CDC director: Data show the fit of masks impacts their effectiveness

When it comes to masks, the American public may want to begin considering wearing two at a time in certain situations.

Speaking at a White House briefing on the COVID-19 pandemic Wednesday, Centers for Disease Control and Prevention (CDC) Director Rochelle Walensky, M.D., urged Americans not to grow complacent as she pointed to new data from the CDC about the effectiveness of masks.

"I know some of you are both tired of hearing about masks as well as tired of wearing them. Masks can be cumbersome. They can be inconvenient," Walensky said. "I also know many of you still have questions about masks. You may be unsure if they work, what kind is best and whether two masks are better than one." 

The answer to that final question, it turns out, is yes. 

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The data, released by the CDC on Wednesday, found doubling up on masks or taking other steps to improve the fit of a mask against the face such as knotting the ear loops can improve a mask's ability to protect the wearer from aerosolized particles that spread COVID-19, she said.

"In the study, wearing any type of mask performed significantly better than not wearing any mask," Walensky said. "Well-fitting masks provided the best performance in terms of blocking emitted aerosols and exposure of aerosols to the receiver. In the breathing experiment, having both the source and the receiver wearing masks modified to fit better reduced the receiver's exposure by more than 95% compared to no mask at all."

She said the new data do not change any of the recommendations about wearing masks in public but do offer more guidance on how to improve their effectiveness.

"This includes wearing a mask with a moldable nose wire, knotting the ear loops on your mask or wearing a cloth mask over a procedure or disposable mask," Walensky said. "The bottom line is this: Masks work, and they work best when they have a good fit and are worn correctly."