Abstract View
Dynamic Behavior and Fate of Model Respiratory Fluids Aerosol in Indoor Environments
LUCY NANDY, Emma Tackman, Miriam Freedman, The Pennsylvania State University
Abstract Number: 87
Working Group: Infectious Aerosols in the Age of COVID-19
Abstract
Recent research suggests respiratory aerosol transmission in COVID-19, influenza, and other infectious diseases in indoor environments. To better understand the role aerosols play in the transmission, there is a requirement to quantify the emission rate, air exchange rate, deposition onto surfaces and size distribution of particles of respiratory fluids for estimating aerosol exposure in the indoor environment. The fate of indoor aerosol is governed by the physical principles of transport – dispersion and deposition on surfaces, depending on the droplet size and phase state.
Our goal is to develop a chemical and physical understanding of transmission mechanics of aerosol particles including their advection and deposition properties. We investigate deposition and bounce factor of aerosol particles that involve Brownian diffusion for fine dry particles less than 200 nm in an experimental plexiglass chamber with peak number concentrations occurring at particle sizes of < 50 nm. At high concentrations, coagulation and deposition dominate aerosol transmission for such small particles; we, therefore, estimate size-resolved decay rates and overall wall loss for different aerosol compositions. We also utilize transmission electron microscopy to characterize particles deposited and collected on substrates to determine their two-dimensional size, as well as viscometer and tensiometer measurements to characterize sticking efficiency on surfaces. In addition, we measure particle bounce to quantify the phase state (solid, semi-solid, viscous liquid, liquid) of aerosol particles, and hypothesize that aerosol viscosity and surface morphology play an important role in particle concentrations and consequences. For the study, we use aerosol particles generated from aqueous solution of physiological concentrations of salt, surfactant, and mucin. This research effort will support future approaches for quantifying aerosol transmission, exposure, and risk management from the source to transport through model indoor environments.