Researchers from the Universities of Bristol and Surrey (UK) have found that well-fitting three-layer fabric masks can be so effective in reducing COVID-19 transmission like surgical masks.
At the height of the pandemic, 139 countries mandated the use of masks in public spaces such as supermarkets and public transport. The World Health Organization (WHO) also advises the use of masks.
In an article published by the journal ‘Physics of Fluids’, the researchers detail how studied the way liquid droplets are captured and filtered in cloth masks, reviewing and modeling filtration processes, including inertial impaction.
Inertial impaction does not filter like a sieve or strainer does, but works by forcing the breathing air to rotate inside the mask so much that the droplets cannot follow the path of the air. Instead, the drops hit the fibers inside the mask to prevent them from being inhaled.
The team found that, under ideal conditions and depending on the fit, three-layer fabric masks can function similarly to surgical masks As for the filtration of the drops, reducing in both cases the exposure between 50 and 75%. For example, if an infected person and a healthy person wear masks, scientists believe that this could lead to up to 94% less exposure.
“Although the use of a simple and relatively inexpensive cloth mask cannot eliminate the risk of contracting Covid, measurements and our theoretical model suggest that they are very effective in reducing transmission. We hope that our work will inspire us to optimize mask design in the future, and we hope that it will help remind people of the importance of continuing to wear masks as long as Covid is present, “says Dr. Richard Sear, study co-author and director. of the Soft Matter Group of the University of Surrey.