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Your face shield probably isn’t helping anyone, new study finds

A new study suggests face shields offer less protection for others compared to regular masks.

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Marci Warren, Utah Transit Authority customer experience researcher, holds a sign up to a FrontRunner train at the Salt Lake Central Station in Salt Lake City on Wednesday, July 1, 2020, as she and her team test where to hang new signs alerting passengers that face masks must be worn in order to ride public transit.

Marci Warren, Utah Transit Authority customer experience researcher, holds a sign up to a FrontRunner train at the Salt Lake Central Station in Salt Lake City on Wednesday, July 1, 2020, as she and her team test where to hang new signs alerting passengers that face masks must be worn in order to ride public transit.

Kristin Murphy, Deseret News

Face shields and masks that have exhalation valves appear to be less effective at stopping you from spreading the coronavirus to others compared to normal face masks and coverings, according to a new study.

What’s going on:

The new study — published in the journal Physics of Fluids — found that face shields and masks with exhalation valves might spread more particles than other face masks.

This means those around you might be in danger of getting the novel coronavirus, especially if you’re asymptomatic.

  • “From this latest study, we were able to observe that face shields are able to block the initial forward motion of the exhaled jet, however, aerosolized droplets expelled with the jet are able to move around the visor with relative ease,” the researchers said in a statement. “Over time, these droplets can disperse over a wide area in both lateral and longitudinal directions, albeit with decreasing droplet concentration.”

A visual demonstration released with the study showed huge clouds of particles escaping from under the face shields and through the vented mask.

  • The researchers wrote: “We observe that face shields are able to block the initial forward motion of the exhaled jet; however, aerosolized droplets expelled with the jet are able to move around the visor with relative ease. There is a possibility that widespread public adoption of the alternatives, in lieu of regular masks, could have an adverse effect on ongoing mitigation efforts against COVID-19.”

Best types of masks

Back in August, a study from Duke University revealed the most effective ways to block COVID-19, as I wrote about for Deseret.com. The study looked at which masks stop droplets from hitting you and others.

  • The best masks include the surgical N95, the three-layered surgical and the cotton.
  • Fleece, bandanas and knitted masks were listed as less effective.