February 03, 2021
Many prominent figures, including President Joe Biden and Vice President Kamala Harris, have started wearing two face masks as the coronavirus enters its second year with multiple, more contagious variants circulating throughout the world.
The U.S. Centers for Disease Control and Prevention still recommends people just wear a single mask, but should we all be doubling up?
The CDC currently recommends choosing a mask that has two or more layers of washable, breathable fabric and fits snugly, completely covering the nose and mouth. That's based on studies showing masks with multiple layers of fabric are more effective at reducing the emission and inhalation of virus particles.
"Multiple layers of cloth with higher thread counts have demonstrated superior performance compared to single layers of cloth with lower thread counts, in some cases filtering nearly 50% of fine particles less than 1 micron," the CDC guidance says.
Yet, some infectious disease experts are saying that adding an extra layer of protection makes sense. Double masking refers to wearing two cloth masks or a cloth one over a surgical mask.
"If you have a physical covering with one layer, you put another layer on, it just makes common sense that it likely would be more effective," Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, told the Today Show.
The extra protection especially could be helpful in situations where social distancing isn't possible or if people are at risk for severe illness, some experts have said.
Dr. John Zurlo, chief of infectious disease at Thomas Jefferson University Hospital, told PhillyVoice that there is no data right now on whether double masking is better than wearing a single mask, but the CDC has begun a study on its effectiveness.
"There could be a case for double-masking," he said. "The idea is that wearing a cloth mask over a surgical mask offers an extra layer of protection and provides better coverage of the nose and mouth."
Double masking makes the most sense in indoor settings where social distancing is more difficult, he said. However, he is concerned that if everyone started doubling up, there would be a run on surgical masks, creating a supply problem for the health care workers who need them the most.
The CDC currently advises against using N95 respirators and other surgical masks meant for health care workers. Zurlo said that as long as a mask fits well and isn't loose, a single mask offers enough protection for most situations.
People who have trouble breathing in a single mask, shouldn't attempt to double up, experts have said. A single mask is better than no covering at all.
Masking is an important mitigation strategy against rising virus cases. A number of observational and epidemiological studies have demonstrated the effectiveness of community masking policies. One study of an outbreak onboard the USS Theodore Roosevelt found masks were tied to a 70% reduction in transmission risk.
Another study found that state mask-wearing mandates were associated with a decline in the daily COVID-19 growth rate.
The most effective masks have at least three layers of material and an interchangeable filter, according to scientists.
Linsey Marr, an engineering professor at Virginia Tech University and a leading aerosol scientist, has conducted tests on different mask materials. Her findings confirm that a properly-fitted mask offers protection from the coronavirus.
She said the best cloth masks have two tightly woven layers of outer material with a filter material in the middle. People can make the filter material from a surgical mask or a piece of vacuum bag, she told The New York Times. Or they simply can wear a two-layer mask over a surgical mask for added protection.
Marr and her team found that adding that a third filter layer can stop 74 to 90% of potentially infectious particles.
In another study, Dr. Loretta Fernandez, an associate professor at Northeastern University, found that adding a layer of nylon to a homemade mask can make it fit more snugly over the nose and mouth.