Science Vs - Coronavirus: Is It Airborne?

Episode Date: April 3, 2020

We’re hearing conflicting things about how the coronavirus spreads — is it through coughs and sneezes only? Or could it be floating in the air, infecting us as we walk down the street or go grocery shopping? We ask Dr. Rachael Jones, an industrial hygienist, and Dr. Zhi Ning, an environmental engineer.  Here’s a link to our transcript: https://bit.ly/3aI1kAE This episode was produced by Rose Rimler, Wendy Zukerman, Michelle Dang, Meryl Horn, Sinduja Srinivasan, Laura Morris, and Meg Driscoll. We’re edited by Blythe Terrell and Caitlin Kenney. Fact checking by Michelle Harris. Mix and sound design by Peter Leonard. Music written by Peter Leonard, Emma Munger, and Bobby Lord. A big thanks to all the researchers that we got in touch with for this episode, including Prof. Natasha Crowcroft, Prof. Linsey Marr, Dr. Stephanie King, and Noah Miller. And special thanks to the Zukerman family and Joseph Lavelle Wilson. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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New episodes drop every other Thursday, starting February 1st. Hi, I'm Wendy Zuckerman, and you're listening to Science Versus from Gimlet. Today on the show, is this coronavirus airborne? This is a question on a lot of people's minds right now as we're wondering, could we get infected from the air? Like when we go outside and no one's around, is it safe just to go for a walk? Our producer, Rose Rimler, tried to figure this one out. And her research took her down this really surprising path, back in time, all the way up to today. Rose takes it from here.

Back when we were first learning about this coronavirus, one of the things I found the most reassuring was what we were being told about how it spreads. Experts were saying that it passes through droplets, the stuff that sprays out of our nose and mouth when we cough or sneeze. And I was like, great. That's fairly easy to avoid, right? I mean, when is the last time

someone actually coughed in your face? But then I read these papers coming out showing that something else is going on too. This coronavirus is trickier than we first thought. And the idea that this coronavirus could be airborne really freaked me out. Because when a virus is airborne, something about that just feels scary. I mean, the first thing that comes to my mind when I think of airborne diseases is actually an episode of The Simpsons. It's an old Halloween episode.

And there's a scene where a fog that turns people inside out sneaks in through the Simpsons window. It looks like a green cloud and it makes an evil hissing sort of noise. Then the whole family screams and turns inside out. So that's what I think of when I think of airborne disease. A toxic cloud traveling from house to house and there's no escape. So when you say something might be airborne or inhaled, that raises the specter of these vicious microorganisms traveling through the air around the globe from office to office, from building to building. It's a very threatening feeling. This is Rachel Jones, associate professor at the University of Utah.

She told me this question about whether this virus, or any virus, is airborne is actually controversial, which surprised me. To understand why it's controversial, you have to understand the history. We have to go back about 100 years. People were starting to have real problems, especially among military hospitals, with these infections that were occurring, and people were trying to figure out how these diseases were being transmitted. Back then, scientists didn't know how viruses and bacteria spread from person to person, although they had some hunches. When sick people

cough and sneeze, they thought, maybe there's something in the stuff that comes out of their noses and mouths. But how could they prove it? One way was to put petri dishes in a room with people coughing and sneezing. It's basically, you're putting out a little bowl and you're going to just see what lands in it. I mean, that's not a terrible idea, really. No, it's absolutely not a terrible idea. And what they thought might happen did. Bacteria started to grow on the dishes, so they knew their hunch was right. Germs could come out,

travel through the air, and then land on the counter or the petri dish or the floor. They started calling the big gunk that came out of people's mouths when they cough or sneeze droplets. And this is the origination of the idea of droplet transmission. These large droplets that they can see those particles visibly when somebody is coughing and that you can actually feel land on your face. Gross. Voila. Getting sick from droplets was officially discovered. But scientists realized this couldn't be the only way sicknesses were spreading. They knew some diseases were really sneaky because sometimes people were getting sick when they were nowhere near an infected person. Take smallpox, for example.

We have a classic case where smallpox was transmitted through a building to another floor and a patient became infected on the third floor, having never contacted the person on the first floor. Something else was obviously going on here. But what? Enter a Harvard professor named William Firth Wells. He was a veteran of World War I, he had a mustache, and he puffed constantly on a pipe. William wanted to prove that diseases were traveling through the air, so he designed a fluffier kind of experiment. He and his team moved a colony of guinea pigs into the tuberculosis ward of a hospital in Baltimore. The patients didn't get to play with

the guinea pigs. The guinea pigs were put far away from the patients, in the air ducts, so they couldn't get coughed on. But they were breathing the same air as the patients with tuberculosis. William maintained this colony, actually his female assistant maintained the colony, for years. And over that time, 100 guinea pigs got infected with TB from the patients in the hospital. And eventually, so did the female assistant. Anyway. And that gives rise did the female assistant. Anyway. And that gives rise to the concept of airborne transmission. The thinking goes like this. For airborne diseases, you are breathing out teeny bits of

liquid that have viruses or bacteria in them. This stuff can survive in the air after you breathe it out, even after the liquid evaporates. And these dried up germs might get carried far away, you know, compared to those droplets that are heavier, so they fall to the ground faster. And so for a long time, that was how we thought about these diseases, airborne or droplet. Two separate things. On team airborne, there's TB and measles. On team droplet, there's the flu, whooping cough. Correct, yeah. But now things are changing. We're finding out that these categories are a lot muddier than we thought. And it's not because people like William Wells were dummies. It's because we have way better technology. We don't have to rely on petri dishes or sick guinea pigs anymore. Now we have the tools to actually pull

stuff out of the air, particles that are called aerosols. Now that we have a lot more sophisticated aerosol techniques, we can measure particles that are very, very small and particles that are large. Now we see that for some diseases that we thought were droplet diseases, you can find little particles hanging out in the air too. Take the flu. Researchers have had people with the flu talk into a cone, and then they collect the air that comes out of their mouths. In that air, their breaths, they found little bits of flu virus. And other studies have found that these viruses can actually move across a room and potentially infect someone.

So much for the flu being a droplet disease. What this means is that for at least some diseases, you can get sick via droplets or from the air. We now have data to demonstrate that droplet and airborne can actually occur simultaneously when a person is standing close to the sick person who's releasing virus into the air. And then science-wise, like it's 2020. Is this like we're kind of hung up on this. It's droplet and not airborne. It's airborne and not droplet. What does the science tell us today about that distinction?

I think that the science tells us today that that distinction is not particularly helpful. So basically, there isn't an obvious line that separates airborne and droplet. But some viruses seem to do better in the air than others, like smallpox and measles. So what does this mean for this coronavirus? We told our audience, like, well, this is primarily spread by droplets, which was a little bit of a reassuring message. So did we get it wrong? Well, I think...

Hmm. I think it's incomplete. The complete story? Coming up. Just after the break. Welcome back. We've just found out that despite the Simpsons and Hollywood blockbusters screeching, it's gone airborne,

the distinction between a virus that is airborne and one that isn't is muddier than it might seem. And there are diseases that we don't normally think of as airborne, which can actually travel a little in the air. So what does this all mean for the coronavirus now? To find out, we called up Zhu Ning from the Hong Kong University of Science and Technology. Hi, Wendy there.

Hello. Over a month ago, as this virus was taking hold in Wuhan, Dr. Ning was watching and wondering. We had a big question in our mind. It's how this virus can transmit in the air, how fast it can spread, and how much harm it can cause to the human being. We want to know more.

So he got in touch with some colleagues in Wuhan, and they decided to start testing the air in a bunch of places around the city. And to sample the air, they don't just wave a glass jar around and quickly screw the lid on. They use a machine that's a bit like a fancy vacuum cleaner. In a way, we have this active pump. We can suck the air through a filter. That filter is specifically designed so that it catches genetic pieces of the virus.

And then back at the lab, the team will see if they've nabbed this coronavirus. Now, Dr Ning's test can only measure the genetic material of the virus. Using this method, we can't actually be sure that any of the virus that he might find would still be alive. But based on other similar tests done by different scientists, we think that at least some of them would be. So knowing all that, one of the first places that these scientists looked were spots that they figured were bound to have a lot of virus. Hospitals, where patient after patient with coronavirus had come through. You could imagine how dangerous those places could be.

The researchers put on big quarantine suits and tested all around the hospital, even going into the health workers' changing rooms. And they went into the room and hold the samplers in the air. So what did they find? Well, when they looked at the hospital air, in some rooms where there were coronavirus patients, they couldn't detect any viral bits.

But in a few hotspots locations, we did see some of the viruses. One of those hotspots was perhaps not where you might expect. It was the bathroom. You see, one of the hospitals had had these makeshift toilets. Yes, indeed, indeed. The toilet is a very simple mobile toilet and without ventilation. And it turned out the air had a bunch of viral particles in it. So Dr Ning couldn't help but wonder.

But where does this virus come from? He figures there are two main explanations. The first is the obvious one, the breath of the patients. As they pooed and weed, they also might have breathed out viral particles into the air. And since the toilet was poorly ventilated, the particles just hung around in there. But there's a second explanation too,

one that's a little more intimate. Because some studies have found that viral bits can be found in faeces. This faeces may find its way during the use of toilet time and is probably re-aerolactylised into the air. Oh, so when people flush the toilet and then it goes whoop and it possibly puts viral particles in the air. Yes, indeed, because the flushing of the toilet or even general the movement of the water,

actually that can stir up the water, the liquid, and aerosolize liquid droplets. So close the lid is one of the messages of your study. Indeed, indeed. Let's do that. And viral particles weren't just found in the air of the dunny. Another hotspot that showed up in the hospital was the room where the healthcare workers took off their protective gear. And the air in that room was actually pretty contaminated,

which was particularly interesting to Dr Ning. Because the thing was, all these hospital workers had been tested and they didn't have coronavirus. And they were the only people that went into that room. No patients. The patients cannot get in. The public cannot get in. This suggests the viral particles might have gotten into the air like this. As the workers came into contact with patients, they also came into contact with this virus from patients coughing and sneezing or

breathing or what have you. The virus then would have landed on the hospital workers' gear. And then perhaps when the workers took it off, the viral bits flung into the air. And it seems that this virus can stick around in the air. In a separate study, scientists who spritzed this coronavirus into the air in a lab found that some of it was still there three hours later. So that's the hospitals. What about other places? Places we all go to. Well, Dr Ning's team also sampled the air at a supermarket, around a university and a residential building. And they didn't find coronavirus in the air. But it wasn't all good news. Dr. Ning did find something concerning.

Viral bits were hanging out inside a department store entrance, where he reckons dozens of people were walking in and out. Oftentimes, there are patients who don't know they got infected. And when this is the case, when they walk around and as. Oftentimes, there are patients who don't know they got infected. And when this is the case, when they walk around and as they talk, they potentially can infect other people, but they don't know. That's a very dangerous side of this coronavirus. So, of course, our next question is,

if I was walking through that department store entrance at the time, would I have gotten sick? I think there is a few steps in the middle to jump into the conclusion. You see, once the virus gets into the air, there's a few more hurdles it has to clear before it infects me. So first, I'd have to breathe it in. And because we think this virus has to get into my body to gain a foothold, if I walk through that cloud of coronavirus and say virus lands on my shirt or my skin, I'd probably be okay. But say it does get into my mouth. The next hurdle? I'd have to breathe in enough viral bits

to make me sick. Now we don't know the cutoff for this virus, like how many viral particles I'd need to get in me to make me sick. But it is possible that maybe I wouldn't have breathed in enough. Okay, so what are we to make of Dr. Ning's study? Well, yes, this virus, it can be found in the air, but it's not everywhere. And other research is finding this too. Like a few small studies looking at rooms where coronavirus patients are being isolated. Well, they only detected viral bits in the air of some of the rooms they tested. And the uncontaminated rooms tended to be well ventilated.

So it's looking like we have to be particularly careful in poorly ventilated places and places that have been visited by lots of people. Oh, and close the lid of the toilet. But there's still so much we don't know here. Like, we did find this one study that kind of threw a wrench in the works. It got a handful of patients to breathe and talk near an air sampler only four inches away from their mouth.

And then they didn't pick up any of the virus from them. Do your findings give us reason to panic? We don't have to panic saying we cannot even breathe air anymore. I say we should be more cautious because we know more. I should use the word cautious, cautious, cautious. Even with everything we're learning about this virus in the air, scientists still think a lot of the time it's spread by those classic old droplets, sneezing, coughing, that kind of thing. Or in a way that we haven't even talked about yet,

through touching something that's been contaminated. And it's that part that raises a ton of questions for people about how they can protect themselves. Like, what are you supposed to do about your packages, or your groceries, or your bed, or your kitchen counter, or your dog or your bed or your kitchen counter or your dog. We're hearing that this virus could be everywhere, like some evil glitter. So is that true? And how cautious do you really have to be? Well, that's coming up next Monday.

But before we say toorah, let's change gears and time for a bit of NCVC, non-coronavirus content. I want to tell you about dolphins. Yes. Researchers have found very recently that male bottlenose dolphins near Western Australia sing together, boy band style, when they're trying to pick up a female. Scientists already knew that these guys sync up their body movements to attract a mate, but now they've caught dolphins singing together too. And these animals are in sync at 600 beats a minute. The researchers sent us the dolphin sounds that they recorded. Here is one dolphin singing alone.

And here are the dolphins singing together. Hear it? And unlike boy bands, these dolphins, sometimes they stay together for decades. That's Science Versus. Hello? Hey, Rosarimla. Oh, I know what this is. I was like oh god

something must be really wrong oh wait citations citations how many citations in this week's episode Roy's Rimmel producer at Science Versus Wendy Zuckerman host of Science Versus today we've got

76 citations 76 and if people want to got 76 citations. 76. And if people want to see these citations, where should they go? They can click on the link to our transcript, which is in the show notes or on our website. Thanks, Rose. Thanks, Wendy. This episode was produced by Rose Rimler, me, Wendy Zuckerman,

Michelle Dang, Meryl Horn, Sindhuja Srinivasan, Laura Morris and Meg Driscoll. We're edited by Blythe Terrell and Caitlin Kenny. Fact-checking by Michelle Harris, mix and sound design by Peter Leonard, music written by Peter Leonard, Emma Munger and Bobby Lord. A big thanks to all the researchers we got in touch with for this episode, including Professor Natasha Crowcroft, Professor Lindsay Maher, Dr Stephanie King and Noah Miller.

And a special thanks to the Zuckerman family and Joseph LaBelle Wilson. I'm Wendy Zuckerman. I'll back to you next time.