He said a general rule of thumb is, “If you have a mask and can see through it in the light and can breathe through it, it certainly is not a very good mask.” A knitted mask also performed poorly in the study.
The study also said that “speaking through some masks (especially neck fur) they seemed to distribute the larger dots into a host of smaller dots, which explains the marked increase in the number of dots relative to no mask in that “Given that smaller particles are air longer than large droplets (larger droplets sink faster), using such a mask may be counterproductive.”
Researchers were trying to determine if the masks blocked air release points, or if they blocked the virus from entering. Public health officials say people should wear masks to prevent the virus from spreading, and mask orders are in effect in dozens of states.
“I think most people really want to do the right thing” and prevent the virus from spreading, Warren said. “If you’re really going to try to do it … you have to think a little more about what kind of mask style you’re wearing.”
The study also provided some good news, revealing that a surgical mask on paper, which was tested, almost worked, as well as an N95 mask in blocking the flow of dots, and a number of household clothes masks also did a good job. good.
“What we’re really seeing is that most home remedies, if you adjust them so that there are no big gaps, they do a pretty good job, working just like the medical masks available,” he said. Warren.
The researchers studied the effectiveness of the masks by asking masked subjects to say the words “Stay healthy, people” in the direction of an extended laser beam within a dark closure. The dot on the laser beam then scattered the light, which was recorded with a telephone camera. A computer algorithm was used to count the points, the researchers in the study said.
The researchers said the equipment needed was “usually available”, inexpensive, and “the experimental set-up is simple and can easily be built and operated by non-experts.”
The researchers noted that they were conducting “principle-proof experiments” involving only a small number of speakers, but suggested that their method could serve as a basis for future studies.
“It’s worth understanding that this is not a clinical trial with 10,000 people in every possible circumstance you can do,” Warren said. But he said the researchers wanted to get some information, instead of “getting a letter in the fall of 2021” when it might be too late to help.
The researchers suggested that the measurement method could be used to guide “mask selection and purchase decisions”. They said their method had already been used to guide a decision to purchase masks for the “Cover Durham” initiative in Durham, NC
Jill Crittenden, a researcher at MIT who is a member of the mask group N95cdecon.org, said, “I think it’s good that they want as many people as possible to test as much as possible.”
The study shows that “masks vary greatly in how they protect other people,” she said.
She also said she found some of the shocking findings, including findings about neck fur. “You can imagine some exactly large dots basically going through a sieve basically and becoming smaller particles, which are known to travel farther, so it’s worse than nothing,” she said.
She also stressed that “fitting the mask is important.” The study looked at points that were being expelled in one direction forward, but, “if you have large gaps on the side, for example, it may swell from the face of your face,” she said.
Martin finucane can be reached at firstname.lastname@example.org