Medical Examiner

Do You Really Need Two Masks Now?

A guide to what is useless, what’s useful, and how to breathe through all those layers.

Two cloth masks on top of each other with a question mark on them.
Photo illustration by Slate. Photos by Getty Images Plus.

Masks—we had finally absorbed that they’re useful, low-lift ways to help keep people safe from the coronavirus (well, most of us). But recently, new questions have come up: Is one mask enough? If two masks are better, are three better still? The answer to these questions are predictably complicated. Here is our best shot at sorting it out.

Should I be wearing two masks when I go places now?

Yes, probably.

“I have started double masking myself when I’m in indoor settings in shared air,” says Lindsey Leininger, a public health educator at Dartmouth and member of Dear Pandemic, a campaign where experts answer questions about COVID-19 on social media. On Feb. 10, the Centers for Disease Control and Protection started recommending double masking as one strategy to improve protection.

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As a refresher: If you’re going to be within 6 feet of someone from outside your bubble, you should be wearing a mask, especially if you’re indoors (where there should be other precautions, too, like ventilation, contact tracing, and a time limit, if possible). For indoor settings, or crowded outdoor ones, considering two masks right now is prudent.

“I started doing the double masking when I started getting a little bit smarter about the [new] variants,” explains Leininger.

Why do the new variants require a better mask?

It’s not because they’re more nimble—“these variants are not any more capable of getting through a mask than any other variants that are circulating,” says Angela Rasmussen, a virologist and sometimes writer for Slate. Scientists still aren’t exactly sure why they appear to be more transmissible, though it could be that it takes less virus to infect someone. If this is the case, it might make a poorly fitting mask more risky to wear now. But Rasmussen emphasizes that there’s nothing special about the new variant that renders masks less effective than they were before. She personally still just wears one mask—either an N95 (her husband happened to find some laying around from a before-times project) or, for short grocery store trips, a surgical mask with a metal nose bridge. “I don’t go out very often,” she adds.

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The bottom line is that against the new variants, “our current protections will work if we’re being more vigilant,” says Leininger. Generally, this point in the pandemic is just a good time to reevaluate our own masking habits. Experts have been at this for a while now and have a bunch of tricks up their sleeves.

All right, give me the best trick.

The basic consensus among expert double mask fans I spoke to was: put a surgical mask on first, with a cloth mask over top. Surgical masks filter well but do not fit well. A cloth mask on top of a surgical mask—especially, a cloth mask that ties around the back of your head, not one with ear loops—can pin the surgical mask down, making the whole thing fit more snuggly. “The oopmh of double masking is improving your fit,” says Leininger. A CDC study published on Feb. 10 found that exposure to aerosols (between two dummies, in a lab) dramatically improved when both wore either a tightly-fitting surgical mask or a cloth and surgical mask combo over their mouth-holes.

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The other thing that experts say works well is to have a cloth mask with a layer of filter material in the middle.

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OK, I did the double mask thing, but there is lots of air coming out of the sides of my two masks.

Yes, you really need a top mask that fits tightly for this to make any sense. Again, ties, not ear loops, could help here. “It needs to press hard around your face,” says John Volckens, a mechanical engineer at Colorado State University. “The people in the know tie it around [their] heads.”

There also might just be too many layers, here, which can wind up “short-circuiting the mask,” as Linsey Marr, an engineer at Virginia Tech and the pandemic’s star expert on transmission, puts it. Try a cloth mask with fewer layers, since it’s going to go over the surgical mask anyway.

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Would doubling up on cloth masks help?

Unless you are stranded somewhere with a couple thin masks, you’d probably just get the too-many-layers issue, making it hard to breathe without the benefit of the surgical layer to filter.

How do I actually know that everything is fitting tightly enough?

Check if your breath fogs up your glasses, advises Volckens (nonglasses wearers can use sunglasses to test). If they fog, “it means that the breath coming out of your body is going around the mask, not through the mask,” he explains. Another trick: set everything up and blow as hard as you can. If you blink, the air is going up, not out and filtering through the mask.

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Lady, this sounds impossible.

Volckens notes that you can get a mask fitter to help, which is a custom-printed frame that sits around your mouth and ties behind your head, pinning the mask to your face.

But, more broadly, it is important to remember that whatever you are doing right now in your effort to mask—if you are wearing a mask, if you are looking into ways to make that mask fit and filter better—is helping keep you and others safe. Volckens has a whole interactive chart on how good bandanas are versus gaiters versus two-ply masks, and on and on. What is clear looking at it is that any face covering is much better than no mask. Improvements from there are useful, and good, and worth pursuing. It is especially worthwhile for people with the power to work on getting us, as a country, better masks. But what’s not useful is if we shut down over how very hard it is to find the perfect setup and give up. “Cruddy cloth masks still offer a good degree of protection,” says Volckens.

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For what it’s worth, the CDC only recently began recommending protection beyond a snug two-ply cloth mask, and only after many, many experts suggested that more protection would be advisable. We’re all trying to catch up an do our best here!

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OK, OK. Back to the task at hand. I’ve seen people wearing a cloth mask over an N95. What’s the point?

An N95 needs to fit well in order to work, so a cloth mask could help pin it down a bit. It can also help keep the front of the N95 clean, making it easier and less risky to reuse.

I do wish I just had an N95.

I wish you did too. “That would be ideal, if everyone had a properly fitted N95,says Marr. But it is hard to get an N95 that isn’t possibly fake (Amazon is really not a good place to get medical gear). And the CDC still recommends against using them because health care workers need them. “The mask marketplace is so confusing for me and I’m an expert,” says Leininger. Three people I spoke to for this piece specifically used the term “Wild West.” (Again, the situation we are trying to navigate is off the rails.) KN95s—again, if you can get one—can be a good solution here, as the difference is mostly just a matter of certification (the one meaningful difference is that N95s have bands that fit around your head, and KN95s have the less-secure ear loops). Marr and other experts have suggested that the Biden administration should supply citizens with high-quality masks, as well as clear instructions on how to evaluate mask quality and fit.

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But also, release yourself from the idea that you need an N95. “I’m not sure that in a perfect world everyone wears an N95 all the time,” says Leininger. The masks can be uncomfortable when worn properly and are overkill for many scenarios, like walking around outside where you’re able to distance pretty well. Even Marr explains that you can get pretty close to the performance of an N95 with a well-fitting cloth-mask-plus-filter setup.

OK, what I have access to are cloth and surgical masks, but I thought I wasn’t supposed to wear surgical masks if I have cloth masks because of the pollution they create.

Yes, mask pollution is a problem. If you’re wearing a surgical mask, cut the ear loops before throwing it away so they don’t end up tangled around sea creatures, and make sure it actually ends up in the trash, and not on the street. If you don’t want to wear a surgical mask, you have the aforementioned option of using a cloth mask plus a filter inside. You can’t wash the filter—that will reduce its effectiveness—so it will end up in the trash, but overall, that’s still less waste. But also, we’re in a pandemic. Wear the surgical mask.

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Ugh, what else am I doing wrong?

Leininger is trying to use this moment to get people to remember that mask hygiene is still an issue. She describes watching dignitaries at the inauguration fiddling with their masks, touching them: “As a public health professor, I was like aaahhhh!” It’s the whole surface transmission thing—our masks are protecting you from coronavirus-laden droplets, therefore it may have  coronavirus on it, therefore we should not be touching them when we’re out and about. Ideally, says Leininger, you should be washing them after each use. Surface transmission might not be the biggest of all the concerns, but this goes along with the advice to, nonetheless, continue to wash your hands.

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One last thing. With the new variants circulating, do I actually need to avoid the grocery store like that Vox piece said?

“Where else are people supposed to get groceries?,” says Rasmussen. Yes, if online ordering is an option for you, that might be smart. But the point is not that things that were low-risk are, suddenly, very risky. It’s that, while we should be limiting our activities and evaluating our masks, we kind of always should be doing those things. We do still need to do some basic things to live.

Update, Feb. 10, 2021: This article has been updated throughout to reflect new CDC guidance.

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