Masks remain extremely effective indoors, but are they needed outside?

Scientists and public health experts agree that masks effectively reduce the spread of coronavirus indoors, where the vast majority of transmission is likely to occur.

But what about the outside?

Approximately two dozen states have mask mandates across the state that typically require people to wear masks outside when they are unable to be at least 6 feet away. Many cities have their own rules.

But with the accumulation of vaccinations, some health experts and journalists argue that now is the right time for authorities to ease demands for outdoor masks. Studies have linked transmission much more to indoor settings than to outdoor ones, although data is limited and there are plenty of warnings.

Dr. Ashish Jha, Dean of the Brown University School of Public Health, notes that the number of cases is not decreasing and for the past month or two has mostly stagnated. But he says there are situations in which groups of people gather indoors without masks.

“Once you go out, the virus becomes real, very unusual to spread,” he tells NPR All things considered.

Some exceptions may include people at crowded gatherings, standing or sitting close by for a long or long time. But beyond those scenarios, “there’s really not much spread outdoors.”

This interview is edited for length and clarity.


We single out from the interview

Is there a number we can put on this? How unusual would it be to pick up a COVID-19 case if you were out?

There are estimates that suggest that perhaps 1 in 1,000 infections occurs outdoors. There are reasons to believe that if you’re just thinking about your risk, if you’re just out there and walking around, it’s probably even much less than that. Thus these rare cases occur in those contexts of the kind of large, crowded gatherings. I don’t know that we’ve really seen cases of someone who just, say, went for a walk or ran and thus picked up an infection. I think you really have to have a lot more exposure than that.

I’m a jogger. … Do we know how much the risk increases when you breathe very hard, when you inflate and smoke, trying to climb that hill?

I think someone would be next to you and spend, say, 10, 15 minutes running in that little breath you exhale, maybe there is a risk. But someone you run to and who’s only there for a second, the risk is – it’s extremely rare.

We will be listened to by people who are currently screaming on their radios saying that it is still spreading and the variants are out there and so far most people are not fully vaccinated. You shouldn’t have this conversation yet. What do you tell them?

I understand that first of all. But it is really important to have the possibility of a nuanced discussion of what is safe and what is not. Since one of the problems is if we can’t lead that discussion, then some people will stick to all the rules, even the ones that aren’t necessarily very helpful, and others will just ignore them.

And this at the moment, while the cases are spreading, while there are variants and very contagious like B.1.1.7 [are] really dominant, I want people to do things that are safe. And part of that is to tell people, you know, what restrictions can be released. And that’s why I think it’s crucial that we keep the mask tasks indoors for a while. We cannot give up on that, even while the number of infections is high. But it also means telling people what they can relax on. And again, masking outside, unless you’re in a very, very crowded space for a long time, probably doesn’t do much to protect you or protect others.

Ayen Bior, Courtney Dorning and Elena Burnett produced and edited the audio interview.

Copyright 2021 NPR. To see more, visit https://www.npr.org.

MARY LOUISE KELLY, HOST:

Is it time to stop wearing masks outside? This is a provocative question for many of us, but as more and more people get vaccinated, as we learn more and more about how the virus actually spreads, it’s also fair to ask a question. What science tells us about what is – for sure, for sure; b, respect for the people around us; ic, is starting to take us back to something that seems like a normal life? Well, we brought dr. Ashish Jha, dean of the Brown University School of Public Health, to take over this one.

Dr. Jha, welcome back to ALL THINGS CONSIDERED.

ASHISH JHA: Thank you for bringing me back.

KELLY: I opened with a reference to continue learning more about how the virus spreads. We’ve been told that by now it’s probably okay, for example, to leave a stage where we obsessively Clorox delete all our mail. So, what is the latest research on how coronavirus spreads outdoors?

JHA: Yes. So we learned a lot about how this virus spreads. And what we do know is that almost all spreading occurs indoors when a large number of people – although it may be a small number – gather without disguise. It’s a super high risk. So when you go out, the virus becomes real, very unusual to spread. Now there are ways the virus can still spread out there. If you imagine sets of gatherings where people stand together or sit together for a long time, very tightly packed, it’s a pretty risky situation. But when you get out of those situations, there really isn’t a lot of spreading outdoors. It is really quite safe for people outdoors

KELLY: When you say pretty sure and that it’s really very unusual, can we put a number on this? How unusual would it be to pick up a COVID case if you were out?

JHA: Yes. You know, there are estimates that suggest that maybe 1 in 1,000 infections happens out there. There are reasons to believe that if you’re just thinking about your risk, if you’re just out there and walking around, it’s probably even much less than that. Thus these rare cases occur in those contexts of species-crowded sets. I don’t know that we’ve really seen cases of someone who just, say, went for a walk or ran and thus picked up an infection. I think you really have to have a lot more exposure than that.

KELLY: Wait, you say we haven’t seen a single case where someone just ran and could pinpoint, yeah, that’s where they got it.

JHA: Yes, none I know.

KELLY: I’m going to share that I’m a runner and I recently did deep unscientific research on the running tracks here in DC. There were about one-third, one-third, one-third, which means a third of the people wearing masks, a third of the people more or less not wearing them, and then a third of us who had them wrapped around our chins, ready to wince if anyone passed. I should mention that DC has a mandate for the mask, but it is not needed if you exercise vigorously. Do we know how much the risk increases when you breathe very hard, when you blow and smoke, trying to climb that hill?

JHA: I think someone would be next to you and spend, say, 10, 15 minutes running in that little breath you exhale, there could be a risk. But someone you run to and who’s only there for a second, the risk is – it’s extremely rare.

KELLY: There will be people listening to us and screaming on their radio, saying it’s still spreading and there are variants out there. And so far, most people are not fully vaccinated. You shouldn’t have this conversation yet. What do you tell them?

JHA: Yes. What I am saying is that I understand this first and foremost, but it is really important to have the opportunity for a nuanced discussion of what is safe and what is not. Since one of the problems is if we can’t lead that discussion, then some people will stick to all the rules, even the ones that aren’t necessarily very helpful, and others will just ignore them. And right now, as cases spread, as long as there are variants and they are very contagious – for example, B.1.1.7 is really dominant – I want people to do things that are safe. And part of that is to tell people, you know, what restrictions can be released. And that’s why I think it’s crucial that we keep the mask tasks indoors for a while. We cannot give up on that, even while the number of infections is high. But it also means telling people what they can relax on. And again, masking outside, unless you’re in a very, very crowded space for a long time, probably doesn’t do much to protect you or protect others.

KELLY: Well, and that’s a big goal for all of us, something we can look forward to. This is Ashish Jha, dean of the Brown University School of Public Health.

Dr. Yeah, thank you.

JHA: Thank you very much.

(SOUND OF MUSIC) Transcript provided by NPR, Copyright NPR.

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