The simple cloth mask significantly reduces the spread of COVID-19 respiratory droplets

Reviewed by Emily Henderson, B.Sc.November 12, 2020

A study conducted by Professor Yifang Zhu of UCLA Fielding School of Public Health determined that even a simple cloth mask provides significant protection against COVID-19 transmission, reducing the spread of respiratory droplets by up to 77%.

We found that a simple cough could send particles more than six feet away, with no face coverings. “

Yifang Zhu, Professor, Department of Environmental and Associate Health Sciences Dean for Academic Programs, UCLA Fielding School of Public Health

“About a foot away from the source of the cough, a face shield alone provided the least protection (ie, 4%). In contrast, a cloth mask reduced cough particles by 77% and the face shield combination and tissue mask improved particle reduction to 89%. “

The article “Evaluating the effectiveness of using various face liners to mitigate the transport of airborne particles produced by coughing into the interior” is published in the current electronic edition of the peer-reviewed journal Aerosol science and technology.

Zhu’s team, which includes UCLA scholars FSPH Liqiao Li and Muchuan Niu, set up a test space in a laboratory and measured the particle number concentration (PNC) and particle size distribution in seven different conditions: (1) no face coverage; (2) visor only; (3) cloth mask; (4) visor + cloth mask; (5) surgical mask; (6) visor + surgical mask; (7) N95 respirator or equivalent (i.e. KN95 mask).

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

“To minimize the risk of aerosol transmission infection, stricter mitigation measures should be taken for indoor environments, which are more likely to be enclosed and crowded,” Li said. “One of the simplest is a mask.”