The Do's And Don'ts Of Double Masking

By Katherine Davis-Young, Mark Brodie
Published: Friday, March 19, 2021 - 1:39pm
Updated: Saturday, March 20, 2021 - 9:54am

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Coronavirus case numbers in Arizona have been trending downward lately, but they are up a bit as of March 19. In their latest update, state health officials added 423 new infections and 46 more deaths to the daily dashboard.

how to layer masks
U.S. Centers for Disease Control and Prevention
The CDC recommends double masking with a disposable mask layered under a cloth mask.

Hospitalizations were down slightly, now at levels not seen since early October. Intensive Care Unit (ICU) use is at 85% overall.

Vaccinations continue at a steady pace. More than 2.7 million doses have been given. About 24% of Arizonans have received at least one dose.

While coronavirus cases continue to decline here in Arizona and across the country, in Europe a third wave of the pandemic is causing cities like Paris to enter another lockdown. Here in the U.S., the Centers for Disease Control and Prevention (CDC) still recommend wearing a mask even if you’ve been fully vaccinated. And double-masking has even been recommended as a further precaution against infection.

"Typically what is recommended also by the CDC is that you use a surgical kind of mask, and then you put a cloth mask on top, as they have fit both more or less, but their weaknesses are in different spots," Pierre Herckes said. "The upper mask helps push the second mask better against the face. In addition, you get the benefit of the double material layer filtration."

Herckes is an ASU professor and aerosol specialist. He has also earned the nickname “mask expert.” He says there’s a right way and a wrong way to double mask.

how not to layer masks
U.S. Centers for Disease Control and Prevention
The CDC does not recommend double masking over a KN95 mask since the mask itself already filters a majority of airborne particles. Layering over a KN95-type mask could also cause breathing difficulties.

"Depending on the mask, if you double mask, it could actually lead to actually increasing your exposure. The most critical thing for a mask is the fit of the mask," Herckes said.

When it comes to wearing two masks, Herckes says they should cover your nose and mouth completely without any gaps. You should also be able to breathe with ease.

Masks that are too hard to breathe through can actually force open spaces where the air can escape or come through, bypassing the mask itself. A loose fitting mask has the same problem. Double masking with the same kind of mask can also be problematic as they have the same weaknesses.

Herckes also says you shouldn’t double mask with the N95 or KN95 masks.

"They already filter more than 95% of the particles. So there's very, very little to gain," Herckes said. "On the other hand, what happens is this mask typically fit very well. And so when you add another mask to that, you actually make it really difficult to breathe through those masks. And chances are that when you force breathing, you open up little holes again against the face so that the air tries to escape or comes in bypassing the double masks."

Whether you’re wearing one mask or two, the most important thing is wearing one that fits well against your face.

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