Researchers test protection of consumer grade and modified masks against COVID-19

Using a custom-built exposure chamber, scientists from the UNC and EPA School of Medicine tested consumer masks and makeshift face coverings to show how effective they can be in protecting people from airborne particles from Similar in size to those carried by SARS-CoV-2, the virus that causes COVID-19.

When two people wearing masks interact, it has been shown that the possibility of COVID-19 transmission is dramatically reduced. That is why public health officials have asked all people to wear masks: they not only protect the user from the expulsion of particles that could carry SARS-CoV-2, the virus that causes coronavirus 2019 (COVID-19 ), but the masks also protect the wearer from inhaling particles that carry the virus. Some people, however, still refuse to wear a mask. So scientists at the UNC School of Medicine, in collaboration with the Environmental Protection Agency, investigated the protection of various types of consumer-grade and modified masks, assuming that the mask user was exposed to the virus, such as when we interact with an infected person without a mask.

Published in the magazine JAMA Internal Medicine, research shows that some masks were up to 79 percent effective at blocking particles that could carry the virus. These were masks made from two layers of woven nylon and fit comfortably on the wearer’s face. Unmodified medical procedure masks with earmuffs, also known as surgical masks, offered a filtration efficiency of 38.5 percent, but when the earmuffs were tied in a specific way to adjust the fit, the effectiveness improved to 60.3 percent. And when a layer of nylon was added, these masks were 80 percent effective.

While modifications to surgical masks can improve filtering capabilities and reduce inhalation of airborne particles by improving mask fit, we demonstrated that the adjusted filtration efficiencies of many consumer masks were nearly equivalent to or better than masks surgical “.

Phillip Clapp, PhD, co-first author, inhalation toxicologist, assistant professor of pediatrics, UNC School of Medicine

Co-first author Emily Sickbert-Bennett, PhD, director of infection prevention at UNC Medical Center, added: “Limiting the amount of virus is important because the more virus particles we are exposed to, the more likely we are to catch it. sick and potentially seriously ill. “

As the adoption of face coverings during the COVID-19 pandemic became common, there was a rapid expansion in public use of commercial, homemade, and makeshift masks that vary considerably in design, material, and construction. There have been a number of innovative “tricks”, devices, and mask enhancements that claim to improve the performance characteristics of conventional masks, generally surgical or procedural masks. Despite their wide spread and use during the pandemic, there have been few evaluations of the efficacy of these face coverings or mask enhancements in filtering airborne particles.

In this study, the researchers used a recently described methodological approach based on OSHA’s fit testing to determine the adjusted filtration efficiency (FFE) of a variety of makeshift and consumer face masks, as well as several popular modifications of procedural masks. doctors. Seven consumer grade masks and five medical procedure mask modifications were placed on an adult male, and FFE measurements were collected during a series of repeated movements of the torso, head, and facial muscles as described in the Protocol of OSHA quantitative fit test.

Here are the different types of face masks with filtration efficiency. Below is the top-of-the-line N-95 mask in bold, which proved to be 98 percent effective.

Consumer face masks:

2-layer woven nylon mask, ear loops, without aluminum nose bridge: 44.7%
2-layer woven nylon mask, earmuffs, with aluminum nose bridge: 56.7%
2-layer woven nylon mask, earmuffs, with nose bridge, 1 non-woven insert: 74.4%
2-later woven nylon mask, loops, with nose bridge, washed, without insert: 79%
Cotton bandana – folded Surgeon General style: 50%
Cotton bandana – folded “Bandit” style: 49%
Single Layer Woven Polyester Gaiter / Neck (Balaclava): 37.8%
Single layer polyester / nylon fabric mask with ties: 39.7%
Non-woven polypropylene mask with fixed earmuffs: 28.6%
Three-layer woven cotton mask with ear flaps: 26.5%

Medical face masks and modifications:

NIOSH Approved 3M 9210 N95 Respirator: 98%
Surgical mask with ties: 71.4%
Procedural mask with earmuffs: 38.5%
Procedure mask with earmuffs + “tied loops and tucked corners”: 60.3%
Procedure mask with earmuffs + “Ear Guard”: 61.7%
Procedural mask with earmuffs + “23mm claw hair clip”: 64.8%
Procedure mask with earmuffs + “Fix-the Mask (3 rubber bands)”: 78.2%
Procedure mask with earmuffs + “nylon sleeve”: 80.2%