Dissertations / Theses on the topic 'ULTRAFINE PARTICLESIN'

Ultrafine particles (UFP) are the smallest constituents of atmospheric particulate matter (PM). Until now, their potential adverse effects on human health are of great concern because of their specific properties and acting mechanisms. The work in this thesis focuses on the measurement of UFP and their effect and contribution to air quality in Leicester, UK and a set of cities in North West (NW) Europe. The thesis explores novel work around new particle formation (NPF) events and their association with Lung Deposited Surface Area (LDSA) in an urban environment. A final focus of this thesis was the identification sources are contribute to the PM10 across NW Europe region. Particle number size distribution were measured at two urban background locations (automatic urban and rural network (AURN), and Brookfield (BF)) in Leicester in order to quantify NPF events. Quantification of primary and secondary sources of UFP was undertaken using black carbon as a tracer for the primary UFP in urban areas. At the AURN site, which is influenced by fresh vehicle exhaust emissions, total number concentrations (TNC) was segregated into two components, TNC = N1 + N2. The component N1 represents components directly emitted as particles and compounds which nucleate immediately after emission. The component N2 represents the particles formed during the dilution and cooling of vehicle exhaust emissions and by in situ NPF. Furthermore, the composition of the PM10 was studied at five sites across NW Europe. The samples collected at four urban background, and one industrial sites were analysed for elements, water soluble ions, organic matter, and monosaccharides, and the principal component analysis (PCA) was applied to the data set. Overall, during the measurement period, the frequency of NPF events was 13.3%, and 22.2% at AURN and BF sites, respectively. The percentage of N2 (57%) was greater than the percentage of N1 (43%) for all days at the AURN site. The PCA yielded 5 factors which apportioned the main pollution sources to PM10 concentrations across NW Europe: (1) traffic emissions, (2) secondary inorganic aerosols, (3) organic matter, (4) industrial and sea salt, (5) biomass burning.

Atmospheric aerosol particles, particularly ultrafine particles (UFPs; particles with less than 100 nm in diameter), and tropospheric ozone (O3) are atmospheric pollutants highly influenced by photochemical reactions, i.e., processes initiated by the absorption of solar radiation. High concentrations of ambient UFPs and O3 have important adverse effects on human health and impact on climate. Areas with high insolation and atmospheric dynamics favoring the accumulation of pollutants by vertical recirculation of air masses, such as the Western Mediterranean and other regions of Southern Europe, often register episodes with high concentrations of UFPs and O3, especially in spring and summer. UFPs episodes might be caused by the emission and accumulation of particles or by the photochemical formation of particles from gaseous precursors (new particle formation; NPF). The objective of this thesis is to characterize the relationship between UFPs and O3 in areas and periods with important photochemical activity. More specifically, this thesis aims at (i) identifying the atmospheric patterns causing the episodes, (ii) establishing whether these pollutants are driven by the same processes or occurring in parallel and (iii) describing how UFP concentrations have evolved over the last years. Based on these objectives, we analyzed data gathered during intensive field campaigns of simultaneous surface-level and vertical measurements, as well as long-term series of continuous measurements. Combining these, we focus on evaluating the seasonality and simultaneity of UFPs and O3 episodes, identifying the key contributing atmospheric factors and providing insights on the influence of NPF on the concentration of UFPs. We found that two distinct scenarios govern the formation and transport of UFPs and O3: recirculation of air masses and venting. The occurrence of either scenario is determined by large-scale meteorology, whereas the magnitude of concentrations is modulated by the availability of precursors and local atmospheric and orographic conditions. Our results indicate that acute UFPs episodes are undoubtedly linked with O3 episodes. Yet, the episodes may or may not be simultaneous on the same day. The occurrence of an O3 episode seems to be always concurrent with an UFPs episode caused by accumulation of primary and secondary particles during recirculation periods. However, high UFPs concentrations caused by NPF are mainly occurring with lower (but relatively high in absolute values) O3 concentrations during venting periods. When considering the average annual UFPs concentrations in urban locations, primary traffic emissions have a greater contribution to the total number of particles than NPF. Yet, on days with NPF events, the contribution from NPF to UFPs might be higher than that from primary emissions. Although NPF events do not occur in most of the days, the number of days with NPF events is increasing, probably due to a decreasing trend in the anthropogenic atmospheric emissions in recent years, which caused a decline in the particle sinks. Thus, the contribution of NPF to the number concentration of UFPs is also increasing. The total concentration of UFPs may either increase or decrease, depending on the local conditions and precursor emissions. In urban environments, the decline in anthropogenic emissions causes a direct decrease in the concentration of UFPs. In rural environments, NPF becomes more favorable and the concentration of UFPs increases. This might be related to increasing local biogenic emission of precursors, as well as a reduction of sinks due to a decline in transported anthropogenic emissions. Abatement policies implemented in recent years aiming at decreasing anthropogenic emissions of atmospheric pollutants have had a major impact in the concentration of UFPs at urban environments. However, these policies have not had a significant impact in the regional background, where UFPs have increased.
Els aerosols atmosfèrics, particularment partícules ultrafines (UFPs; partícules de menys de 100 nm de diàmetre), i l'ozó troposfèric (O3) són contaminants atmosfèrics molt influenciats per reaccions fotoquímiques, processos iniciats per l'absorció de radiació solar. Concentracions elevades d'UFPs i O3 en l'ambient tenen importants afectes adversos en la salut humana i impactes en el clima. En àrees amb una alta insolació i dinàmiques atmosfèriques que afavoreixen l'acumulació de contaminants degut a recirculacions verticals de masses d¿aire, com el Mediterrani occidental i altres regions del sud d'Europa, sovint s'enregistren episodis d'altes concentracions d'UFPs i O3, especialment a la primavera i a l¿estiu. Els episodis d¿UFPs poden estar causats per l'emissió i acumulació de partícules o per la formació fotoquímica de partícules a partir de precursors gasosos (formació de partícules noves; NPF). L'objectiu d¿aquesta tesi és caracteritzar la relació entre UFPs i O3 en àrees amb una alta activitat fotoquímica. Concretament, aquesta tesi té com objectius identificar els patrons atmosfèrics que causen els episodis, determinant si aquests contaminants estan regits pels mateixos processos o bé ocorren en paral·lel, i descriure l'evolució de les concentracions d'UFP en els darrers anys. S'han analitzat dades recopilades durant campanyes intensives de mesures simultànies a nivell de superfície i en altura, així com sèries de dades de mesures contínues de llarg termini. Mitjançant la combinació d¿aquestes dades, s'ha avaluat l'estacionalitat i la simultaneïtat dels episodis d'UFPs i d'O3, identificant els factors que hi contribueixen i aportant informació sobre la influencia de la NPF en les concentracions d'UFPs. Hi ha dos escenaris que controlen la formació i el transport d'UFPs i O3: la recirculació vertical de masses d'aire i la ventilació. L'ocurrència d'un o altre escenari ve determinada per les condicions meteorològiques a escala sinòptica, mentre que la magnitud de les concentracions ve donada per la disponibilitat de precursors i les condicions atmosfèriques i orogràfiques locals. Els episodis aguts d¿UFPs estan indubtablement vinculats amb els episodis d¿O3. Tot i així, els episodis poden ser simultanis en un mateix dia o no ser-ho. Un episodi d'O3 és sempre simultani amb un episodi d'UFPs causat per acumulació de partícules primàries i secundàries durant períodes de recirculació. Tanmateix, altes concentracions d'UFPs causades per NPF es donen principalment amb concentracions relativament baixes d'O3 durant períodes de ventilació. Quan es consideren les concentracions mitjanes anuals d'UFPs en àrees urbanes, les emissions primàries del trànsit tenen una major contribució al nombre total de partícules que la NPF. No obstant, en dies amb episodis de NPF, la NPF contribueix més al nombre total d'UFPs que les emissions primàries. Tot i que en la majoria dels dies no es detecten episodis de NPF, el nombre de dies amb NPF està incrementant, probablement degut a una tendència a la baixa de les emissions atmosfèriques antropogèniques en els darrers anys, que han causat una disminució en les embornals de condensació i coagulació de partícules. En conseqüència, la contribució de NPF al nombre d'UFPs també està augmentat. La concentració total d'UFPs pot augmentar o disminuir, depenent de les condicions locals. En àrees urbanes, la disminució d'emissions antropogèniques causa una disminució directa de la concentració d¿UFPs. En canvi, en ambients rurals, la NPF esdevé més favorable fins al punt que la concentració d'UFPs creix. Això pot ser degut a un augment de les emissions biogèniques locals de precursors i a una disminució del transport d'emissions antropogèniques. Les polítiques implementades en els darrers anys amb l'objectiu de reduir les emissions antropogèniques de contaminants atmosfèrics han tingut un gran impacte en la concentració del nombre de partícules en ambients urbans. Per contra, aquestes polítiques no han tingut un impacte significatiu en el fons regional, on el nombre de partícules ha augmentat
Los aerosoles atmosféricos, en particular las partículas ultrafinas (UFPs por sus siglas en inglés; partículas de menos de 100 nanómetros de diámetro), y el ozono troposférico (O3) son contaminantes atmosféricos muy influenciados por reacciones fotoquímicas, i.e., procesos iniciados por la absorción de radiación solar. Concentraciones elevadas de UFPs y O3 en el ambiente tienen importantes efectos adversos en la salud humana e impactos en el clima. En áreas con una alta insolación y dinámicas atmosféricas que favorecen la acumulación de contaminantes debido a recirculaciones verticales de masas de aire, como en el Mediterráneo occidental y otras regiones del sur de Europa, a menudo se registran episodios de altas concentraciones de UFPs y O3, especialmente en primavera y verano. Los episodios de UFPs pueden estar causados por la emisión y acumulación de partículas o por la formación fotoquímica de partículas a partir de precursores gaseosos (formación de nuevas partículas; NPF por sus siglas en inglés). El objetivo de esta tesis es caracterizar la relación entre UFPs y O3 en áreas y períodos con una actividad fotoquímica importante. Concretamente, esta tesis tiene como objetivos identificar los patrones atmosféricos que causan los episodios, determinando si estos contaminantes están regidos por los mismos procesos o bien ocurren en paralelo, así como describir la evolución de las concentraciones de UFPs en los últimos años. Basándonos en estos objetivos, se han analizado datos recopilados durante campañas de medidas intensivas simultáneas a nivel de superficie y en altura, así como series de datos de medidas continuas a largo plazo. Mediante la combinación de estos datos, se ha evaluado la estacionalidad y la simultaneidad de los episodios de UFPs y O3, identificando los factores que contribuyen a ellos y aportando información sobre la influencia de la NPF en las concentraciones de UFPs. Hemos encontrado que hay dos escenarios que controlan la formación y el transporte de UFPs y O3: la recirculación vertical de masas de aire y la ventilación. El acontecimiento de uno u otro escenario viene determinado por las condiciones meteorológicas a escala sinóptica, mientras que la magnitud de las concentraciones viene dada por la disponibilidad de precursores y las condiciones atmosféricas y orográficas locales. Nuestros resultados indican que los episodios agudos de UFPs están indudablemente vinculados con los episodios de O3. Aun así, los episodios pueden ser simultáneos en el mismo día o no serlo. Un episodio de O3 parece ser siempre simultáneo con un episodio de UFPs causado por acumulación de partículas primarias y secundarias durante períodos de recirculación. Sin embargo, altas concentraciones de UFPs causadas por NPF tienen lugar principalmente con concentraciones relativamente bajas (pero altas en valor absoluto) de O3 durante períodos de ventilación. Cuando se considera el promedio de las concentraciones anuales de UFPs en áreas urbanas, las emisiones primarias del tráfico tienen una mayor contribución al número total de partículas que la NPF. No obstante, en días con episodios de NPF, la contribución de NPF al número total de UFPs puede ser mayor que la de las emisiones primarias. Aunque en la mayoría de días no se detectan episodios de NPF, el número de días con NPF está incrementando, probablemente debido a una tendencia a la baja en los últimos años de las emisiones atmosféricas antrópicas, que han causado una disminución en los sumideros de condensación y coagulación. En consecuencia, la contribución de la NPF al número de UFPs también va en aumento. La concentración total de UFPs puede aumentar o disminuir, dependiendo de las condiciones locales y las emisiones de precursores. En áreas urbanas, la disminución de emisiones antrópicas causa una disminución directa de la concentración de UFPs. En cambio, en ambientes rurales, la NPF se hace más favorable, hasta el punto de aumentar las concentraciones de UFPs. Esto puede ser debido a un incremento de las emisiones biogénicas locales de precursores debido al aumento de temperaturas, así como a una reducción de los sumideros de partículas debido a una disminución del transporte de emisiones antrópicas. Las políticas implementadas en los últimos años con el objetivo de reducir las emisiones antrópicas de contaminantes atmosféricos han tenido un gran impacto en las concentraciones del número de UFPs en ambientes urbanos. Por el contrario, estas políticas no han tenido un impacto significativo en el fondo regional, donde la concentración de UFPs ha aumentado.
Enginyeria ambiental

V mnoha oborech jsou stále využívána anorganická filtrační media založená na materiálech, jejichž výroba využívá primární suroviny. Jejich výroba je tedy energeticky náročná a v důsledku nákladná a neohleduplná k životnímu prostředí. Cílem této práce je ověřit možnost využití alkalicky aktivovaných materiálů na bázi sekundárních surovin, především vysokopecních strusek (BFS) a popílků z uhelných elektráren (FA), pro výrobu porézních médií schopných v budoucnosti nahradit keramické a jiné anorganické filtry. Výzkum je rozvinut skrze experimentální design založený na výpočetním schématu samostatně vyvinutém s pomocí programu MATLAB. Toto schéma počítá vhodná složení směsí na základě poměrů obsahu nejdůležitějších oxidů ve vstupních surovinách. Tak je zajištěno zohlednění proměnlivého složení vstupních surovin a práce je tím hodnotnější, že její výsledky jsou skrze početní nástroj zohledňující základní oxidové složení surovin zobecnitelné. Zároveň byly však pro srovnání a lepší názornost závislostí vlastností na složení navrhnuty a připraveny i série vzorků založené vždy pouze na jedné ze surovin. Z výsledků vyplývá, že pevnost vzorků z těchto směsí (vytvrzených 24 hodin při 70 °C) ve čtyřbodové ohybové zkoušce dle ČSN EN 12390 5 může přesáhnout 7,6 MPa. Dosažením co možná nejvyšší porozity však zákonitě negativně ovlivňuje pevnost materiálu a výsledný materiál tedy dosahuje pevnosti těsně nad hranicí 6,3 MPa. Výsledky obecně dokazují, že nejvíce je pevnost materiálů ovlivněna poměrem SiO2/Al2O3 a množstvím alkalického aktivátoru. Z výsledků vyplývá, že alkalicky aktivované materiály (AAM) na bázi strusky dosahují i více než dvojnásobné pevnosti analogických materiálů na bázi elektrárenského popílku. Velikost pórů materiálů připravených z tříděných surovin s velikostí zrna od desítek po lehce přes sto mikronů se ve většině případů pohybuje v rozmezí desetin ž jednotek mikronů, v případě výsledného materiálu je to pak přibližně 0,2 mikronu. Celková porozita lisovaných těles se pohybuje těsně pod 40 %, což je v tomto případě téměř dvojnásobek ve srovnání s totožnými materiály na bázi netříděných surovin. Výsledky rovněž ukazují, že materiály na bázi strusky vykazují nižší porozitu než ty na bázi popílku, což je patrně způsobeno rozdílnou morfologií částic obou materiálů – částice strusky jsou nepravidelně hranaté a částice popílku kulaté. V průběhu experimentální činnosti byla pozorována tvorba výkvětů u materiálů na bázi elektrárenských popílků. Pomocí Energo-disperzní spektroskopické analýzy (EDS) byly výkvěty identifikovány jako hydroxid sodný procházející karbonatací za účasti vzdušného CO2. Test permeability vyžadoval, kvůli velmi jemné povaze porézní struktury, přípravu asymetrických filtračních přepážek. Tyto přepážky dosáhli propustnosti 138 L/h.m2.bar pro vodu a 1320 L/h.m2.bar pro vzduch.

Recently, powders of the size d (0.1 μm < d < 10 μm) have been referred to ultrafine particles. The particle shape considered is assumed to be a sphere of the diameter d. The handling of powders is of great importance for processing of pharmaceuticals, cement, chemicals and other products. Most of these technological processes involve powder compaction, storage, transportation, mixing, etc, therefore, understanding of the fundamentals of particles interaction behaviour is very essential in the design of machines and equipment as well as in powder technology, cleaning of environment and other areas. The dynamic behaviour of particulate systems is very complicated due to the complex interactions between individual particles and their interaction with the surroundings. Understanding the underlying mechanisms can be effectively achieved via particle scale research. The problem of a normal contact may be resolved in a number of ways. In spite of huge progress in experimental techniques, direct lab tests with individual particles are still rather time-consuming and expensive. The interaction of particles as solid bodies is actually a classical problem of contact mechanics. In the case of ultrafine particles, the reduction of the particle size shifts the contact zones into the nanoscale or subnanoscale. Thus, steadily increasing contribution of adhesion has to be considered in the development of the physically correct constitutive models and numerical tools. Consequently, it may... [to full text]
Ultrasmulkios dalelės yra šiuolaikinės chemijos, farmacijos, maisto ir kitų pramonės šakų produktų sudėtinė dalis. Tiriant pramoninius technologinius procesus, neišvengiamai reikalingos teorinės žinios apie ultrasmulkių dalelių elgseną. Išsamus supratimas įmanomas tik atlikus įvairius tyrimus. Pastaruoju metu milteliai, klasifikuojami kaip ultrasmulkios (0,1 < d < 10 μm) dalelės, imti plačiai naudoti pramoniniuose procesuose, todėl suprasti ultrasmulkių dalelių elgsenos fundamentalumą miltelių technologijoje yra labai svarbu. Ultrasmulki dalelė yra itin maža, todėl su ja atlikti fizinį eksperimentą, kuris reikalauja specialios įrangos bei žinių, labai sunku. Tokiu atveju dažniausiai naudojamas skaitinis eksperimentas, kurį galima atlikti virtualiai. Skaitinio eksperimento metu yra tiriamos dinaminės ultrasmulkios dalelės savybės bei sprendžiamas dinaminis uždavinys. Taikant skaitinius modelius bei dalelės judėjimą aprašančias jėgų lygtis, naudojami sąveikos modeliai, apimantys adhezinę, klampią, tamprią bei tampriai plastinę sąveikas. Mikroskopinis adhezinės sąveikos modeliavimas – aktualus mechanikos mokslo uždavinys. Taikant sąveikos modelius, svarbu pritaikyti ir diskrečiųjų elementų metodą, kadangi, norint aprašyti dalelių elgseną, visų pirma reikia su-vokti ir aprašyti dalelės modelį. Dalelės elgsenos skaitiniam modeliavimui siūlomi teoriniai modeliai leidžia tirti dalelės sąveiką su dalele ar tampria puserdve bei sąveikos dinamiką. Šie modeliai galėtų būti pritaikyti... [toliau žr. visą tekstą]

The demands for copper and rare earth elements (REEs) in the U.S. will keep rising due to their applications in green energy technologies. Meanwhile, copper production in the U.S. has been declining over the past five years due to the depletion of high-grade ore deposits. The situation for REEs is worse; there is no domestic supply chain of REEs in the U.S. since the demise of Molycorp, Inc. in 2016. Studies have shown that the rejected materials from copper and coal processing plants contain significant amounts of valuable metals. As such, this rejected material can be considered as potential secondary sources for extracting copper and REEs, which may help combat future supply risks for the supply of copper and REEs in the U.S. However, the valuable mineral particles in these resources are ultrafine in size, which poses considerable challenges to the most widely used fine particle beneficiation technique, i.e., froth flotation. A novel technology called the Hydrophobic-Hydrophilic Separation (HHS) process, developed at Virginia Tech, has been successfully applied to recover fine coal in previous research. The results of research into the HHS process showed that the process has no lower particle size limit, similar to solvent extraction. Therefore, the primary objective of this research is to explore the feasibility of using the new process to recover ultrafine particles of coal, copper minerals, and rare earth minerals (REMs) associated with coal byproducts. In the present work, a series of laboratory-scale oil agglomeration and HHS tests have been carried out on coal with the objectives of assisting the HHS tests in pilot-scale, and the scale-up of the process. The knowledge gained from this study was successfully applied to solving the problems encountered in the pilot-scale tests. Additionally, a new and more efficient equipment known as the Morganizer has been designed and constructed to break up the agglomerates in oil phase as a means to remove entrained gangue minerals and water. The effectiveness of the new Morganizers has been demonstrated in laboratory-scale HHS tests, which may potentially result in the reduction of capital costs in commercializing the HHS process. Furthermore, the prospect of using the HHS process for processing high-sulfur coals has been explored. The results of this study showed that the HHS process can be used to increase the production of cleaner coal from waste streams. Application of the HHS process was further extended to recover the micron-sized REMs from a thickener underflow sample from the LW coal preparation plant, Kentucky. The results showed that the HHS process was far superior to the forced-air flotation process. In one test conducted during the earlier stages of the present study, a concentrate assaying 17,590 ppm total REEs was obtained from a 300 ppm feed. In this test, the Morganizer was not used to upgrade the rougher concentrate due to the lack of proper understanding of the fundamental mechanisms involved in converting oil-in-water (o/w) Pickering emulsions to water-in-oil (w/o) Pickering emulsions. Many of the studies has, therefore, been focused on the studies of phase inversion mechanisms. The results showed that phase inversion requires that i) the oil contact angles (θo) of the particles be increased above 90o, ii) the phase volume of oil (ϕo) be increased, and iii) the o/w emulsion be subjected to a high-shear agitation. It has been found that the first criterion can be readily met by using a hydrophobicity-enhancing agent. These findings were applied to produce high-grade REM concentrates from an artificial mixture of micron-sized monazite and silica. Based on the improved understanding of phase inversion, a modified HHS process has been developed to recover ultrafine particles of copper minerals. After successfully demonstrating the efficacy and effectiveness of this process on a series of artificial copper ore samples, the modified HHS process was used to produce high-grade copper concentrates from a series of cleaner scavenger tails obtained from operating plants.
Doctor of Philosophy
Recovery and dewatering of ultrafine particles have been the major challenges in the minerals and coal industries. Based on the thermodynamic advantage that oil droplets form contact angles about twice as large as those obtainable with air bubbles, a novel separation technology called the hydrophobic-hydrophilic separation (HHS) process was developed at Virginia Tech to address this issues. The research into the HHS process previously was only conducted on the recovery of ultrafine coal particles; also, the fundamental aspects of the HHS process were not fully understood, particularly the mechanisms of phase inversion of oil-in-water emulsions to water-in-oil emulsions. As a follow-up to the previous studies, emulsification tests have been conducted using ultrafine silica and chalcopyrite particles as emulsifiers, and the results showed that phase inversion requires high contact angles, high phase volumes, and high-shear agitation. These findings were applied to improve the HHS process for the recovery of ultrafine particles of coal, copper minerals, and rare earth minerals (REMs). The results obtained in the present work show that the HHS process can be used to efficiently recover and dewater fine particles without no lower particle size limits.

Ultrafine particle emissions in motor-vehicle exhaust are associated with cardiopulmonary health impacts and increased mortality. The emission, evolution, and exposure-uptake of these particles, one hundred nanometers and smaller in diameter, are fundamentally quantified by the number concentration as a function of particle size. Ultrafine particle number distributions are widely varying and fast changing as they are strongly influenced by local environmental conditions and variation in vehicle operation and maintenance. Research and regulation to quantify and control such emissions rely on measurement of the number distribution of ultrafine particles in vehicle exhaust and by the roadside. Instruments to make such measurements are commercially available, but they are expensive, non-portable, and have slow response times. A new instrument, the NanoAPA, is being developed for these in-situ applications as an inexpensive, portable, and real-time instrument. The instrument is designed to perform ultrafine particle sizing and counting through electronic control of a microfabricated device that charges sampled airborne particles with a corona ionizer and then incrementally size-separates, collects, and counts the number of particles in the aerosol. The focus of this thesis was the development and characterization of the smallest device known that can perform these sizing and counting functions. The device miniaturizes a classical instrument from the aerosol field, the double-condenser of Whipple (1960) used for the sizing and counting of atmospheric ions, into a microfabricated device designed to utilize voltage-and-flowrate-variable electrophoresis to measure ultrafine particle aerosols. Performance characterization of the microfabricated device required development of an apparatus for the generation and conditioning of aerosols appropriate to this application. This Standard Aerosol apparatus was demonstrated to produce repeatable, temperature and humidity stable, charge-neutral, monodisperse exhaust-analog aerosols of particles 10 to 100 nanometer in diameter. The microfabricated device was characterized with the Standard Aerosol apparatus for the operating conditions of 0.1 to 1.5 liter per minute flow rate and 0 to 3000 volt separator voltage. Results of the characterization demonstrated effective selection and collection of solvent droplets in the diameter range 10-100nm. The selection and collection results for engine-exhaust analog particles were inconclusive, likely due to particle re-entrainment. Repeatable measurements of particle number proved elusive, likely due to electrical field interference, the limited particle concentration obtainable from the Standard Aerosol apparatus, and signal-to-noise and temporal stability issues with the electrometer electronics. Recommendations are made for approaches likely to overcome these issues.

Fine tailings exhibit extremely poor dewatering characteristics. The research presented here deals with two closely related projects. The first project concentrated on finding an efficient treatment method for already existing fine tailings. The second project was to evaluate process modifications aimed at fine tailings reduction and to develop an understanding of the effect of electrolyte in the process water of the characteristics of fine tailings. The behavior of ultrafines separated from fine tailings was further investigated. A $\sp2$H NMR technique was applied to determine the gelation rates for ultrafines at different electrolyte concentrations. The gelation concentration was determined using ultrafines suspensions diluted with salt solutions. Results indicate, that while gelation time varies from minutes to weeks, the gelation concentration is always about 3-4 wt%, even at an extremely high salt concentrations further floc densification (dewatering) is impossible. Although adequate floc densification could not be achieved using chemical treatment, dewatering was increased markedly using freeze-thaw (a physical method). To evaluate process modifications, samples of different process streams produced during comparison pilot plant runs performed at Syncrude Canada Ltd. were investigated. The aggregation state and distribution of ultrafines were determined in all stream samples. In conjunction with the characteristics of parent oil sand ores, results prove that the settling rate was different only up to the point where the gelation onset concentration of the ultrafines fraction was reached, regardless of the ionic composition of water. Modifications to the extraction process resulted only in marginal differences in the characteristics of the discharge streams. The final volume of fine tailings depends on the ultrafine content in the oil sand ore, and not on the type and concentration of the electrolyte in th process water. Although modified extraction processes resulted in faster settling, the modification produced "dirtier" (containing more clay) secondary froths, thus bringing about other process problems.

Background and Aims: Epidemiologic studies have associated adverse health outcomes with exposure to traffic-related air pollutants, principally NO₂, at levels below those showing effects in controlled exposure studies. This suggests the importance of related outdoor air contaminants, such as ultrafine particles (UFP) (<0.1µm in diameter). Presently, no UFP monitoring exists in North America and little information is available regarding UFP spatial distributions. We measured particle number concentrations (PNC) in Vancouver to develop a land use regression (LUR) model for use in epidemiologic studies and to identify important sources of UFP. Methods: During a two-week sampling period in spring 2010, PNC were measured with portable condensation particle counters (CPC) for 60-minutes at eighty locations used previously to characterize spatial variability in nitrogen oxides. Continuous PNC measuring occurred at four additional locations to assess temporal variation. LUR modeling was conducted using 135 geographic predictors, including: road length, vehicle density, intersection and bus stop density, land use type, fast food restaurant density, population density and others, following previously developed methods. A novel buffer approach incorporated meteorologic data through wedge-shaped wind roses from measurements made during PNC sampling, in addition to circular buffers. Results: The range of measured (60-minute median) PNC across locations varied 70-fold (range: 1500 – 105 000 particles/cm³, mean [SD] = 18 200 [15 900] particles/cm³). Correlations of PNC with concurrently measured two-week average NO₂, NO and NOX concentrations at the same sites were 0.64, 0.65 and 0.70. A model (R² = 0.48, leave-one-out cross validation R² = 0.32) predicting PNC included length of truck routes within 50m, density of fast food locations within 200m and ln-distance to the nearest port. LUR models created with wind rose shaped buffers had lower predictive power than models with circular buffers (R² = 0.29 – 0.34). Conclusions: Measured PNC was highly variable across the Metro Vancouver region and correlated with nitrogen oxides. Geographic predictors explained a smaller proportion of variability in PNC than found previously for nitrogen oxides, suggesting some common sources and additional unknown factors influencing PNC spatial variability. This represents the first LUR model for UFP in North America.

Dans l’industrie, les sources d’expositions aux particules ultrafines (PUF) sont nombreuses et connues depuis longtemps. Ces particules quelles soient manufacturées ou non intentionnelles (générées au cours de procédés industriels) présentent des propriétés singulières qui impliquent des effets sur la santé différents de ceux induits par des particules de plus grande taille (micrométrique). L’étude spécifique des PUF nécessite donc le développement de méthodes de prélèvement et d’analyse adaptées permettant d’obtenir des informations pertinentes complémentaires à la masse totale de poussières prélevées. Cette métrique semblerait insuffisante pour caractériser correctement les effets toxiques des PUF. La thèse a donc été menée dans l’optique de disposer de méthodes dédiées à l’analyse des nanoparticules et en particulier sur la caractérisation chimique des particules en fonction de leur taille (couplage entre dispositifs de prélèvement en fonction de la taille des particules et méthode d’analyse). Les méthodes développées ont ensuite été testées sur des échantillons provenant soit de sites et/ou procédés industriels (fonderie, projection thermique) soit d’essais en laboratoire par prélèvement sur banc de génération de PUF
Expositions to nanoparticles (NPs) are known in industrial hygiene for a long time. Either from primary or secondary sources (industrial processes), these particles have specific properties which imply different toxicities compared to larger particles (micrometric) from the same material. Therefore NPs study requires adapted sampling and analytical technique development and more specifically methods allowing to access relevant information other than total dust mass. The latter seems not be sufficient for toxic effect assessment. Thus, this work has been conducted in order to dispose of analytical methods dedicated to NPs and especially on size-dependent particle chemical analysis. Then, the developed methods have been applied on samples collected either from industrial sites and/or processes (smelter, thermal projection), either from NP generation bench

This thesis developed semi-parametric regression models for estimating the spatio-temporal distribution of outdoor airborne ultrafine particle number concentration (PNC). The models developed incorporate multivariate penalised splines and random walks and autoregressive errors in order to estimate non-linear functions of space, time and other covariates. The models were applied to data from the "Ultrafine Particles from Traffic Emissions and Child" project in Brisbane, Australia, and to longitudinal measurements of air quality in Helsinki, Finland. The spline and random walk aspects of the models reveal how the daily trend in PNC changes over the year in Helsinki and the similarities and differences in the daily and weekly trends across multiple primary schools in Brisbane. Midday peaks in PNC in Brisbane locations are attributed to new particle formation events at the Port of Brisbane and Brisbane Airport.

Les particules ultrafines (PUF) sont de nos jours susceptibles de se retrouver massivement dans l’air des lieux de travail et dans l’environnement, notamment de par leur génération non-intentionnelle par certains procédés industriels. Du fait de la toxicité de plus en plus avérée de ces particules, l’air contaminé doit être extrait des lieux de travail et filtré avant d’être rejeté dans l’atmosphère. Les filtres classiquement utilisés sont des filtres à fibres plissés présentant l’inconvénient vis-à-vis des PUF d’être rapidement et irréversiblement colmatés. Afin de trouver une alternative à ces filtres, il a été décidé d’étudier les lits granulaires. Pour ce faire, la cinétique de colmatage des lits granulaires par des PUF a dans un premier temps été étudiée à l’échelle macroscopique et microscopique par suivi des évolutions des performances ainsi qu’en procédant à des observations de structure de dépôt. Evaluer la capacité des lits granulaires à se positionner en tant qu’alternative aux médias fibreux peut nécessiter la connaissance des performances des lits granulaires dans un grand nombre de configurations. Pour s’affranchir des expériences correspondantes, un modèle théorique de prédictions des performances des lits granulaires en cours de colmatage a été développé. Ce modèle a par la suite permis par une optimisation multicritère de trouver la configuration optimale d’un lit granulaire amélioré. Enfin, des essais préliminaires très prometteurs d’une manche granulaire permettant d’augmenter la surface de filtration et l’efficacité de collecte ont posé les bases d’une potentielle utilisation des lits granulaires pour la filtration de PUF dans l’industrie
The air of workplaces and the environment can be contaminated by ultrafine particles (UFP) coming mainly from a non-intentional generation emitted by some industrial processes. The toxicity of these particles being more and more admitted nowadays, the polluted air of the workplaces has to be extracted and filtered in order to protect the workers and the public, respectively. The commonly used filters are pleated fiber filters which are rapidly and sometimes irreversibly clogged by the UFP. In order to find an alternative to these pleated filters, it was decided to study the granular beds. To do so, the clogging kinetic of granular bed by UFP was studied. This was achieved by conducting both macroscopic and microscopic studies of the granular bed clogging consisting in the monitoring of the evolution of the performances and in performing visualizations of UFP deposit structures. Evaluate the ability of granular beds to be an alternative to fiber filters can require the knowledge of the granular bed performances evolution for a large number of configurations. In order to avoid the realization of the corresponding experiments, a theoretical model was developed. Then, this model permitted by a multi-criteria optimization method to find the optimal configuration of an improved granular bed. Finally, some preliminary and very promising tests of a cylindrical granular bed filter permitting to increase the surface filtration and the collection efficiency laid the groundwork of a potential use of granular beds for the industrial UFP filtration

A separate but related investigated of a database of respiratory and cardiovascular admissions revealed a significant variation by category of road but the observed associations were not what were expected.

The drivers of human health and changing climate are important areas of environmental and atmospheric studies. Among many environmental factors present in our biosphere, small particles, also known as ultrafine particles or UFPs, have direct and indirect pathways to affect human health and climatic processes. The rapid change in their properties makes UFPs dynamic and often challenging to quantify their effect on health and radiative forcing. To reduce uncertainty in the climate effects of UFPs and to strengthen the evidence on health effects, accurate characterizations of physical and chemical properties of UFPs are needed. In this thesis, two broad aspects of UFPs were investigated: (1) the development of particle instrumentation to study particle properties; and (2) measurement of physical and chemical properties of UFPs relevant to human health and climate. These two broad aspects are divided into four specific aims in this thesis. The measurement of UFP concentration at different locations in an urban location, from roadside to various residential areas, can be improved by using a mobile particle counter. A TSI 3786 Condensation Particle Counter (CPC) was modified for mobile battery-power operation. This design provided high-frequency, one second time resolution measurements of particle number and carbon dioxide (CO2). An independent electric power system, a central controller and robust data acquisition system, and a GPS system are the major components of this mobile unit. These capabilities make the system remotely deployable, and also offer flexibility to integrate other analog and digital sensors. A Volatility Tandem Differential Mobility Analyzer (V-TDMA) system was designed and built to characterize the volatility behavior of UFPs. The physical and chemical properties of UFPs are often challenging to measure due to limited availability of instruments, detection limit in terms of particle size and concentration, and sampling frequency. Indirect methods such as V-TDMA are useful, for small mass (<1 µg/m3), and nuclei mode particles (<30nm). Another advantage of V-TDMA is its fast response in terms of sampling frequency. A secondary motivation for building a V-TDMA system was to improve instrumentation capability of our group, thus enabling study of kinetic and thermodynamic properties of novel aerosols. Chapter four describes the design detail of the built V-TDMA system, which measures the change in UFP size and concentration during heated and non-heated (or ambient) condition. The V-TDMA system has an acceptable penetration efficiency of 85% for 10 nm and maintains a uniform temperature profile in the heating system. Calibration of V-TDMA using ammonium sulfate particles indicated that the system produces comparable evaporation curves (in terms of volatilization temperature) or volatility profiles to other published V-TDMA designs. Additionally the system is fully programmable with respect to particle size, temperature and sampling frequency and can be run autonomously after initial set up. The thesis describes a part of yearlong study to provide a complete perspective on particle formation and growth in a rural and agricultural Midwestern site. Volatility characterizations of UFPs were conducted to enable inference about particle chemistry, and formation of low volatile core or evaporation resistant residue in the UFP in the Midwest. This study addresses identification of the volatility signature of particles in the UFP size range, quantification of physical differences of UFPs between NPF1 and non-NPF events and relation of evaporation resistant residue with particle size, seasonality and mixing state. K-means clustering was applied to determine three unique volatility clusters in 15, 30, 50 and 80 nm particle sizes. Based on the proposed average volatility, the identified volatility clusters were classified into high volatile, intermediate volatile and least volatile group. Although VFR alone is insufficient to establish chemical composition definitively, least volatile cluster based on average volatility may be characteristically similar to the pure ammonium sulfate. The amount of evaporation residue at 200 °C was positively correlated with particle size and showed significant correlation with ozone, sulfur dioxide and solar radiation. Residue also indicated the presence of external mixture, often during morning and night time. Air quality science and management of an accidental urban tire fire occurring in Iowa City in May and June of 2012 were investigated. Urban air quality emergencies near populated areas are difficult to evaluate without a proper air quality management and response system. To support the development of an appropriate air quality system, this thesis identified and created a rank for health-related acute and chronic compounds in the tire smoke. For health risk assessment, the study proposed an empirical equation for estimating multi-pollutant air quality index. Using mobile measurements and a dispersion model in conjunction with the proposed air quality index, smoke concentrations and likely health impact were evaluated for Iowa City and surrounding areas. It was concluded that the smoke levels reached unhealthy outdoor levels for sensitive groups out to distances of 3.1 km and 18 km at 24 h and 1h average times. Tire smoke characterization was another important aspect of this study which provided important and new information about tire smoke. Revised emission factors for coarse particle mass and aerosol-PAH and new emission factors and enhancement ratios values for a wide range of fine particulate mass, particle size (0.001-2.5 µm), and trace gas were estimated. Overall the thesis added new instrumentation in our research group to measure various physical properties such as size, concentration, and volatility UFP. The built instruments, data processing algorithm and visualization tools will be useful in estimation of accurate concentration and emission factors of UFP for health exposure studies, and generate a fast response measurement of kinetic and thermodynamics properties of ambient particles. This thesis also makes a strong case for the development of an air quality emergency system for accidental fires for urban location. It provides useful evaluation and estimation of many aspects of such system such as smoke characterization, method of air quality monitoring and impact assessment, and develops communicable method of exposure risk assessment.

L'exposition aux particules fines et ultrafines, pouvant contenir des éléments métalliques, est un sujet de préoccupation sanitaire majeure, notamment dans les zones fortement industrialisées. Cette thèse a consisté à mieux caractériser la fraction métallique des particules fines et ultrafines émises dans un contexte industrialo-urbain (Littoral dunkerquois) et à déterminer leur bioaccessibilité pulmonaire, en lien avec l'impact sanitaire. Des particules ont été collectées selon leur granulométrie dans des environnements très contrastés : (i) en milieu urbain sous l'influence du trafic automobile et d'émissions industrielles et (ii) à proximité immédiate et à la source même d'une usine de ferromanganèse (Glencore), caractéristique de l'activité industrielle du dunkerquois. La bioaccessibilité pulmonaire des éléménts métalliques a été déterminée par une extraction avec un fluide pulmonaire synthétique (solution "Gamble") et comparée avec une méthode d'extraction séquentielle. En milieu urbain, les concentrations élémentaires dans les particules ultrafines sont principalement liées aux sources locales (issues d'émissions de véhicules ou de chauffage). Les particules submicroniques (< 1µm) sont elles, principalement affectées par les sources industrielles, notamment la métallurgie, principale émettrice de métaux particulaires de la zone industrielle. Les autres sources identifiées par les traceurs métalliques sont la pétrochimie, la combustion des fiouls lourds et des charbons et les sources naturelles (terrigène et marine). Une variabilité temporelle importante des concentrations en masse des particules fines et ultrafines et de leurs teneurs en éléments métalliques a été observée, en cheminée et en champ proche de l'usine de ferromanganèse. Les fortes concentrations en particules ultrafines (PM₀,₁ : 60% de la masse des PM₂,₅), enrichies en métaux de cheminée, diminuent rapidement à proximité immédiate de l'usine, dû au changement rapide des conditions de température et d'humidité induisant des transformations précoces de la matière particulaire. Ce travail a permis par ailleurs de montrer que la bioaccessibilité des métaux associés aux particules est variable selon les propriétés physicochimiques des particules (spéciation chimique des métaux et distribution granulométrique), en lien avec leurs origines et leurs processus de formation. La bioaccessibilité des métaux peut aussi être affectée par des transformations physico-chimiques (mélange/agglomération, agrégation, oxydoréduction...) des particules fines durant leur transport atmosphérique. L'estimation in-vitro de la bioaccessibilité permet de mieux comprendre la biodosponibilité des métaux dans l'organiqme et donc de mieux appréhender l'impact sanitaire des métaux toxiques
Exposure to metals from fine and ultrafine particles is of major health concern, especially in heavily industrialized areas. This thesis aims to better characterize the metal fraction of fine and ultrafine particles emitted in an industrial-marked urban context (Dunkirk harbour) and to determine their lung bioaccessibility, in relation with their health impact. Particles were collected according to their size in specific environments : (i) in an urban area influenced by traffic and industrial emissions and (ii) at the stacks and in the vicinity of a ferromanganese plant (Glencore), characteristic of the industrial activity in Dunkirk. Pulmonary bioaccessibility of metals was determined using a synthetic lung fluid (Gamble solution), and compared to a sequential extraction method. In the urban area, the elemental concentrations in ultrafine particles are primarily related to lacal sources (traffic and housse heating), while submicronic particles (< 1µm) are mainly affected by industrial sources, especially metallurgical plants, the main source of particulate metals in the industrial area. The other sources identified are petrochemistry, coal and heavy-fuels burning and natural sources (sea salts and crustal particles). A high temporal variability of fine and ultrafine particles mass concentrations and of their metal contents was observed at the stacks and in the close environment of the ferromanganese plant. The high concentrations of ultrafine particles (PM₀,₁ : 60% of the total PM₂,₅ mass), enriched in metals, as observed in stack flues, decrease rapidly in the vicinity of the plant, due to the changes in temperatureand humidity, inducing rapid transformations. The metal bioaccessibility varies according to the particle properties (metals chemical speciation and particle size distribution), depending on their origin and formation processes. This metal bioaccessibility may also be affected by physicochemical transformations of fine particles occuring during atmospheric transport (mixing/agglomeration, aggregation, oxidation or reduction processes). The in-vitro bioaccessibility assessment is of interest to better understand the metal bioavailability and thus for a better appreciation of the health impact of toxic metals

The purpose of this study was to investigate whether or not differing base metals and filler wires used during welding processes contributed to differing amounts of ultrafine particles (UFP) and nanoparticles being emitted during the welding procedure. The study was also conducted to determine UFP and nanoparticle exposure in the breathing zones of the welders as well as the breathing zones of pipefitters and fire watchers, who commonly sit 6ft behind the welding arc. In order to determine if UFP and NP exposures differed with base metal and filler wire, all welding processes utilized the same welding machine for metal inert gas (MIG), the same wire speed, and the same voltages during each welding process. The only variation in welding procedures were cover gases used, base metals, and filler wires. Measurements gathered during welding procedures were conducted in the breathing zone of the welder and pipefitters consisted of UFP measurements taken by two different condensation particle counters (CPC), which operated in synchrony at the start and cessation of the welding process. NP measurements were taken by a NanoScan Scanning Mobility Particle Sizer (SMPS) and were also placed in the breathing zone of the welder. Lastly, particle characterization measurements for transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were gathered using a filter attached to a high flow pump, which was placed in the breathing zone of the welder. According to the results, base metal and filler wire do emit differing amounts of NP and UFP during the welding processes. Carbon steel emits the highest amount of nanoparticles, while stainless steel emits the second highest amount, and inconel emits the least. The results also concluded that welders are exposed to a greater concentration of nanoparticles and UFPs than those experienced by pipefitters who stand 6ft from the welding arc.

In recent years, the effect of ions and ultrafine particles on ambient air quality and human health has been well documented, however, knowledge about their sources, concentrations and interactions within different types of urban environments remains limited. This thesis presents the results of numerous field studies aimed at quantifying variations in ion concentration with distance from the source, as well as identifying the dynamics of the particle ionisation processes which lead to the formation of charged particles in the air. In order to select the most appropriate measurement instruments and locations for the studies, a literature review was also conducted on studies that reported ion and ultrafine particle emissions from different sources in a typical urban environment. The initial study involved laboratory experiments on the attachment of ions to aerosols, so as to gain a better understanding of the interaction between ions and particles. This study determined the efficiency of corona ions at charging and removing particles from the air, as a function of different particle number and ion concentrations. The results showed that particle number loss was directly proportional to particle charge concentration, and that higher small ion concentrations led to higher particle deposition rates in all size ranges investigated. Nanoparticles were also observed to decrease with increasing particle charge concentration, due to their higher Brownian mobility and subsequent attachment to charged particles. Given that corona discharge from high voltage powerlines is considered one of the major ion sources in urban areas, a detailed study was then conducted under three parallel overhead powerlines, with a steady wind blowing in a perpendicular direction to the lines. The results showed that large sections of the lines did not produce any corona at all, while strong positive emissions were observed from discrete components such as a particular set of spacers on one of the lines. Measurements were also conducted at eight upwind and downwind points perpendicular to the powerlines, spanning a total distance of about 160m. The maximum positive small and large ion concentrations, and DC electric field were observed at a point 20 m downwind from the lines, with median values of 4.4×103 cm-3, 1.3×103 cm-3 and 530 V m-1, respectively. It was estimated that, at this point, less than 7% of the total number of particles was charged. The electrical parameters decreased steadily with increasing downwind distance from the lines but remained significantly higher than background levels at the limit of the measurements. Moreover, vehicles are one of the most prevalent ion and particle emitting sources in urban environments, and therefore, experiments were also conducted behind a motor vehicle exhaust pipe and near busy motorways, with the aim of quantifying small ion and particle charge concentration, as well as their distribution as a function of distance from the source. The study found that approximately equal numbers of positive and negative ions were observed in the vehicle exhaust plume, as well as near motorways, of which heavy duty vehicles were believed to be the main contributor. In addition, cluster ion concentration was observed to decrease rapidly within the first 10-15 m from the road and ion-ion recombination and ion-aerosol attachment were the most likely cause of ion depletion, rather than dilution and turbulence related processes. In addition to the above-mentioned dominant ion sources, other sources also exist within urban environments where intensive human activities take place. In this part of the study, airborne concentrations of small ions, particles and net particle charge were measured at 32 different outdoor sites in and around Brisbane, Australia, which were classified into seven different groups as follows: park, woodland, city centre, residential, freeway, powerlines and power substation. Whilst the study confirmed that powerlines, power substations and freeways were the main ion sources in an urban environment, it also suggested that not all powerlines emitted ions, only those with discrete corona discharge points. In addition to the main ion sources, higher ion concentrations were also observed environments affected by vehicle traffic and human activities, such as the city centre and residential areas. A considerable number of ions were also observed in a woodland area and it is still unclear if they were emitted directly from the trees, or if they originated from some other local source. Overall, it was found that different types of environments had different types of ion sources, which could be classified as unipolar or bipolar particle sources, as well as ion sources that co-exist with particle sources. In general, fewer small ions were observed at sites with co-existing sources, however particle charge was often higher due to the effect of ion-particle attachment. In summary, this study quantified ion concentrations in typical urban environments, identified major charge sources in urban areas, and determined the spatial dispersion of ions as a function of distance from the source, as well as their controlling factors. The study also presented ion-aerosol attachment efficiencies under high ion concentration conditions, both in the laboratory and in real outdoor environments. The outcomes of these studies addressed the aims of this work and advanced understanding of the charge status of aerosols in the urban environment.

Building works include construction and demolition activities, which are common in cities across the world. Building-related activities contribute a considerable amount of the construction and demolition waste material worldwide. These activities have the potential to produce particulate matter (PM), including PM10 (≤10 μm), PM2.5 (≤2.5 μm) and PM1 (≤1 μm), and airborne ultrafine particles (≤0.1 μm). Recent studies have indicated that the rate of building works undertaken each year is growing exponentially, to meet new urban design guidelines and respond to demand from the adoption of new building technologies, which highlights the importance of measuring the amounts of particle emissions from these sources. The principles of sustainable urban development are well established, but the extent of pollution due to construction and demolition activities is still unknown. Through laboratory and field studies, this thesis aims to comprehensively investigate the release of coarse (referred to as PM2.5–10 fraction), fine (PM2.5) and ultrafine particles from various building works, assess their physicochemical properties, and estimate the associated occupational exposure risk from them to on-site workers and individuals in the close vicinity. Experiments for this thesis were carried out to measure PM and airborne ultrafine particles in the size range of (0.005–10 µm) using a fast response differential mobility spectrometer (DMS50), a tapered element oscillating micro balance (TEOM 1400), a GRIMM particle spectrometer (1.107 E) and OSIRIS (2315). Measurements were made in various locations: a controlled laboratory environment (i.e. concrete mixing, drilling, cutting), indoor field sites (i.e. building refurbishment) and at outdoor field sites (i.e. construction and demolition). Moreover, dust samples were collected simultaneously for physiochemical analyses (e.g. SEM, EDS, XPS and IBA). Several important findings were then extrapolated during the analysis. These findings indicated that ultrafine particles dominated (74-97%) the total particle number concentrations (PNCs) while the coarse particles (PM2.5-10) contributed to the majority of the total particle mass concentrations (PMCs), during the laboratory, indoor and outdoor field experiments. The highest proportion of PNCs and PMCs was found during the concrete cutting, drilling and wall chasing activities. In addition, the highest proportion of PMCs was observed in the excavator cabin during a building demolition at an outdoor field measurement site. Moreover, combining the results of SEM, EDS, XPS and IBA analysis suggested the dominance of elements such as Si, Al and S in the collected samples. The data were also used to assess the horizontal decay of the PMC through a modified box model to determine the emission factors and the occupational exposure to on-site workers and nearby individuals. The results confirmed that building-related works produce significant levels of coarse, fine and ultrafine particles, and that there is a need to limit particle emissions and reduce the occupational exposure of individuals by enforcing effective engineering controls. These findings could also be useful for the building industry to develop mitigation strategies to limit exposure to particulate matter during building works, particularly for ultrafine particles, which are currently non-existent.

Les études épidémiologiques sur les effets de la fraction ultrafine de la pollution particulaire et les études sur la toxicité in vitro et in vivo des nanoparticules manufacturées témoignent d’un danger potentiel pour l’homme en raison de nouvelles propriétés physico-chimiques de la matière à l’échelle nanométrique. L’évaluation du risque lié à des expositions professionnelles ou environnementales ou le diagnostic d’un lien causal entre ces expositions et d’éventuelles pathologies peuvent être limités par l’absence de méthode de référence pour caractériser et quantifier les particules nanométriques dans les tissus et fluides biologiques. Ce travail a permis de mettre au point une méthode remplissant ces objectifs, basée sur la préparation des échantillons par digestion alcaline et microfiltration et sur l’analyse en microscopie électronique analytique. L’application de cette méthode dans deux études a permis de confirmer qu’une translocation des particules nanométriques était possible d’une part au niveau pleural avec concentration dans les black spots et d’autre part à travers le placenta avec une possible exposition du foetus. Ce travail a également permis de caractériser des sources d’expositions professionnelles ou environnementales aux particules nanométriques. Sous réserve d’optimiser le coût et le temps nécessaire pour ce type d’analyse, cette méthode pourrait permettre de définir des valeurs de référence sur des échantillons plus larges et représentatifs de la population générale ou être utilisée dans le cadre de la surveillance de travailleurs exposés
Epidemiologic studies on the health effects of ultrafine particles from atmospheric pollution and in vitro or in vivo studies on manufactured nanoparticles toxicity suggest that potential hazards may result from new physico-chemical properties of materials at nanometric scale. To assess human health risk after occupational or environmental exposure or to demonstrate a causal relationship between such exposures and diseases may be hindered by the lack of reference method to characterize and quantify nanometric particles in biological tissues and fluids. This work allowed us to develop such a method based on samples preparation by alkaline digestion and microfiltration followed by analytical electron microscopy analysis. This method applied in two studies allowed us to confirm that pleural translocation of nanometric particles and accumulation in black spots were possible in human and that they also may pass through the placental barrier with potential fetal exposure. This work also allowed us to characterize some sources of occupational and environmental exposures. After time-cost optimization of this method, it could be used to define reference values on larger population-representative samples or used for the medical follow-up of exposed workers

Flertalet studier har påvisat ett samband mellan koncentrationen av partiklar ≤ 10µm i luftföroreningar och cardiovaskulär- och pulmonell morbiditet och mortalitet. Vid resektion, koagulering/bränning med diatermipenna under operationer alstras rök. Denna rök innehåller bland annat mutagena och carcinogena partiklar i inhalerbar storlek (partiklar ≤ 10µm).

Ett första syfte med denna studie var att kvantifiera den mängd ultra-fina partiklar (UFP) och partiklar ≤ 10µm som operationspersonal exponeras för i operationsrummet, vid användande av diatermi med mobilt rökutsug. Ett andra syfte var också att ta reda på om operations-personal exponeras olika mycket beroende på var i rummet de befinner sig, samt undersöka om partikelnivåerna skiljer sig på olika operationssalar. Partikelmätningar utfördes under 14 ortopediska operationer där diatermi med rökutsug använts.

Medelvärdena av UFP visar på relativt låga partikelkoncentrationer på höftprotes- och ryggoperationer, med mycket korta stunder av höga värden upp till ett maxvärde på 88 396pt/ml vid operationsområdet. Även partiklar i storleken 1-10µm låg inom låga nivåer och under gränsvärdena vid jämförelse med organisk damm. Resultaten i studien indikerar att personal som står vid operationssåret exponeras av högre partikelkoncentrationer av ultra-fina partiklar och partiklar 1-10µm än övrig personal, även vid användande av mobilt rökutsug. Vid jämförelse av partikelnivåer av ultra-fina partiklar på två olika operationssalar framkom det att på den sal med lägst antal luftväxlingar i operationsrummet, var partikelkoncentrationen signifikant högre.

La pollution de l’air cause de près de 7 millions de décès annuels dans le monde. L’exposition aux Particules Ultrafines (PUF), polluants parmi les plus néfastes pour la santé, atteint ses niveaux les plus importants en milieu urbain, principalement dus au transport routier. Dans cette thèse, nous examinons les liens entre les champs de concentration en nombre des PUF émises à l'échappement dans le sillage de modèles simplifiés d'automobiles (corps d’Ahmed) et les propriétés de ces écoulements. Ces travaux permettent de mieux comprendre les niveaux d'exposition aux PUF auxquels sont soumis tous les usagers de la route à l’échelle du sillage du véhicule. Trois modèles simplifiés de véhicules ont été utilisés. Ils sont caractérisés par leur angle de lunette arrière permettant de reproduire en soufflerie les structures principales des écoulements de sillage automobile. A l’aide d’une méthode innovante de traitement des données, des mesures de vitesses acquises grâce à des techniques différentes (LDV/PIV) ont été analysées. Elles ont révélé que l’angle d’inclinaison de la lunette a un rôle déterminant sur la structure des écoulements de sillage. Par ailleurs, la comparaison avec les mesures des concentrations en nombre de PUF a permis de montrer que le volume de la structure torique de recirculation en proche culot, dépendant de la géométrie, a un impact majeur sur la dispersion des particules dans la direction verticale. Enfin, il est mis en évidence que les structures tourbillonnaires longitudinales existantes pour une inclinaison intermédiaire de la lunette ont un impact prépondérant sur la dispersion transversale ainsi que sur la symétrie des champs de concentration
Around 7 million worldwide annual death sare due to air pollution. Among all pollutants, UltrafineParticles (UFP) cause strong adverse effects. Due to road transport, UFP exposure reaches its most significant levels in urban areas. In this thesis, the aim is to assess the links between the wake flow properties of simplified car models(Ahmed bodies) and UFP number concentration fields due to exhaust emission. This study enables the knowledge about UFP exposure levels of all road users at vehicle wake scale to be better understood. Three simplified car models with three corresponding rear slant angles have been used in order to reproduce the principal wake structures of road vehicles in a wind tunnel. Thanks to an innovative data processing method, velocity measurements with two techniques(LDV/PIV) point out the major role of the rear slantangle on the model wake structures. Moreover, comparisons have been made with particle number concentration measurements of UFP in the wake of the same models. We highlighted the link between the volume of the toric recirculation region close to the rear and the vertical dispersion of UFP. Furthermore, longitudinal vortices that exist with the intermediate rear slant angle geometry play an important role on the transversal dispersion as well as on the concentration field symetry

Thesis (Ph. D.)--Ohio State University, 2003.
Title from first page of PDF file. Document formatted into pages; contains xix, 172 p.; also includes graphics. Includes bibliographical references (p. 168-172).

This research measured particle and gaseous emissions from ships and trains operating within the Port of Brisbane, and explored their influence on ambient air composition at a downwind suburban measurement site. The ship and train emission factor investigations resulted in the development of novel measurement techniques which permit the quantification of particle and gaseous emission factors using samples collected from post-emission exhaust plumes. The urban influence investigation phase of the project produced a new approach to identifying influences from ship emissions.

Airborne particulate matter is today recognized as an important category of air pollutants. Current air quality standards, and hence most particle instruments, are based on particle mass concentration-the European standard, for example, on the PM10 fraction. For other metrics, such as number concentration, there is currently a lack of suitable instrumentation for monitoring purposes. A novel realtime particle-counting instrument has been developed in an attempt to fill this gap. The new instrument is capable of detecting and counting particles from about 10 nm to 10 pm particle diameter. This instrument, aimed at monitoring ambient air quality, uses a parallel combination of optical particle counting for larger particles plus condensation particle counting for the smallest particles. The particles are classified into several size fractions, which allows discrimination between ultrafine, fine, and coarse particles. The instrument also enables gravimetric measurement of PM10 or PM2.5 providing the possibility of comparing the measured number concentrations with the mass concentration standards. Furthermore, a conversion of the number concentration data into PMIO.P. M2.5,a nd also PMl mass concentration is possible. The new instrument is unique in offering number and mass information over the complete size range of interest in urban air quality monitoring. The design of the instrument and the development and construction of first prototypes are described as well as calibration and performance results. The performance tests included side-by-side comparisons of two identical prototypes and comparison studies with traditional instrumentation in an urban field environment at a monitoring station in Birmingham (UK). Here, very good correlation was observed between the ultrafine particle concentration indicated by the new instrument and the total number concentration measured by a CPC (TSI model 3022A). Number-to-mass conversion results correlated well with mass concentration measured by TEOM. Possibilities for a further size fractionation in the ultrafine particle size range were investigated and selected techniques tested. Size separation using diffusion devices was identified as a suitable technique to be implemented in the new instrument for ultrafine fractionation. Other future possibilities for further developments are also discussed.

Ultrafine particles (UFPs) are released in ambient air from natural and anthropogenic sources but also certain workplace conditions are responsible for the unintentional emission of this kind of particles. The small size and corresponding large specific surface area of UFPs and nanoparticles (NPs) are responsible for the great biological activity per given mass. Other specific characteristics of UFPs such as number concentration, shape, agglomeration state and chemical composition play an important role in determining toxicity and reactivity. Even though UFPs represent a major concern in terms of human exposure, excluding some guidelines for workplace air currently there is no legal threshold for controlling them in ambient air. The aim of this thesis is to measure and characterize UFPs that can be found in working environments and ambient air and, afterwards, explore possible exposure routes. UFPs emission from three kinds of industrial processes were investigated in real working conditions by means of real-time measurements of number concentration and size, morpho-chemical characterization and quantitative analysis of metals in airborne and deposited particles. We demonstrated that iron/manganese oxide nanoparticles are the most representative particles released during automatic gas tungsten arc welding (GTAW) of steel. Moreover, despite the respect of the American Conference of Governmental Industrial Hygienists (ACGIH) limits for respirable aluminium, we found that oxy-fuel welding and the die casting production cycle of aluminium-based products involve the release of UFPs with a chemical composition consistent with the raw materials. From our findings, surface and skin contamination seems to be a secondary source of exposure to UFPs, suggesting a possible increased risk in workers mainly for inhalation exposure. Regarding the evaluation of the presence of UFPs in ambient air, a study was performed in proximity of an industrial “hot spot” in Servola district in Trieste where an integral cycle steel plant is located. Particle number concentration (PNC) in the range 10-300 nm in “Servola” site was about two times higher than “background” values. Moreover, an increase of PNC corresponding to a decrease of the particle size and vice versa was observed. In the particulate matter, agglomerates of nanoparticles containing Fe, Zn and Mn were observed by means of a transmission electron microscope coupled with an energy-dispersive X-ray analytical system (TEM-EDS). The contribution of Fe concentration in the PM1 and, in particular, in the particle fraction below 250 nm seems to be not negligible. This result is highly significant from a toxicological point of view. Servola district is densely inhabited and people live very close to the integrated steel plant that is a relevant emission source. Afterwards, nanoparticles compatible with those found in the aforementioned studies were tested in vitro using the method of static Franz diffusion cells in order to explore possible exposure routes. In particular, dermal and meningeal absorption of Al2O3NPs and MnFe2O4NPs respectively were investigated leaning, in both cases, towards a reassuring absorption profile in physiological conditions.

Atmospheric ultrafine particles play an important role in affecting human health, altering climate and degrading visibility. Numerous studies have been conducted to better understand the formation process of these particles, including field measurements, laboratory chamber studies and mathematical modeling approaches. Field studies on new particle formation found that formation processes were significantly affected by atmospheric conditions, such as the availability of particle precursors and meteorological conditions. However, those studies were mainly carried out in rural areas of the northern hemisphere and information on new particle formation in urban areas, especially those in subtropical regions, is limited. In general, subtropical regions display a higher level of solar radiation, along with stronger photochemical reactivity, than those regions investigated in previous studies. However, based on the results of these studies, the mechanisms involved in the new particle formation process remain unclear, particularly in the Southern Hemisphere. Therefore, in order to fill this gap in knowledge, a new particle formation study was conducted in a subtropical urban area in the Southern Hemisphere during 2009, which measured particle size distribution in different locations in Brisbane, Australia. Characterisation of nucleation events was conducted at the campus building of the Queensland University of Technology (QUT), located in an urban area of Brisbane. Overall, the annual average number concentrations of ultrafine, Aitken and nucleation mode particles were found to be 9.3 x 103, 3.7 x 103 and 5.6 x 103 cm-3, respectively. This was comparable to levels measured in urban areas of northern Europe, but lower than those from polluted urban areas such as the Yangtze River Delta, China and Huelva and Santa Cruz de Tenerife, Spain. Average particle number concentration (PNC) in the Brisbane region did not show significant seasonal variation, however a relatively large variation was observed during the warmer season. Diurnal variation of Aitken and nucleation mode particles displayed different patterns, which suggested that direct vehicle exhaust emissions were a major contributor of Aitken mode particles, while nucleation mode particles originated from vehicle exhaust emissions in the morning and photochemical production at around noon. A total of 65 nucleation events were observed during 2009, in which 40 events were classified as nucleation growth events and the remainder were nucleation burst events. An interesting observation in this study was that all nucleation growth events were associated with vehicle exhaust emission plumes, while the nucleation burst events were associated with industrial emission plumes from an industrial area. The average particle growth rate for nucleation events was found to be 4.6 nm hr-1 (ranging from 1.79-7.78 nm hr-1), which is comparable to other urban studies conducted in the United States, while monthly particle growth rates were found to be positively related to monthly solar radiation (r = 0.76, p <0.05). The particle growth rate values reported in this work are the first of their kind to be reported for the subtropical urban area of Australia. Furthermore, the influence of nucleation events on PNC within the urban airshed was also investigated. PNC was simultaneously measured at urban (QUT), roadside (Woolloongabba) and semi-urban (Rocklea) sites in Brisbane during 2009. Total PNC at these sites was found to be significantly affected by regional nucleation events. The relative fractions of PNC to total daily PNC observed at QUT, Woolloongabba and Rocklea were found to be 12%, 9% and 14%, respectively, during regional nucleation events. These values were higher than those observed as a result of vehicle exhaust emissions during weekday mornings, which ranged from 5.1-5.5% at QUT and Woolloongabba. In addition, PNC in the semi-urban area of Rocklea increased by a factor of 15.4 when it was upwind from urban pollution sources under the influence of nucleation burst events. Finally, we investigated the influence of sulfuric acid on new particle formation in the study region. A H2SO4 proxy was calculated by using [SO2], solar radiation and particle condensation sink data to represent the new particle production strength for the urban, roadside and semi-urban areas of Brisbane during the period June-July of 2009. The temporal variations of the H2SO4 proxies and the nucleation mode particle concentration were found to be in phase during nucleation events in the urban and roadside areas. In contrast, the peak of proxy concentration occurred 1-2 hr prior to the observed peak in nucleation mode particle concentration at the downwind semi-urban area of Brisbane. A moderate to strong linear relationship was found between the proxy and the freshly formed particles, with r2 values of 0.26-0.77 during the nucleation events. In addition, the log[H2SO4 proxy] required to produce new particles was found to be ~1.0 ppb Wm-2 s and below 0.5 ppb Wm-2 s for the urban and semi-urban areas, respectively. The particle growth rates were similar during nucleation events at the three study locations, with an average value of 2.7 ± 0.5 nm hr-1. This result suggested that a similar nucleation mechanism dominated in the study region, which was strongly related to sulphuric acid concentration, however the relationship between the proxy and PNC was poor in the semi-urban area of Rocklea. This can be explained by the fact that the nucleation process was initiated upwind of the site and the resultant particles were transported via the wind to Rocklea. This explanation is also supported by the higher geometric mean diameter value observed for particles during the nucleation event and the time lag relationship between the H2SO4 proxy and PNC observed at Rocklea. In summary, particle size distribution was continuously measured in a subtropical urban area of southern hemisphere during 2009, the findings from which formed the first particle size distribution dataset in the study region. The characteristics of nucleation events in the Brisbane region were quantified and the properties of the nucleation growth and burst events are discussed in detail using a case studies approach. To further investigate the influence of nucleation events on PNC in the study region, PNC was simultaneously measured at three locations to examine the spatial variation of PNC during the regional nucleation events. In addition, the impact of upwind urban pollution on the downwind semi-urban area was quantified during these nucleation events. Sulphuric acid was found to be an important factor influencing new particle formation in the urban and roadside areas of the study region, however, a direct relationship with nucleation events at the semi-urban site was not observed. This study provided an overview of new particle formation in the Brisbane region, and its influence on PNC in the surrounding area. The findings of this work are the first of their kind for an urban area in the southern hemisphere.

Air pollution is a major environmental and public health concern, especially in urban areas where both emission sources and population are concentrated. The pollution sources and the evolution of aerosols and gaseous pollutants once emitted into the atmosphere depend on geographical, climatological and meteorological conditions of the study area. In the Western Mediterranean Basin, the coastal city of Barcelona (Spain) is characterized by a warm dry climate, scarce precipitation and high urban density, as well as being geographically constrained by the coastal range thus hindering the dispersion of pollutants. Within this context, the intensive SAPUSS (Solving Aerosol Problems by Using Synergistic Strategies) campaign developed in October 2010 in Barcelona consisted on concurrent aerosol measurements at different sites in the city region, with the aim of studying the aerosol temporal variability and spatial distribution, progressively moving away from urban aerosol sources. Several sites were selected: Road Site (RS) and Urban Background (UB) were located on ground levels, whereas Torre Mapfre (TM) and Torre Collserola (TC), representative of the urban/suburban environment were located at certain height (150 m a.s.l. and 415 m a.s.I., respectively). Finally, the Regional Background site (RB) located 50 km from the city allowed for the study of the transport of urban emissions outside the city. Results from simultaneous measurements of aerosol size distributions at the RS, UB, TC and RB with a Scanning Mobility Particle Sizer (SMPS) were studied after performing a k-means cluster analysis on the combined data sets. This allowed the classification of all size distributions in 9 clusters: three clusters account for traffic conditions (30% of the time), three account for background pollution (54%) and three described specific special cases (16%). Traffic emissions heavily impact the closest sites, and some of these particles evaporate when the air mass move away from the traffic hot spots. The analysis of long term SMPS data sets in the high insolation urban environments of Barcelona, Madrid, Brisbane, Rome and Los Angeles also by k-means clustering analysis revealed traffic and nucleation events as the two most relevant sources of ultrafine particles (44-63% and 14-19% of the time, respectively). Moreover, nucleation particles accounted for 21% of total N, evidencing the importance of nucleation processes to ultrafine particles concentrations in high insolation urban areas. The urban nucleation events consist on particles bursts starting around midday and lasting 3-4 hours while growing to 20-40 nm, opposite to regional nucleation “banana shape” events which usually grow to larger sizes. Regarding the composition of the PM1 fraction (PM mass levels below 1 μm) at the RS and UB during SAPUSS, a source apportionment PMF analysis was carried out. The resulting 9 factors could be broadly grouped in the following categories: road traffic (23-36% of PM1 mass), industrial and shipping emissions (42%), secondary aerosols (29%) and biomass burning (1%). The joint analysis of organic and inorganic species was able to identify a high number of sources resulting in in a more complete and realistic study of the aerosol sources in Barcelona. The study of the PM10 fraction (PM mass levels below 10 μm) at the RS, UB, TM and TC during SAPUSS by means of a PMF source apportionment study enabled the assessment of the spatial variability in vertical and horizontal levels. The 8 resulting factors accounted for primary traffic emissions (Exhaust and wear and Road dust, 19- 38% of PM10 mass), primary inorganic aerosols (Mineral dust and Aged marine, 28- 39%), industry (Heavy oil and Industrial, 5-7%) and secondary aerosols (Sulphate and Nitrate,28-36%). The main factors influencing the different sources concentration at each site were: proximity to the emission source, air mass origin and meteorological parameters. The complete study of aerosol fractions affecting the urban area of Barcelona and similar urban environments (Madrid, Brisbane, Roma and Los Angeles), from ultrafine to coarse particles, enables the identification of the main sources affecting each size fraction in particular and aerosols in general. Owing to the results obtained and the different techniques applied, recommendations regarding air pollution studies and air quality measures have been proposed.
La contaminació atmosfèrica en ambients urbans és motiu de preocupació pel seu impacte en el medi ambient i en la salut de la població. Les fonts d'emissió d'aerosols atmosfèrics i la seva evolució a l'atmosfera depenen de factors geogràfics així com de les condicions climàtiques i meteorològiques de l'àrea d'estudi. A la conca Mediterrània Occidental, i a la ciutat de Barcelona en particular, el clima càlid, l'escassa precipitació, l'alta densitat de població i determinats factors geogràfics que poden dificultar la dispersió dels contaminants i influenciar molt marcadament els nivells i composició dels aerosols. En aquest context es va desenvolupar la campanya intensiva SAPUSS (Solving Aerosol Problems by Using Synergistic Strategies) a Barcelona a l'octubre de 2010, que consistia en mesures simultànies d'aerosols a diversos llocs de la ciutat, amb l'objectiu d'estudiar la variabilitat espacial i temporal dels aerosols. L'estudi dels nivells d'aerosols en funció de la mida de les partícules a 4 ciutats més amb un clima d'alta insolació similar al de Barcelona (Madrid, Brisbane, Roma i Los Angeles) ha permès avaluar les fonts que afecten a la variabilitat de partícules ultrafines en aquests ambients urbans. En particular s'han estudiat les característiques dels episodis de nucleació urbans (formació de noves partícules), així com la seva freqüència. També s'han caracteritzat les principals fonts d'aerosols de diàmetre inferior a 1µm i 10 iim (PM1 i PM10, respectivament) en diverses ambients urbans de Barcelona durant SAPUSS. Això ha permès estudiar la variabilitat a nivells horitzontal i vertical dins l'atmosfera urbana. L'estudi de les fonts que afecten els aerosols de l' àrea urbana de Barcelona i ambients similars en funció de la seua mida (des de les ultrafines fins a les grolleres) ha permès identificar les principals fonts que afecten a cada fracció en particular i als aerosols en general i per tant proposar mesures aplicables per a l'avaluació i millora de la qualitat de l'aire.

Various epidemiological studies have linked exposure to Ultrafine Particles (UFP; diameter< 100 nm) to adverse health impacts. Roadway traffic is one of the major sources of UFPs and heavily influences UFP concentrations in the nearby vicinity of major roadways. Modeling efforts to predict UFPs have been limited due to the scarcity of reliable information on emissions, lack of monitoring data and limited understanding of complex processes affecting UFP concentrations near sources. In this study continuous measurement of ultrafine particle number concentrations (PNC) and mass concentrations of nitric oxide (NO), nitrogen dioxide (NO2) and PM2.5 was conducted near an arterial road and freeway at different seasons and meteorological conditions and integrated with traffic count data. PNC showed high correlation with NO (r=0.64 for arterial; 0.61 for freeway), NO2 (r=0.57 for arterial; 0.53 for freeway) and NOx (NOx=NO+NO2; r=0.63 for arterial; 0.59 for freeway) and moderate to low correlation with traffic volume (r=0.33 for arterial; 0.32 for freeway) and PM2.5 (r=0.28 for arterial; 0.23 for freeway); respectively; for both sites at 15 minute averages. The PNC-NOx relationship prevailed on a shorter term (15 min), hourly, and throughout the day basis. Both PNC and NOx showed comparatively higher correlation with traffic during the morning period but became lower during evening which can be attributed to the higher boundary layer and wind speeds. The variable meteorology in the evening affects both PNC and NOx concentrations in the same way and the correlation between NOx and PNC is maintained high both during morning (r=0.74 for arterial; 0.69 for freeway), and evening (r=0.62 for arterial; 0.59 for freeway) periods. Thus nitrogen oxides can be used as a proxy for traffic-related UFP number concentration reflecting the effect of both traffic intensity and meteorological dilution. The PNC-NOx relation was explored for various meteorological parameters i.e. wind speed and temperature. It is found that NOx emission is temperature independent and can be used to reflect the effect of traffic intensity and meteorological dilution. Once the effect of traffic intensity and dilution is removed, the effect of temperature on PNC-NOx ratio becomes important which can be attributed to the variation in PNC emission factors with temperature. The high morning PNC-NOx ratio found at the arterial road is a result of new particle formation due to lower temperature and low concentration of exhaust gases in the morning air favoring nucleation over condensation. This finding has important implication when calculating emission factors for UFP number concentrations. Thus it can be concluded that roadside concentration of ultrafine particles not only depends on traffic intensity but also on meteorological parameters affecting dilution or new particle formation. High concentrations of ultrafine particle number concentration close to a roadway is expected due to higher traffic intensity , as well as during low wind speed causing low dilution and low temperature conditions favoring new particle formation. Finally a simplified approach of calculating particle number emission factor was developed using existing and easily available emission inventory for traffic related tracer gases. Using NOx emission factors from MOVES emission model, the emission ratio of PNC to NOx was converted to develop particle number emission factors. NOx was selected as the traffic related tracer gas since the number concentration of particles is closely correlated to NOx, NOx and particles are diluted in the same way and NOx emission factors are available for a variety of traffic situations. To ensure contribution of fresh traffic exhaust, the average of the difference of pollutant concentrations at high traffic condition and background condition was used to calculate PNC-NOX ratio. Using nitrogen oxides to define background and high-traffic conditions and MOVES emission factor for NOX to convert corresponding PNC-NOX ratio, an average emission factor of (1.82 ± 0.17) E+ 14 particle/ vehicle-km was obtained, suitable for summertime. When compared to existing particle number emission factors derived from dynamometer tests, it was found that there exits reasonable agreement between the calculated real world particle number emission factors and emission factors from dynamometer tests. The calculated emission factor and R-Line dispersion model was tested in predicting near-road particle number concentrations. Although only 23% of the variability in PNC was explained by the dispersion model, 84.33% of the measurements fell within the factor of two envelope. This suggests that there is potential to effectively use these models and thus warrants more in-depth analysis. Finally, a simple map of PNC gradients from major roads of Portland was developed. The results of this study helped identify proxy-indicators to provide reference values for estimating UFP concentrations and emissions that can be used for simple evaluation of particle concentration near major roadways for environmental and urban planning purposes and to assess expected impact of UFP pollution on population living near roadways exposed to elevated concentrations.

This thesis is a quantitative analysis of the spatial and temporal variability as well as trends of the particulate matter concentrations in the ambient urban air. The outcome provided a clear understanding on how the different metrics (particle number, particle mass and oxidative potential) were affected by mitigation measures and other important drivers such as emission sources and meteorological factors.