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.... Master of Science (MSc) projects of the Candidates (2003) ....

Abstract (Exposure Assessment in a Busway Canyon):
The study of ultrafine particles (particles with diameters less than 100 nm) emitted by diesel buses and the assessment of human exposure was part of our recent research activities. This study was conducted at the Woolloongabba busway station in Brisbane, Australia in the winter months during which temperature inversions occur frequently. Most buses that utilize the station are fuelled by diesel, which causes the exhaust to contain a significant quantity of PM. Such particles may be composed of toxic and carcinogenic substances. The aim of this project was to investigate the exposure of waiting passengers to particles emitted from buses. During the course of this study, passenger census was conducted, based on video surveillance, yielding person-by-person waiting time data. Furthermore, a bus census revealed accurate information about the total number of diesel versus CNG-powered buses. Background (outside of the bus station) and platform measurements of ultrafine particulate number-size distributions were made to determine ambient aerosol concentrations. It was assumed that significant differences between platform and background distributions were due to bus emissions which, combined with passenger waiting times, yielded an estimate of passenger exposure to ultra-fine particles from diesel buses.

Mari's MSc-Project:

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Exposure Assessment (approx. 10MB)

Abstract (Instrumental Development and Application of a Thermodenuder):
This report describes the development and application of a thermodenuder (TD). Such an instrument enables near real time measurements of total volatile and non-volatile particle concentrations in engine exhausts by conditioning exhaust emission samples in the ultrafine particle regime of diesel and petrol engines. The TD is designed to strip off the volatile and semi-volatile fraction (short-chained hydrocarbons) attached to the surface of particles by thermal desorption. As it was not possible to improve the performance of a commercially available TD (TSI model 3065), the only practicable solution involved the development and construction of an alternative instrument as it enables simple parameter control, and Better accessibility to key elements of the instrument. Innovative aspects of this instrument include the direct heating system (based on a galvanically separated power unit) and the registration of the aerosol's core temperature. Both features keep the temperature gradient stable and, at the same time, prevent unexpected sample transformations due to uncontrolled condensation and nucleation under supersaturated conditions. Although the core topic is the TD, supplemental information regarding the instrumentation employed during the practical phase of the work will be presented as well. The TD is suitable for use with a Scanning Mobility Particle Sizer and has the potential to monitor existing engines (incl. stoves) with respect to environmental standards, aids in the maintenance and proper functioning of existing fossil fuel powered engines, and can even be employed as a tool to improve the design of combustion engines.

Piero's MSc-Project:

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Thermodenuder (approx. 10MB)

.... Doktorate - Dissertation Candidates (2009) ....

Abstract Anthropogenic Environmental Aerosols: Measurements and Biological Implications:
Technically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas - or in other words, a suspension in which matter "floats" in air (aero-). To differentiate suspensions from true solutions, the term -sol evolved to characterize a dispersions of nanoscopic to microscopic particles in a liquid or gaseous medium. Together, the word aerosol encompasses examples like clouds, oceanic haze, fog, smoke, smog, particle matter, and volatile organic compounds. Thus, aerosols embrace both liquid droplets, solid particles, and combinations of these. An aerosol may originate from natural as well as anthropogenic sources. Anthropogenic aerosols released into the troposphere, particularly particle matter such as sulfates from fossil fuel combustion, exert a cooling influence on the climate, while carbonaceous aerosols are known to result in an opposing effect. On the other hand, ground-level aerosols originating from household, traffic and manufacturing processes are known to be the prime culprits of urban air pollution and smog formation. While all research projects presented here focus on ground-level aerosol formation and subsequent inhalation, some investigation focused on natural aerosols (like salt) while other studies highlighted manmade exhaust aerosols from various combustion processes. Hence, with the available tools it was possible to account for both workplace and therapeutic exposure as well as environmental long-term exposure. While probing and monitoring is a rather straight forward process, investigating the fate of inhaled particles into the respiratory tract can not be easily done with human subjects. The commonly used animal substitute was used to approach this challenge. At this stage, it may be appropriate to refer to a famous medieval fellow, alchemist, physician, astrologer, and general occultist known by the name Paracelsus - sometimes also called the father of toxicology, when he wrote: "All things are poison and nothing is without poison, only the dose permits something not to be poisonous." Thus the line between beneficial and adverse effects for respiratory and circulatory diseases associated to aerosol exposure can not be drawn as a sharp line of demarcation rather the gradient that leads from one to the other and vice versa is diffuse and obscured by the fact that it largely depends on individual predispositions. The compilation presented herein should provide an insight over the sheer infinite modes of aerosol exposure, starting from the site of aerosol formation, therapeutic aerosol application, fate of aerosol deposition as well as the wider eco-systemic affects of long-term environmental monitoring.

Piero's PhD-Project:

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Anthropogenic Environmental Aerosols (approx. 16MB)