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Vyhodnocení kontaminace pracovního prostředí aerosoly řezných kapalin při soustružení kovů / Evaluation of cutting fluids aerosol contamination of working environment during metal turningSvoboda, Svetozár January 2017 (has links)
The thesis deals with the contamination of the workspace with a liquid aerosol, which is generated by scattering and evaporation of the cooling fluid. Cooling fluid are primarily intended to lubricate, cool and clean the tool and the workpiece, but the unwanted side effect is the formation of a liquid aerosol that holds in the air of the workspace. In such a contaminated work environment, the operator is exposed to a certain dose of a liquid aerosol that causes dermatological and respiratory problems. The topic of the thesis was to find out the number of particles of liquid aerosol that arises under varying working conditions and its dispersion in space. This amount was determined by image analysis using a high-speed camera.
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STUDIES ON AEROSOL SIZE DISTRIBUTIONS, EMISSIONS, AND EXPOSURESTianren Wu (8802641) 07 May 2020 (has links)
<p>Aerosols are solid or liquid particles
that span in size from a few nanometers to tens of micrometers. They are important
in both outdoor and indoor environments due to their impact on climate and
human health.
Many aerosol processes of interest to the environment, health, and
filtration are strongly size-dependent.
Aerosol particle size distributions (PSDs) provide a basis to better
understand outdoor and indoor air pollution sources, evaluate human exposure to
air pollution, and aerosol deposition in the human respiratory tract and
filters in building ventilation systems. Monitoring the temporal evolution of aerosol
PSDs enable for characterization of dynamic aerosol transport and
transformation processes, such as direct emissions, nucleation, condensation,
coagulation, resuspension, deposition, and filtration. This thesis presents three studies on the PSDs
of: (i.) urban aerosols in cities around the world in order to identify
geographical trends in the shape and magnitude of PSDs and to frame future research
needs for PSD observations at a global-scale, (ii.) synthesized salt particles
from a novel thermal aerosol generator to evaluate its suitability for air filter
testing, and (iii.) indoor biological particulate matter (<i>bio</i>PM) to characterize transient inhalation exposures of infants
and adults to resuspended <i>bio</i>PM from
carpet dust induced by crawling and walking.</p>
<p>First,
this thesis presents the current state-of-knowledge of urban aerosol PSDs by critically
analyzing <i>n</i>=793 urban aerosol PSD
observations made between 1998 to 2017 in <i>n</i>=125 cities in <i>n</i>=51
countries across the following regions of the
world: Africa (AF), Central, South, and Southeast Asia
(CSSA), East Asia (EA), Europe (EU), Latin America (LA), North America,
Australia, and New Zealand (NAAN), and West Asia (WA). Prominent geographical variations in the
shape and magnitude of urban aerosol number and mass PSDs were identified and significant
variations in number PSDs were found between cities in EU and NAAN with those
in CSSA and EA. Most PSD observations published
in the literature are short-term, with only 14% providing data for longer than
six months. There is a paucity of PSDs
measured in AF, CSSA, LA, and WA, demonstrating the need for long-term aerosol
measurements across wide size ranges in many cities around the globe. Inter-region variations in PSDs have
important implications for population exposure, driving large differences in
the urban aerosol inhaled
deposited dose rate received in each region of the human
respiratory system. Similarly, inter-region
variations in the shape of PSDs impact the penetration of urban aerosols
through filters in building ventilation systems, which serve as an important
interface between the outdoor and indoor atmospheres. The results of this critical review
demonstrate that global initiatives are urgently needed to develop
infrastructure for routine and long-term monitoring of urban aerosol PSDs
spanning the nucleation to coarse modes.</p>
<p>Second, this
thesis evaluates a newly designed commercially available thermal aerosol
generator for ageing air filters in building heating, ventilation, and
air-conditioning (HVAC) systems. The
physical characteristics of the synthesized salt aerosol (NaCl and KCl) under
different generator operational conditions were evaluated. The shape of the number and mass PSD output of the thermal
aerosol generator are similar to those found in outdoor (urban) and indoor air
and can be modulated by varying the rate at which the salt stick is fed into
the flame. The morphology of the NaCl
and KCl particles varied with size, with compact
spherical or cubic structures observed below 100 nm and agglomerates
observed above 100 nm. The thermal
aerosol generator is a cost-effective technique for rapid ageing of HVAC
filters with a PSD that more accurately represents, compared to conventional
loading dusts, what filters encounter in real HVAC installations.</p>
<p>Lastly, this thesis characterizes infant and adult
inhalation exposures and respiratory tract deposited dose rates of resuspended <i>bio</i>PM from carpets. Chamber experiments were conducted with a
robotic crawling infant and an adult performing a walking sequence. Breathing zone (BZ) size distributions of
resuspended fluorescent biological aerosol particles (FBAPs), a <i>bio</i>PM proxy, were monitored in
real-time. FBAP exposures were highly
transient during periods of locomotion.
Both crawling and walking delivered a significant number of resuspended
FBAPs to the BZ, with concentrations ranging from 0.5-2 cm<sup>-3</sup>. Infants and adults are primarily exposed to a
unimodal FBAP size distribution between 2 and 6 μm, with infants receiving greater exposures to
super-10 μm FBAPs. In just one minute
of crawling or walking, 10<sup>2</sup>-10<sup>3</sup> resuspended FBAPs can
deposit in the respiratory tract, with an infant receiving much of their
respiratory tract deposited dose in their lower airways. Per kg body mass, an infant will receive
nearly four times greater respiratory tract deposited dose of resuspended FBAPs
compared to an adult.</p>
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MULTIPHASE ATMOSPHERIC CHEMISTRY OF SELECTED SECONDARY ORGANIC AEROSOLSAna C Morales (14216438) 06 December 2022 (has links)
<p> </p>
<p>Secondary organic aerosols (SOA) play an important role in the Earth’s radiative budget due to their potential to either warm or cool the atmosphere through light absorption or light scattering, respectively, and to cool or warm the lower atmosphere by acting as cloud condensation nuclei. SOA are air-suspended liquid and semi-solid droplets that form through multiphase chemical processes. Atmospheric photochemical oxidation of volatile organic compounds (VOCs) in the presence of air pollutants, such as NO<sub>x</sub> (NO + NO<sub>2</sub>) and the OH radical, promote formation of low volatility organic products that eventually condense to form SOA. To better understand the sources and sinks, formation, and fate of SOA, laboratory studies investigating oxidation of a biogenic VOC as well as anthropogenic emissions of SOA precursors were conducted. The first study (<em>Chapter 3</em>) investigated the OH-initiated oxidation of β-ocimene, a biogenic volatile organic compound (BVOC) released from vegetation, including forests, agricultural landscapes, and grasslands emitted during the daytime. The oxidation of BVOCs in the presence of NO<sub>x</sub> leads to the formation of functionalized organic nitrate (RONO<sub>2</sub>) compounds and isomers that easily condense to form SOA. To understand their atmospheric fate, the RONO<sub>2</sub> hydrolysis rate constants were quantified and found to be highly pH dependent. The findings of this study provide key insights into the formation and fate of organic nitrates and NO<sub>x</sub> cycling in forested environments from daytime monoterpenes that were not previously included in atmospheric models. </p>
<p>The second study (<em>Chapters 4 and 5</em>) investigated condensed waste emissions generated during Cured-In-Place-Pipe (CIPP) installations. This installation process is the most popular, least expensive, and most frequently used technology that cures leaking sanitary and stormwater sewers. Waste plumes discharged during pipe manufacture are complex multi-phase mixtures of volatile and semi-volatile organic compounds (VOC and SVOC, respectively), primary organic aerosols and SOA, fine debris of partially cured resin, and direct emission of nanoplastic particles that are all blown into the atmospheric environment at significant concentrations at worksites. This work unveiled a direct emission source of airborne nanoplastic particles as well as substantial concentrations of hazardous compounds and SOA precursors that were previously unrecognized. </p>
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