Particle Size Distribution Of Material Research Articles

Ambient Particulate Matter Size Distributions Drive Regional and Global Variability in Particle Deposition in the Respiratory Tract.

Human exposure to airborne particulate matter (PM) increases the risk of negative health outcomes; however, substantial uncertainty remains in quantifying these exposure‐response relationships. In particular, relating increased risk of mortality to exposure to PM with diameters smaller than 2.5 μm (PM2.5) neglects variability in the underlying size distribution of PM2.5 exposure and size‐resolved deposition in human airways. In this study, we combine a size‐resolved respiratory particle‐deposition model with a global size‐resolved aerosol model to estimate the variability in particle deposition along the respiratory tract due to variability in ambient PM size distributions. We find that the ratio of deposited PM mass in the tracheobronchial and alveolar regions per unit ambient PM2.5 exposure (deposition ratio and DRTB + AV) varies by 20–30% between populated regions due to variability in ambient PM size distributions. Furthermore, DRTB + AV can vary by as high as a factor of 4 between the fossil‐fuel‐dominated region of the Eastern United States and the desert‐dust‐dominated region of North Africa. When considering individual PM species, such as sulfate or organic matter, we still find variability in the DRTB + AV on the order of 30% due to regional variability in the size distribution. Finally, the spatial distribution of DRTB + AV based on number or surface area is substantially different than the DRTB + AV based on mass. These results suggest that regional variability in ambient aerosol size distributions drive variability in PM deposition in the body, which may lead to variability in the health response from exposure to PM2.5.

Size distributions of atmospheric particulate matter and associated trace metals in the multi-industrial city of Ulsan, Korea

Size distributions of atmospheric particulate matter and associated trace metals in the multi-industrial city of Ulsan, Korea

Susceptibility of Individuals with COPD to Air Pollution Exposure: A Case-Control Panel Study in Beijing, China

Introduction Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death worldwide, characterized by chronic inflammation, and is one of the main diseases contribute to mortality attributable to PM2.5. Exposure to air pollution is one of the high-risk factors contributing to occurrence and development of COPD, it is important to reveal the biological mechanism of inflammation associated with exposure to air pollution in COPD patients and to know if subjects with COPD are more susceptible to air pollution than health one.Methodology With a case-control panel study (COPD), we recruited 44 stable COPD patients and 58 healthy control from Beijing Xicheng District Shichahai Community Health Center. Each subject has undergone 4 times repeated clinical visits from 2016 to 2017. Biomarkers, including breath volatile organic carbons, lung function, fractional exhaled nitric oxide(FeNO), fasting blood and cholesterol, inflammatory cytokines and cells, heart rate and blood oxygen were repeatedly collected from each subject in four visits. Gaseous air pollutants along with detailed chemical components and size distribution of particulate matter were continuously measured before and during each visits, 24 hours personal exposure to PM2.5 of each subjects prior to clinical visit was measured with a personal PM2.5 sampler. Linear mixed-effect model was fitted to estimate the association.Results Preliminary results shows increases in the levels of FeNO and heart rate, and decreases in the capabilities of pulmonary ventilation following air pollution exposure were more serious in the COPD patients, and adjusted by the forced expiratory volume. The association these effects with the exposure to CO, SO2, black carbon, organic carbon, and ultrafine particles were most robust.Conclusions After exposure to air pollution, the COPD patients had higher acute responses and worse capability of inflammatory regulation.

Chemical composition and size distribution of particulate matters from marine diesel engines with different fuel oils

In this work, detailed physicochemical characteristics of particulate emissions were investigated over ranges of fuel properties, particles size distribution, chemical compositions and toxicity based on dynamometry experiments with marine diesel engines. The results indicated that lower fuel sulfur content (FSC) can decrease the specific emissions of total particle matters (PM). Organic carbon (OC) emissions were more than elemental carbon (EC), especially for 2-stroke marine diesel engine with heavy fuel oil (HFO), and carbonaceous substances were found to be load and size dependent. The suppression effect of low-sulfur light diesel fuel (LSDF/DF) for PM mass emissions was exhibited mostly in the reduction of OC and sulfate, compared with high-sulfur light diesel fuel (HSDF). PM mass emissions with low-sulfur HFO were still higher due to larger OC emissions. Emissions of 16 priority polycyclic aromatic hydrocarbons (PAHs) were highest in particle-phase PAHs, among which 3 and 4-benzene ring PAHs were predominant. Flua and Pyr were the PAHs with the highest emissions in the PM emitted from marine diesel engines. The PAHs had very high toxic equivalent, with the highest contribution of BaP and DahA. According to benzene rings number, the proportion of 5-benzene ring PAHs had the highest equivalent toxic concentration. Size distribution of PAHs had high correlations with OC and the PM with small size had higher equivalent toxicity concentration.

A simplified combustion model integrated with a particle growth dynamic model for top-lit updraft cookstoves

Solid fuel stoves are used by over a third of the world's population for cooking and space heating. Efforts are being made to develop cookstoves with higher combustion and thermal efficiencies, but these efforts lack support of numerical models for predicting emissions that can be used in the design process. This work presents a simplified steady-state model to simulate combustion in a top-lit updraft (TLUD) cookstove integrated with a model for particle growth dynamics. The model incorporates the effects of cookstove operating parameters, specifically primary and secondary air fluxes and their temperatures and fuel composition (moisture, char, and volatile content) on various emissions and thermal characteristics of the cookstove, such as emission factors (EF), emission rates (ER), and size distribution of particulate matter. The results demonstrated that EF and ER do not necessarily follow the same trends, and therefore a lower EF might lead to a higher personal exposure. This raises serious concern over the high reliance on EFs as a metric to assess the performance of cookstoves. Emissions trends obtained from the model matched with the trends reported in previous studies. Sensitivity analyses demonstrated that a small variation in the cookstove operating parameters or fuel properties drastically changes emission.

Size distribution and source of heavy metals in particulate matter on the lead and zinc smelting affected area

In order to understand the size distribution and the main kind of heavy metals in particulate matter on the lead and zinc smelting affected area, particulate matter (PM) and the source samples were collected in Zhuzhou, Hunan Province from December 2011 to January 2012 and the results were discussed and interpreted. Atmospheric particles were collected with different sizes by a cascade impactor. The concentrations of heavy metals in atmospheric particles of different sizes, collected from the air and from factories, were measured using an inductively coupled plasma mass spectrometry (ICP-MS). The results indicated that the average concentration of PM, chromium (Cr), arsenic (As), cadmium (Cd) and lead (Pb) in PM was 177.3 ± 33.2 μg/m3, 37.3 ± 8.8 ng/m3, 17.3 ± 8.1 ng/m3, 4.8 ± 3.1 ng/m3 and 141.6 ± 49.1 ng/m3, respectively. The size distribution of PM displayed a bimodal distribution; the maximum PM size distribution was at 1.1–2.1 μm, followed by 9–10 μm. The size distribution of As, Cd and Pb in PM was similar to the distribution of the PM mass, with peaks observed at the range of 1.1–2.1 μm and 9–10 μm ranges while for Cr, only a single-mode at 4.7–5.8 μm was observed. PM (64.7%), As (72.5%), Cd (72.2%) and Pb (75.8%) were associated with the fine mode below 2.1 μm, respectively, while Cr (46.6%) was associated with the coarse mode. The size distribution characteristics, enrichment factor, correlation coefficient values, source information and the analysis of source samples showed that As, Cd and Pb in PM were the typical heavy metal in lead and zinc smelting affected areas, which originated mainly from lead and zinc smelting sources.

Optimization of Secondary Air Injection in a Wood-Burning Cookstove: An Experimental Study.

Nearly 40% of the world's population regularly cooks on inefficient biomass stoves that emit harmful airborne pollutants, such as particulate matter (PM). Secondary air injection can significantly reduce PM mass emissions to mitigate the health and climate impacts associated with biomass cookstoves. However, secondary air injection can also increase the number of ultrafine particles emitted, which may be more harmful to health. This research investigates the effect of secondary air injection on the mass and size distribution of PM emitted during solid biomass combustion. An experimental wood-burning cookstove platform and parametric testing approach are presented to identify and optimize secondary air injection parameters that reduce PM and other harmful pollutants. Size-resolved measurements of PM emissions were collected and analyzed as a function of parametric stove design settings. The results show that PM emissions are highly sensitive to secondary air injection flow rate and velocity. Although increasing turbulent mixing (through increased velocity) can promote more complete combustion, increasing the total flow rate of secondary air may cause localized flame quenching that increases particle emissions. Therefore, biomass cookstoves that implement secondary air injection should be carefully optimized and validated to ensure that PM emission reductions are achieved throughout the particle size range.

Impact of human activities on the concentration of indoor air particles in an antarctic research station

Abstract One of the main characteristics of Antarctic buildings is the fact that they are designed mostly with a focus on energy efficiency. Although human activity is a major source of pollution, indoor air quality is not a matter of significant concern during building planning. This study examines the relationship between indoor activities in an Antarctic Research Station and the size distribution of particulate matter. Real-time particle size distribution data is used in conjunction with time-activity data. The activity number ratio is calculated using the mean number of particles found in each size range during each activity divided by the average number of particles found during a period characterized by the absence of human activities. Cooking, the use of cosmetics, waste incineration and exhaust from light vehicles were responsible for significant deterioration of indoor air related to the presence of fine and ultrafine particles. Cleaning, physical exercise and the movement of people were responsible for the emission of coarse particles. This article emphasizes the importance of post-occupancy evaluation of buildings, generating results relevant to the planning and layout of new buildings, especially regarding better indoor air quality.

Effect of ball and feed particle size distribution on the milling efficiency of a ball mill: An attainable region approach

In this article, alternative forms of optimizing the milling efficiency of a laboratory scale ball mill by varying the grinding media size distribution and the feed material particle size distribution were investigated. Silica ore was used as the test material. The experimental parameters that were kept constant in this investigation was the grinding media filling, powder filling and the mill rotational speed. The data obtained from these batch tests was then analyzed using a model free technique called the Attainable Region method. This analysis technique showed that the required product fineness is a function of grinding media and feed material size distributions. It was also observed from the experimental results that in order to increase the milling efficiency of a ball mill, towards optimum production of material in the desired size class, there is a need to correlate the ball size and the feed size distributions.

Chemically and size-resolved particulate matter dry deposition on stone and surrogate surfaces inside and outside the low emission zone of Milan: application of a newly developed "Deposition Box".

The collection of atmospheric particles on not-filtering substrates via dry deposition, and the subsequent study of the particle-induced material decay, is trivial due to the high number of variables simultaneously acting on the investigated surface. This work reports seasonally resolved data of chemical composition and size distribution of particulate matter deposed on stone and surrogate surfaces obtained using a new method, especially developed at this purpose. A "Deposition Box" was designed allowing the particulate matter dry deposition to occur selectively removing, at the same time, variables that can mask the effect of airborne particles on material decay. A pitched roof avoided rainfall and wind variability; a standardised gentle air exchange rate ensured a continuous "sampling" of ambient air leaving unchanged the sampled particle size distribution and, at the same time, leaving quite calm condition inside the box, allowing the deposition to occur. Thus, the "Deposition Box" represents an affordable tool that can be used complementary to traditional exposure systems. With this system, several exposure campaigns, involving investigated stone materials (ISMs) (Carrara Marble, Botticino limestone, Noto calcarenite and Granite) and surrogate (Quartz, PTFE, and Aluminium) substrates, have been performed in two different sites placed in Milan (Italy) inside and outside the low emission zone. Deposition rates (30-90μgcm-2month-1) showed significant differences between sites and seasons, becoming less evident considering long-period exposures due to a positive feedback on the deposition induced by the deposited particles. Similarly, different stone substrates influenced the deposition rates too. The collected deposits have been observed with optical and scanning electron microscopes and analysed by ion chromatography. Ion deposition rates were similar in the two sites during winter, whereas it was greater outside the low emission zone during summer and considering the long-period exposure. The dimensional distribution of the collected deposits showed a significant presence of fine particles in agreement with deposition rate of the ionic fraction. The obtained results allowed to point out the role of the fine particles fraction and the importance of making seasonal studies.

Optically sizing single atmospheric particulates with a 10-nm resolution using a strong evanescent field

Although an accurate evaluation of the distribution of ultrafine particulate matter in air is of utmost significance to public health, the usually used PM2.5 index fails to provide size distribution information. Here we demonstrate a low-profile and cavity-free size spectrometer for probing fine and ultrafine particulate matter by using the enhanced particle-perturbed scattering in strong optical evanescent fields of a nanofiber array. The unprecedented size resolution reaches 10 nm for detecting single 100-nm-diameter nanoparticles by employing uniform nanofibers and controlling the polarizations of the probe light. This size spectrometry was tested and used to retrieve the size distribution of particulate matter in the air of Beijing, yielding mass concentrations of nanoparticles, as a secondary exercise, consistent with the officially released data. This nanofiber-array probe shows potential for the full monitoring of air pollution and for studying early-stage haze evolution and can be further extended to explore nanoparticle interactions.

Research of interaction between technological and material parameters during densification of sunflower hulls

During the biomass densification can be recognized various technological variables and also material parameters which significantly influences the final solid biofuels (pellets) quality. In this paper, we will present the research findings concerning relationships between technological and material variables during densification of sunflower hulls. Sunflower hulls as an unused source is a typical product of agricultural industry in Slovakia and belongs to the group of herbaceous biomass. The main goal of presented experimental research is to determine the impact of compression pressure, compression temperature and material particle size distribution on final biofuels quality. Experimental research described in this paper was realized by single-axis densification, which was represented by experimental pressing stand. The impact of mentioned investigated variables on the final briquettes density and briquettes dilatation was determined. Mutual interactions of these variables on final briquettes quality are showing the importance of mentioned variables during the densification process. Impact of raw material particle size distribution on final biofuels quality was also proven by experimental research on semi-production pelleting plant.

Morphologic and chemical composition of particulate matter in motorcycle engine exhaust.

Despite the fact that environmental pollution due to motorcycle exhaust gases reports a great increase, motorcycle production exhibits a great increase through the last years. Countries of Asia and Africa are reported to be the major regions where two-wheeled vehicles are a major transportation mode, with tens of millions of units sold per year. Motorcycle exhaust particles are considered to be the major contributor to environmental pollution due to their airborne dispersion, containing great amount of polycyclic aromatic hydrocarbons (PAHs). This study aims at reporting an objective analysis of the main sources of the ambient air pollution as also particle size distribution and chemical composition analysis of particulate matter originated from the exhausts of two-wheeled vehicles used in the territory of Vladivostok, Russia. Various types of two-wheeled vehicles were examined (motorcycles, ATVs, scooters and wet bikes) using different types of engine and fuel system. Experimental results showed that there was no clear relation to the particle size distribution with the engine displacement of motorcycle and the number of strokes and the fuel system. Instead, there were reported two clear assumptions. The first one is that regarding to the motorcycle brand, a few samples did not exhibit a great percentage of PM10 fraction. The second one is that more modern vehicles, that have a harmful gas afterburning system, are usually the source of an increased percentage of PM10 emitted particles. At last, it should be mentioned that the laser particle size analysis method is capable of determining the particle sizes after their agglomeration whereas the optical morphometry method allows to determine the real particle size of emissions. In conclusion, it can be pointed out that the agglomeration of particles can lead to the reduction in the toxicity of particles emissions originated from two wheeled-vehicles.

Variations of Particle Size Distribution, Black Carbon, and Brown Carbon during a Severe Winter Pollution Event over Xi’an, China

Real-time particulate matter (PM) size distributions, 4-hour time resolution, PM2.5, carbonaceous materials, and their optical properties were measured during a severe pollution event in Xi’an, China. High PM2.5/PM10 ratios were observed on both pollution (0.83) and non-pollution (0.73) days, emphasizing the abundance of fine particles during sampling days. The particle number (PN) first peaked with a wide size range (30–100 nm) before morning rush hours (approximately 01:00–05:00) on pollution and non-pollution days, demonstrating that PN was governed by the accumulation of freshly emitted diesel particles and characterized by distinct aerosol condensation growth. By contrast, the second peak time and size range differed between pollution and non-pollution days because of different formation mechanisms. The light-absorbing coefficients of both black carbon (BC, babs-880nm, BC) and brown carbon (BrC, babs-370nm, BrC) were high on pollution days and decreased to approximately half of those values on non-pollution days, indicating that the degree of light absorption is reduced by rain. The diurnal variation in babs-880nm, BC pollution peaked with traffic on January 1 and 2. By contrast, it remained in relatively stable and high ranges (120–160 Mm–1) in the second period (January 3–5) without traffic peaks, illustrating that the dominant sources changed even during the same pollution period. High values of both babs-370nm, BrC and babs-880nm, BC coincided in the afternoon and evening due to emissions from primary sources, and abundant aqueous secondary organic carbon, respectively. A highly variable mass absorption coefficient of BrC also indicated the variety of fuel combustion sources of primary BrC in Xi’an.

The Effect of Emission Control on the Submicron Particulate Matter Size Distribution in Hangzhou during the 2016 G20 Summit

A number of observational and modeling studies have been conducted in China to study the effectiveness of radical short-term emission control measures with regard to air quality improvement. However, none of them have focused on the effect on submicron aerosols. Measurements on the size distribution of particles as small as 3 nm were conducted before, during and after the source emission control period for the 2016 G20 Summit held in Hangzhou, a megacity in eastern China. The measurement provided a unique opportunity to gain insight into the sources of submicron aerosols in Hangzhou and the effectiveness of radical emission control strategies. A WRF-Chem simulation suggested that the sources inside the emission control region contributed more than 70% to PM1 in Hangzhou from September 2 to 7, 2016, even under the strictest control scheme. Source restrictions on emissions from coal-fired power plants, on-road vehicles and industrial VOCs resulted in concentration decreases for PM1, PM0.01 and PM0.1, respectively. New particle formation (NPF) events, which were not suppressed completely by the emission control, enhanced the maximum PM0.01 concentration, at around 11:00 AM, by a factor of 4 compared to non-NPF days. Even during the strictest emission control period, two PM1 episodes still occurred due to the dominance of subsidence airflows, a low wind speed, and a weak vertical temperature gradient.

Effect of CO2/H2O on the Incipient Ultrafine Particulate Matter Formation in Oxy-fuel Combustion of High-Sodium Lignite

In this work, the formation of incipient ultrafine particulate matter (PM) from high-sodium lignite combustion, under both dry and wet oxy-fuel conditions, is intensively investigated using an optically accessible flat-flame burner. The ambient temperature was set at 1500 K, and measurements were performed along the zones with the coal residence time of 0–40 ms. We simultaneously introduced thermophoresis sampling, dilution sampling, and phase-selective laser-induced breakdown spectroscopy (PS-LIBS) to characterize the morphologies, components, and particle size distributions (PSDs) of ultrafine PM as well as the behaviors of Na. The results indicate that incipient particles formed in CO2–O2 ambience are more abundant in Na and Si. The substitution of CO2 may accelerate the mass loss rate of coal in the early devolatilization stage, whereas the Na-based incipient particles form around a time of ∼10 ms that is similar to conventional N2–O2 ambience. In combination with the computational fluid dynamics (CFD...

An investigation of the leaf retention capacity, efficiency and mechanism for atmospheric particulate matter of five greening tree species in Beijing, China

Urban trees have the potential to reduce air pollution, but the retention capacity and efficiency of different tree species for atmospheric particulate matter (PM) accumulation and the underlying mechanism hasn't been well understood. To select tree species with high air purification abilities, the supplementing ultrasonic cleaning (UC) procedure was first introduced into the conventional leaf cleaning methods [single water cleaning (WC) or plus brush cleaning (BC)] for eluting the leaf-retained PM. Further updates to the methodology were applied to investigate the retention capacity, efficiency, and mechanism for PM of five typical greening tree species in Beijing, China. Meanwhile, the particle size distribution of PM on the leaves, the PM retention efficiencies of easily removable (ERP), difficult-to-remove (DRP) and totally removable (TRP) particles on the leaf (AEleaf), and the individual tree scales were estimated. The experimental leaf samples were collected from trees with similar sizes 4 (SDR) and 14days (LDR) after rainfall. When the leaves were cleaned by WC+BC, there was, on average, 29%–46% of the PM remaining on the leaves of different species, which could be removed almost completely if UC was supplemented. From SDR to LDR, the mass of the leaf-retained PM increased greatly, and the particle size distribution changed markedly for all species except for Sophorajaponica. Pinus tabuliformis retains particles with the largest average diameter (34.2μm), followed by Ginkgo biloba (20.5μm), Sabina chinensis (16.4μm), Salix babylonica (16.0μm), and S. japonica (13.1μm). S. japonica and S. chinensis had the highest AEleaf to retain the TRP and ERP of both PM1 and PM1−2.5, respectively. Conversely, S. babylonica and P. tabuliformis could retain both TRP and ERP of PM2.5–5 and PM5–10, and PM>10 and TSP with the highest AEleaf, respectively. In conclusion, our results could be useful in selecting greening tree species with high air purification abilities.

Particulate matter emission and K/S/Cl transformation during biomass combustion in an entrained flow reactor

This study aims to demonstrate the effect of ash chemistry, especially, the transformation of potassium (K), chlorine (Cl), and sulfur (S) species, on the fine particle emission during biomass combustion. Biomass was burned in an entrained flow reactor at varied temperature from 1000 to 1300 °C, where fine particles were sampled using a 13-stage low pressure impactor, and the morphology and composition of the fine particles were analyzed. The fates of K, Cl, and S during biomass combustion were compared between the entrained flow reactor and the muffle furnace. Results show that the particle size distributions of PM10 are bimodal for all studied cases. A higher concentration of fine-mode particle is observed at 1000 °C, with the peak position at 0.274 μm. When the temperature is increased from 1000 to 1100 °C or higher, the concentration of fine-mode particle is reduced by about 50%, and its size becomes smaller with a peak position at 0.097 μm. K, Cl and S are enriched as potassium chloride and sulfate, dominantly in PM1.0; while Mg, Ca and Si are enriched in PM1.0–10. A certain amount of sulfur in PM1.0 at 1000 °C is observed, while the sulfur disappears above 1100 °C. This indicates that the process of potassium sulfation tends to occur at a moderate temperature, and affects the emission amount and the particle size distribution of particulate matters. Analyzing results of the fates of K, Cl and S in the particle phase indicate a completed sulfur-release from biomass ash above 1200 °C, as well as a maximum capture efficiency for potassium-containing vapors at 1100 °C, which results in a minimum PM1.0 emission at 1100 °C.

Indoor environmental quality index for conservation environments: The importance of including particulate matter

It is commonly known that the conservation state of works of arts exhibited inside museums is strongly influenced by the indoor environmental quality (IEQ). Heritage institutions traditionally record and evaluate their IEQ by monitoring temperature, relative humidity, and -more rarely-light. However, smart use of technology enables monitoring other parameters that give a more complete insight in environmental ‘air aggressiveness’. One of this parameters is particulate matter (PM) and especially its concentration, size distribution and chemical composition. In this work, we present a selection of data sets which were obtained in a measuring campaign performed in the War Heritage Institute in Brussels, Belgium. A continuous monitoring of PM concentration with a light scattering based particle counter was performed. In addition the daily mass concentration and size distribution of airborne PM was monitored by means of Harvard impactors. The chemical composition of sampled PM was inferred from the results of XRF and IC analysis. The insights from these datasets are combined with the results of traditional environmental monitoring (temperature, relative humidity and light intensity), and assessed against the recommended guidelines for conservation environments. By using an integrated approach based on the calculation of an IEQ-index, we present a straightforward methodology to evaluate and visualize the IEQ including also continuous PM monitoring. It is clear from the results of this study how including PM in IEQ analysis allows to identify potential risks for museum collections that remain invisible when only traditional parameters are considered.

Particle size distribution of bed materials in the sandy river bed of alluvial rivers

The particle size distribution of bed materials in the sandy river bed of alluvial rivers is important in the study of topics such as friction, river bed evolution, erosion, and siltation. It also can reflect the dependency relation between river bed sediment and flow intensity. In this paper, the critical pattern of sediment movement in the near-wall region of a sandy river bed was analyzed. According to the principle of momentum balance, the critical settling-rising condition of bed material in a sandy river bed was found to be instantaneous turbulent velocity equal to 2.7 times the sediment settling velocity in quiescent water. Based on a vertical instantaneous turbulent velocity with a Gaussian distribution, a theoretical relation for calculating the particle size distribution of bed materials in a sandy river bed without pre-known characteristic grain sizes was developed by solving a stochastic equation. The formula is verified using measured data, and the results show that the proposed formula was in accordance with the measured data. This study has theoretical significance and practical value for determining the bed material particle size distribution of the sandy bed of alluvial rivers.