Two words on the problem with face shields: Vortex rings

For better or worse, the COVID-19 pandemic has ushered in a new world that looks like at least for now, it’s here to stay. And one of the biggest changes most of us deal with on a daily basis is those masks we must don to head to the grocery store, pump gas or even walk to a table in a restaurant.

Yet, many people worry about what the masks themselves mean to their health, and even how not being able to see the expressions of the people around us could damage social interactions.

This has led some to turn to face shields — clear coverings they hope will afford protection against coronavirus droplets that could be lurking in the air, while mitigating reasons they may have for not wearing the traditional cloth masks.

But does wearing a face shield alone provide enough protection against COVID-19 transmission? After what Researchers at Fukuoka University in Japan discovered, they, at least, would probably say “no.”

And it’s all due to what they call sneeze “vortex rings.”

A donut-shaped vortex with microscopic droplets

Research published in Physics of Fluids, explored the efficacy of surgical masks and face shields in helping stop the spread of the virus that causes COVID-19.

But what they ended up learning was what exactly happens to the airflow around a face shield when someone nearby sneezes.

Basically, the researchers found that when someone sneezes, it produces a fluid phenomenon — this is what they’ve labeled the “vortex ring.”

According to the team, the ring is shaped like a donut since it’s made up of fluid being expelled from a circular orifice — your nostrils or mouth.

They say these vortex rings look very similar to the bubble rings made by dolphins when they breathe.

And guess what…

Those vortex rings suck up the microscopic droplets a sneeze generates. If those droplets are carrying the flu virus, the vortex rings are carrying the flu virus. If you have droplets with COVID-19, you’ve got a vortex ring packed with COVID-19 that you’re sharing with those around you.

But what about your personal protection from a face shield?

Now, here’s where things get interesting (or, really gross) when it comes to only wearing a face shield…

The team found that when a face shield wearer is exposed to a sneeze from an infected person standing 1 meter (39.3 inches) in front of them, the vortex rings grab the potentially virus-laden droplets and transport them to the top and bottom edges of the face shield.

So, if you’re the one wearing that face shield and happen to be taking a breath when that happens, you inhale those infected droplets along with the air you breathe.

Of course, using cloth masks has not been found to be 100 percent effective either, but after learning about the vortex ring phenomenon, it’s a safe bet the cloth masks could do a better job of keeping you safe from a sneeze.

Wearing a cloth mask for long periods of time is certainly not fun. But there are steps you can take to minimize the discomort, including skin damage. Certain fabrics have also been found to work better than others if you’re adventurous enough to make your own face mask.

Mask up or add a face shield on top of your mask, but never go with a face shield alone.

Sources:

Face shields no match for sneeze vortex rings — EurekAlert!