MARY LOUISE KELLY, HOST:

As lockdowns lift across the country, is there any workplace that has figured out how to open and keep employees safe even as they interact with each other and with customers? Dr. Atul Gawande poses the question in the New Yorker, and then he answers it - his workplace. Gawande works in the Mass General Brigham Hospital System. Seventy-five-thousand employees - most of them have been coming in, working on-site, and yet they have reported few workplace transmissions.

Now, the reasons, Gawande writes, are now familiar - good hand-washing, screening for illness, social distancing, wearing masks. You have to do them all. You have to do them all consistently. We wanted to focus on that last piece - masks - and so we have called Dr. Gawande.

Hey there. Welcome.

ATUL GAWANDE: Thank you for having me.

KELLY: First off, with masks, how strong is the evidence of their benefit?

GAWANDE: Well, at this point, there has been an accumulation of a lot of evidence that masks are highly beneficial. There are large reductions in the likelihood that you would infect others if you're carrying the infection, and a lot of us are unwittingly carrying the virus and spreading it. But it also - there's some evidence that it does reduce your risk of catching an infection yourself. The more effective the mask is, the more likely it's also protecting you.

KELLY: You cite a paper, a scientific paper that found that if a majority of people wore masks, this pandemic could end.

GAWANDE: That's right. You need at least 60- to 75% of us wearing a mask, which means we don't have to be 100%. And the second thing is we've got to be wearing masks that are at least 60- to 75% effective. It needs to be at least a double-layer cloth mask or a proper surgical mask like people wear in the medical world. And it has to fit reasonably well.

One of the things that I see is a lot of people are wearing masks, but then they have their nose sticking out or they're pulling it down in order to talk, which defeats the purpose of the mask. So a lot of this is about making sure that we are not having mask theater but actually using the masks in the ways that prevent the infection from spreading.

KELLY: And just explain - what is the difference between what you just called a surgical mask and the cloth masks that so many of us are wearing?

GAWANDE: So the kinds of masks that people wear in the hospital, those disposable masks, are thin. And you think, like, how is that practically paper thing actually be beneficial? But it's made of a melt blown, cotton candy-like plastic material, sort of like in air filters. And they're charged. They are electrostatically charged. And that catches virus particles.

KELLY: You have a great line in the piece that captures this, where you say these surgical masks capture viral particles kind of like the way a blanket in our dryer catches socks. And they just stick.

GAWANDE: That's exactly right. That's what makes them breathable is that electrostatic charge allows you to use pretty thin material, so it's not really hot. They're easier to wear all day, and yet they're also much more effective than the cloth masks. Now, if you get them wet, that ruins the electrostatic charge. So at that point, you have to throw them away.

The cloth masks are ones made of cotton, or they may have other materials. If they're multilayer and thick enough, then they keep you also from spreading the infection. The other aspect, though, is you have to get up to 12 to 16 layers for it to filter as well as a surgical mask. And even then...

KELLY: Which would be hot.

GAWANDE: Which is hot. And then people find it uncomfortable to wear such a thick-layered mask. But for preventing you from infecting others, they both work. The preference is, especially now that more surgical masks are available on the market, that - you know, we need to make sure our health care workers have it, our nursing homes have it, but they do more and more. And so now getting these kinds of masks to be a regular part of what we do will help even more.

KELLY: You know, it's worth remembering at the start of this pandemic in the U.S., the CDC was recommending against masks for the general public. They were saying only people who were caring for somebody sick with COVID-19 needed to wear them, saying they might actually - if they didn't fit right or if people didn't socially distance because they thought they were safe in a mask, it might actually be counterproductive. In hindsight, was that CDC guidance wrong?

GAWANDE: I don't think it was helpful, and I think it led to some contradictory feeling for the public that they were unsure what the message really was. Now, the reality is that we did not know in early April how valuable and important mask wearing would be. You know, at this point as we see in multiple states - from the Carolinas to Tennessee to Arizona - that cases are up. Testing is not keeping up. Hospitalizations have been rising since Memorial Day.

If this is happening, the only way that we're going to turn around without having to lock down again is going to be if we are being assiduous about wearing masks again and getting this message in clear. You know, we started behind the eight ball because we weren't advocating it from the very beginning. And now we're trying to advocate it more broadly. I think that's a challenge, but, you know, very clearly, it's what we have to do.

KELLY: Atul Gawande is a surgeon at Brigham and Women's Hospital in Boston and a staff writer at the New Yorker.

Thank you very much.

GAWANDE: Thank you. Transcript provided by NPR, Copyright NPR.