3-layered cloth masks effective as surgical masks against Covid
London: A team of researchers have found that well-fitting, three-layered cloth masks can be as effective at reducing the transmission of Covid-19 as surgical masks.
The team from the Universities of Bristol and Surrey 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 per cent.
For example, if an infected person and a healthy individual are both wearing masks, scientists believe this could result in up to 94 per cent less exposure, showed the findings published in the journal Physics of Fluids.
“While wearing a simple and relatively inexpensive cloth face mask cannot eliminate the risk of contracting Covid-19, measurements and our theoretical model suggests they are highly effective in reducing transmission,” Richard Sear from the University of Surrey, said.
“We hope that our work inspires mask designs to be optimised in the future and we hope it helps to remind people of the importance of continuing to wear masks while Covid-19 remains present in the community,” he added.
At the height of the Covid-19 pandemic, 139 countries mandated the use of face coverings in public space such as supermarkets and public transports. The World Health Organization also advises the use of face coverings and offers guidance on their effective features. Face coverings suppress the onward transmission of Covid-19 through exhalation and protect the wearer on inhalation.
To better understand, the team looked at how liquid droplets are captured and filtered out in cloth masks by reviewing and modelling 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 fibres inside the mask to prevent inhalation, the team explained.