ENVIRONMENTAL FACTORS AFFECTING THE MEASUREMENT OF THE PHYSICAL AND CHEMICAL PROPERTIES OF AEROSOLIZED BIOLOGICAL PARTICLES
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Date
2014-01-01
Type of Work
Department
Chemical, Biochemical & Environmental Engineering
Program
Engineering, Chemical and Biochemical
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Distribution Rights granted to UMBC by the author.
Distribution Rights granted to UMBC by the author.
Abstract
Biological aerosols, also known as bioaerosols, are a subset of organic carbon aerosols that consist of airborne particles that may be alive, may contain other live organisms, or released from living organisms. Many methods can be used to study bioaerosols. These methods range from collection and characterization of samples via culture, polymerase chain reaction, and immunoassay, to spectroscopic methods such as Raman spectroscopy and fluorometry. When biological particles are released into the atmosphere, they have the potential to interact with atmospheric constituents such as water vapor, solar radiation, free radicals, volatile organic, semi-volatile organic and inorganic gas-phase compounds. The objective of this work was to access the environmental factors that affect the physical and chemical properties and measurement of aerosolized biological aerosols. A novel test system was demonstrated to re-create natural fluctuations in biological and non-biological aerosol concentrations in a controllable laboratory setting for evaluating sensor performance. The Dynamic Concentration Aerosol Generator (DyCAG) can be used for bioaerosol sensor evaluation by generation of challenges of biological aerosols of interest at specific concentrations in the presence of varying levels of environmentally relevant aerosols. To understand the limitations of fluorescence-based measurements for detection and characterization of biological aerosols and to develop improved instrumentation and methods for making measurements, changes that occurred to biological particles due atmospheric exposure to ozone and water vapor were measured using a rotating drum chamber. The spectral properties of ultra-violet laser-induced fluorescence (UV-LIF) of two types of biological aerosols, Bacillus thuringiensis Al Hakam (Bt Al Hakam) spores and MS2 bacteriophage when excited at 263, 351, and 355 nm were shown to change when exposed to ozone and water vapor. In addition, changes in the biological activity of these bioaerosols as a function of the exposure conditions were observed. The hygroscopic properties of several types of biological aerosols and the media used for culturing and aerosolized bioaerosols were measured. Media containing high concentrations of salt showed the highest affinity for the uptake of water and dominated the hygroscopic properties of the aerosols measured. The studies presented in this dissertations describe some of the factors that contribute to how the physical and chemical properties of biological aerosols and their measurement are impacted by external factors when in their native state.