Cotton mask or neck warmer? Discover the effectiveness of different types of masks

© Karl Gelles / USA TODAY
effectiveness of masks

The body of evidence continues to grow: masks protect the wearer from COVID-19, in addition to those around them. But with so much to choose from, what’s your best option?

Regardless of the mask type, fewer coronavirus particles are reaching people wearing face masks, according to a new article due to be published in the Journal of General Internal Medicine shortly. Fewer particles could lead to milder infections if the virus gets through.

Another study, published last month, compared the growth rate of COVID-19 before and after mask warrants in 15 states and the District of Columbia. He found that the mask warrants coincided with slowdowns in daily COVID-19 growth rates.

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Testing the effectiveness of coronavirus masks

While working on another recently published study, researchers at Duke University evaluated the effectiveness of 14 different types of masks by estimating the number of droplets passing through the mask during normal speech.

The researchers used a laser beam, a lens that turned a laser beam into a sheet of light, and a mirror that directed the light into a dark cardboard box. People said the same sentence in the box with and without a mask. The particles that hit the lens produced visible flashes recorded by a phone’s camera on the other end of the box.

“The key point of this article is that we offer a very simple and easily duplicable system, in which community groups could test the masks themselves,” said one of the study’s co-authors, Warren S. Warren, professor of physics and chemistry. and radiology at Duke.

So what is the most effective type of mask against COVID-19?

Solid dots represent the results of 10 tests for a mask by a loudspeaker. Hollow circles represent the relative number of droplets for four speakers.

1. N95 mask adjusted

The N95 medical mask without an exhalation valve turned out to be the most effective. However, the CDC is asking the general public not to wear N95 respirators, the supply of which is limited, so they can be reserved for healthcare workers and first responders.

2. Three-layer surgical mask

When study participants said the phrase “keep people healthy” wearing a three-layer surgical mask, only a tiny fraction of the droplets got passed.

Surgical masks are for single use only and are designed to protect the wearer’s nose and mouth from contact with droplets, splashes and sprays that may contain germs. They also filter out large particles in the air.

3. Cotton-polypropylene-cotton mask

A mask consisting of two layers of cotton and one layer of synthetic material has proven to be the most protective option apart from masks intended for healthcare professionals. Another recent study suggested that a homemade fabric face mask likely needed two or three layers to effectively prevent the spread of the coronavirus.

A single-layer coating reduced the spread of speech droplets, while the double-layer coating was better at reducing cough and sneeze droplets, the researchers said.

4. Polypropylene apron mask

This mask had two layers of polypropylene, a soft, easy-to-clean synthetic fabric. Polypropylene is one of the most popular materials for masks because viruses and bacteria cannot live on the fabric for long.

According to a study published in Nano Letters, polypropylene may be one of the best materials for a homemade mask. It has the electrostatic charge which traps the incoming and outgoing particles. It loses its electrostatic charge when washed, but can be recharged by rubbing it with a plastic glove.

5. Windrow

The researchers used a slightly damp washcloth in another experiment. Using the high-speed video, they found that saying a single sentence generated hundreds of droplets ranging from 20 to 500 microns. The washcloth blocked almost all of these droplets from the person’s mouth.

6 – 7. Two-layer pleated style masks

When choosing the material, make sure the cotton is woven at a high density so that there are no pores visible under light, according to the study by Nano Letters. If not, it may be better to use multiple coats.

“I wouldn’t give too much importance to the small differences that we saw between the different cotton masks; I want to stress that fit is important,” Warren said.

8. N95 valve

The researchers noted that while the valve does not compromise the protection of the wearer, it may decrease the protection of people around because the masks release exhaled air through their openings, according to the CDC.

The CDC also recently updated its guidelines advising Americans to avoid face masks with exhalation valves or vents because they are not as effective at preventing the spread of COVID-19.

9. Olson style mask

The Olson mask model was named after the nurse who created fabric masks to use when medical masks were not available. It is curved to fit the nose and mouth. These masks are not a replacement for N95 masks in healthcare settings, but they can be good for personal use.

10. Maxima AT Mask

This “Maxima AT 1-Layer Mask” may look slightly like surgical masks, but it doesn’t offer as much protection, research shows.

11. Single layer pleated style mask

The mask with a diaper malfunctioned. The World Health Organization recommends that fabric masks have three layers: an inner layer that absorbs, a middle layer, which can be inserted in the middle to act as a filter, and an outer layer made of a non-absorbent material. like polyester.

12. Two-layer pleated style mask

It is important to make sure the mask fits properly and covers your nose and mouth. Studies suggest that 60% of users fail to install surgical masks on the first attempt.

If the mask is loose, this allows significant air leakage around the seal areas and may contribute to aerosol exposure. Having a mustache or beard can also make it difficult to fit the mask properly.

13. Knitted mask

For this one, the researchers used a mask with a looser weave.

“Think of fabric as something more similar to a sock than a bed sheet, which is more like what you get for standard cotton,” Warren said.

Larger pores in masks can allow more particles to penetrate. Washing and drying the mask can further reduce its effectiveness.

14. Bandana

Bandannas were found to be one of the least effective in the study published in June in the journal Physics of Fluids. Although a bandana can reduce the range of particles expelled during a cough, it scores lower than a cough discovered to stop the smaller aerosolized respiratory droplets.

15. Neck warmer

A neck warmer, a favorite with runners, was worse than no mask at all. Porous fabric can break larger particles into smaller ones. Smaller particles stay in the air longer than large droplets.

However, Warren stresses that the research he co-wrote was not a large-scale clinical trial, so the results cannot be generalized. The result for the gaiter was worse because some of the more comfortable masks are generally thin and don’t do a good job of blocking particles.

The study gaiter was made from a single layer of polyester-spandex blend. “When we take a look at the gaiter that we used, for example, if you hold it the only layer to a light, stretched as it would be when worn, you can see the light through” , Warren said. the feeling is that if it does, it doesn’t do a very good job protecting the people around. “

This article originally appeared on USA TODAY: Cotton mask or neck warmer? Discover the effectiveness of different types of masks

Gallery: Here are the best and worst face masks, say experts (ETNT Health)