And little was known about how effective each one was at preventing respiratory drops.
That is, until Duke University researcher Drs. Martin Fisher came up with a simple test to measure it.
The experiment, published on Friday in Science Advances, tested 14 different types of masks, and Fisher’s colleague Dr. Eric was inspired by Westman’s request, which works with Cover Durham, which takes the initiative to cover reusable faces to those in need. . Westman asked if someone at the school could assure him that the masks he received as donations were effective.
To test the coverings, scientists designed a black box with a laser and a cellphone camera, and four testers tried out 14 donated options. Wearing each mask, a tester speaks in the direction of the laser beam inside the box, saying the phrase “stay healthy, people” five times. A camera recorded the amount of respiratory drops determined by speech, and an algorithm determined how many drops were leaking through the face covering.
“A simple measurement was about establishing a technique that could be reproduced,” Fisher told the Post.
And while he does not advocate a specific mask, Fisher – who wears an original cotton version himself – says the overarching point of the study is that many varieties are very effective. But you are better off wearing a real mask than trying to stick to the bank in the Wild West.
The face coverings here are a breakdown of Fisher and his team, ranging from a strong sealed medical N95 mask to a shattering neck garter.
1. medical n95 mask
No wonder the “3M 1860 Surgical Mask and Particulate Respirator” is worn by health care workers: it was the most effective of the bunch on the logarithmic scale of the study.
2. Surgical Mask
This disposable surgical mask was the second most effective variety, ranging from zero to 0.1 in the case of particles that spread during speaking during a wear.
3. Polypropylene and Cotton
Polypropylene, a synthetic material placed between two layers of cotton, was the third best.
4. Polypropylene Apron Mask
This mask, made with two layers of synthetic material, was only marginally worse than the one made with both cotton and polypropylene.
5. Cotton mask with ties
The next six cotton masks all perform around the same level, which Fisher said shows variable matter. “It depends how loud you speak, and how well it fits around your face,” or if the facial hair is loosely fitted, he said.
6. Two-layer cotton with ties
Just behind the green tie mask was another cotton version with two layers, and straps that went downward and tied behind the ears.
7. Velvet n95
The N95 masks with exhalation valves are designed to protect the user from inhaling harmful material, not necessarily some other way around, which could have contributed to its performance.
8. sewn by hand
This cotton mask was sewn using the popular “Olson” pattern, which is available online.
9. ‘Maxima AT’ Mask
A variety of cotton from the North Carolina-based company Hudson Hill was tied with essentially identical-looking single-layer cotton masks.
10. Single-layer cotton
This one-layer mask outperformed the one with two layers, which should serve as a reminder of the variables in the experiment and in life, Fisher said.
11. Two Layered Cotton
It is a two layered cotton pleated style mask, which is slightly worse than its other similar styles.
A mask made of what appears to be a T-shirt knit (Fisher wanted to say that researchers are not textile experts) had more variability of droplet projection than other styles.
Acclaimed by celebrities such as Johnny Depp and Kristen Stewart, the folded bandana has become a chic covering option, but it is basically useless, with many studies – including Duke’s – found.
Here the stretcher garter (a style darling by the runner) was tested which was worse than applying a full mask, and larger particles were shown to break into smaller ones, allowing them to slip more easily from the sides. Is found.