Simple Face Mask Modifications Could Lead to Better COVID-19 Protection: Study

Researchers at the UNC School of Medicine have discovered that making certain modifications to face masks can increase protection even more.

Studies have already shown that when two people wear face masks, they have a greatly reduced risk of contracting COVID-19. But the UNC researchers wanted to see how other modifications might enhance protection. They subjected face masks to a variety of modifications and tests, then analyzed the level of protection the modified masks offered. With the right modifications, some masks were found to be as high as 79% effective at blocking particles that could carry SARS-CoV-2—the virus that causes COVID-19. This excludes N95 respirators, which are significantly more effective.

The findings were published in the journal JAMA Internal Medicine.

The researchers used seven consumer-grade masks and five medical masks on a volunteer. Using a methodological approach based on the Occupational Safety and Health Administration (OSHA) Fit Test, the researchers determined the fitted filtration efficiency (FFE) of the masks.

Once they were fitted on the volunteer, FFE measurements were collected during a series of repeated movements of the torso, head, and facial muscles as outlined by the OSHA Quantitative Fit Testing Protocol.

The researchers tested a variety of masks, including:

• A 2-layer woven nylon mask with ear loops (tested with an optional aluminum nose bridge and nonwoven filter insert in place)
• A cotton bandana folded diagonally once (i.e., “bandit” style) or in a multilayer rectangle according to the instructions presented by the U.S. Surgeon General
• A single-layer woven polyester/nylon mask with ties
• A nonwoven polypropylene mask with fixed ear loops
• A single-layer woven polyester gaiter/neck cover balaclava bandana
• A 3-layer woven cotton mask with ear loops.

The researchers also looked at specific face mask modifications, such as:

• Enhancing the mask/face seal with rubber bands over the mask
• Enhancing the mask/face seal with a band of nylon hosiery over the fitted mask
• Fastening ear loops behind the head with 3-dimensional–printed ear guards
• Fastening ear loops behind the head with a claw-type hair clip
• Tying the mask’s ear loops and tucking in the side pleats

Lead study author Phillip Clapp, PhD, an inhalation toxicologist and assistant professor of pediatrics at the UNC School of Medicine, tells Verywell that his team wanted to study mask efficacy because of the “wide variety of masks available” to the general public.

“The effectiveness of cloth masks as PPE has not been clearly quantified before our evaluations,” says Clapp. “In addition, simple fixes to readily available masks (e.g., earloop masks) have become popular and widely-shared on websites such as YouTube. These modifications claim to greatly improve fit and overall effectiveness but haven’t been tested to assess whether they actually increase protection for the wearer.”

The Results

N95 masks were the most efficient at blocking particles, but consumer face masks also did a good job with certain modifications. Here’s a breakdown of the findings, and how effective they were at filtrating particles.

Consumer-grade face masks:

• 2-layer woven nylon mask, ear loops, w/o aluminum nose bridge: 44.7%
• 2-layer woven nylon mask, ear loops, w/ aluminum nose bridge: 56.3%
• 2-layer woven nylon mask, ear loops, w/ nose bridge, 1 non-woven insert: 74.4%
• 2-later woven nylon mask, ear loops, w/ nose bridge, washed, no insert: 79%
• Cotton bandana – folded Surgeon General style: 50%
• Cotton bandana – folded “Bandit” style: 49%
• Single-layer woven polyester gaiter/neck cover (balaclava bandana): 37.8%
• Single-layer woven polyester/nylon mask with ties: 39.3%
• Non-woven polypropylene mask with fixed ear loops: 28.6%
• Three-layer woven cotton mask with ear loops: 26.5%

Medical face masks and modifications:

• 3M 9210 NIOSH-approved N95 Respirator: 98%
• Surgical mask with ties: 71.5%
• Procedure mask with ear loops: 38.5%
• Procedure mask with ear loops + “loops tied and corners tucked in”: 60.3%
• Procedure mask with ear loops + “Ear Guard”: 61.7%
• Procedure mask with ear loops + “23mm claw hair clip”: 64.8%
• Procedure mask with ear loops + “Fix-the Mask (3 rubber bands)”: 78.2%
• Procedure mask with ear loops + “nylon hosiery sleeve”: 80.2%

Which Masks and Modifications Are the Most Effective?

For most people, making easy modifications to a standard cloth mask is a good start, study co-author Emily Sickbert-Bennett, PhD, director of infection prevention at the UNC Medical Center, tells Verywell. “The simple tying of the mask’s ear loops and tucking in the side pleats is an easy, effective method that requires no additional supplies."

Sickbert-Bennett says that people should choose a modification that improves the fit and is comfortable, but adds that "Ultimately, the best mask is one that you will wear.”

Clapp says that mask modifications are "simple and can improve fit and overall effectiveness." While it's not yet known what overall effectiveness is needed to prevent the transmission of SARS-CoV-2, Clapp adds that “improving fit is a simple measure that can offer us more protection in the midst of a surging pandemic.”

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.