99% Invisible - Air-Borne

Episode Date: July 29, 2025

Old ideas about air and disease were wrong on the science, but looking to the past might actually help us design healthier buildings today.Air-Borne Subscribe to SiriusXM Podcasts+ to listen to new episodes of 99% Invisible ad-free and a whole week early. Start a free trial now on Apple Podcasts or by visiting siriusxm.com/podcastsplus. 

This is 99% Invisible. I'm Roman Mars. When I look at a body of water, I assume that it's teeming with microbes. And for that reason, I wouldn't fill my water bottle from a puddle or a pond or probably even a stream because I know that I have a chance of getting a waterborne disease. But I don't apply the same scrutiny to the air I breathe, which is a little odd because it too is chock full of life. Scientists call it the aerobiome.

It's this huge ecosystem that we really barely understand at all. This is science writer Carl Zimmer, who has written an amazing new book called Airborne, all about the life that is wafting about in the air all around us. The aeroboom is not just important for how nature itself works, but you are breathing in living things. things pretty much with every breath. You know, most of the time they don't kill you.

But, you know, when you have a pandemic, sometimes a lot of people do die. Carl Zimmer's book is a scientific history of the air and its relationship to disease. I started reading the book for fun, but I decided to interview Carl on the show because it actually has a lot to do with architecture. Most of our breathing happens indoors,

and yet modern architects rarely designed buildings with airborne disease in mind. Carl Zimmer thinks that's in part because for over a century, scientific institutions have been reluctant to take the air seriously as an important vector for disease. We got a taste of this during the early days of the COVID-19 pandemic, when there was a lot of conflict and confusion about whether the virus was airborne and what airborne even means. But this conflict and confusion, it didn't start in 2020. I mean, the fact is that our struggle to understand the air and what the air means to us and our health actually goes back thousands of years.

So, okay, so I want you to guide us through this history of how we think about the error and its relationship to disease. So where should we start? Well, if you go way back to the ancient world, there were a lot of concepts about the air being the cause of many diseases. And so Hippocrates would talk about myasmas, which were like a corruption of the air. You know, why is it that all these people in this village all got the plague around the same time? Well, it must be because there was a miasma in the air that just

traveled along and everybody inhaled it and they all died. So there was this powerful concept, which held on in one way or another for many, many centuries. Could you describe what was the conception of what a miasma was? Like, what was it made of? Like, I don't quite get it. Of course you don't get it because you don't live in ancient Greece and you don't have an ancient Greek worldview, you know? I mean, you got to think about the world as being made of four elements. So you have to think about your body is being made of four humors. I mean, it takes a lot of rejiggering to really try to even begin to understand what Hippocrates is talking about. It's a corruption. Corruption was a very powerful idea in ancient Western thought in

particular. And so, you know, you would have the four humors in your body, which were in this delicate balance. And, you know, if you inhale this corrupted air, that would throw your humors out of balance. Actually, yeah, like myasmas were believed to be caused by lots of different things. So they might be caused by bad weather. They might be caused by the stars. They might be caused by waste lying on the ground or stagnant water. So there are all these potential sources for corrupting the air. And then when you breathed it in, then you would get sick. And there were different myasmas for different diseases. You know, plague, influenza, so on and on and on. Each one, had its own miasma.

So how did thinking about disease as a myasma affect the way people behaved? Myasma would actually affect the way people built their world, the way that cities were designed and the way that houses were built. So canals would be built, you know, so that you didn't have water just getting stagnant. Waste would be required to be cleared out of the center of cities. When you had reform movements in Britain in the 1700s that were trying to improve the health of people in prisons, people were dying in prisons of diseases, including something they were called jail fever. They thought what you needed to do was to bring in fresh air because wholesome fresh air would replace the stagnant air that, you know, filled with myasmas that was building up inside these prisons. And so there was even a British prison that had a windmill built on the roof to try to circulate fresh air through the whole building. And so a lot of the response to this belief in

myasmas was urban planning and architecture. I want to bring in this character, or this person that is a character in your book named Max von Pettencalfer. Can you tell me about him and where he sits in the miasma world? So Max von Pettencalfer was the last great defender of miasmas. He was born in 1818, and he died in 1901, and pretty much to the end, he was arguing and fighting passionately for miasmas as being the cause of diseases like cholera and typhoid and on and on and on. In his day, he was not considered a crank. In fact, just the opposite. He was revered. He was considered the world. expert on cholera. And so what were Van Pettankoffer's ideas about cholera?

Colora comes to Europe in the 19th century. In this series of epidemics, they're totally terrifying. A city would be running along smoothly and everything seemed fine one day. And the next day, people are just dropping dead in the street. Their faces are turning blue. They are suffering violent cramps and diarrhea. And within a few days, they're dead. You know, thousands and thousands and thousands of people are dying in city after city after city. So what is it? So Van Pentecofer believed that cholera was actually caused by fumes that came out of the ground, that there were the certain kinds of bacteria that could ferment, basically, in soil that was damp and just had just the right conditions.

So you would have these fumes that they would release and they would be. build up inside of buildings, inside of people's homes, especially if they were poorly ventilated. So people would, you know, be breathing this stuff in and out, in and out, and it would create damage inside their bodies that would eventually trigger all the horrible, deadly symptoms of cholera. And so he was very concerned to keep the air safe. So what were his ideas about how to do that, about how to keep the air safe? Well, he believed that, that, that you have to prevent these fumes from reaching people. So one way you can do that is to try to avoid the circumstances

in which these fumes can form. You can build buildings on soil that he believed was safer, for example. He made lots of changes in Munich to the water system so that you wouldn't have a lot of stagnant water sitting around, which he believed that would be a problem. he emphasizes ventilation. You want to get fresh air moving through your house or your office or your school. Because if there's no way for air to get out, these fumes that he imagined were rising up from the ground are just going to get into these rooms and get trapped in there.

And then you just breathe them and breathe them and breathe them. And he was part of a movement. You know, they called themselves sanitarians and they wanted to help everyone. And so, you know, tenements in New York or hospitals for the poor in London or what have you, they were all trying to get fresh air to people. They were all trying to fight miasmas and thereby fight disease. I mean, you wrote that the New York City Board of Health forced the installation of 46,000 new windows throughout the city, which sounds, that's something, that's an intense buy-in. I mean, that's a very expensive proposition. Yeah, absolutely.

Absolutely. I mean, you know, New York was much smaller of a city at the time. So that is just huge. Yeah. These sanitarians and these reformers were able to get a lot of things pushed through. And, you know, Florence Nightingale was very much part of this movement as well. And she designed new kinds of hospitals with long corridors and rooms branching off of them, all designed to maximize the flow of air, to get fresh air. into for these patients because she was convinced that they were getting sick, not from contagious disease, but from myasmas. So as popular as the myasma theory was, the idea that bad vibes or animal carcasses or stagnant water was corrupting the air with poisonous fumes was obviously wrong. And over time, you get this competing philosophy, which is germ theory, which we now know is correct. Can you talk about how germ theorists started to win the battle of ideas against sanitarians like von Pettenkofer? You know, in the 1600s, people are starting to invent microscopes. And when they look through the microscopes, they suddenly discover there are all these

tiny creatures that we didn't know about before. They would call them germs or microbes or, you know, bacteria. They had all sorts of names for these things. And as early as the early 1700s, you had people saying, you know, these germs are the cause of diseases, like plague and tuberculosis and on and on and on. And they got to be known as the contagionists. And everyone thought they were crazy. But slowly in the 19th century, the evidence started to accrue that, yeah, actually, there are particular microbes, species of microbes that can cause particular diseases. And by the late 1800s, there's a German scientist named Robert Koch, who is really starting to nail one disease after another. And he establishes a link between one

kind of bacteria and cholera. So this thing that Maximum Pettenkofer was saying, oh, this is a choleraa, it's caused by these fumes. You've got to be careful about the air that you breathe and blah, blah, blah. Robert Koch is saying, no. it's caused by this bacteria. You know, I find it in people's stool who are sick with cholera. You know, when there's an outbreak in a village and I go to a water tank in India, I find the same bacteria in there. Like, this is, this is it.

And it is spread through water. The last great cholera outbreak was in the 19th century in Europe, was in Hamburg in 1892. And Robert Koch, like, comes in there and says, okay, we have got to deal with this as it really is. as a waterborne microbe. And he brought in clean water. He disinfected houses, so and so forth. The epidemic ended, and national laws were put in place to follow these rules to ensure clean water, you know, to make sure our water doesn't make us sick.

Yeah. And Bon Pencroft refused to accept this. He just kept fighting with Coke over and over again. And now he's like in his 70s, like, no, no, no, no, no. I mean, so much so that he, like, ingests a bunch of cholera just to prove his point. Like, he really put his money where his mouth is. Yeah, right in his mouth that you could say. I mean, what happened was that Von Pettnkopfer sends a very mysterious note to a colleague of Robert Koch in Hamburg.

Says something along the lines of it. I would like to have a sample of this bacteria for my own study. so they send it to him and he gets up one morning and then he goes to a lecture hall and he brings together all of his acolytes and in front of them he declares holding up this tube that he is going to drink it he's going to prove once and for all that cholera is not caused by bacteria that it is you know that it is this this airborne miasma disease and you know his students are like no no no let let us do it for you and he's like no no no No. He says, I should die in the cause of science like a soldier on the field of honor.

He was such a dramatic person. He actually, like, tried to be an actor when he was young. He ran off from pharmacy school for a year and was in the theater and then decided that wasn't going to work. But he never lost a dramatic streak. So he's putting on this performance and he kicks it back. And over the next couple days, he doesn't feel great, but he gets over. And he sends a note to Robert Koch, you know, declaring that he was in good health, just wanted Coke to know. But what Pettencalford didn't know is that when he asked for the bacteria that causes cholera, Coke and his pals kind of had an idea of what he wanted. And they're like, hmm, what do we do? And amazingly, weirdly, you know, they said, let's give him some

bacteria isolated from someone who had very mild symptoms, someone who did not die. So they took pity on him. They didn't tell him what they had done, but they had just said, like, oh, just give him a harmless strain, which he then drank and thought that he had proved at last that my asthma were real. But by then, you know, the evidence was just piling up and piling up and piling up. And, you know, he got very depressed. And it's a very sad story. In 1901, he shot himself. He committed suicide. And, you know, the obituaries were polite at first, but eventually as the germ theory of disease really took hold and myasmas really started to look like like an embarrassing vestige of a superstitious age, Pettenkofer was lost to history. People would just say he is

just a, one journal said he's just a shadow of a name. He was gone. So I'm struck by a certain irony when it comes to von Pettincoffer and the whole myasma theory, which is, you know, the underlying science is complete nonsense, but some of his ideas about how to keep people healthy, particularly his focus on ventilation and clean air, actually do make sense in the context of airborne infections like tuberculosis or COVID-19. I mean, can you talk about that weird irony of being so wrong, but like right enough that, you know, things are actually made better, you know, in the built world and for people's health? Yeah.

It's strange that, you know, we think that when, you know, people are wrong, they're just wrong, wrong. And we think about the history of science as giving up wrong ideas to embrace the right ideas. Yeah. And, you know, those people who were wrong, they're, you know, cast back into history. as being the wrong ones. Right.

And their ideas, we would think of them as just nothing but superstition. And the idea that cholera or typhoid was something that was caused by you inhaling fumes, that's wrong. That's really wrong. And if you were to try to protect yourself from cholera or typhoid that way, you would be so wrong, you'd be dead. Right. And yet, you know, the idea that the air can kill you with some of these infectious diseases, that's true. That's absolutely true. And in some ways, we would do very well to go back to the ideas of people like Max von Pettncalfour and learn a lot from them.

To learn about the importance of fresh air, of clean air, of ventilation, all these things that. Crawford was developing in the 1860s. He was right in a lot of ways, as wrong as he was in other ways. Coming up after the break, Carl Zimmer and I talk about how in the 20th century, our perception of the air totally flipped, and we went from being too scared of the air to not scared enough. Okay, so we're back with Carl Zimmer, and we just got done talking about the end of the miasma theory of disease in the late 1800s. So let's fast forward a little bit into the 1930s and 40s. By this point, there was broad acceptance that germs were causing diseases. And scientists thought

you might spread germs by coughing saliva particles right into someone's face, but they didn't think that germs could float around in the air like smoke. That's right. So by the early 1900s, public health experts generally feel that, you know, they've got a handle on how diseases spread. And they're just of a few basic ways. Either they're spreading by contact, they're, you know, contaminated surfaces, sex, contaminated food. contaminated water, that's about it. And the air, which had been so dominant for many, many centuries, now, you know, in the words of some of these public health experts, it was basically harmless. And, you know, somebody even said, like, we should be relieved. That's great. We don't

have to have to worry about these myasms as a way that, you know, generations and generations were worried about it. Relax. The air is fine. But in your book, you talk about these two scientists who started to really question whether that was actually true. Yeah. William and Mildred Wells in the 1930s, this husband and wife team, said, wait a minute, like, that's not right. And, you know, they develop the basic ideas and the basic concepts for how actually airborne transmission really works. They understood that when we exhale, we're exhaling tiny droplets all the time.

You don't have to be coughing or sneezing. And they might have viruses or bacteria in them. And if they're small enough, they'll just float along. And if you're in a poorly ventilated room, they're going to be hanging around with you. And as people keep exhaling those droplets with the bacteria and the viruses in them, those concentrations are going to increase. And so your risk of getting a disease from these airborne germs will increase. And because myasmas were so out of fashion at this point, did they sort of fight, have to fight? the stigma of being like called myasmistists or something like that.

They did. They did. They actually wrote. We're not talking about myasmas. We're not myasmatists. Please, like listen to us. Listen to what we have to say. And don't dismiss us as if we were from 400 years ago. We're talking about real physics right now and based on real experiments. And this could be a major source of disease. They were concerned for example, that the influenza pandemic of 1918, which had killed 50 million people, they were saying, you know, that might have been airborne. And, you know, tuberculosis, one of the biggest killers year in, you're out. They were saying, we think this is airborne too.

And we're not talking about mysterious my answers. We are germ theorists. There are germs that are doing this, but they're going through the air. They're traveling through the air. And you can stop them in the air. But despite Mildred and William Wells' research showing that, certain diseases were traveling through the air, the scientific establishment remains pretty reluctant to jump on the idea of airborne infection. And this remains true really up until the 21st

century. Yeah. William Wells dies in 1963 and, you know, there's a tiny little obituary for him, but his work is pretty much forgotten right after that, except for a few people that are trying to sort of carry on his memory and his ideas, but for the most part, it's forgotten. And in 2003, in China and in Hong Kong, suddenly there's this pneumonia that breaks out, SARS that, you know, can cause quite a lot of people to die in its spreading in strange ways. You know, there was an outbreak in a hospital where there were cases that went, you know, new cases that cropped up all the way down a ward from a patient, like a long distance. And people were like, well, how is this happening?

And there was an apartment block where lots of people were getting sick, so much so that this giant apartment block had to be emptied out. People were sent off outside of Hong Kong so that the building could be disinfected. And so as a few scientists started to look carefully at that and think about that. And how do you get that sort of spread? They're like, ways we talk about don't, they don't make sense. And they started to dig into this old, old literature about airborne disease, William and Mildred Wells, who they had not heard of.

Like, they had to rediscover these folks and say like, huh, this seems like this explains it. It seems like SARS is airborne. And so you had this small group of people in the early 2000s who were studying SARS, who were studying influenza, who were actually trying to capture the droplets coming out of people's mouths and actually finding those viruses that were in the droplets and they were doing this very basic research, but pretty much ignored by public health community. They just kept saying, no, no, no, this doesn't matter. This can't happen. It's not airborne. They just wouldn't accept it right up through into the COVID pandemic. Yeah. And I still just like, why? Why do you think scientific institutions have been so reluctant,

to see airborne infection for what it is. I mean, because, I mean, when you say this is happening in 2003 and then developing, you know, up until today, it's just like, usually you read science history books and you go, oh, those dummies didn't know anything back then or whatever, and you're like, it's so obvious now and that this is a fight that's brought right to our contemporary doorstep is so shocking to me.

Yes, it's certainly like working on this book. was just really vexing in the sense of like I'd be reading things from the 1930s where I'm like, oh, right, yeah, like, okay, like all this stuff that we've learned in the past few years about airborne disease, like we didn't learn this. We weren't the first, you know? Like people were understanding this stuff in the 30s. And it wasn't a secret in the 30s either. You know, there were newspaper articles about William and Mildred Wells. Not only had they established that diseases might be able to spread through the air, but they could kill them in the air.

They discovered that ultraviolet light could disinfect the air. And so you had an article saying, oh, like, we are going to be protected in the future. Schools and theaters and hospitals and public spaces will be protected by ultraviolet light. So we don't have to worry about things like the 1918 flu pandemic in the future. This is what people were thinking in the 1930s. And then it went away. You know, these are powerful, durable ideas that take hold and don't move very easily. Right.

And we saw this persistent reluctance to embrace the reality of airborne infection as recently as five years ago during the early days of the COVID pandemic. I don't know. Part of me felt like the reason the public health officials didn't want to declare that COVID was airborne was just because they knew that our society was so ill-prepared to deal with. disease like that? There are things you can do, but it takes a lot of work. And so if you treat a disease as if it is only spread through contact or through very large droplets that only go a very short distance, you know, three feet or something like that, there are things that you can do both in hospitals and in the community that are pretty straightforward. You know, you just, you just tell people like, okay, you know, if you're not feeling well, you know, stay at

home. If you see someone who's sick, keep an arm's link for them and you'll be fine, you know. Whereas if you are dealing with an airborne disease that is raging through your community, you've got to like deal with that really seriously on another level. Because the, because now the air itself effectively is making people sick. And so you have to deal with the air as a whole. And that's not something that people are eager to embrace. Yeah. We're all like the mayor of Amity, you know, island. And we're just not willing to accept that Jaws is here. You know what I mean? Because it's just, it's too much to handle, you know? That's right. And I mean, I'm not just inferring this, you know, the fact is that during the COVID pandemic, when there were scientists who

were saying this thing looks airborne and you, the World Health Organization, need to treat it that way, the World Health Organization responded to them saying, we are not going to tell countries with limited health care budgets that they're going to have to go spend it all to deal with big airborne control systems when, you know, we're not entirely convinced of it. People actually said this out loud. Yeah, yeah, yeah.

Those beaches will be open on July 4th, is what they said. Basically. So it took way too long, but eventually we recognized COVID-19 as an airborne infection. And that recognition led to some changes in our behavior, you know,

like outdoor dining and masks. but you personally had a change in your lifestyle that I think is pretty neat. Can you talk about the little device that you now carry around with you to help you measure the level of ventilation in indoor spaces? I have a carbon dioxide meter that I keep with me, and I'm looking at it now. So when we started talking, I had the window open just because it's a nice day here, and it was at 441 parts per million. And then I thought I'd close the window so that, you know, if someone starts mowing their lawn outside, it wouldn't bother our conversation.

And it's gone up to 746 parts per million since we've been talking. That's just my own carbon dioxide. I mean, this strikes me as super funny to me because the inventor of measuring CO2 and who sort of pioneered that. And in fact, the sort of count of CO2, the Pettencalfour number, is Max von Pettencalfour. The myasmatist, you know, the last standing miasmatist. It is crazy. It is crazy. This guy who was, yeah, was willing to drink cholera bacteria to prove his miasma theory.

That's what we call it now. We still call it the peten cougher number. And really because it serves as this useful analog for something else. It's not like you're measuring the amount of bacteria or virus. is in the, you're just measuring the CO2 load, which means it's gone through your body and expelled again? Yeah. So, so Pettenkofer, Maxwell and Pettencalfer thought that he couldn't directly measure the miasmas.

So he would use carbon dioxide as a proxy for the ventilation in a room. You know, he could say a room that has high CO2 is poorly ventilated and therefore can be dangerous if there are fumes that rise in. to it. We can use our carbon dioxide meters to also measure the ventilation in rooms. And if it's a poorly ventilated room and there are a lot of people, the carbon dioxide level is going to build up. And along with that, so are the little droplets that we exhale. And if somebody in the room has got COVID or has got tuberculosis or it's got the flu, it's got measles, I got a whole set of airborne diseases, the risk that you will get sick goes up.

So when your CO2 meter gets to the Pettenkofer number above that number where you're uncomfortable, what do you do? If I'm on a plane and, you know, I'm not able to get off of it, I will break out my mask, you know, an N95 respirator because I know from lots of research that scientists have done, that N95 respirators are really good at preventing you from inhaling airborne viruses or bacteria or what have you. That seems like a very responsible course of action to put on a mask if you notice the number coming up. But should we demand a world in which the expectation is that this number shouldn't get up that high, you know, to begin with, or that the built environment should be

taken care of us in some way? Absolutely. If you are looking at at a carbon dioxide meter, and it's going up over a thousand parts per million, I mean, that's telling you that we're dealing with a systemic failure. We're dealing with a failure to protect the air for all of us. This air in our indoor spaces, we share it. So, you know, we want to find ways to actually make that air healthier for everybody. And there are are lots of ways that you can do that. So one of the interesting ideas in your book is, you know, once we have determined, you know, that the air, the indoor air in particular, is full of this aerobiome that could make us

sick, is that we should think of it. Like we think of tap water, getting clean water. Like if there was, if tap water was spreading a disease, we would fix that problem right away. Should we be thinking about air in this way? Absolutely. Absolutely. Yes. And many of the scientists who led the charge to get the world to recognize that COVID is airborne have been continuing to fight for clean air. They have proposed a whole set of benchmarks that buildings should meet in order to ensure that we're not at really great risk of getting sick so that we don't have these super spreader events. And so how do we do that?

Like, how do we move towards a world where healthy air is an expectation the way clean water is an expectation? Well, I mean, I think to begin with, people need to monitor the air. And then if you've got a space that was built poorly and is poorly ventilated, you've got to find out ways to make them better ventilated. Back in, you know, the 1800s, New York City said, okay, we're chopping windows into buildings. Right. We don't necessarily have to do that. but, you know, there are ways to retrofit buildings so that you can bring in more fresh air to mix into the ventilation systems. That's one way. You can use filters, you know, like hepa filters

and other types of filters. Those work. In some circumstances, ultraviolet light might actually work really well. There still needs to be more testing to really, you know, nail down the best way to use it. But we've known since the 1930s that ultraviolet light can disinfect air. So that that could be another tool. And then when new buildings are built, you know, they need to take these facts into consideration. It's a lot easier to build a healthy building than it is to try to retrofit a sick building. You know, building engineers and building engineers societies are thinking about these issues very seriously and some of them are implementing these things into their building's designs, which is great. But, you know, it's just on a sort of case-by-case basis. You know, you don't

walk into some building and go into a bathroom and, you know, washing your hands, thinking, well, I hope this building, you know, has clean water that won't give me cholera, you know. You don't say that because you don't have to say it because there are standards for that. So there's no country in the world yet that has standards along the lines that I'm talking about. I mean, could there be standards for indoor air quality that could be met? Oh, yeah, yeah. No, I mean, these scientists who championed recognizing COVID as airborne, they have come out with proposed standards to meet. There have been model bills that have been drafted at Johns Hopkins University. It's all in place that it can all go, but there is still a lot

of inertia. I mean, this seems like a real call to arms and a provocation for architects and designers in particular. Like, you know, like to make this central to the way that they're designing our built world is to prepare us for this. Yeah, absolutely. I mean, we were in a bad position when COVID hit in 2020 because so many of our buildings and our spaces were poorly ventilated and were just great places for this virus to build up and go from one person to another spreading around like smoke. I mean, that was, you know, that's one of the particular cruelties of diseases like COVID

because they pray on us when we come together. I do think we deserve to enjoy each other's company and not just out in the park. Outside is fine, but inside is important too. And there are ways that we can make that experience safer. And that will help us for diseases that we deal with sort of on a day-to-day basis now, like familiar diseases. And we do have to think about the next pandemic

because, unfortunately, there will be one. And, you know, if it's airborne, the way COVID was, that will really turbocharge it and make it, you know, particularly bad. It is definitely a wake-up call. And, I mean, you know, this wake-up call started in most recently in 2020. So we've had five years of wake-up call. So it's time to stop hitting the snooze button on it. It's time to wake up and start to build safer buildings. So one of the final scenes of this book is at Club Cafe in Boston.

And it is kind of doing some of the things. things that you are recommending in terms of how to make our air biome safe for us. Can you describe what it's like there and what they're doing? So in working on the book, I got to know a retired tuberculosis expert named Ed Nardell. And he had worked a lot in using ultraviolet light to protect homeless shelters when there were tuberculosis outbreaks happening. So Ed, in his retirement, discovers he really likes to sing, he likes to sing cabaret songs. And there's this club called a club cafe where every week in a little space called the Napoleon Room, people get together and there's a piano in there and they take turns singing songs. So after

people got vaccinated, you know, Ed was thinking, well, like, we need to get back together. We need to get together. And so he talked the club into letting him install these little far UBC lights on the ceiling in the Napoleon room. And far UVC lights are this new kind of ultraviolet light fixture that you talk about in the book. They can still disinfect the air, but they're designed in such a way that they won't burn your skin or hurt you. That's right. And that would be, you know, the ultimate safe space. You could go in there, you could sing, and you could be pretty confident

that you wouldn't get sick from COVID. And he invited me along to join him one night. So me and my wife came, and we had a great time singing away and just enjoying this experience with other folks, quite confident that we were not going to get COVID while we were there. And we didn't.

And, you know, Ed is not aware of anybody who has gotten COVID coming to the Napoleon room for these performances. So, you know, I think that gives you a picture of what life could be like taking airborne disease seriously. It doesn't mean that we have to be all in lockdown, in total isolation, and being really depressed. We can get together. We can do stuff.

We can sing. We can have a good time. we just need to take the right precautions. Yeah. Carl Zimmer, thank you so much for talking with me. I enjoyed the book so much. There's so many details in the book that we didn't cover, but I just, so I encourage people to read it. It's so much fun. Thank you so much for talking with me. Oh, thank you so much for having me. 99% Invisible was produced this week by Emmett Fitzgerald, mixed by Martine Gonzales,

music by Swan Real and George Langford. And hey, just a heads up, Emmett is going to be interviewing author and 99PI contributor Sam Block at the Commonwealth Club in San Francisco on Tuesday, July 29th. They'll be talking all about Sam's fantastic new book, which is called Shade, The Promise of a Forgotten Natural Resource. If you're in the Bay Area, you should totally check it out. Kathy Two is our executive producer. Kurt Colstead is the digital director.

Delaney Hall is our senior editor. The rest of the team includes Chris Barubei, Jason Dillard. Leone, Christopher Johnson, Vivian Lay, Lashma Don, Joe Rosenberg, Kelly Prime, Jacob Medina Gleason, and me, Roman Mars. The 99% of visible logo was created by Stefan Lawrence. We are part of the Series XM podcast family, now headquartered six blocks north in the Pandora building. In beautiful, uptown, Oakland, California. You can find us on all the usual social media sites as well as your own Discord server. There's a link to that as well as every past episode of 99 PM.

at 99PI.org.