Why Cloth Masks Don’t Cut It for Keeping COVID Away

If you’re counting on a cloth mask to protect you from COVID-19, you may need to re-think that strategy, a new study shows.

Researchers found that cloth face masks do little to fend off tiny airborne particles while concluding that specialized N95 and similar masks do a much better job.

“Masks are air filters, and woven fabrics, such as cotton, make for good jeans, shirts, and other apparel, but they are lousy air filters,” says study co-author Richard Sear. “So, use woven fabric for clothing, and N95s, FFP2s or KF94s for masks,” adds Sear, of the University of Surrey in England.

Filtering out airborne particles

COVID-19 is transmitted primarily via airborne particles. An infected person breathes out virus-carrying particles that can be inhaled by another person, causing them to become infected.

RELATED: BEWARE of Airborne COVID Particles in Your Home

That’s why masks are widely considered an important first-line defense against airborne transmission of the disease, but, as research is increasingly showing, not all masks provide equal levels of protection.

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In this study, published March 1 in the journal Physics of Fluids, researchers compared woven fabric masks with N95 masks and similar face coverings. They looked to see how effective they are at filtering out particles a micrometer and larger in diameter.

Airflow simulations showed that when breathing through cloth, most of the air flows through the gaps between the fibers in cloth masks, bringing with it more than 90% of the particles.

“In other words, these relatively large gaps are responsible for cloth being a bad material to make air filters from,” Sear said in a journal news release.

“In contrast, the filtering layer of an N95 mask is made from much smaller, 5-micrometer fibers with gaps that are 10 times smaller, making it much better for filtering nasty particles from the air, such as those containing virus,” Sear explains.

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The signs of a good mask

Sear notes that good masks should feature the “two Fs: good filtration and good fit.”

“Surgical masks fit badly, so a lot of air goes unfiltered past the edges of the mask by the cheeks and nose,” Sear says.

RELATED: 3 Things to Consider With Mask Mandates Lifting

Knowing when to wear a mask

With mask mandates lifting in most places, it’s important to know when and how to protect yourself. Visit COVID-19 Community Levels, a tool to help communities decide what prevention steps to take based on the latest data.

RELATED: CDC Loosens Mask Guidelines as Omicron Surge Subsides

Additionally, this guide, provided by the CDC, will help you determine when you should consider wearing a face mask:

Low

• Wear a mask based on your personal preference, informed by your personal level of risk

Medium

• If you are immunocompromised or at high risk for severe illness
  • Talk to your healthcare provider about additional precautions, such as wearing masks or respirators indoors in public
• If you live with or have social contact with someone at high risk for severe illness, consider testing yourself for infection before you get together and wearing a mask when indoors with them.

High

• Wear a well-fitting mask indoors in public, regardless of vaccination status or individual risk (including in K-12 schools and other community settings)
• If you are immunocompromised or at high risk for severe illness
  • Wear a mask or respirator that provides you with greater protection