The COVID-19 pandemic has made research into virus transmission a top scientific priority. SARS-CoV-2, the virus that causes COVID-19, can be spread through virus-infected saliva droplets and particles. The details of how far and fast saliva droplets and particles disperse through the air, and under what circumstances, remain under investigation.
Dr. Sima Asadi, Postdoctoral Associate with the Department of Chemical Engineering at Massachusetts Institute of Technology (MIT), discusses her research on the role of talking in aerosol particle emission leading up to the American Association for the Advancement of Science's (AAAS) panel, 'Transmission of Airborne Pathogens through Expiratory Activities' happening at the AAAS Annual Meeting on February. 18, 2022. Learn more about the panel here.
What does your current research focus on?
After graduating from UC Davis where I worked on airborne infectious disease transmission, I joined the Department of Chemical Engineering at MIT as a postdoctoral associate, where I work on synthetizing shape-engineered functional hydrogel particles for biomedical and pharmaceutical applications. In parallel, I continue working with colleagues and collaborators at UC Davis and Icahn School of Medicine at Mount Sinai on infectious disease transmission.
What is something people may be surprised to learn about the transmission of airborne viruses via aerosol particles?
Talking may pose a higher risk of airborne disease transmission than breathing, coughing, and sneezing.
The majority of droplets emitted during sneezing and coughing are relatively large (approximately 50μm or larger) and easily visible to the naked eye. These droplets quickly deposit on the floor by gravity. However, the smaller aerosol particles emitted during the expiratory activities can stay suspended in the air for hours and even days. On the other hand, sneezing and coughing are infrequent expiratory events, while speaking is frequent and is usually done when other people are present. Moreover, although breathing is the most frequent expiratory activity, previous measurements show that it emits very few aerosol particles. Therefore, speaking might be the primary mode of airborne disease transmission.
Can you share a small taste of what people might expect to learn from you on the AAAS panel, 'Transmission of Airborne Pathogens through Expiratory Activities'?
I hope to shed light onto the importance and role of talking in aerosol particle emission and therefore airborne disease transmission. First, I demonstrate how different features of speech (loudness, pitch, and articulation manner) affect the rate of aerosol particle emission. I then introduce speech superemitters, i.e., individuals who emit many more aerosol particles that their peers, and discuss their contribution to disease transmission. Finally, I evaluate the efficacy of medial-grade and homemade masks in controlling the outward emission of aerosol particles during talking, coughing, and breathing.
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Written by Kelsea Franzke