Vaccum Cleaner Bag Scores Best for DIY Facemask Material in Study

Using vacuum cleaner bags in DIY masks could protect the wearer from the COVID-19, according to a study.

Public health bodies including the U.S. Centers for Disease Control (CDC) advise the public to wear face coverings made of materials not used in medical-grade masks which should be reserved for healthcare professionals. The CDC states that the cloth face covering may not protect the wearer, but may keep them from spreading the virus to others. According to the authors of the study published in the Journal of Hospital Infection, People in social-care settings may also be advised to use such masks.

While different materials can filter large droplets expelled when people cough or sneeze, smaller aerosol particles may pass through or exploit leakage points, they said.

The researchers set out to estimate a worker's risk of infection when exposed to a COVID-19 patient for 30 seconds, or the length of a brief check-up, and 20 minutes, which is about how long it takes to intubate a patient.

They collected existing data on masks and turned the information into a computer model. This included information on how much air different people inhale over time, and how the coronavirus spreads.

Compared with not wearing a mask for 20-minute or 30-second exposures, wearing a face covering could cut the average risk of infection by 24 to 94 percent and 44 to 99 percent, respectively.

Masks used by healthcare workers performed the best, with what is known as an FFP3 mask giving 94 to 99 percent protection in the respective time scenarios.

When it came to DIY materials, the bag of a vacuum cleaner was found to be the best at reducing the risk of infection, at 58 percent after 20 minutes, and 83 percent after 30 seconds. This was followed, in descending order, by a tea towel, cotton mix fabric, an antimicrobial pillowcase, linen, a regular pillowcase, silk and a 100 percent cotton T-shirt. After the T-shirt, scarves were the worst at protecting from the virus, at 24 percent after 20 minutes, and 44 percent for 30 seconds.

The study was limited because the team didn't account for the virus transferring from a wearer's hands to the mask when they made adjustments, and they also assumed all masks were worn the same way. There is likely a greater variation in the fit of homemade versus manufactured masks, they said.

The longer a person spent in the room, the higher their chance of catching the coronavirus, according to the study.

Lead author Amanda Wilson, an environmental health sciences doctoral candidate in the Department of Community, Environment and Policy in the University of Arizona Mel and Enid Zuckerman College of Public Health, said in a statement: "That doesn't mean take your mask off after 20 minutes, but it does mean that a mask can't reduce your risk to zero.

"Don't go to a bar for four hours and think you're risk free because you're wearing a mask. Stay home as much as possible, wash your hands often, wear a mask when you're out and don't touch your face."

Wilson said: "The denser the fibers of a material, the better it is at filtering. That's why higher thread counts lead to higher efficacy. There's just more to block the virus.

"But some masks (such as those made from silk) also have electrostatic properties, which can attract smaller particles and keep them from passing through the mask as well."

Wilson said: "We were focusing on masks protecting the wearer, but they're most important to protect others around you if you're infected. If you put less virus out into the air, you're creating a less contaminated environment around you. As our model shows, the amount of infectious virus you're exposed to has a big impact on your infection risk and the potential for others' masks to protect them as well."

Last month, the authors of a separate study found woven fabrics, like cotton flannel, appeared to prevent a person spreading the coronavirus as they disrupted the flow of air and provided surfaces for particles could stick to. The findings were published in the journal ACS Nano.

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A fashion student sews homemade protective face masks to be distributed to medical staff and charity organisations, at her home in Paris on May 8, 2020. GEOFFROY VAN DER HASSELT/AFP via Getty Images