Die vorliegende Doktorarbeit beschäftigt sich mit der numerischen Ausbreitungssimulation von Luftschadstoffen im urbanen Raum. Als Strömungshindernisse prägen Gebäude maßgeblich das kleinskalige Windfeld und damit den horizontalen Transport und die Verteilung von urbanen Luftschadstoffen. Die häufig im Rahmen von Großwirbelsimulationen (engl.: Large Eddy Simulation, LES) zur expliziten Darstellung von Gebäuden verwendeten hohen räumlichen Auflösungen in Bereich von wenigen Metern erforden einen hohen Rechenaufwand und beschränken daher die Anwendung meist auf wenige Gebäudeblöcke. Mittels eines neuen Diskretisierungsansatzes können Gebäude auch bei deutlich geringeren Auflösungen in Bereich der sogenannten urbanen Grauzone (horizontale Gitterweite > 10m) mittels diffuser Gebäudekanten explizit dargestellt werden. Im Rahmen dieser Arbeit wurde das urbane Dispersionsmodells CAIRDIO (v1.0) mit diesem neuen Diskretisierungsansatz entwickelt. Das Modell wurde zunächst mit einem Windkanalexperiment, welches die turbulente Ausbreitung eines Test-Tracers in einer Modellstadt beinhaltet, validiert. Dabei konnte bis zu einer horizontalen Auflösung von 40m noch eine hinreichend gute Übereinstimmung des Modells mit Konzentrationsmessungen erzielt werden, es wurde jedoch nur ein Bruchteil der Rechenzeit einer Referenzsimulation mit 5m Gitterweite benötigt. Der Ansatz mit diffusen Gebäuden erlaubt daher den Anwendungsbereich mikroskaliger Simulationen im Vergleich zu klassischen LES Simulationen erheblich zu erweitern, z.B. auf die Simulation ganzer Städte. In einer ersten realistischen Fallstudie wurde das Modell CAIRDIO auf die Stadt Leipzig in Mitteldeutschland angewandt. Dabei wurde die Ausbreitung von realistischen Feinstaub und Ruß-Emissionen bei einer horizontalen Auflösung von 40m für das gesamte Stadtgebiet über einen Zeitraum von 2 Tagen (Anfang März 2020) berechnet und mit Messungen validiert. Es konnten die Auswirkungen der variablen Grenzschichtdynamik auf den urbanen Luftschadstofftransport mit dem Modell qualitativ korrekt wiedergegeben werden. Nur für verkehrsnahe Standorte führte eine höhere räumliche Auflösung von bis zu 5m noch zu einer besseren Übereinstimmung mit den Messungen. Insgesamt stellten jedoch bereits bei 40m Auflösung die Unsicherheiten in den Emissionen und den Randbedingungen den größten Anteil am Modellfehler dar. In einer zweiten Fallstudie wurde eine weiter entwickelte Version des Modells CAIRDIO auf die Stadt Dresden im Elbtal angewandt. Der Fokus dieser Studie lag diesmal auf der den urbanen Raum umgebenden Orographie, welche erhebliche Auswirkungen auf die lokale Luftqualität bei Inversionswetterlagen haben kann. Dazu wurde das Dresdner Becken mittels geländefolgender Koordinaten zusammen mit den nach wie vor diffus repräsentierten Stadtgebäuden auf der Skala der urbanen Grauzone im Modell dargestellt. Neben der Dispersion von Ruß-Emissionen wurde auch die Ruß-Alterskonzentration, welche sich besonders gut zur Identifikation von orographisch bedingten Akkumulation von Luftschadstoffen eignet, über einen Zeitraum von insgesamt 24 Tagen modelliert. Die räumliche Verteilung der Alterskonzentrations-Hotspots wurde bei stabilen Wetterlagen neben den Gebäudeeffekten maßgeblich durch die Orographie beeinflusst, während bei neutraler Schichtung orographische Effekte nur gering ausgeprägt waren.

No / Ambient air pollution has been associated with restricted fetal growth, which is linked with adverse respiratory health in childhood. We assessed the effect of maternal exposure to low concentrations of ambient air pollution on birthweight. We pooled data from 14 population-based mother-child cohort studies in 12 European countries. Overall, the study population included 74-178 women who had singleton deliveries between Feb 11, 1994, and June 2, 2011, and for whom information about infant birthweight, gestational age, and sex was available. The primary outcome of interest was low birthweight at term (weight <2500 g at birth after 37 weeks of gestation). Mean concentrations of particulate matter with an aerodynamic diameter of less than 2·5 μm (PM2·5), less than 10 μm (PM10), and between 2·5 μm and 10 μm during pregnancy were estimated at maternal home addresses with temporally adjusted land-use regression models, as was PM2·5 absorbance and concentrations of nitrogen dioxide (NO2) and nitrogen oxides. We also investigated traffic density on the nearest road and total traffic load. We calculated pooled effect estimates with random-effects models. A 5 μg/m3 increase in concentration of PM2·5 during pregnancy was associated with an increased risk of low birthweight at term (adjusted odds ratio [OR] 1·18, 95% CI 1·06-1·33). An increased risk was also recorded for pregnancy concentrations lower than the present European Union annual PM2·5 limit of 25 μg/m3 (OR for 5 μg/m3 increase in participants exposed to concentrations of less than 20 μg/m3 1·41, 95% CI 1·20-1·65). PM10 (OR for 10 μg/m3 increase 1·16, 95% CI 1·00-1·35), NO2 (OR for 10 μg/m3 increase 1·09, 1·00-1·19), and traffic density on nearest street (OR for increase of 5000 vehicles per day 1·06, 1·01-1·11) were also associated with increased risk of low birthweight at term. The population attributable risk estimated for a reduction in PM2·5 concentration to 10 μg/m3 during pregnancy corresponded to a decrease of 22% (95% CI 8-33%) in cases of low birthweight at term. Exposure to ambient air pollutants and traffic during pregnancy is associated with restricted fetal growth. A substantial proportion of cases of low birthweight at term could be prevented in Europe if urban air pollution was reduced. / The European Union

Nitrogen oxides, sulfur dioxide, ozone, light scattering and relative humidity were measured in the sphere of influence of the Radford Army Ammunition Plant using an airborne platform. Data were obtained on twelve days between May and July 1980 and were used to map the upwind-downwind pollutant concentrations around the arsenal. Results of this investigation indicate that an airborne platform can be used successfully in characterizing pollutant parameters in the sphere of influence of an area source. Results also indicate the complexity of NO-NO₂-O₃ cycle when hydrocarbons and sulfur dioxide are present. Benefits of this type of study may prove useful for the technical and administrative decision making processes of regulatory agencies and munitions manufacturing personnel. / M. S.

Titre de l'écran-titre (visionné le 11 janvier 2024) / Les accidents vasculaires cérébraux (AVC) constituent une cause majeure de décès et d'handicap des adultes au Canada. Les AVC ischémiques sont causés par l'interruption du débit sanguin cérébral par une thrombose ou embolie, et représentent 87 % des AVC. Les études épidémiologiques récentes ont souligné un rôle important, mais sous-estimé, des facteurs de risque environnemental dans les AVC ischémiques, notamment la pollution de l'air. L'exposition aux polluants atmosphériques, et en particulier aux particules fines (particulate matter; PM), corrèle avec une incidence élevée des AVC. Les données actuelles suggèrent que les PM induisent un stress oxydatif et conduisent au dysfonctionnement du système vasculaire et subséquemment à la progression des dommages cérébraux. Cependant, les mécanismes associés aux effets des PM sur la pathobiologie des AVC, restent peu étudiés. Après AVC ischémique, les fonctions de l'unité neurovasculaire qui intègre les interactions entre les cellules neuronales, gliales et vasculaires pour maintenir l'homéostasie cérébrale, sont dérégulées. Les études récentes suggèrent que les PM sont capables de traverser la barrière hémato-encéphalique (BHE) pour s'accumuler dans l'espace périvasculaire. Les péricytes sont des cellules périvasculaires multifonctionnelles qui jouent un rôle central dans la régulation des fonctions neurovasculaires. L'AVC induit le dysfonctionnement des péricytes, contribuant à la dérégulation de l'unité neurovasculaire. Les péricytes sont localisés dans l'espace périvasculaire ce qui les rend particulièrement exposés aux PM. Malgré cela, l'impact des PM sur les péricytes reste méconnu. Dans ce projet, nous avons étudié l'impact de l'exposition des péricytes aux PM in vitro, et avons évalué la réponse inflammatoire, la viabilité, le stress oxydatif et la mobilité des cellules. Nos résultats ont révélé que les PM activent la voie de signalisation stress-activated protein kinase (SAPK), impliquée dans la réponse des cellules exposées au stress. Nous avons démontré également que la viabilité des péricytes était fortement atténuée par les PM, surtout en conditions ischémiques. Ensuite, nous avons observé une altération de la voie endocytaire-lysosomale dans les péricytes exposés aux PM, ainsi qu'une dérégulation de leur capacité migratoire. Ces observations ont été associées à l'internalisation des PM par les péricytes. Nous avons établi que les cellules endothéliales cérébrales sont plus résistantes comparativement aux péricytes suite à l'exposition aux PM, et donc, l'impact des PM sur les fonctions vasculaires est médié essentiellement par le dysfonctionnement des péricytes. L'ensemble de nos résultats suggère que les PM induisent le dysfonctionnement des péricytes, entraînant ainsi la dérégulation des fonctions neurovasculaires et potentiellement la progression des dommages après AVC ischémique. / Stroke constitutes a major cause of death and handicap in adults in Canada. Ischemic stroke is caused by the interruption of the cerebral blood flow (CBF) by a thrombus or embolus, and represents 87% of all stroke cases. Epidemiological studies have highlighted an important, yet underestimated, role of environmental risk factors in ischemic stroke, notably air pollution. The exposure to atmospheric pollutants, and more particularly to particulate matter (PM), correlates with a high incidence of stroke. Recent findings suggest that PM induces oxidative stress and leads to the dysfunction of the vascular system, and subsequently to the progression of cerebral damage. However, the mechanisms associated with the effects of PM on the pathobiology of stroke, remain not fully studied. Following ischemic stroke, the functions of the neurovascular unit (NVU), which integrates the interactions among neuronal, glial, and vascular cells to maintain brain's homeostasis, are deregulated. Recent studies suggest that PM can cross the blood-brain barrier (BBB) to accumulate within the perivascular space. Pericytes are multifunctional perivascular cells that play an essential role in regulating neurovascular functions. Stroke induces the dysfunction of pericytes, leading to the deregulation of the NVU. Pericytes are localised in the perivascular space, which makes them particularly exposed to PM. Nevertheless, the impact of PM on pericytes remains elusive. In this project, we have studied the impact of the exposure of pericytes to PM in vitro, and have evaluated the inflammatory response, the viability, oxidative stress, and the mobility of cells. Our results have revealed that PM activates the stressactivated protein kinase (SAPK) signaling pathway, which is implicated in the responses of cells tostress stimuli. We have also demonstrated that the viability of pericytes was severely attenuated by PM, mainly under ischemic conditions. Next, we have observed alterations of the endocytic-lysosomal pathway in pericytes exposed to PM, as well as a deregulation of their migratory capacity. These observations were associated with the internalisation of PM in pericytes. We have as well established that brain endothelial cells are more resistant to PM exposure compared to pericytes, hence, the impact of PM on the vascular functions is mainly mediated by the dysfunction of pericytes. Our overall results suggest that PM induces the dysfunction of pericytes, leading to the deregulation of neurovascular functions, and potentially to the progression of damage following ischemic stroke.

Dans cette étude, différentes configurations d'un poêle à bois sont comparées afin de caractériser les principaux facteurs influençant la formation de particules et leur rejet. Ainsi, les paramètres de conception d'un poêle à bois seront étudiés expérimentalement et à l'aide de la dynamique des fluides numérique pour découvrir les lignes directrices en ce qui concerne la réduction de l'émission de particules. La méthode expérimentale utilisée est une adaptation de celle utilisée par l'industrie pour la certification de poêle à bois développée par EPA/CSA. Afin de mieux décrire le comportement d'un concept de poêle à bois donné, à un taux de combustion donné, l'étude abordera également : la distribution de température interne, la composition des émissions gazeuses, le ratio air carburant (), l'efficacité globale du poêle, l'humidité et la distribution d'air à l'intérieur de la chambre de combustion. Le suivi de ces paramètres a permis de révéler leur influence significative sur les émissions en considérant les modifications et les conditions d'opération du poêle.

by Luk Shiu-fai. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (p. 234-240). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

Background: This dissertation comprises research conducted on two distinct projects. Project I focuses on the connection between household air pollution (HAP) from cooking with biomass fuels and blood pressure (BP); this research is situated in the context of a large randomized trial of a cookstove intervention in Ghana, West Africa. The setting of Project II, meanwhile, is the residential environment of New York City, where we explore temperature and humidity conditions in homes and relate these conditions to summertime heat wave risk and to the survival and transmission of respiratory viruses in the winter. Although these projects are quite distinct, each relates to the complex relationship between climate change and health. Reducing HAP to improve health (the focus of Project I) will simultaneously reduce climate change through a reduction in emissions of short-lived climate pollutants into the atmosphere. Meanwhile, furthering our understanding of heat and humidity levels inside urban residences (the focus of Project II) is crucial to our ability to protect health in light of projections for a changing climate. Domestic activities associated with heating, cooling, and cooking are thus very relevant both to human health and to climate change mitigation and adaptation. Objectives and Methods: Our overall objective for Project I was to investigate exposure- response relationships between HAP and BP in a cohort of pregnant women taking part in the Ghana Randomized Air Pollution and Health Study (GRAPHS). We first explored this association in a cross-sectional study (Chapter 1), in which we used 72-hour personal monitoring to ascertain levels of exposure among the GRAPHS women to carbon monoxide (CO), one of the pollutants emitted by traditional wood-fed cooking fires. These exposure data were collected at enrollment into the GRAPHS study, prior to the initiation of cooking with improved cookstoves. We investigated the association between these “baseline” CO exposure levels and the women’s blood pressure at enrollment into GRAPHS. A limitation of this study was that BP was only measured once. We followed this with a second study of 44 women drawn from the same cohort (Chapter 2), for whom we designed BP protocols using 24-hour ambulatory blood pressure monitoring (ABPM), the current gold standard for clinical diagnosis of hypertension. As we were not aware of any prior research in Africa that had employed ABPM, we also designed a parallel BP protocol using home blood pressure monitoring (HBPM) equipment for comparison with ABPM. The use of ABPM with concurrent personal CO monitoring enabled us to investigate hourly associations between CO exposure and changes in BP. We also evaluated BP in these women both before and after the cookstove intervention; this allowed us to investigate whether any changes in BP were associated with switching to an improved cookstove. Our objectives for Project II were to understand the distribution of temperature and humidity conditions in a range of New York City homes during the summer and winter seasons, to evaluate the impact of structural and behavioral factors (e.g. building size, use of air conditioning, and use of humidifiers) on these conditions, and to build models that could help predict indoor conditions from more readily available outdoor measurements. We conducted this research in two ways. We first analyzed a set of indoor temperature and humidity measurements that were collected in 285 New York City apartments during portions of summers 2003-2011 and used these data to simulate indoor conditions during two heat wave scenarios, one of which was more moderate and the other of which was more extreme (Chapter 3). Second, we designed and conducted a new study in which temperature and humidity were monitored in a set of 40 NYC apartments between 2013 and 2015 (Chapters 4-6). This second study enabled us extend our research into the winter season, and also to explore how factors such as air conditioning and humidifier use impacted indoor temperature and humidity. We also investigated relationships between the monitored conditions, self-reported perceptions of the indoor environment, and symptoms that were experienced among household members. Results: In the cross-sectional analysis of CO and BP in the GRAPHS cohort (Chapter 1), we found a significant positive association between CO exposure and diastolic blood pressure (DBP): on average, each 1 ppm increase in exposure to CO was associated with 0.43 mmHg higher DBP [0.01, 0.86]. A non-significant positive trend was also observed for systolic blood pressure (SBP). In our study of the acute relationship between CO exposure and BP (Chapter 2), we determined that peak CO exposure (defined as above the 90th percentile of the exposure distribution, or an average of 4.1ppm) in the two hours prior to BP measurement was associated with elevations in hourly systolic BP (4.3 mmHg [95% CI: 1.1, 7.4]) and diastolic BP (4.5 mmHg [95% CI: 1.9, 7.2]), as compared to BP following lower CO exposures. We also observed a non-significant trend toward lower BP following initiation of cooking with an improved cookstove. Lastly, we demonstrated that ABPM was a feasible and well-tolerated tool for BP assessment in a rural West African setting. For Project II in New York City, we first determined that there was a great deal of variability in indoor summer heat index (HI) between homes in association with similar outdoor conditions, and that this variability increased with increasing outdoor heat (Chapter 3). Our simulation of a moderate heat wave led us to conclude that the hottest 5% of the homes would reach peak indoor heat index (HI) values of 39°C. In a more extreme heat wave simulation, HI in the hottest 5% of homes reached a peak of 41oC and did not drop below 34oC for the entire nine- day simulated heat wave period. Our second indoor monitoring study yielded the following findings: in the summer season (Chapter 4), we found significant differences in indoor temperature and heat index according to the type of air conditioning (AC) in the home. Homes with central AC were the coolest, followed by homes with ductless AC, window AC, and no AC. Apartments on the top floor of a building were significantly hotter than other apartments regardless of the presence of AC. During the winter season (Chapter 5), median vapor pressure in our sample of apartments was 6.5mb. Comparing humidity levels in the apartments to a threshold of 10mb vapor pressure that has been proposed as protective against influenza virus transmission, levels of absolute humidity in the homes remained below this threshold for 86% of the winter: a total of over three months. Residential use of humidifiers was not associated with higher indoor humidity levels. Larger building size (above 100 units) was significantly associated with lower humidity, while the presence of a radiator heating system was non-significantly associated with higher humidity. Lastly, perceptions of indoor temperature and measured temperature were significantly associated in both the summer and the winter (Chapter 6), while sleep quality was inversely related to measured indoor temperature in the summer season only. Reports of heat- stress symptoms were associated with perceived, but not measured, temperature in the summer season. Conclusions: The work presented in this dissertation adds to a growing body of evidence on the importance of exposures in the domestic environment to health and well-being. The research reported here on household air pollution in Ghana documents an exposure-response relationship between air pollution from cookstoves and elevations in blood pressure, on both a chronic and an acute basis. As elevated BP is a known risk factor for cardiovascular disease (CVD), our research provides support for a plausible factor linking HAP exposure to CVD. Meanwhile, our research on temperature and humidity in New York City residences provides concrete data to supplement the very slim literature to date documenting these conditions in the home environment, where Americans spend over half their time. We conclude, first, that AC may not be fully protective against summertime heat risk, and second, that the levels of humidity we observed in residential environments are consistent with levels that have been shown to promote enhanced survival and transmission of respiratory viruses in experimental settings. We suggest that interventions that can reduce exposure to household air pollution and excess indoor heat can also mitigate climate change, and that with thoughtful planning we can improve health at the same time as we foster resiliency in the face of a changing climate.

Emissions of air pollutants from non-conventional sources have been on the rise in the North Texas area over the past decade. These include primary pollutants such as volatile organic compound (VOC) and oxides of nitrogen (NOx) which also act as precursors in the formation of ozone. Most of these have been attributed to a significant increase in oil and gas production activities since 2000 within the Barnett Shale region adjacent to the Dallas-Fort Worth metroplex region. In this study, air quality concentrations measured at the Denton Airport and Dallas Hinton monitoring sites operated by the Texas Commission on Environmental Quality (TCEQ) were evaluated. VOC concentration data from canister-based sampling along with continuous measurement of oxides of nitrogen (NOx), ozone (O3), particulate matter (PM2.5), and meteorological conditions at these two sites spanning from 2000 through 2014 were employed in this study. The Dallas site is located within the urban core of one of the fastest growing cities in the United States, while the Denton site is an exurban site with rural characteristics to it. The Denton Airport site was influenced by natural gas pads surrounding it while there are very few natural gas production facilities within close proximity to the Dallas Hinton site. As of 2013, there were 1362 gas pads within a 10 mile radius to the Denton Airport site but there were only 2 within a 10 mile radius to Dallas Hinton site. The Dallas site displayed higher concentrations of NOx and much lower concentrations of VOC than the Denton site. Extremely high levels of VOC measured at the Denton site corresponded with the increase in oil and gas production activities in close proximity to the monitoring site. Ethane and propane are two major contributors to the measured VOC concentration, suggesting the influence of fugitive emissions of natural gas. In Dallas, the mean and maximum values of ozone had decreased since 2000 by about 2% and 25%, respectively. Similarly NOx decreased by 50% and 18% in the mean and maximum values. However, the mean VOC value showed a 21% decrease while the maximum value increased by about 46%. In Denton, the change in percentage of ozone and NOx were similar to Dallas but the mean VOC concentration increased by about 620% while the max value increased 1960%. Source apportionment analysis confirmed the findings by identifying the production of natural gas to be the primary source of VOC emissions in Denton, while traffic sources were more influential near the Dallas site. In light of the recent proposal by EPA to revise the ozone standard, the influence of these new unconventional sources should be further evaluated.

Positive associations between short-term exposure to ambient particulate matter (PM) pollution and cardio-respiratory morbidity and mortality have been established in epidemiologic studies. However, scientific uncertainties remain regarding which PM constituents and sources are most harmful to the exposed population. While tentative evidence of positive links between certain PM constituents and sources with specific health outcomes exists, significant heterogeneity in study findings remains. The chemical composition and emission source of air pollution vary not only temporally, but also geographically. Thus, substantial research on these characteristics under different atmospheres (e.g., Asian atmosphere) is warranted to enhance our understanding of PM-related health effects. / In Hong Kong, air pollution levels often exceed the World Health Organization’s air quality guidelines, posing serious public health threat. Although two decades of active research have associated PM mass (weights) concentration in Hong Kong with elevated risk of daily mortality and emergency hospital admissions, individual chemical constituents and sources responsible for the adverse health effects associated with PM mass have rarely been examined. This thesis attempted to reduce the current scientific uncertainty by making use of the speciation data for PM with aerodynamic diameter ≤ 10 μm (PM₁₀) to examine the associations between chemical constituents and daily cardio-respiratory emergency hospital admissions in Hong Kong between 2001 and 2008. It also capitalized on Positive Matrix Factorization (PMF) source apportionment model to create an alternative measure of PM concentrations that quantified the relative contribution of PM₁₀ sources. This enabled the assessment of health risks associated with exposure to particle mixture from specific sources. / Time-series analyses conducted in this work showed evidence of positive links of emergency hospitalizations with multiple PM₁₀ constituents for various exposure lags examined. In multipollutant models adjusting for gaseous co-pollutants, three groups of constituents were significantly associated with increased risk of cause-specific hospitalizations. They included: combustion-related constituents (i.e., elemental carbon, organic matter, potassium ion, manganese, nitrate ion, arsenic, lead), sea salt-related constituents (i.e., sodium ion, chloride ion, magnesium), and constituents related to soil/road dust (i.e., aluminum, iron). Significant associations were most evident between November to April. PMF model identified eight PM₁₀ sources: 1) vehicle exhaust, 2) soil/road dust, 3) regional combustion, 4) residual oil, 5) fresh sea salt, 6) aged sea salt, 7) secondary nitrate, and 8) secondary sulfate. Health effect analysis demonstrated that all PM₁₀ sources, except fresh sea salt, were positively associated with emergency hospitalizations. Combustion-related sources were positively associated with risk of cardiovascular hospitalizations at shorter cumulative lags than with respiratory hospitalization. Sources that primarily generate coarser particles (i.e., soil/road dust and aged sea salt) were linked to respiratory hospitalizations at shorter cumulative lags than combustion sources that emit fine particles, which were associated with respiratory hospitalization at delayed cumulative lags. / This work may help prioritize future toxicological research on the biologic mechanisms linking PM pollution to cardio-respiratory health. It also stresses the importance of regulation and reduction of traffic and other combustion-related emissions, reconfiguration of urban environment to reduce personal exposure to traffic emissions, as well as establishment of a coordinated and robust regional-scale air quality management plan. Constituent- and source-based air quality standards and policy strategies should be considered, supplementary to standards for total PM mass (e.g., PM₁₀ and PM₂.₅), to effectively protect the population from air pollution mixture. For example, policy measures aiming at controlling anthropogenic sources of coarse particles (e.g., soil/road dust, precursor gases for atmospheric conversion of aged sea salt) should be advisable. / 以往流行病學研究已經建立大氣懸浮顆粒（PM）污染短期暴露和心血管﹑呼吸系統疾病的發病率以及死亡率之間的關聯，但仍然不能確定究竟那種PM化學成分和排放源對暴露人群最有害。初步證據已經顯示了個別PM化學成分和排放源與某些疾病的相關聯，但是，現今研究結果之間依然存在顯著差異。此外，顆粒污染物的化學成分和排放源會隨地理空間不同而變化，因此有必要在不同地域的大氣環境下（如亞洲）進行研究，從而提高我們對PM影響健康的認識。 / 香港的空氣質量常超過世界衛生組織規定的可接受空氣質量標準，空氣污染已經成為一個嚴重的公共衛生問題。香港二十年的空氣污染研究已顯示PM質量濃度會增加死亡率和緊急入院的風險，然而仍然缺乏PM化學成分和排放源對健康影響的研究。本港環境保護署擁有十多年連續測量的可吸入懸浮粒子（PM₁₀）成分數據，因此本論文利用這數據與公共衛生數據來填補這個學術空白。具體的，本論文探索香港2001年至2008年間的PM化學成分與期間每日心血管和呼吸系統緊急入院的關聯。本論文還利用正交矩陣因子分解法（PMF），即大氣顆粒物的源解析技術，進行顆粒源分離，已建立替代單元以分別代表PM₁₀不同排放源的相對貢獻建立一個替代措施量化PM₁₀的成分中不同來源相對的貢獻，最終評估暴露於特定來源的PM₁₀混合成分的健康風險。 / 本文中的時間序列分析研究結果表明緊急入院率與多個PM化學成分在不同的暴露滯後時間上均存在正關聯。本論文的多種污染物時間序列的模型對氣體的共污染性進行了控制，研究發現以下三种顆粒物對某些具體疾病的緊急入院風險有顯著增加︰燃燒有關的顆粒（即︰碳元素，有機物，鉀離子，錳，硝酸根離子，砷，鉛），與海鹽有關的顆粒（即︰鈉離子，氯離子，鎂），以及與土壤/道路粉塵有關的顆粒（即︰鋁，鐵），這種相關性在寒冷的季節更為明顯（即每年的11月至4月）。PMF鑑定了八個PM₁₀的排放源或排放組合，包括︰1）汽車排氣，2）土壤/道路粉塵，3）區域燃燒產物，4）渣油，5）鮮海鹽，6）陳海鹽，7）二次硝酸鹽，和8）二次硫酸鹽。分析發現，除鮮海鹽外，其他PM₁₀的排放源與緊急入院呈正關係。研究顯示與燃燒有關的排放源能增加即時因心血管疾病緊急入院的風險，而主要含有粗顆粒的排放源能增加即時呼吸系統疾病緊急入院的風險，且在作用時間上比燃燒排放源（主要含有細顆粒）的危害更快。 / 本論文所提供的研究成果有助於重新定位未來有關空氣污染與心肺健康的生物學機制毒理學研究方向。研究結果強調監管和降低交通以及其他有關燃燒排放的重要性，利用合理城市環境結構及配置來減少居民暴露交通空氣污染的風險，以及建立區域性的空氣質量管理計劃。此外，本研究還建議除了PM質量濃度（如PM₁₀和PM₂.₅）的空氣質量標準以外，針對PM化學成分和排放源的空氣質量標準也應加以考慮，以有效地保護居民免受空氣污染的危害，例如，應考慮有關粗顆粒（如土壤/道路麈和前驅氣體）的人為來源的政策措施。 / Pun, Chit. / Thesis Ph.D. Chinese University of Hong Kong 2014. / Includes bibliographical references (leaves 108-133). / Abstracts also in Chinese. / Title from PDF title page (viewed on 18, October, 2016). / Pun, Chit. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

This work studied the production of aerosol-phase organic nitrates in both Portland and the Columbia River Gorge (CRG). Ozone and NOx species were investigated for correlation with organic nitrate aerosol, as they function as precursors to the production of organic nitrates. These ambient gas-phase measurements were collected in the same locations as high-volume (Hi-Vol) filters samples, in an urban and rural gorge setting to investigate correlations at the origin of the pollution plume and downwind. A novel Soxhlet extraction method for Hi-Vol filters was developed based on literature and EPA standard methods. Analysis for nitrate production was done by segregating data based on times when the wind blew out of Portland and down the CRG versus times when flow was not westerly. Filters were then compared to ambient gas-phase measurements and derived NO3 radical production rates to look for trends. Wind direction had a strong influence on the concentrations of precursor molecules in the CRG. On days with a westerly wind direction into the gorge, concentrations of the measure aerosol organic nitrates were similar at both sides. This suggests some contribution of a broader regional production of organic nitrates. There was some correlation between the production rate of NO3 radicals and the measured organic nitrate aerosol, suggesting a role for NO3 + VOC production of organic nitrates that later partition to the aerosol phase. This information will better illuminate the fate of nitrogen downwind of pollution sources. The information will also help to create a better understanding of the way topography and meteorological conditions can influence the flow of pollution. Understanding the downwind oxidative chemistry that happens in the CRG would better support both pollution prevention and mitigation efforts.