Understanding and optimizing transport of aerosol particles in indoor environments and aerosol concentrators.

Abstract

Our post-pandemic world has given rise to an increased interest in the fate and transportof exhaled particles (human respiratory aerosol), and in advancing methods to appropriately sample bioaerosols, which, while infectious, are in low concentration in the environment. The work in my dissertation is motivated by both developing bioaerosol sampling techniques for improved signal-to-noise ratios and limits of detection with biological assays and improving understanding of exhaled particle dispersion and deposition in the environment. My dissertation is specifically sectioned into four distinct sub-studies. The first study is a numerical and experimental effort to develop inertial concentrators for submicrometer particles sampled from ambient air. Such concentrators operate close to the sonic limit and are hence distinct in behavior from traditional aerosol inertial concentrators. The second study, following from the first, is an engineering effort to multiplex submicrometer particle concentrators for high volume sampling. In this study one single nozzle impactor and three double nozzle impactors with varying nozzle distances were manufactured and then tested in an ASHRAE wind tunnel in order to test the limits of multinozzle design optimization. The third study focuses on optimizing intermediate flow rate inertial concentrators for personal exposure assessment. The link between exposure to PM2.5 particles and increased cancer risk has been highlighted by multiple research studies. Understanding the relationship between the level of exposure to specific pollutants and the risk of cancer in an individual is essential for identifying at risk populations. In this study I will develop and implement a wearable virtual impactor concentrator, which separates PM2.5 from larger particles, enabling subsequent chemical analysis. The fourth and final chapter of this dissertation is a stand-alone study focused on the development and implementation of methods to understand particle transport and deposition in indoor environments using an anatomically correct breathing simulator and fluorescein doped particles to infer particle deposition velocity.