What you need to know about protective face masks

• By Maria Godoy, Sarah McCammon/NPR

There’s growing evidence that masks help curb the spread of the coronavirus. Committing to wearing a mask out in the world all the time, though, can also raise some questions. What do you do when you want to take a sip of water? Or when you’re exercising?

NPR’s Sarah McCammon asked Maria Godoy, NPR’s health correspondent, some common questions about wearing masks.

This conversation has been edited for length and clarity.

Do we know how much mask-wearing prevents the spread of the coronavirus? Is it for your own protection? Or for other people’s protection?

It’s primarily to protect other people from the person wearing the mask because we know that people can spread the coronavirus even if they aren’t showing symptoms yet or never show symptoms. There’s research showing even a loose-fitting surgical mask can block almost all the infectious droplets a person might emit when they’re talking.

The important thing is that the more people are wearing a mask, the more everyone is protected. Your mask protects me, and mine protects you.

Dr. David Aronoff, director of the division of infectious diseases at Vanderbilt University Medical Center, says to think of masks like seat belts: “When people started wanting seat belt laws, there was a lot of pushback about personal freedom and about how seat belts aren’t 100 percent effective. Now, if you asked my children to drive a car without a seat belt or to go into a car as a passenger without a seat belt, they would feel naked without it. It’s part of the culture.”

Masks help stop the spread of the coronavirus — that’s important. But is there a downside? Can wearing one limit oxygen intake in ways that can be harmful? Is this anything people should worry about?

No, not for the types of cloth masks or surgical masks that the general public wears. Aronoff says the fibers they’re made of aren’t dense enough to block the exchange of gases like oxygen or carbon dioxide. And these masks aren’t so tight that air can’t get in around the sides.

Now there is some evidence that wearing N95 respirators for long periods of time without a break may potentially affect oxygen levels, but not to a dangerous extent, especially in healthy people. N95 respirators seal more tightly to the face, and the risk there is really for people predisposed to breathing problems — for example, someone with emphysema. But really only medical workers should be wearing N95s, because they’re in short supply. When it comes to cloth and surgical masks, there’s really no evidence of risk to healthy people.

If you find it uncomfortable to wear a mask, try out different types to see what actually works for you.

In terms of different types of masks, which one’s better: surgical masks or cloth masks?

First of all, a mask is only useful if you actually wear it. That said, there’s a lot more research on surgical masks than cloth masks when it comes to reducing the spread of respiratory viruses.

As I mentioned, there’s good research showing that surgical masks can block most of the infectious droplets emitted by the wearer. But here’s the rub: It’s hard to know how much a surgical mask is protecting you in terms of blocking out small particles. That’s because when researchers test how well surgical masks filter out particles, and they use the same test methods used to test an N95 respirator, the results are all over the place. Some test at 80% filtration efficiency; some are as low as 10%. There doesn’t seem to be a great way of knowing what you’re getting.

Lisa Brosseau, a research consultant with the University of Minnesota’s Center for Infectious Disease Research and Policy, says she’s seen some surgical masks that have been cleared for medical use by the Food and Drug Administration and have better filtration efficiencies, but most surgical masks sold in the U.S. aren’t cleared by the FDA.

Prior to the coronavirus pandemic, there hadn’t been much research on the efficacy of cloth masks, so those studies are being conducted now. What studies suggest so far is that depending on how many layers a cloth mask has, what kind of fabric you use, whether there’s a filter, how tightly it seals to your face, etc., you can get pretty decent filtration efficiencies. I wrote a whole guide about cloth masks and other types of masks and respirators.

Brosseau says the research she’s seen and conducted suggests that you might get less air leakage with a surgical mask. But the bottom line is, regardless of whether you are wearing a cloth mask or a surgical mask, you can’t think you’re now invincible — these masks can limit your exposure, but they aren’t giving you full protection. You can’t suddenly be in prolonged close contact with people. Brosseau says these masks can buy you a few extra minutes of protection, not hours.

You still need to be keeping at least 6 feet away from other people and avoiding crowds and poorly ventilated, enclosed spaces. When you combine masks with other measures like social distancing, hand-washing and avoiding crowds, you can really cut down on transmission of the virus. Let’s go back to our seat belt analogy. Is a seat belt going to all deaths in car crashes? No. But are you better off wearing a seat belt than not? Yes. Same thing goes with masks.

What about people with serious respiratory conditions? Should they not wear a mask?

Doctors say people with these conditions especially need to be masking up in public because they are at greater risk for severe disease if they get COVID-19. Even someone who relies on oxygen can wear a loose-fitting cloth or surgical mask over their cannula.

If someone with a preexisting respiratory condition is having a hard time breathing through a mask, Aronoff says they should consult their doctor, but he suggests they could try wearing a plastic face shield. Face shields can block incoming respiratory droplets, but it’s not yet known how well they protect other people from the wearer.

What about exercising with a mask? Is there a risk that you won’t be able to catch your breath?

That’s a legitimate concern. If you’re doing something like running or biking outdoors and you’re alone or just with the people you live with, it’s OK to have your mask down if there’s no one else around, says Abraar Karan, a physician at Harvard Medical School and a member of the Massachusetts COVID-19 response team.

As long as you haven’t been touching stuff along the way, like benches or rails, you haven’t had a close conversation with a stranger, it’s OK to use your hands to pull it down. If you see someone coming, put up your mask until they pass. And if you’re running and passing someone, give them at least 6 feet of space.

What should we do with that dirty mask? How often should we be washing a cloth mask?

Aronoff recommends washing your mask at least every day: “It’s fine to wash it by hand with soap and water or with laundry detergent or put it in the washing machine. These masks can be air-dried, or they can be put into a dryer on high heat.” The most important thing is that the mask gets cleaned. It’s a good idea to have several cloth masks that you can rotate in and out so you don’t have to wash just one every day.

A lot of people find masks really uncomfortable to wear — they’re hot, they make some people feel really anxious. Is it OK to take breaks from wearing a mask? Like, what if you need to remove it to take a sip of water, or you’re out on a walk and no one’s around?

Experts say it’s OK to take periodic breaks from wearing a mask. Make sure you do it when no one is around. Don’t touch the front of the mask when you take it off, so you don’t touch any infectious droplets it might have blocked. Instead, take it off by the ear loops.

To be clear, you wouldn’t want to touch your mask if you’re indoors, like in a store, where your fingers might have come into contact with virus droplets on objects that other shoppers touched. But if you’re outdoors and solo and you haven’t been touching stuff along the way, it’s OK to pull down your mask.

As Karan told me, nobody is 100% perfect with this: “How many people do anything 100% of the time? Almost none. We’re not perfect. We all miss things.” Karan says we all just need to do the best we can. Even if we’re not 100% perfect with our masking technique, if most of us are wearing masks in public, we can make a big difference in slowing the spread of the coronavirus.