts in the range of 22.6%-42.3% and 38.0%-65.5% on a mass basis, as well as 18.7%-78.1% and 51.0%-84.9% on a toxicity basis. The addition of water-containing butanol introduced a lower content of aromatic compounds and most importantly, lead to more complete combustion, thus resulting in a great reduction in the POP emissions. Not only did the self-provided oxygen of butanol promote complete oxidation but also the water content in butanol diesel blends could cause a microexplosion mechanism, which provided a better turbulence and well-mixed environment for complete combustion.

Energy recovery and emissions of PBDD/Fs and PBDEs from cocombustion of woodchip and wastewater sludge in an industrial boiler.

The emissions of polybrominated dibenzo-pdioxins,dibenzofurans (PBDD/Fs), and polybrominated diphenyl ethers (PBDEs) from trial combustion of 10 wt % dried industrial wastewater-treatment sludge (IWTS) and 90 wt % woodchip in an industrial boiler were investigated and compared to that from woodchip combustion. The PBDD/F toxic equivalent (TEQ) andPBDE emissions increased from 0.121 pg TEQ Nm−3 and 2260 pgNm−3, respectively, of the woodchip combustion to 0.211 pg TEQNm−3 and 4200 pg Nm−3, respectively, of the trial combustion.PBDD/F and PBDE congener profiles of inputs and outputs of the same type of combustion were similar; they also show similarity between woodchip and trial combustions, revealing that the destruction pathway was little affected by the introduction of the IWTS. The fates of PBDD/Fs and PBDEs show that the indigenous pollutants in the feed were effectively depleted (>93.5%). The dominant releasing route of PBDD/F and PBDE shifted from the stack flue gas of woodchip combustion to the ashes of trial combustion. This study demonstrates that co-combustion not only handles the fast growing sludge stream but also yields a saving of 26.3% in the fuel cost and treatment fees of sludge and ashes.

Characteristics of particulate emissions from a diesel generator fueled with varying blends of biodiesel and fossil diesel.

This study investigated the particulate matter (PM), particle-bound carbons, and polycyclic aromatic hydrocarbons (PAHs) emitted from a diesel-engine generator fuelled with blends of pure fossil diesel oil (D100) and varying percentages of waste-edible-oil biodiesel (W10, 10 vol %; W20, 20 vol %; W30, 30 vol %; and W50, 50 vol %) under generator loads of 0, 1.5, and 3 kW. On average, the PM emission factors of all blends was 30.5 % (range, 13.7-52.3 %) lower than that of D100 under the tested loads. Substituting pure fossil diesel oil with varying percentages of waste-edible-oil biodiesel reduced emissions of particle-bound total carbon (TC) and elemental carbon (EC). The W20 blend had the lowest particle-bound organic carbon (OC) emissions. Notably, W10, W20, and W30 also had lower Total-PAH emissions and lower total equivalent toxicity (Total-BaP(eq)) compared to D100. Additionally, the brake-specific fuel consumption of the generator correlated positively with the ratio of waste-edible-oil biodiesel to pure fossil diesel. However, generator energy efficiency correlated negatively with the ratio of waste-edible-oil biodiesel to pure fossil diesel.

Aerosol deposition and airflow dynamics in healthy and asthmatic human airways during inhalation.

Inhalation of aerosols such as pharmaceutical aerosols or virus aerosol uptake is of great concern to the human population. To elucidate the underlying aerosol dynamics, the deposition fractions (DFs) of aerosols in healthy and asthmatic human airways of generations 13-15 are predicted. The Navier-stokes equations governing the gaseous phase and the discrete phase model for particles' motion are solved using numerical methods. The main forces responsible for deposition are inertial impaction forces and complex secondary flow velocities. The curvatures and sinusoidal folds in the asthmatic geometry lead to the formation of complex secondary flows and hence higher DFs. The intensities of complex secondary flows are strongest at the generations affected by asthma. The DF in the healthy airways is 0%, and it ranges from 1.69% to 52.93% in the asthmatic ones. From this study, the effects of the pharmaceutical aerosol particle diameters in the treatment of asthma patients can be established, which is conducive to inhibiting the inflammation of asthma airways. Furthermore, with the recent development of COVID-19 which causes pneumonia, the predicted physics and effective simulation methods of bioaerosols delivery to asthma patients are vital to prevent the exacerbation of the chronic ailment and the epidemic.

Recycle of synthetic calcium fluoride and waste sulfuric acid to produce electronic grade hydrofluoric acid.

An innovative method for utilizing synthetic calcium fluoride (CaF2), recovered from fluoride-containing semiconductor wastewater, and waste sulfuric acid (H2SO4) to produce hydrofluoric acid (HF) was investigated. The research was set to study the low-temperature production of HF via reaction of synthetic CaF2 and waste H2SO4. The impact of four factors, including H2SO4 concentration, total volume (H2SO4 + H2O)/CaF2 ratio, drying temperature of synthetic CaF2, and reaction carried out under different temperature, on HF productivity was investigated in this study. HF yield increased with increasing H2SO4 concentration and total volume/CaF2 ratio under room temperature. Generally, reactions carried out under low-temperature (< 100 °C) had a positive impact on HF yield. The higher temperature led to an increase in absorbed-HF but a decrease in total-HF. The reaction of commercial CaF2 and 70% H2SO4 had a higher absorbed-HF yield of 61.7% than synthetic CaF2 and 70% waste H2SO4, which had a yield of 36%. This was due to the higher purity of the commercial CaF2 and fewer interference ions in H2SO4. HF productivity was lowered by CaSO4, which hindered the reaction of reactants and also the generation of fluorosulfuric acid.

Polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofurans and polychlorinated biphenyls in farmed fish, water, sediment, and feed.

This investigation was undertaken to determine the levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dizenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) in farmed grouper tissues and environmental medium samples, including sediment, water, and feed. The water concentrations of DL-PCBs were low at 4.33-7.63 pg/L, and those of PCDD/Fs were 0.399-0.794 pg/L. The concentrations of PCDD/Fs in sediment samples were 21.4-35.3 pg/g, and those of PCBs were 54.7-100 pg/g. To identify changes in PCDD/Fs and PCBs levels in fish throughout growth, the tissue samples from hatchlings, 2-month, 15-month, 24-month, and 36-month-old orange spotted grouper (Epinephelus coioides) were analyzed. In grouper tissue samples, the total toxicity equivalent (TEQ) of the total PCBs were 0.129-0.745 pg World Health Organization- toxicity equivalent (WHO-TEQ/g) wet weight (w.w.), while total PCDD/Fs TEQ were 0.022-0.073 pg WHO-TEQ/g w.w The DL-PCBs were contributed more to the TEQ than PCDD/Fs in all fish tissue samples. Both PCDD/F and DL-PCB concentrations increase as grouper age increased. Results of this study demonstrate that PCDD/Fs and PCBs accumulate in fish tissues, and diet is the main source of PCDD/Fs and PCBs accumulations.

Reduction of carbon content in waste-tire combustion ashes by bio-thermal treatment.

Application of bio-catalyst (NOE-7F) in thermal treatment can adequately dispose dark-black fly ashes from co-combustion of both waste tires and coal. After thermal treatment of fly ashes by adding 10% NOE-7F, the carbon contents reduced by 37.6% and the weight losses increased by 405%, compared with the fly ashes without mixing with NOE-7F. The combustion behaviors of wasted tires combustion fly ashes with NOE-7F were also investigated by both thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The results verify that NOE-7F has positive effects on the combustion of residual carbon and toxic polycyclic aromatic hydrocarbons (PAHs) enhance the energy release and reduce the toxicity during the process of thermal treatment. Furthermore, using NOE-7F to dispose high-carbon content fly ashes did improve the compressive strength of fly ashes and concrete mixtures. Therefore, NOE-7F is a promising additive which could decrease treatment cost of high-carbon content fly ashes and reduce the amount of survival toxic PAHs.

Exposure and health-risk assessment of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) for sinter plant workers.

This study was set out to assess polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) exposures and health-risk impact posed on sinter plant workers. One sinter plant located in southern Taiwan was selected and their workers were divided into four exposure groups based on their work tasks, including raw material charging workers, sintering grate workers, shredding workers, and others. Results show that their mean total PCDD/F and the corresponding total I-TEQ exposure levels shared the same trend as: shredding workers>others>sintering grate workers>raw material charging workers. For all selected exposure groups, their PCDD/F exposures were dominated by the particle phase contents. Congener profiles of the gaseous+particle phase PCDD/Fs were found with more fractions of high chlorinated congeners than low chlorinated congeners. The lifetime average daily doses (LADDs) and their resultant excess cancer risks (ECRs) found for sinter plant workers were higher than those residents living at the residential area and rural area, but were lower than those living at the nearby of the selected sinter plant, urban area, industrial area. Considering ECRs of the sinter plant workers were still higher than 10(-6) suggesting the need for adopting proper control measurements for reducing workers' PCDD/F exposures, particularly for those sinter zone workers.

Metal recovery from spent hydrodesulfurization catalysts using a combined acid-leaching and electrolysis process.

This study focuses on recovering valuable metals from spent hydrodesulfurization (HDS) catalysts using a combined acid-leaching and fluidized-bed electrolysis process. The electrolytic cell was equipped with a glass bead medium, an iridium oxide mesh anode, and a stainless steel plate cathode. An acid solution consisting of concentrated HNO3/H2SO4/HCl with a volume ratio of 2:1:1 was found to be better than the other tested solution (HNO3/H2SO4=1:1) to leach the metals. For the three-acid mixture, the best solid/liquid ratio and leaching time were 40 g/L and 1 h, respectively, at 70 degrees C; under this condition, the leaching yields of target metals (Mo, Ni, and V) in the 1st stage of leaching reached 90, 99, and 99%, respectively, much higher than those in the 2nd/3rd/4th stages. When this acid leachate was electrolyzed for 2 h at 2 A constant current (current density=approximately 35.7 mA/cm2), a stable cell voltage of 5 V was observed. The electrolytic recoveries of Mo, Ni, and V were approximately 15, 61, and 66%, respectively, but extending the electrolysis time from 2 to 4 h did not increase the recoveries. For this operation, the total recoveries (leaching yieldxelectrolytic recovery) of Mo, Ni, and V were approximately 14, 60, and 65%, respectively.

Characterization of PAHs exposure in workplace atmospheres of a sinter plant and health-risk assessment for sintering workers.

This study first measured concentrations of polycyclic aromatic hydrocarbons (PAHs) in four selected workplace atmospheres, including the raw materials inlet, sintering grate, rough roll shredder and control room, and the outdoor environment of a sinter plant. Then, PAHs exposures and their resultant health-risks were assessed for sintering workers. We found that total PAH concentrations of the three selected sintering process areas were higher than that of the control room. The above results could be explained by the filtration effect of the air conditioning device installed inside the control room. PAH homologue distributions of the three selected sintering process areas were significantly different from that of the outdoor environment suggesting that PAHs found in the sintering workplace atmospheres were mainly contributed by process fugitives. Total PAH exposure levels were lower than the current permissible exposure limits, thus revealing that sintering workers are not a high risk group for long-term effects attributable to PAHs. Moreover, the lung cancer risks associated with the above PAH exposures were lower than the significant risk level defined by US Supreme Court further confirming that their exposures could be acceptable at this stage.

Thermal treatment of polychlorinated dibenzo-p-dioxins and dibenzofurans from contaminated soils.

Thermal treatment technology was used to remove polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from heavily contaminated soil. For a soil with an original PCDD/F content of 35,970ng International Toxic Equivalents (I-TEQ)/kg, >99.99% PCDD/F removal efficiency was obtained with a primary furnace at two different treatment temperatures (750 degrees C and 850 degrees C), while a secondary furnace at 1200 degrees C gave >98% decomposition efficiency. The total PCDD/F I-TEQ contents in treated soils at 750 degrees C and 850 degrees C were 1.56ngI-TEQ/kg and 2.15ngI-TEQ/kg, respectively, which were far below the soil pollution standard of Taiwan (1000ngI-TEQ/kg soil). Although air pollution control devices had significant effects on the removal of PCDD/Fs, the total I-TEQ concentrations in the upstream flue gas of PUF cartridge at 750 degrees C and 850 degrees C (2.61ngI-TEQ/Nm(3) and 2.38ngI-TEQ/Nm(3), respectively) were still higher than the stationary emission limit of the Taiwan EPA (0.5ngI-TEQ/Nm(3)). The above results also suggested that additional APCDs, such as activated carbon injection in front of the filter are needed to enhance PCDD/F removal efficiency.

A novel method to enhance polychlorinated dibenzo-p-dioxins and dibenzofurans removal by adding bio-solution in EAF dust treatment plant.

In order to understand the effect of different amounts of powder-activated carbon (PAC) injection and bio-solution (NOE-7F) addition on the removal efficiencies of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in a fly ash treatment plant with Waelz rotary kiln process, the PCDD/F concentrations in the stack flue gasses were measured and discussed. In the amount of 20, 40 and 50 kg/h PAC injection, the removal efficiencies of PCDD/Fs in the stack flue gas were 86, 96 and 97%, respectively. While adding more amounts of PAC did enhance the removal efficiencies, the reduction fractions of low chlorinated PCDD/F congeners were much higher than those of highly chlorinated PCDD/F congeners. Particularly, a lower amount of PAC injection (20 kg/h), not only cannot remove highly chlorinated PCDD/Fs, but also the carbon surface of the PAC can act as a precursor for the formation promotion of highly chlorinated PCDD/F congeners. The addition of NOE-7F in the raw materials had the dechlorination effect on the PCDD/F removal and mainly inhibited highly chlorinated PCDD/F formation. The combination of both PAC injection and NOE-7F addition has a high potential for practical application.

Significance of biomass open burning on the levels of polychlorinated dibenzo-p-dioxins and dibenzofurans in the ambient air.

In southern Taiwan, two areas (L- and Y-) with/without biomass open burning were selected to compare the PCDD/F concentrations and their congener profiles in the ambient air. The results of this study indicate that biomass (rice straw) open burning exhibited a significant impact on the PCDD/F concentration level in the ambient air. During the biomass burning season, the total PCDD/F I-TEQ concentrations in the ambient air of L- and Y-areas were approximately 4 and 17 times higher than those without biomass open burning, respectively. When 10% mass fraction of rice straw was burned, the contribution fraction of biomass burning on annual total PCDD/F I-TEQ emission was 3.28 and 8.11% for KC County and for Taiwan, respectively; however, when the calculation was on a weekly basis, the contribution fraction of biomass burning on weekly total PCDD/F I-TEQ emission was 30.6 and 53.4% for KC County and for Taiwan, respectively. The results of this study imply that during the week of biomass burning, it appears to be the most significant source of total I-TEQ PCDD emission. The results of this research can be applied to the study of other agricultural areas.

Validation of the CALUX bioassay as a screening and semi-quantitative method for PCDD/F levels in cow's milk.

The objectives of this study were first to set up and validate the quality criteria of the Xenobiotic Detection Systems-chemical activated luciferase gene expression (CALUX) bioassay for the analysis of cow's milk samples spiked with polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). The application of this bioassay was then tested by analyzing 28 commercially available pasteurized milk samples and comparing the data with the reference method for PCDD/F analysis. The CALUX criteria from the U.S. EPA and the European Union (EU) were calculated from 16 replaced spiked milk (SM) samples and 8 performance evaluation (PE) samples to validate the CALUX bioassay system. The CALUX bioassay criteria included control chart for quality control (QC) standards, recovery efficiency, and data comparability. The control chart for QC standards were both within the micro+/-2sigma range. The recovery efficiencies ranged from 60.4% to 106% with an average of 79.9% (relative standard deviation (RSD): 20.7%). The mean of data comparability (i.e., relative percent difference, RPD) between CALUX bioassay and high-resolution gas chromatography and high-resolution mass spectrometry (HRGC/HRMS) was 19.0% for SM samples. For the PE samples, Pearson's correlation coefficient between CALUX and the HRGC/HRMS method was 0.953. The high correlation shows that the CALUX system is suitable as a screening method and a semi-quantitative method to analyze the PCDD/F concentration in milk samples. Next, the validated CALUX bioassay was applied to measure 28 commercially available pasteurized milk samples. These milk samples were also analyzed with the HRGC/HRMS method to compare the analysis data from two different methods. There is no false negative sample when applying the bioassay to pasteurized milk and PE samples as a screening method and a semi-quantitative method. The present study indicates that CALUX is a powerful bioassay method for screening a large number of milk samples.

National surveillance of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins/furans in soil in Taiwan.

In this study, the polychlorinated dibenzo-p-dioxin/furan (PCDD/F) levels in 381 soil samples coming from different background areas (n = 238) and contaminated areas (n = 143) in Taiwan were investigated from 2011 to 2015 using high resolution gas chromatograph/high resolution mass spectrometry (HRGC/HRMS). The contaminated areas showed higher PCDD/F contamination as compared to the background areas (1230 vs 749 pg/g dry weight (dw)); 14.0 vs 6.25 pg WHO2005-TEQ/g dw). The lowest levels were recorded in the outlying islands (1.28 pg WHO2005-TEQ/g dw). PCDD/F congener distribution profiles in the background and contaminated areas as well as on the islands varied. OCDD was the dominant congener in almost all locations, including the northern background (87.7%) and central contaminated (74.2%) areas. Other dominant species included OCDF and 1,2,3,4,6,7,8-HpCDD. Levels of PCDD/F-TEQs in Taiwanese soils, including the background areas, were higher than in some developing countries and regions with global background levels due to high industrialization except for the contaminated areas. Geographic differences in dioxin-contaminated soils were also shown in this study. Higher soil dioxin-TEQs were observed in locations with high populations and population densities. Despite the limitations, the economic status of Taiwan represented by the annual averaged family income (AAFI) was positively correlated to soil dioxin-TEQs.

Levels of polybrominated diphenyl ethers (PBDEs) in breast milk from central Taiwan and their relation to infant birth outcome and maternal menstruation effects.

In utero exposure to polybrominated diphenyl ethers (PBDEs) reduces the number of ovarian follicles in rat females and causes permanent effects on rat males. Little data have been gathered on the associations between PBDEs exposure and birth outcome and female menstruation characteristics in both epidemiological and animal studies. The aim of this study was to examine how PBDEs in breast milk are associated with infant birth outcome and maternal menstruation characteristics. Study participants were healthy women recruited from central Taiwan between December 2000 and November 2001. Twelve congener levels of PBDEs (BDE-17, 28, 47, 66, 85, 99, 100, 138, 153, 154, 183, 209) in 20 breast milk samples were measured by gas chromatography with high resolution mass spectrometer. The mean level of PBDEs in breast milk was 3.93+/-1.74 ng/g lipid. The estimated PBDE daily intake for a breastfed infant was 20.6 ng/kg b.w./day after delivery. After maternal age, pre-pregnant BMI, and parity were adjusted, increased PBDEs in breast milk was related with decreased birth outcome, particularly for birth weight and length, chest circumference, and Quetelet's index of infants. No significant differences in PBDEs were found between the two groups of menstrual cycle length higher and lower than 30 days after we adjusted for maternal age, pre-pregnant BMI, and parity. In utero exposure to low doses of PBDEs may result in lower birth weight and short or birth length. Our findings are limited based on the low doses of PBDEs and the small sampling size.

Long-term visibility trends in one highly urbanized, one highly industrialized, and two rural areas of Taiwan.

Visibility trends on the island of Taiwan were investigated employing visibility and meteorological (1961-2003), and air pollutant (1994-2003) data from one highly urbanized center (Taipei), one highly industrialized center (Kaohsiung), and two rural centers (Hualien and Taitung). Average annual visibility (1961-2003) was significantly higher at the rural centers. Unlike at the other centers, visibility in Taipei improved between 1992 (6.6 km) and 2003 (9.9 km), and this can be linked to the construction and expansion of a mass transit rail system in Taipei, the use of which has helped reduce emissions of traffic related air pollutants, particles, and NO2. This has left Kaohsiung with the lowest annual visibility since 1994, despite its 1961-2003 average being superior to that of Taipei. Precipitation lowers visibility, as demonstrated by the all-centers correlation coefficient for visibility and precipitation of -0.92. Hence, frequency of precipitation is one of the factors contributing to the average annual visibility number. The poorest air quality category ('episode'), most commonly experienced in Taipei and Kaohsiung, was characterized by relatively high concentrations of PM10 and NOx at those centers, with comparatively high atmospheric pressure and comparatively low visibility and wind speed. Excepting O3, pollutant concentrations were slightly higher during weekdays, although there was no consistent, significant difference in weekday-weekend visibility. Principal component analysis demonstrated that visibility was markedly reduced in Taipei, Kaohsiung, and Hualien by increased vehicular emissions, road traffic dust, and industrial activity, but not in Taitung, where visibility was as a result superior to that at the other centers and degradation in visibility was likely a response to long-range transport of pollutants rather than local sources. Optimal empirical regression models indicated a negative impact on visibility for each of PM10, SO2 and NO2, particularly so for PM10, and validity of these models for Taipei, Kaohsiung, and Hualien was confirmed by correlation coefficients of simulated and observed average visibility of 0.63-0.72 for daily visibility and 0.85-0.88 for monthly visibility. For Taitung these figures were only 0.46 and 0.50, respectively, indicating that simulations for Taitung should include long-range transport as a pollutant source.

Water-soluble ions in nano/ultrafine/fine/coarse particles collected near a busy road and at a rural site.

This study investigated water-soluble ions in the sized particles (particularly nano (PM(0.01-0.056))/ultrafine (PM(0.01-0.1))) collected using MOUDI and Nano-MOUDI samplers near a busy road site and at a rural site. The analytical results demonstrate that nano and coarse particles exhibited the highest (16.3%) and lowest (8.37%) nitrate mass ratios, respectively. The mass ratio of NO(3)(-) was higher than that of SO(4)(2-) in all the sized particles at the traffic site. The secondary aerosols all displayed trimodal distributions. The aerosols in ultrafine particles collected at the roadside site exhibited Aitken mode distributions indicating they were of local origin. This finding was not observed for those ultrafine particles collected at the rural site. The mass median diameters (MMDs) of the nano, ultrafine, and fine particles were smaller at the traffic site than at the rural site, possibly related to the contribution of mobile engine emissions.