Doctor of Philosophy (PhD)
Medical Sciences Interdepartmental Area
The recent COVID-19 pandemic has highlighted the need for better tools to understand and characterize phases of the aerobiological pathway, a model for understanding how infectious bioaerosols are sourced, generated, transported, deposit, and affect human health. This dissertation presents validation of methodologies for studying transport of airborne biological agents and variations on their consequences, especially focusing on their physical and chemical fate. Chapter 1 focuses on a parallel comparison of two methods of aging bioaerosols in real-world outdoor environments with complex sunlight, atmospheric chemistry, and pollutants. Both capture on microfibers and the use of Goldberg rotating drums to keep a test population of particles aloft performed nearly identically for the aging of Bacillus thuringiensis spores, suggesting that both techniques are valid for understanding how biological agents interact with and deactivate in their unique environment.
Chapter 2 establishes a real-time fluorescent particle tracer technique, historically used in biodefense, to characterize physical fate of bioaerosols in complex environments, focusing on exposure risk upon Boeing 767 and 777 aircraft. Both aircraft had high air-change rates, and limited forward to aft air movement, such that overall risk of superspreader events is likely low, but contaminants do remain within the immediate space of a release, especially the same row.
Coupling physical and chemical fate allows better capture of the overall risk of infection to susceptible persons, and Chapter 3 applies the Chapter 2 methodology to quantify and optimize the placement of portable HEPA filters as a mitigation for infectious airborne disease within a hospital ship environment. Testing real-time differences in aerosol clearance, allows for comparison of possible outcomes to uninfected patients and staff. Combining physical removal and biological decay (as in Chapter 1) comes in a Wells-Riley probability of infection model, utilized across a wide range of possible number of patients or severity of cases. Ultimately, portable HEPA filters can both bring function of an older clinical space to more modern ventilation standards and reduce the probability of infection in statistically significant ways, with a 2.8x increase in time to achieve a similar probability of infection in this study.
Kinahan, Sean, "Understanding and Quantifying Bioaerosol Fate Within the Aerobiological Pathway: Physical Transport, Environmental Decay, and Mitigation" (2023). Theses & Dissertations. 758.
Available for download on Wednesday, July 24, 2024