UC San Diego

The recent COVID-19 pandemic, which was spread mainly by airborne transmission, changed how society functioned across the globe. A significant reason for the virus’s rapid spread was human interactions through speaking and the release of tiny respiratory aerosols. My projects encompass studying how certain physiological aspects of speech, including vocal amplitude (loudness), associated airflow, and different sound types, affect respiratory aerosol size, emission rates, and concentrations during speech. I am optimizing a technique to measure particles as small as viruses and at a timescale coherent with individual sounds. This resolution will allow me to better understand respiratory aerosol emissions on a scale unattainable previously, marking an important advancement in potentially better predicting how viruses spread when people communicate verbally. Respiratory aerosols are expected to transform in their physical state and chemical composition upon emission from the mouth and into the surrounding air. Water condensation and evaporation from the particles, depending on the temperature and relative humidity of the air, will cause them to alter their phase and viscosity. Aerosols become less viscous when they take up water, similar to how it’s easier to clean dried toothpaste from the sink basin when wetting it. However, the growth rates and changes in respiratory aerosol phase and viscosity following water uptake have not been studied. Understanding how their physical state evolves in the air is critical in understanding aerosol lifetimes and the potential survivability of viruses in respiratory aerosols. My research is designed to fill these important gaps due to their implications for public health, as airborne disease transmission greatly depends on respiratory aerosol emission characteristics and particle properties. Knowing and predicting which pathway(s) certain diseases may spread will enable more comprehensive models to be made. These more complete models will, in turn, allow leadership to provide the public with more effective instructions on how to behave and the safety measures to limit the spread of disease and ultimately decrease the chances of epidemics or pandemics occurring.