Study: 14 Face Masks, Here Are The Best, Worst For Covid-19 Coronavirus


Face masks can be like pizza, at least in certain ways.

People can end up wearing both on their faces, albeit for different reasons. Both can come in a wide variety of types and designs. And not all are created equal. Some (face masks and not pizza) are better than others at blocking droplets that may come out of your nose and mouth. In fact, some face coverings can actually make things worse, causing even more droplets to spew out into the air, according to a study just published in Science Advances.

Yes, you heard that correctly. Wearing some face coverings can be even worse than when you wear nothing at all. That isn’t quite how the Alison Krauss song goes, so how then can a face covering possibly be worse than wearing nothing but the smile on your face? Aren’t face coverings supposed to block all that stuff that comes out of your mouth and nose when you do thing like cough, sneeze, talk, sing, pant, and say, “ohhh, pizza”? Aren’t face coverings supposed to help block your filthy nose and mouth from transmitting the Covid-19 coronavirus to others?

For the study, a team from Duke University (Emma P. Fischer, Martin C. Fischer, David Grass, Isaac Henrion, Warren S. Warren, and Eric Westman) creating some “spitting” images of a person talking into a box. They used freaking laser beams to do this. The laser beams created a sheet of light in the black box in front of a hole in the box. So, essentially the experiment wasn’t just a black box.

Next, the research team asked a person to position his or her mouth at the hole and repeat the phrase, “stay healthy, people,” five times. Therefore, anything that came of the person’s mouth, whether it’s small droplets or hot dog fragments, would subsequently hit the sheet of light, causing the light to scatter. Yes, any droplets would scatter the sheet out of it. A cell phone camera filmed this sheet show, which would allow the researchers to quantify how much stuff was coming out of the person’s mouth.

The person repeated this procedure multiple times, first without any face covering and subsequently with 14 different types of face masks. The person didn’t wear all 14 masks at once, which would look ridiculous. Instead, the person tried them one at a time. The research team established a relative droplet count scale with a 1.0 relative droplet count representing the number droplets that hit the sheet when the person had no face covering and 0.0 representing what happened with the best mask of the bunch.

It should come as no surprise that the best mask was clearly the fitted N95 mask that didn’t have an exhalation valve. After all, this is what health care workers are supposed to wear when their health care facilities actually have enough such masks on hand. These masks are designed to keep droplets and viruses from going either direction, out or in, and protect both the wearer and everyone else. Experiments with this kind of mask in essence kept the sheet together. Such masks aren’t perfect but served as the standard with a relative droplet count of basically zero.

The second place finisher was not too surprising either. Compared to the N95 mask, the three-layer surgical mask had a more variable relative droplet count that ranged from zero to 0.1. These masks are medical grade as well and can be like boxers (the underwear and not Mike Tyson). They keep most things in but every now and then can let something sneak outside.

The third and fourth ranking masks were the ones with polypropylene: the cotton-polypropylene-cotton mask and the 2-layer polypropylene apron mask. These had relative droplet counts around 0.1.

The fifth through eleventh place finishers included four different two-layer cotton pleated masks and one one-layer cotton pleated mask. These fell in the zero to 0.4 relative droplet count range.

Number seven was another type of N95 mask: one with an exhalation valve. This registered a relative droplet count ranging from 0.1 to 0.2. When using an N95 mask, it is important to note whether the mask has an exhalation valve. N95 masks for health care workers don’t tend to have this valve. The valve allows air to move from the wearers mouth and nose to get outside without going through a filter. This makes it a little easier to breathe but at the same time makes it easier for viruses to get out into the air. This exhalation valve be fine if the sole purpose were to protect yourself from what may be in the air, such as when you doing construction. But it doesn’t offer the same protection for others from you that a N95 mask without an exhalation valve would.

The ninth place finisher was a one-layer Maxima AT mask that had an average relative droplet count of 0.2 with its range going no higher than 0.3.

At number 12 was the knitted mask. Not surprisingly this mask had a pretty large range, going from a relative droplet count of around 0.1 to just under 0.6. A knitted mask tends to be like a politician’s speech. It has a lot of holes.

Then there were two masks that could actually be worse than wearing no mask at all. At number 13, the bandanna had a range of 0.2 to 1.2. This suggested that going Axl Rose on your nose and mouth could in some cases allow more droplets to could get through than when going bare-mouthed. How could this be? How could a bandanna create even more droplets? Well, the answer is shear reality.

Depending on its arrangement, construction, and positioning, a bandanna may actually shear larger droplets into many more smaller ones. Think about the last time you try to push a block of Parmesan cheese through a screen window (because who hasn’t tried that). Smaller droplets are worse than larger droplets because they can float in the air longer and may make it through a person’s respiratory tract easier.

The last place finisher showed why when purchasing a face covering, you shouldn’t get fleeced. The fleece mask finished at number 14 on the list, worse even than wearing nothing at all. The average relative droplet county for the fleece face mask was 1.1. Yes, on average, wearing a fleece mask was worse than nose and mouth nakedness.

Of course, this study was not perfect and has its limitations. It didn’t test all possible versions of the different masks and many different people wearing each mask. Spraying droplets doesn’t mean that you necessarily spraying severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) in each and every droplet. And “stay healthy, people,” is not the only thing that you may be saying each day that you are outside. You may be saying other things such as “it is what it is.”

Nonetheless, all of this is a reminder that there are nuances with public health recommendations. When you are covering your face, think about what you using to cover it. Covering your face with sweat, chocolate, or pizza sauce is not quite the same as a mask. And even masks can be quite different. Be careful when purchasing a mask. After all, you wouldn’t say, “just bring me some pizza, any kind of pizza,” would you?



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