Tag Archive for: Double Masking

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Cloth face coverings can be as effective as surgical masks at protecting against COVID-19

Cloth face coverings can be as effective as surgical masks at protecting against COVID19 - تاثیر بالای ماسک های پارچه ای

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.

In a paper published by the Physics of Fluids journal, the researchers detail how they 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 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.

Release date: 28 April 2021
Source: University of Surrey

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Fit Matters Most When Double Masking to Protect Yourself from COVID-19

Fit Matters Most When Double Masking to Protect Yourself from COVID19 - محافظت با دو ماسک

A study published in JAMA Internal Medicine shows that wearing two face coverings can nearly double the effectiveness of filtering out SARS-CoV-2-sized particles, preventing them from reaching the wearer’s nose and mouth and causing COVID-19. The reason for the enhanced filtration isn’t so much adding layers of cloth, but eliminating any gaps or poor-fitting areas of a mask.

To test the fitted filtration efficiency (FFE) of a range of masks, UNC researchers worked with James Samet, PhD, and colleagues in the USEPA Human Studies Facility on the campus of UNC-Chapel Hill. There they filled a 10-foot by 10-foot stainless-steel exposure chamber with small salt particle aerosols, and had researchers don combinations of masks to test how effective they were at keeping particles out of their breathing space.

Each individual mask or layered mask combination was fitted with a metal sample port, which was attached to tubing in the exposure chamber that measured the concentration of particles entering the breathing space underneath the researcher’s mask. A second tube measured the ambient concentration of particles in the chamber. By measuring particle concentration in the breathing space underneath the mask compared to that in the chamber, researchers determined the FFE.

Release date: 16 April 2021
Source: University of North Carolina Health Care