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UCLA Fielding School Scholar Honored for Study on Simple Cloth Masks as Protection Against COVID-19

UCLA Fielding School of Public Health scholar Liqiao (Vicky) Li chosen for first-ever American Association for Aerosol Research Lecture Series

Tuesday, March 16, 2021

A UCLA Fielding School of Public Health scholar has been chosen to deliver the inaugural American Association for Aerosol Research Lecture because of her work on proving the effectiveness of simple cloth masks in preventing infection during the pandemic.

Liqiao (Vicky) Li, a Ph.D. candidate in the Fielding School’s Department of Environmental Health Sciences, was selected by the American Association for Aerosol Research, or AAAR, because of the “high impact” of her work, published in the November edition of the peer-reviewed journal Aerosol Science and Technology.

“To minimize the infection risk of aerosol transmission, stricter mitigation measures should be adopted for indoor environments, which are more likely to be enclosed and crowded,” said Li, who delivered the lecture virtually to an audience of students and scientists from across the United States and internationally. “One of the simplest is a mask.”

Li’s research team determined that even a simple cloth mask provides significant protections against COVID-19 transmission, reducing the spread of respiratory droplets by as much as 77%, said Dr. Yifang Zhu, UCLA Fielding School of Public Health professor of environmental health sciences and senior associate dean for academic programs, who served as the faculty advisor on the project.

“They found that a simple cough could send particles more than six feet away, without face coverings,” Zhu said. “The impact of this research, and the honor of being asked to deliver this lecture, really serves to highlight our students’ accomplishments.”

The study team, which included FSPH staff research associate Muchuan Niu, found that at about a foot away from the coughing source, a face shield by itself provided the least protection (i.e., 4%). In contrast, a cloth mask reduced cough particles by 77%, and the combination of face shield and cloth mask improved the particle reduction to 89%.

Li and Niu set up a test space in a lab and measured the particle number concentration (PNC) and particle size distribution under seven different conditions: (1) no face covering; (2) face shield only; (3) cloth mask; (4) face shield + cloth mask; (5) surgical mask; (6) face shield + surgical mask; (7) N95 respirator or equivalent (i.e., KN95 mask).

The research suggests that relatively simple measures like masking, combined with physical distancing, hand hygiene, and specific steps taken with regards to being indoors or outside, can make a significant difference in slowing the spread of COVID-19, which has resulted in more than 1.26 million deaths worldwide.

Li was asked to present by a team of evaluators from the American Association for Aerosol Research, a nonprofit professional organization for scientists and engineers who wish to promote and communicate technical advances in the field of aerosol research. The Association supports conferences, symposia, and publication of a professional journal, Aerosol Science and Technology (AS&T).

The new lecture series initiative is supported by the Sheldon K. Friedlander Memorial Fund, and with the editors of AS&T. Each lecture is recorded and available on-demand following the live webinar.

The Friedlander memorial fund honors the late Sheldon K. Friedlander, UCLA Parsons Professor of Chemical Engineering and Director of the Air Quality/Aerosol Technology Laboratory. Friedlander (1927 – 2007) came to UCLA in 1978 from Caltech as a founding member of the Chemical Engineering Department, and served as Chair from 1984-1988. In 1982, he helped found the American Association for Aerosol Research (AAAR); and in 1997, AAAR established the Friedlander Award, recognizing an outstanding dissertation by a doctoral student in the field of aerosol science and technology.