A $10 band makes surgical masks stop 15x more COVID droplets

We thought we were almost done with masks. Then omicron hit, reminding us that even with vaccines, COVID is likely to stick around as an endemic, resurfacing with new variants. And so cyclical masking may simply be a way of life.

[Photo: Robinson Lab/Rice University]

No one is more surprised than Jacob Robinson, an associate professor of engineering at Rice University, who thought that his team’s creation would be old news by the time their latest research was published. their invention? A rubber harness that wraps around a surgical mask, which can be washed and reused. While we’ve seen this approach before, Rice’s project is proven in the lab: A surgical mask fit with this can filter 15 times the droplets of a standard surgical mask. And in more than half of test subjects, this simple add-on was found to make a surgical mask fit at the same standard as an N95 mask. (While most articles categorize N95s as a filtration technology, the truth is that an N95’s more distinguishing feature may be its snug fit, which forces air to filter through the mask rather than sneaking around the sides.)

Jeannette Ingabire [Photo: Jeff Fitlow/Rice University]

“This is something that can be produced very cheaply,” says Robinson of the harness, which cost the lab $10 to produce but would be cheaper at scale. “We make the designs freely available. Anyone can cut them out on a laser printer [or blade] out of a single thin sheet [of rubber]”

The project kicked off when Robinson’s lab was closed due to COVID He and his colleague Caleb Kemere “got, in a sense, bored. We wanted to do something,” says Robinson. “And we have all this equipment in our lab and we were trying to figure out how to put it to use in the early days of the pandemic when research stopped.”

While they couldn’t do their regular work, Rice labs were open for COVID-related research. In early 2020, N95s were a rare commodity, and hospital staffs were getting by wearing surgical masks. After a chance encounter with a doctor who’d hacked together a series of rubber bands to seal a surgical mask to his face, Belt began experimenting with his own rubber shape designed around real ergonomics.

“[In] a lot of our early conversations, [we asked], ‘What is a mask really doing for you?’ We looked into the fabrics behind surgical masks, and they are the melt spun materials that offer high particle filtration [much like N95s]. Clearly, a big difference between an N95 and surgical mask was fit,” says Robinson. “Rather than make something hacky, we wanted to quantify it: Does it perform comparably to an n95?”

To craft their bands, the researchers contacted NIOSH, the certification board behind industrial safety standards like N95 masks. NIOSH has a deep database of more than 1,000 face shapes, which it’s averaged into five types of heads. Rice researchers 3D-printed these heads, fitted them with N95s and their own surgical mask hacks, and hooked them up to a particle measurement machine—called a Portacount—they acquired off eBay. With lab restrictions still in effect, Rice graduate research assistant Jeannette Ingabire ran much of this early testing on her own.

What they learned was what you may have noticed on your own: Most leakage happens around the nose. So they adjusted their design.

[Image: Robinson Lab/Rice University]

Following the redesign, Robinson’s team tested their band on 18 healthcare professionals, using a NIOSH-standardized fit test to measure particles inside the mask and the room, proving the harness fit 78% of people with an N95-level seal. While they didn’t test the active COVID-19 virus, the team concluded that their clever rubber band is a useful tool that may vastly improve the performance of a surgical mask. And that could be useful if and when another COVID variant arises, or whenever we face our next airborne pandemic. Even though they’re single-use items, surgical masks have been in steady supply during the pandemic, while the reusable harness upgrades them to function more like an N95.

“Most [mask studies] we could find came out during the SARS outbreak. We thought, look, even if what we do doesn’t make a difference this time, people will go back and look at the literature for COVID [in the future]. These are the pieces people will build on the next time an outbreak happened,” says Robinson. “Interestingly, we thought [COVID] was going to be over by the time this paper came out . . . we had no idea this would still be relevant research when it came to print.”

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