ByErika Edwards

Federal health officials now recommend people cover their mouths and noses with cloth face masks when in public to help prevent the spread of coronavirus.

Friday afternoon, the Centers for Disease Control and Prevention updated its guidance on the matter, recommending individuals use cloth face coverings "in public settings where other social distancing measures are difficult to maintain," such as grocery stores and pharmacies. The guidance recommends people use fabric coverings, not surgical masks or specialized N95 masks, which should be reserved for health care providers.

If you are making your own covering, new research finds that some fabrics are better than others at filtering out viral particles.

"You have to use relatively high-quality cloth," Dr. Scott Segal, chair of anesthesiology at Wake Forest Baptist Health in Winston-Salem, North Carolina, said.

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Face coverings made of fabric, public health experts note, aren't intended to protect wearers from getting sick, but rather, to prevent them from spreading the virus to others. And the guidance will still exclude using surgical or medical grade masks, which experts say should be reserved for people who are sick and for the health care workers who care for them.

Segal came up with the idea to study which fabrics would work best.

In partnership with the Wake Forest Institute for Regenerative Medicine, he tested a variety of cloth materials to see which ones not only allowed for breathability, but also filtered small particles — such as viruses. The research from Wake Forest has not been submitted for publication and has not been peer-reviewed.

On the left, researchers used a special filtration test to determine how many small particles were blocked with a variety of masks and fabrics. On the right, a piece of cloth lets light shine through easily, signalling a lower quality fabric.

On the left, researchers used a special filtration test to determine how many small particles were blocked with a variety of masks and fabrics. On the right, a piece of cloth lets light shine through easily, signalling a lower quality fabric.Courtesy of Wake Forest Baptist Health

To test various masks and fabrics, the team pumped air through both types of face coverings.

"Our instruments could read down to 0.3 microns, which is about the size of a big virus," Segal said.

Regular surgical masks filtered out 62 percent to 65 percent of particles. For comparison, N95 masks filter 95 percent of those particles.

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