Are cloth masks just as good as surgical masks in stopping the transmission of COVID-19? Researchers from the Universities of Bristol and Surrey are saying yes – as long as it’s a three-layered cloth mask.
The researchers published a paper detailing their work in the Physics of Fluids journal. The paper detailed how they looked at how liquid droplets are captured and filtered out in cloth masks by reviewing and modeling filtration processes, including inertial impaction.
Inertial impaction does not filter as a sieve or colander does -- it works by forcing the air in your breath to twist and turn inside the mask so much that the droplets can't follow the path of the air. Instead, the droplets crash into fibers inside the mask to prevent inhalation.
The team found that, under ideal conditions and dependent on the fit, three-layered cloth masks can perform similarly to surgical masks for filtering droplets -- with both reducing exposure by around 50% to 75%. For example, if an infected person and a healthy individual are both wearing masks, scientists believe this could result in up to 94% less exposure.