What is it about?

To curb COVID-19's spread, scientists have advised wearing face masks. Many businesses and governments also made masks compulsory while in public. Recently, people have started to use plastic face shields or respirators with breathing valves as well. However, it is unclear if these are as effective as regular cloth or surgical masks. To address this gap, this study's authors checked if the new masks could keep out infectious droplets and perform better than regular masks. Apparently, the face shield and the mask with valves could keep large droplets that we breathe out from escaping the covering. The smaller droplets, however, kept flowing on the surface and increased chances of contamination. With the valve, a good amount of air passed unfiltered. This allowed droplets to escape faster than with a regular N95 mask.

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Why is it important?

Several factors come into play while trying to explain why people avoid surgical and cloth masks. To begin with, the shield is more comfortable to wear. It does not restrict breathing or cause fogging. Second, it is easier to communicate while wearing the shield. This is because we can see the person's face behind the shield. Clearly, these options are comfortable. Despite the improved comfort, these options violate the Center for Disease Control (CDC) guidelines. Ac-cording to the CDC, these should not be used alone. Another concern is that two similar looking surgical masks can have different filtering efficiencies. This depends on their fabric and quality. KEY TAKEAWAY: Studies show that wearing high quality cloth or surgical masks can protect against COVID-19. Face shields or valve masks may not be as effective at keeping infectious droplets out of the mouth or nose. This can increase the risk of infection.

Read the Original

This page is a summary of: Visualizing droplet dispersal for face shields and masks with exhalation valves, Physics of Fluids, September 2020, American Institute of Physics, DOI: 10.1063/5.0022968.
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