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The CDC Now Recommends Double Masking

Woman putting on a second mask
Credit: Bekker24 - Shutterstock

Doubling up on masks can improve their filtration, and the CDC is now recommending that people double their masks or use layered masks and take steps to improve the masks’ fit.

The CDC says that appropriate ways to layer include:

  • Wearing a cloth mask over a disposable or surgical mask

  • Wearing a cloth mask that has multiple layers of fabric

Doubling up a disposable mask doesn’t really help, they note, because disposables fit so loosely. The CDC also warns against wearing any other mask with a KN95, although they do not indicate the reasoning for that.

The CDC’s recommendation page also points out that it’s essential to be sure the mask fits well. The more layers you use, the easier it is for air to follow the path of least resistance by leaking out the edges of your mask.

Not all masks are equal

Cloth masks by themselves are not and were never the best option for everyone to wear during a pandemic; they were, instead, just the best way to get a lot of masks to a lot of people without making too much of an impact on supplies needed for healthcare workers.

Any mask can be placed on a continuum from “blocks almost everything” (example: a well-fitted N95) to “better than nothing” (a loosely tied bandana). Disposable surgical masks are toward the good end of the continuum; a cloth mask with two or three layers is probably in the middle. Sadly, a year into this pandemic, we don’t have much authoritative research on how to place a given cloth mask on that continuum—but we do know that the tighter the weave and the more layers, the better.

Which is how we’ve gotten to the point where double masks are becoming a more common sight. Poet Amanda Gorman doubled up at the inauguration (when she wasn’t speaking), for example. And Germany is now requiring people to wear N95s or the equivalent when they’re shopping or taking public transit.

Why the sudden focus on better masks?

I’d say there are three reasons. First, we have enough data now to know that masks stand a good chance of protecting the wearer from small aerosol droplets; they aren’t just for catching the spit and snot that come out of your own mouth. Second, there has been time for supplies to catch up enough that medical-grade masks are more available than they were last spring. But third, several new variants of the coronavirus seem to be more transmissible than the garden-variety ones that we’re familiar with. That means we need to be even more vigilant about preventing transmission. Blocking more and smaller droplets is part of that effort. And if you can be more protected, why wouldn’t you?

Just remember that a mask is only as good as its fit, so if you feel (or, in cold weather, see) your breath escaping around your cheeks or nose, you know you have gaps where unfiltered air can enter and escape. Masks also only decrease your risk, but they aren’t a magical force field, so it’s still best to avoid being in indoor spaces with people outside your household.

This post was originally published in January 2021 to discuss double masking, and was updated on February 10, 2021 to note the CDC’s explicit recommendations.