Cloth masks a worthy line of defense to mitigate COVID-19 pandemic

ASU professor tests homemade cloth mask to see how effective it can be at stopping aerosolized microparticles

May 14, 2020

Editor’s note:  This story is being highlighted in ASU Now’s year in review. Read more top stories from 2020.

Sarah Arrowsmith, a scientist and lab coordinator with the Arizona State University Biodesign Swette Center for Environmental Biotechnology, was stuck at home starting in mid-March — just like the rest of us. But unlike others, she pulled out her sewing machine and set to work making masks. Illustration by Christine Lewis Download Full Image

Arrowsmith was prompted to action after Diana Calvo, a doctoral candidate in the center, asked whether the center could donate face masks to her husband’s medical facility. The global shortage of personal protective gear has resulted in countless medical facilities scrambling for supplies. Unfortunately, the center had already donated its masks elsewhere, but it occurred to Arrowsmith that she could still help.

“Sarah searched for masks everywhere — online, Home Depot, fire departments and veterinary offices, to name a few. But she could not find any,” Calvo said.

After looking at a 2013 publication that studied the effectiveness of cloth masks against viral particles, Arrowsmith was convinced that homemade masks could work. So, she made a pattern, pulled out some cloth and constructed some masks on her own. In just 48 hours, she not only sewed masks for the medical facility but also for several local first responders, totaling 50 masks in all. 

“She did this without asking for anything in return and even made them sustainable — a quality we really prize in environmental engineering,” Calvo said. “The medical facility can autoclave and reuse them.”

Arrowsmith was ahead of the curve for a nationwide mask-making movement that was just gearing up. Countless people under quarantine are dusting off sewing machines to make masks for health care workers who are pleading for help. A general consensus is that they are better than nothing. The American Hospital Association (AHA) agrees. In late March, the AHA launched the 100 Million Mask Challenge calling on manufacturers and individuals at home to produce essential gear for medical facilities across the nation.

Cloth masks are the first line of defense

As of May 13, the U.S. reported 1 million confirmed infections and 84,243 fatalities, far surpassing the statistics of other countries. With the spread of COVID-19 so rapid and red zone eruptions unpredictable, the Centers for Disease Control and Prevention redirected its guidelines to advise all individuals leaving their homes to wear masks made from cloth.

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ASU Professor Pierre Herckes.

“This absolutely helps,” said Pierre Herckes, a professor in the ASU School of Molecular Sciences and an expert in aerosolized particles that can affect health. “The most effective action right now is social distancing, but the cloth masks offer a first line of defense if you have to go out in public.”

“Tiny particles don’t just move in a straight path — they are subject to Brownian motion — darting about randomly,” Herckes said. “Due to this —the masks catch more than you would imagine in both directions. They protect and prevent much of the viral particles in droplets from dispersing into ambient air.”

Infected individuals can shed the virus for three to 10 days before showing symptoms — if they show symptoms at all. So, foregoing a mask because you feel well can still pose a danger to others.

“Imagine someone sneezes at the grocery store. The droplets expelled can actually stay in the air from 30 minutes to hours. This is because airborne droplets evaporate, and the smaller particles left behind remain suspended,” Herckes said.

Tiny particles are subject to Brownian motion, where they dart about randomly. This allows cloth masks to have more efficiency than expected. Image composed by Christine Lewis

Maskless crowds are especially daunting when considering air transfer through a ventilation system to rooms where people think they are isolated.

Herckes does point out that it’s uncertain as to how long the virus is "active" indoors when suspended since there are very few studies on this. Although, there was a recent report from the U.S. White House that shows when the virus suspended in the air outside, it is active for one to 1½ hours.

Mask versus particle

N95 masks are the gold standard for catching tiny particles but should be reserved for COVID-19 health care workers. So, Herckes began testing different materials he found at home to see what would be effective for public use. Even with one layer of a T-shirt, the test results showed the masks captured larger droplets pretty efficiently.

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Sarah Arrowsmith, lab coordinator and scientist at Biodesign Institute Center for Environmental Biotechnology. 

Herckes and Arrowsmith decided to put her multilayered, home-made mask to a real test; mask versus particle.

“I really did want to know if my masks were making a difference,” Arrowsmith said. “There are such mixed messages about masks in the media right now.”

Zhaobo Zhang, a graduate student in Herckes lab ran the test. The lab used a special device that disperses particles of different sizes against the mask material that is clamped in place. 

“These results are quite good,” Zhang said. “But we must remember that this test was run quickly under controlled conditions, different from official testing methods. Our set-up presses the mask material tightly together and the material will be much looser when you are actually wearing it.”

Arrowsmith’s mask caught roughly 95%-99% of particles that ranged in size between 0.07 and 0.209 microns — that is at least 1000 times smaller than the diameter of a human hair. These small particles, some smaller than virus particles, are typically the most challenging to capture. Larger particles or droplets are more readily stopped. 

“A lot of the coughing and sneezing droplets are in the range of a few microns to tens of microns (a human hair is approximately 75 microns). However, studies show that we exhale smaller particles too, called microdroplets — not only related to sneezing or coughing — but also just speaking and exhaling. These can be hundreds of times smaller,” Herckes said.

“It is always true with cloth masks that there can be particles that make it through the gaps between the face and the mask edges, so the tighter the fit, the better. I must admit Arrowsmith’s did much better when compared to other homemade masks — which is great,” he said. The secret was that she used two layers of cotton and had a HEPA filter she placed inside to catch even the tiny particles.

“Actually, this makes me really happy and now I know it was worth the effort. I guess the moral of this story is that using homemade masks will make us safer,” Arrowsmith said.

How to make a mask

Arrowsmith constructed the masks with ties rather than elastics to avoid sterilization or disinfectant breakdown.

Double-layered masks constructed from all-cotton tea-towels show the most filtration promise. However, there is a tradeoff between comfort, breathability and filtration. A double layer of high-weave, all-cotton material is a safe bet. If sewing yourself, pre-wash the material to make sure to account for any shrinking.

“I used a 100% cotton cloth with two layers. I theorized that the mask should capture more than half the particles it came into contact with. I also added a pocket between the layers for an insertable HEPA (high-efficiency particulate air) filter which would make the capture rate even higher. I purposely stayed away from synthetic blends since I wanted my masks to withstand under high heat or chemical sterilization,” said Arrowsmith.

To make your own, you can follow directions on Arrowsmith’s YouTube tutorial. For more information, visit the CDC website.

Christine Lewis

PhD candidate and science writer, Biodesign Institute Center for Applied Structural Discovery and the School of Molecular Sciences


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ASU Speech and Hearing Clinic makes the most of telehealth opportunity

May 14, 2020

Fast action, generous donations make speech and hearing services accessible during pandemic

Even before the COVID-19 crisis wreaked havoc on America’s health care system, there were other challenges faced by those in need of care, not least of all being access and cost. Telehealth seemed like a good solution, but it came with a new set of issues, including how to meet HIPAA regulations, reimbursement for telepractice visits and a lack of licensure portability across state lines.

Now, the pandemic having forced its hand, the system has liberalized technical barriers due to HIPAA compliance, a majority of health care providers are being reimbursed by both third-party payers and Medicare, and some providers’ licensure regulations have been lifted.

All of that has been music to the ears of practitioners at the ASU College of Health Solutions Speech and Hearing Clinic. The clinic had dabbled in telehealth before, but it hadn’t been able to expand its offerings as much as it would have liked in order to fully serve its diverse, and often vulnerable, patient population. With these recent changes, the clinic was able to fully transition to telepractice in just over a month.

“There was a lot of red tape before,” clinic Director Joshua Breger said. “It’s amazing how fast that got out of the way. It allows us to have a larger reach to the community and those individuals who might not have as easy access to the clinic due to financial or physical restraints.”

While the clinic already accepted Medicare and most major insurances, and offered group discounts, thanks to recent donations from the Scottish Rite Dyslexia Programs and ASU’s own National Student Speech Language Hearing Association (NSSLHA), the majority of their services will be provided at no cost throughout the summer.

As a result, since the virtual transition, the average number of clients served by the clinic has not wavered, remaining at roughly 90 per week, both through the Tempe Adult Clinic and the Pediatric Communication Clinics. Some of the services provided include adult aphasia groups, pediatric language and literacy camps, Parkinson’s voice groups and transgender voice therapy.

The need for these kinds of services to continue is at the forefront of clinic practitioners’ minds. When it comes to children, clinical professors of speech and hearing science and pediatric clinic practitioners Jean Brown, Dawn Greer and Victoria Clark said in a joint statement that “high quality early intervention programs for vulnerable infants and toddlers can reduce the incidence of future problems in their learning, behavior and health status,” and “intervention is likely to be more effective and less costly when it is provided earlier in life.”

As for adults, Breger said, services like aphasia therapy and accent modification can have huge impacts on things like social life, personal identity, job interview outcomes and overall quality of life.

Mansooreh Karami, a PhD student in computer engineering at ASU and a native of Iran, has been taking accent modification classes for two semesters to Americanize her unique Persian-British accent. She said the transition online was very smooth, and she has noticed that as a teacher’s assistant, the students in her classes are finding it easier to understand her.

“I can see the reactions throughout the semester from my students’ faces,” Karami said. “At the beginning, they’re concentrating so hard to figure out what I’m saying, but right now I can see that they clearly understand me.

“It has really helped me in gaining a lot of confidence.”

In addition to serving the community, transitioning to telehealth has also allowed the clinic to continue the other half of its mission: educating the next generation of speech and hearing providers.

Communications disorders graduate student Alexandra Werner is one of 45 graduate student clinicians who meet with clients and provide services on a weekly basis throughout the semester. Currently, she is working with a 6-year-old with a fluency disorder, commonly known as stuttering. Though keeping children’s attention via Zoom can be difficult, there is a silver lining in some of the online platform’s capabilities that she has been able to put to use, such as screen sharing so that she can draw and spell out words for him.

“I think this whole thing will change a lot of things in our society, and possibly will change the way we interact with clients more than before,” Werner said. “So I think it’s really helpful to have this telehealth practice and experience.”

College of Health Solutions Clinical Assistant Professor Elizabeth Trueba, one of the clinic’s eight faculty supervisors who oversee student clinicians, has been impressed with their ability to adapt.

“Students have been really creative in thinking of ways they can still challenge clients and give them the best therapy,” Trueba said. “We will be remote all summer, so this is a nice opportunity for us to play with it and find what works, because we’ve been talking about how we can access other remote areas around Arizona. It opens up a world of opportunity for us and for people living in smaller towns in Arizona that unfortunately don’t have access to any sort of out-patient speech therapy.”

Breger echoed Trueba’s sentiments: “The moment we knew the clinic was going remote, everybody did such a great job thinking about what we could do for our clients, how to reach out to them to make sure they still have the services they need. And it hasn’t been easy. Going online can be a challenge, especially for certain populations, but everybody has been really innovative, and hopefully after this is all done, we can continue to use this technology to reach more people.”

Top photo courtesy Pixabay