Luftföroreningar skadar människors hälsa och orsakar miljöproblem. Luftföroreningar kommer från många olika källor och ett stort bidrag står transporter och industrier för. Förbränningsanläggningar är en sorts industrier som bidrar med föroreningar av exempelvis kväveoxider, partiklar och koldioxid. För att motverka att skadliga halter uppkommer finns miljökvalitetsnormerna som innehåller gränsvärden för olika luftföroreningar. För att en verksamhet ska få släppa ut föroreningar måste de utföra en tillståndsansökan. I ansökan ska det bevisas att verksamheten inte kommer bidra till att något av miljökvalitetsnormernas gränsvärden överskrids. Det utförs ofta spridningsberäkningar i form av simuleringar för att beräkna vilket haltbidrag utsläppen kommer generera. Dessa utredningar kan vara tidskrävande och i många fall överflödiga eftersom resultatet ofta visar att haltbidraget blir väldigt litet. Haltbidraget av kvävedioxid från mindre värmeverk och kraftvärmeverk har beräknatsmed hjälp av programmet AERMOD. Simuleringar har utförts för två olika platser i Sundsvall och det har undersökts hur mycket haltbidraget förändras när värden för olika parametrar varierar. Påverkan av rökgasens hastighet och temperatur har studerats tillsammans med egenskaper hos skorstenen i form av skorstenshöjd och diameter. I det här projektet har olika fall där spridningsberäkningar inte är nödvändiga identifierats för att förenkla processen för utredningar. Ett flödesdiagram tagits fram med syfte att kunna användas vid bedömning om beräkningar är nödvändiga eller inte för värmeverk. Beroende på värden för olika parametrar ger flödesdiagrammet en hänvisning om beräkningar krävs, noggrannare utredning behövs utföras eller om beräkningar inte krävs. Efter att olika fall studerats kunde slutsatser dras att för värmeverk och kraftvärmeverk med en skorstensdiameter större än 0,5 m, rökgashastighet över 10 m/s, rökgastemperatur över 50 ◦C och massflöde under 1,2 g/s krävs inga beräkningar då skorstenshöjden är 45 m eller högre. För dessa fall påverkade en förändring av någon parameter haltbidraget ytterst lite och alla haltbidrag blev väldigt låga. När skorstenshöjden var lägre än 15 m ansågs det att beräkningar alltid är nödvändiga eftersom små förändringar av någon parameter gav stora skillnader i haltbidraget. För skorstenshöjder mellan 15 och 45 m ansågs det att beräkningar inte alltid är nödvändiga men att mer noggranna utredningar krävs. Topografins och meteorologins påverkan på haltbidraget har också studerats genom att simuleringar utförts för två platser med olika omgivande topografin. Det kunde konstateras att med en komplex topografi blev haltbidraget överlag högre och sambandet mellan olika parametrar och haltbidraget frångick ibland den allmänna trenden. Slutsatsen drogs att noggranna beräkningar alltid bör utföras om topografin är komplex. / Air pollutions generate health problems to humans and have negative impact on the environment. Environmental quality standards in Sweden are based on requirements on various European Community directives. Combustion is a source for air pollution and a new plant must always prove that the pollution will not exceeded environmental quality standards. An investigation is therefore made and often modeling is performed to calculate how high the contribution from the plant will be. The process can be time consuming and sometimes not necessary because the result often shows that the contribution is very low. In this project a way to simplify the investigation by trying to find cases when calculation is not necessary have been made. The dispersion of nitrogen dioxide from a heating plant have been studied by simulations in the program AERMOD for two different places in Sundsvall. The impact of different parameters as gas velocity, gas temperature, stack height and stack diameter on the result have been studied together with the effect of different topographies. A flow chart has been constructed with the result from the simulations. The flow chart can be used to decide if calculation is necessary or not for different heating plants. From the results the conclusion was that for a heating plant with a stack diameter larger than 0.5 m, a gas velocity higher than 10 m/s, gas temperature over 50 ◦C and a mass flow lower than 1.2 g/s calculations are not needed for a stack higher than 45 m. For these cases the contribution from the plant is very low and also the risk for exceeding limits. A stack height lower than 15 m was considered as a case where calculation always is needed. For a height between 15 and 45 m the conclusion was made that more investigation is needed before a decision can be made. The study of how the topography affecting the dispersion of the pollution resulted in the conclusion that for a complex topography a careful investigation always is needed.

The photocatalytic properties of titanium dioxide have been widely studied over recent decades since the discovery in 1972 of water photolysis by TiO2 electrodes. There are a number of different TiO2 polymorphs. Rutile and anatase are the most studied due to their chemo-physical properties. Under ultraviolet light, TiO2 is able to absorb photons, creating a charge separation on the surface, an electron and a positive “hole”. This electron-hole pair then reacts with water and oxygen, generating radicals, very unstable and reactive species which show great potential for neutralisation of pollutants. In the introduction the state of art of photocatalysis; chemo-physical principles, applications and current analysis are described. A number of protocols to test photoactivity are discussed with particular emphasis on the importance of gas phase reactions. The development of a novel system to study gas phase reactions by mass spectrometry was explored, detailing the conditions and parameters that were optimised. This instrument was used to analyse photocatalytic properties of TiO2 powders and photocatalytic coatings under different UV light conditions. The results showed how TiO2 in the form of anatase and rutile removed nitrogen and carbon dioxide under different UV light sources, with anatase being more effective. A comprehensive study of several commercially available TiO2 powders and coatings was performed to identify the differences between photocatalytic properties, using electron microscopy, Raman and UV-vis diffusive spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. An important question that was answered in this thesis is whether the physical properties of nanoparticles or their electronic properties are critical for their photocatalytic behaviour. Results for anatase powders of different particle size and surface area showed how the positioning of their electronic band gap with the wavelength of the UV light source was fundamental for an effective photocatalyic process. In order to improve the photocatalytic process, “self-doping” TiO2 was investigated. Different reduction temperatures were studied to generate the best ratio of Ti3+-Ti4+ that stabilised the charge distribution process to maximize the electron-hole pairs generated per photon in the gas phase. From a wide range of reduction temperatures, titanium sub-oxime reduced at 400 oC showed the best performance in removing carbon dioxide. In the application of TiO2 for the built environment, the best commercially available TiO2 powder, anatase P25 was applied with two different techniques. Electrophoretic deposition has the potential to scale up the process for prefabricated panels in construction. Solvent, iv deposition time, voltage and substrate were optimised. The resulting photoactivity of the coatings was evaluated showing a higher efficiency than a compressed pellet of anatase P25. The final part of the thesis was dedicated to the formulation and application of a photocatalytic enhanced lime based coatings for the built heritage. The use of calcium hydroxide dispersions is widely used in the conservation and restoration community, reinforcing limestone when it carbonates. Anatase P25, was added to improve the performance in polluted atmospheres, acting as a sacrificial barrier. Results showed that by adding anatase to the formulation, calcium hydroxide reacted preferentially with sulphur dioxide over carbon dioxide. The final product in the formulation with anatase was calcium sulphate, whereas the final product for the calcium hydroxide formulation was calcium sulphite. Finally, a general discussion of the results is presented and the conclusions of this research are drawn. Recommendations for further work are presented in the last chapter.

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Includes bibliographical references. / by Simon Peter Hanson. / Sc.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Catherine E. Teague. / M.S.

Made available in DSpace on 2015-04-22T22:01:54Z (GMT). No. of bitstreams: 1 Najara Marinho de Assis.pdf: 4136541 bytes, checksum: e841bade3c95236a92cf25313bf4398e (MD5) Previous issue date: 2007-06-30 / Fundação de Amparo à Pesquisa do Estado do Amazonas / Nitrogen Dioxide (NO2) is a toxic gas and contributed to the environmental impact. This work showed an evaluation of the levels and distribution of NO2 in Manaus by passive technique of sampling. Twenty points were distributed in strategic points in the city. The NO2 varied from 4,56 ± 1,29 to 22,48 ± 3,91 μg m-3 in 2006. The largest values were found at places of great flow of vehicles. The minimum value were found at Marina Tauá (place with little urban influence). The method detection limit observed was (0,37 ± 0,26 μg m-3). / Dióxido de nitrogênio (NO2) é um gás tóxico e contribui para o desequilíbrio ambiental. Neste trabalho fez-se uma avaliação dos níveis e distribuição de NO2 em Manaus usando técnica passiva de amostragem. Vinte pontos foram distribuídos de maneira estratégica na cidade. Os níveis médios de NO2 encontrados variaram de 5,0 ± 1,0 a 23,5 ± 4,0 μg m-3 de NO2 no ano de 2006, sendo os maiores valores encontrados em locais de grande fluxo de veículos. O valor mínimo representa a região da Marina Tauá (referência de pouca influência urbana). O limite de detecção para o método usado foi de (0,4 ± 0,3) μg m-3.

Thesis. 1978. M.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / M.S.

Triethanolamine (TEA) is a semiconducting polymer which exhibits a resistance change when exposed to various gases. The polymer also exhibits a number of reactions with nitrogen dioxide, with the reaction products being heavily dependent on the presence or absence of water vapor. Previous studies have attempted the incorporation of a TEA-carbon nanoparticle composite as the active sensing layer in a chemresistive sensor for detection of NO₂. The incorporation of carbon nanoparticles in the polymer nanocomposite was thought to amplify the sensor's response. There are a number of chemical reactions that can occur between TEA and NO₂, with the reaction products being heavily dependent on the presence and amount of water vapor in the environment. Because of this influence, it becomes necessary to know to what degree the presence of water vapor interferes with the sensing response. In this work we show that the sensor exhibits a reversible resistance change as background humidity changes. This sensitivity to humidity changes is so large that it renders undetectable any resistance change that could be caused by the reaction of TEA with NO₂. Furthermore, we show that the presence of low levels of NO₂ do not interfere with adsorption of water vapor. The detection mechanism is based on measuring resistance changes in the TEA film due to the adsorption/desorption of water vapor. The sensing response can be described by Langmuir adsorption by using a site-based model for the polymer film resistance. Breakdown of the polymer film over time due to continuous adsorption of water vapor, as well as photodegradation of the polymer film, will be discussed. SEM images will also be presented showing growth of crystallites on the electrode walls, as well as experimental results demonstrating degradation of the sensing film during sensor operation.

Thesis (Ph. D.)--Brigham Young University. Dept. of Chemical Engineering, 2006. / Includes bibliographical references (p. 141-147).

With the increasing availability of observational data from different sources at a global level, joint analysis of these data is becoming especially attractive. For such an analysis – oftentimes with little prior knowledge about local and global interactions between the different observational variables at hand – an exploratory, data-driven analysis of the data may be of particular relevance. In the present work we used generalized additive models (GAM) in an exemplary study of spatio-temporal patterns in the tropospheric NO2-distribution derived from GOME satellite observations (1996 to 2001) at global scale. We focused on identifying correlations between NO2 and local wind fields, a quantity which is of particular interest in the analysis of spatio-temporal interactions. Formulating general functional, parametric relationships between the observed NO2 distribution and local wind fields, however, is difficult – if not impossible. So, rather than following a modelbased analysis testing the data for predefined hypotheses (assuming, for example, sinusoidal seasonal trends), we used a GAM with non-parametric model terms to learn this functional relationship between NO2 and wind directly from the data. The NO2 observations showed to be affected by winddominated processes over large areas. We estimated the extent of areas affected by specific NO2 emission sources, and were able to highlight likely atmospheric transport “pathways”. General temporal trends which were also part of our model – weekly, seasonal and linear changes – showed to be in good agreement with previous studies and alternative ways of analysing the time series. Overall, using a non-parametric model provided favorable means for a rapid inspection of this large spatio-temporal NO2 data set, with less bias than parametric approaches, and allowing to visualize dynamical processes of the NO2 distribution at a global scale.

Background: Air pollution is associated with negative health effects. Exposure to combustion-derived particulate matter (PM) air pollution has been related to increased incidence of cardiovascular and respiratory morbidity and mortality, specifically in susceptible populations. Ambient particles, with a diameter of less than 2.5 mm, have been suggested to be the strongest contributor to these health effects. Diesel exhaust (DE) is a major source of small combustion-derived PM air pollution world wide.  In healthy volunteers, exposure to DE, has been associated with airway inflammation and impaired vasomotor function and endogenous fibrinolysis. The aims of this thesis were to further elucidate the underlying mechanisms to the reported cardiovascular effects following exposure to DE, with specific focus on endothelin-1 (ET-1). Additionally, the vascular effects of the major gaseous component of DE, nitrogen dioxide (NO2), were assessed together with the impact of an exhaust particle trap to reduce the observed negative vascular effects after DE exposure. Methods: In all studies healthy, non-smoking male volunteers were included and exposed for one hour during intermittent exercise in a randomised double-blind crossover fashion. In studies I-III, subjects were exposed to DE at a particulate matter concentration of approximately 300 μg/m3 and filtered air, on two different occasions. In study V an additional exposure was employed, during which DE was filtered through an exhaust particle trap. In study IV subjects were exposed to nitrogen dioxide (NO2) at 4 ppm or filtered air. In study I, thrombus formation and platelet activation were assessed using the Badimon ex vivo perfusion chamber and flow cytometry. Study II comprised the determination of arterial stiffness including pulse wave analysis and velocity. In studies III-V, vascular assessment was performed using venous occlusion plethysmography. In studies IV and V, the vascular responses to intra-arterially infused endothelial-dependent and endothelial-independent vasodilatators were registered. In study III, vascular responses to intra-arterial infusion of Endothelin-1 (ET-1) and ET-1-receptor antagonists were assessed. Venous occlusion phlethysmography was in all cases performed 4-6 hours following exposures. Blood samples for markers of inflammation, coagulation and platelet activation were collected before and throughout the study periods in studies III and V. Results: Exposure to DE increased ex vivo thrombus formation and arterial stiffness, in terms of augmentation index. DE inhalation impaired vasomotor function and endogenous fibrinolysis. The exhaust particle trap reduced the particle concentration by 98% and abolished the effects on vasomotor function, endogenous fibrinolysis and ex vivo thrombus formation. Plasma concentrations of ET-1 and its precursor big-ET-1 were unchanged following exposure. Dual endothelial receptor antagonism caused similar vasodilatation after both exposures, although vasodilatation to the endothelin-A receptor alone was blunted after DE exposure. ET-1 infusion induced vasoconstriction only following DE exposure. Exposure to nitrogen dioxide did not affect vascular function. Conclusion: Inhalation of diesel exhaust in young healthy men impaired important and complementary aspects of vascular function in humans; regulation of vascular tone and endogenous fibrinolysis as well as increased ex vivo thrombus formation. The use of an exhaust particle trap significantly reduced particle emissions and abolished the DE-induced vascular and prothrombotic effects. The adverse vascular effects following DE exposure do not appear to be directly mediated through the endothelin system. Neither is NO2 suggested to be a major arbiter of the DE-induced cardiovascular responses. Arterial stiffness is a non-invasive and easily accessible method and could thus be employed to address vascular function in larger field studies. Taken together, this thesis has given further knowledge about the mechanisms underlying the DE-induced vascular effects.