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Home / Health / Research raises questions about the effectiveness of gowns, towels, and knit masks in preventing the spread of the virus.

Research raises questions about the effectiveness of gowns, towels, and knit masks in preventing the spread of the virus.



He says a general rule of thumb: ‘If you have a mask and you can see through it under the light and you can blow through it, that’s probably not a very good mask. “The knitted mask also performed poorly in research.

Duke University researchers tested more than a dozen different types of face masks.
Duke University researchers tested more than a dozen different types of face masks.Emma Fischer / Duke University

The study also states that “speaking through some masks (especially the wool of the neck) seems to scatter the largest droplets into a myriad of smaller droplets, which explains the apparent increase in the number of drops compared with no mask in that case. Considering that smaller particles stay in the air longer than large ones (large droplets sink faster), using such a mask can be counterproductive.

Researchers are trying to determine if masks block droplets from being released into the air, but not if they stop viruses from entering. Public health officials say people should wear masks to stop the spread of the virus and the masking orders take effect. dozens of states.

“I think most people really want to do the right thing,” Warren said and stop the spread of the virus. “If you’re really going to do that … you have to think a little more about the type of mask you’re wearing.”

The study also provides some good news, finding that the tested paper surgical masks function almost similar to the N95 mask in stopping the flow of water droplets and some fabric masks. Homemade also works well.

“What we actually found is that most homemade solutions, if you fit them so that there are no large gaps, they work pretty well, work similarly to disposable medical masks,” Warren said.

The researchers studied the mask’s effectiveness by asking the masked subjects to say the words “Be healthy, everyone” in the direction of a laser beam extending inside a dark crust. The droplets in the laser beam will then scatter the light, captured by cell phone cameras. The researchers said in this study used a computer algorithm to count water droplets.

The required equipment is “generally available”, inexpensive and “the test setup is very simple and can easily be built and operated by non-specialists,” the researchers said.

The researchers noted that they were conducting “proof-of-principle experiments” that involved only a small number of speakers, but suggested that their method could serve as a basis for future studies. hybrid.

“It is important to understand that this is not a clinical trial with 10,000 people in every possible case,” Warren said. But he said the researchers wanted to give some information, rather than “giving out a newspaper in the fall of 2021”, when it might be too late to help.

The researchers propose that the measurement method can be used to guide “mask buying and selection decisions”. They say their method has been used to guide the mask buying decision for the “Che Durham” initiative in Durham, NC.

“I think it’s great that they want as many testers as possible,” said Jill Crittenden, a researcher at MIT who is part of the N95cdecon.org group of masking specialists.

Research shows that “masks change a lot in how well they protect others,” she says.

She also said she found a number of shocking findings, including the finding of wool in the neck. She said: “You can imagine some really big drops going through a sieve and becoming smaller particles, which are known to move further, so that’s even worse than nothing. .

She also emphasized that “the fit of the mask is very important.” The study looked at the droplets being pushed out in the forward direction, but, “if you have a large gap on the side, for example, it could blow out one side of your face,” she said.


Martin finucane can be contacted at martin.finucane@globe.com




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