August 5, 2025 • 49 mins
In the first years of the COVID pandemic, a debate raged: was the virus transmitted via respiratory droplets, or was it airborne? For some, this distinction seemed overly technical, pedantic even. But for others, it represented decades of dismissal and missed opportunities - opportunities that had cost untold lives. In this week’s TPWKY book club episode, renowned science writer and journalist Carl Zimmer joins us to discuss his latest book Airborne: The Hidden History of the Life We Breathe, which uncovers the long-forgotten story of an entire field of study - aerobiology - and the pioneering scientists who discovered life where there was thought to be none. Tune in for a fascinating conversation about why airborne transmission matters and the incredible work that some researchers are doing to breathe new life into its study.
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Episode Transcript
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Speaker 1 (00:43):
Hi, I'm Aaron Welsh and this is this Podcast Will
Kill You. Welcome to our newest episode in the tp
w k Y book Club series, where I get to
chat with authors about their latest books in science and medicine.
We have covered some great books so far this season
and in past seasons, and we've got plenty more excellent
(01:07):
books to add to your to read list throughout the
rest of this season. If you would like to see
the full list of books that we've covered so far,
as well as get a sneak peek of the books
that will be featured later this season, head over to
our website This Podcast will Kill You dot com, where
you'll find a link to our bookshop dot Org affiliate account.
Under the extra tab, there you'll see several TPWKY lists,
(01:31):
including a book club list. Check back on that list regularly,
as I'll be updating it throughout the season. As always,
we love getting your feedback, whether that's a topic request,
a suggestion for a book to feature in one of
these episodes, or just any other thoughts you have. You
can reach out to us via the contact dose form
on our website. Two last pieces of business before we
(01:54):
get into the meat of the episode Number one, Please rate, review, subscribe.
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(02:16):
By now, we are all fairly familiar with the concept
of the microbiome, the community of microbes that live in
a particular environment, such as your gut, or your skin,
or maybe even inside your belly button. But how many
of you have heard of the aerobiome. We don't often
think of the air as a medium teeming with microbial life,
(02:38):
but as Carl Zimmer demonstrates in his latest book Airborne,
The Hidden History of the life We breathe, that may
be a critical oversight. In this book Club episode, award
winning science writer Carl Zimmer joins me to discuss the
long neglected science of aerial life and the public health
implications of this research. Many of you may recall the
(03:02):
debate that sprung up seemingly out of nowhere in the
first couple of years of the COVID pandemic, when scientists
couldn't seem to agree on whether the virus was transmitted
via respiratory droplets or whether it was airborne. Why this
distinction mattered and how the issue grew so contentious is
just part of what Zimmer covers in Airborne. By placing
(03:25):
this debate in the broader context of the history of
aerial biology, he draws a line from the early days
of germ theory to the pioneers of this emerging field,
from the height of biowarfare research to a Washington State
choir in the first weeks of the COVID pandemic. Linking
together these disparate stories from the history of science, Zimmer
(03:48):
presents a revelatory picture of a scientific field you didn't
know existed. How might the COVID pandemic have been different
if we acknowledged the airborne potential of this virus earlier?
What lessons can we draw from this oversight to apply
to future outbreaks? What even lives in the air, and
(04:08):
why does it matter? We get into all of these
questions and so many more. According to a quick Google search,
we breathe about twenty two thousand breaths a day, breaths
that we don't often think about, but after this episode,
you'll have a newfound respect for those breaths and the
invisible airborne life all around us.
Speaker 2 (04:31):
I am very.
Speaker 1 (04:32):
Excited to be bringing this episode to you, so let's
just take a quick break and get started. Carl, thank
(05:01):
you so much for joining me today.
Speaker 2 (05:03):
Thanks for having me.
Speaker 1 (05:04):
I have long been such a fan of your work,
and I really especially appreciated your latest book, Airborne, which
tells us really fascinating story of discovery, dismissal, and then
ultimately kind of redemption in the end. To start us off,
can you give us this big picture view of what
the story that you explore in your book and what
(05:25):
inspired you to write about it.
Speaker 2 (05:27):
The story is about the air and how humanity has
slowly come to appreciate the fact that it's alive. In
other words, we really are walking around on the floor
of a giant, living ocean that is filled with trillions
upon trillions of organisms, thousands of different species, a few
(05:51):
of which we can see, you know, we can, you know,
see a goose flying overhead, but for the most part,
it's totally invisible to us. And I guess I say
this the seed of this book came about during the
COVID pandemic. I was working at the New York Times,
and I, along with my colleagues, we were just trying
(06:11):
to write as fast as we could about this totally
new disease. And you know, it was challenging because scientists
themselves are trying to figure out what exactly this disease
is like. And one of the biggest sumbling points, one
of the areas with the most debate and uncertainty, was
(06:31):
how it spreads. You had people telling you on TV
to wipe down your groceries. I know I did, and
just you know, keep your distance from people, and you know,
you'll be fine. Then there were other there were scientists,
a small number of scientists at first, who were saying,
we think this might be airborne. World Heart Organization explicitly
(06:52):
saying COVID is not airborne, and you know, it took
a couple of years, and then world health organizations that yeah,
it's airborne. And I just thought, why was that so hardy?
And the scientists themselves said to me, like, well, you
need to understand the history. One scientist said, you know,
(07:13):
history set us up. And so that led me down
this path to discover this whole history of this science
of the life in the air, which is called aerobiology.
Speaker 1 (07:23):
Yes, and as you discussed, you know this, we're living
underneath this ocean of all of these different organisms. This
the aerobiome. What can you tell me about the aerobiom
Like who's up there? Who's floating around besides the geese
that we.
Speaker 2 (07:38):
See, well, all sorts of things. The numbers are kind
of crazy. I mean, actually you have to write them
down and double check them because I'm like, did I
get that right? Because they're just so I'll just give
you one example. So insects. Okay, so you know you
presumably seen you know, some dragonflies flying by, or maybe
(08:00):
like a little swarm of mayflies or what have you.
I mean, it's not unusual to see an insect in
the air, but scientists have long suspected that that maybe
large numbers of insects flying long distances high in the air,
thousands of feet in the air. The problem is you
can't see them, and so scientists have invented technology st
(08:21):
barring radar and tuning it so that you can detect
insects that are in large numbers that are way up
in the air. Lo and behold, there are a lot
of insects up there. And just to give you one example,
and there's a study that came out last year and
from China where just in a small region of China,
they set up some radar systems to look up and
(08:41):
over the course of a year they recorded nine point
four trillion insects just in that place.
Speaker 1 (08:50):
I can't comprehend that.
Speaker 2 (08:51):
Yeah, yeah, right now, these numbers are incomprehensible. When you
get to fungi, you walk around in a forest trail,
you see some mushrooms. You think you know what fungi are,
but you really don't, because they're everywhere. They're on everything,
and they make a living by sending their spores into
the air. I mean they have adapted beautiful like little
(09:13):
cannons and other devices to get their spores up high
enough so that the air can carry them away and
then they can go all the way up to the stratosphere.
Fungi loan they lift up about a trillion trillion spores
every year.
Speaker 1 (09:29):
Again, I can't I don't know what that means even
right right.
Speaker 2 (09:33):
What do you do with that? The you know they're
back also bacteria, viruses, algae like and again they probably
comprise thousands tens of thousands, maybe millions of species. You know,
we've barely begun to sample this habitat, this living habitat
in the air called the aerobiome.
Speaker 1 (09:53):
And I love how you describe it as an ecosystem
of visitors. You know, this is a for most of
these species. This is a transitory period. If you take
one you know, cubic meter of air or something wherever
it is, how often that changes just within a second,
within a minute, within a day, it's completely different.
Speaker 2 (10:12):
Yeah, it really depends for the individual organism on how
high they get up initially, you know, and what the
air conditions are like when they get lofted into the air.
The oceans, for example, every time a wave breaks, there
are lots of tiny droplets that rise up, and some
(10:35):
of them have bacteria, viruses, other marine organisms in them. Now,
if there's enough of a breeze, they may get carried
up and maybe they fall right back down after you know,
a few seconds. But it is possible for them to
go up and then keep going up, and then eventually
they get so high that they're just riding along long
(10:57):
distance waves and they can actually go thousands of miles,
so they can be floating for days. You know eventually
they will land. I mean, it's just a matter of time.
But because there's so many things coming up all the time,
it's always a very lively space. So like the clouds,
for example, every cloud you look at is alive. It's
(11:18):
it's got you know, trillions of bacteria something something on
the order of that. And you know the bacteria, there
are signs that they might be growing in the clouds,
and that means that they are eating the clouds. So
you know, it's a different way to look at the
sky and think about what's up there.
Speaker 1 (11:39):
Let's take a short break, and when we get back,
there's still so much to discuss. Welcome back everyone. I've
(12:03):
been chatting with Carl Zimmer about his latest book Airborne,
The Hidden History of the life We breathe. Let's get
back into things. Which certain types of pathogens are more
likely to be airborne? Do they share certain evolutionary history
or drivers that might make them more likely to be airborne.
Speaker 2 (12:21):
That's a really good question, and I honestly, I don't
think anybody has a good answer for you. Yet. Part
of the challenge is it's hard to really carefully study
airborne disease if you're talking particularly about pathogens. Now, certainly
there are some very familiar pathogens that are clearly we
(12:43):
know are airborne, but that's by no means an exhaustive list.
There probably are lots of other things that we are
not appreciating fully yet. But just to give a couple examples,
the biggest infectious disease killer by far is tuberculosis. It's
caused by bacteria, and those bacteria are totally airborne. In
other words, they really can't infect people in any other
(13:07):
way other than people releasing little droplets that float out,
not just you know, maybe when they cough or sneeze,
but even when they're just breathing, they are going to
release droplets, some of which have tuberculosis bacteria in them.
These are so good at being airborne that they actually
(13:28):
manipulate us. They actually have adaptations to sort of essentially
tickle our airway to get us to cough more, because
that gets them out and gets them into the air,
propels them and then they can float off and infect
someone else, and they make the droplets make their way
into the very finest tips of our airway endings. In
the lungs, the lvoli and that's where the bacteria can grow.
(13:49):
So tuberculosis kills over a million people a year. But
you know, it's also a huge threat to in terms
of pathogens. It's also a huge threat to our crops.
So there are lots of disease is, particularly fungi that
spread through the air in part or entirely. I write
a lot about a kind of fungus called rust, which
(14:11):
can just you know, it can endanger the food supply
of whole countries if it really breaks out seriously. So
I'm just giving you two examples, but there's a long list.
And you know, is there something about airborne pathogens that
you know they all have in common? I would say
they're rugged in the sense that they can survive being
(14:34):
floating around in the air. It's not easy to be
a pathogen floating around out in the air. It's hard.
And there's some viruses that don't last very long when
they're exposed air. Other viruses can last a really long time,
and it might be that they sort of they have
adaptations that let them kind of use the chemicals inside
(14:55):
of those droplets that come out of our lungs to
sort of shield themselves from the elements.
Speaker 1 (15:01):
This respiratory droplet versus airborne debate, you know, as you say,
really took center stage during COVID as we all remember,
and kind of, like you it seemed baffling, like why
is this so controversial? Why is this something that we're
so resistant to the idea of this being airborne, especially
when it seemed like, you know, this research had been
(15:21):
going on for quite some time. And before we get
into how that controversy started in the germ theory myasthma debate,
what role did people think the air played in diseases
before germ theory.
Speaker 2 (15:35):
So if you go all the way back to say Hippocrates,
in the sort of the world of Western thought in particular,
there was this idea that obviously, you know, air is
essential to us. The Greeks considered it, you know, one
of the main elements we obviously we need to breathe.
But people couldn't really say why. And yet there was
(15:57):
sort of a sinister dark side to the atmosphere. And
you know, like I mean, we've all, I suppose we've
all had that experience walking around. It's you know, today
here in Connecticut, it's a beautiful sunny day. The air
feels very lovely, but you know there are also days
where you like, it smells really wrong, or there's a
there's a weird light in the sky because there are
(16:19):
wildfires someplace, and you know, like the the air is unpredictable.
And so Greeks had this idea that gods could visit
curses on them and they would call these miasthmas. And
Hippocrates said sort of took that name and applied it
to what do you call it, like corruptions of the air,
(16:39):
so that if you breathed in that air, you would
become sick. And there were different miasthmas for different diseases,
and even different species could get different diseases because they
had their own miasthmas, but they were all transformations of
the air itself. It had a certain explanatory power. I mean,
how was it that, you know, a bunch of people
in this same town all would get the same disease
(17:03):
around the same time. You can imagine, well, you know,
a breeze just came through and people all inhaled it
and then they all keeled over. But that explained plague,
and you know influenza, and you know malaria literally like
bad air, like that's what the disease name means. And
so it held on for a long long time until
(17:25):
people who had been discovering and studying microbes said no, wait,
we think these are responsible for these diseases. And it
was a very you know, it was a very long
slog I mean to us in hindsight, it seems obvious,
but you know, this was a battle that started around
seventeen hundred and lasted up until about nineteen hundred, so
(17:47):
about two hundred years of a long drawn out fight.
Speaker 1 (17:51):
It seems like a blink of an eye, like Louis
Pasture came in and solved everything, But it's not. That's
not what actually happened. But I think it's it's so
interesting to think about miasma and airborne transmission because they
seem like almost the same thing, right, Like, how was
that distinction made between microbes in the air causing disease
and miasma causing disease?
Speaker 2 (18:13):
There were a lot of confusing, seemingly contradictory pieces of
evidence flying around. So Louis Pasteur, who you mentioned it
was an architect of the germ theory disease. He actually
was the first person to really clearly demonstrate that there
were germs floating in the air. And people said at
(18:33):
the time when he was trying to persuade them of this,
that this was crazy. One journalists said, this is you
want to lead us into a world that's too fantastic
to believe. I love that line. But he would go
outside with flasks and he would catch bacteria. They would
fall down the long neck of the flask and fall
into sterile broth and start multiplying. And he did it
(18:56):
in Paris streets, he did it in farmland around France,
and the even climbed a glacier, which was my favorite
episode of this. And he actually initially said that he
thought that lots of diseases were caused by these floating germs,
by airborne germs, but it didn't really go that way,
and what happened instead was that as as scientists definitely
(19:22):
showed that the diseases were caused by germs. So, for example,
cholera not caused by miasma as the authority is claimed. Instead,
it was caused by Fibrio cholerae, like one particular bacteria,
and that particular bacteria spread in water, so you have
a water borne disease and then you have other bacteria
(19:42):
that get into food and contaminate food, so you have
food borne diseases. You have you know, bacteria that spread
through sex, sexually transmitted diseases, and on and on and on.
So it was like the germ theory disease was taking
one disease after another out of the air. Yeah, and
by the early nineteen hundreds you had very prominent public
(20:05):
health figures saying we don't need to worry about the
air anymore, like this should be a relief. The air
has been this specter of infection since Hippocrates. They literally
said this, and now you don't need to worry that.
I think that really did keep people from really thinking
very much about life in the air. And they also
(20:25):
didn't have very good technology for really measuring and capturing
life in the air. So that combination really did lead
to a real, very strong consensus starting in the early
nineteen hundreds that has endured for over a century.
Speaker 1 (20:41):
Let's take a quick break here, we'll be back before
you know it. Welcome back. I'm here chatting with Carl
(21:01):
Zimmer about his book Airborne, The Hidden History of the
Life We Breathe. Let's get into some more questions. There
were still some people that did remain intrigued by the
concept of, you know, living things that the aerobiome. And
I want to ask you about one of these, which
is Fred Meyer. How did he end up turning what
(21:22):
was first a hobby into this branch, this whole branch
of science.
Speaker 2 (21:27):
Yes, Fred Meyer is a really remarkable figure, and it's
kind of typical for early aerobiology figures completely forgotten, so
you know, I had to dig into archives to really
figure out what I could about his life. So I
had mentioned before about, you know how there are these
(21:48):
pathogens of plants, particularly of crops. So fred Meyer was
a plant pathologist. He worked at the US Department of
Agriculture ever since he was like twenty years old, was
just his lifelong employer, and he was part of this
tradition of studying diseases that affected crop like watermelon and
(22:08):
wheat and so on. And they were very comfortable with
the idea of airborne disease because there are these spectacular
crop failures, like you know, the the Great Irish Famine
that was caused by potato blight that in part was
airborne that organism. So by the early nineteen hundreds, plant pathologists.
(22:28):
They knew that things moved through the air, they just
didn't know how far they could go or high they
could go. And so eventually fred Meyer says, like, I
am going to try to figure out how high and
far I can go to catch them. And this was
something that his bosses did not want him to do,
so he just did it on the side on his
(22:49):
off hours, and it's kind of spectacular. He would he
would jump into planes, these open cockpit cockpit biplanes, and
you know, he'd have these petra dishes stuck on to
handle wooden handles, and he would just basically be waving
his arms around out of a flying plane in the clouds,
and the pilots would just be totally baffled by him.
(23:11):
But he'd bring these prejudicies back to his lab and
he would grow stuff. He was catching things. So then
he started looking for opportunities to send more sophisticated devices
higher and farther. So, for example, Charles and n. Lindberg,
they flew in ninety thirty four across the North Atlantic
over Greenland, and he talked them into trying to catch
(23:35):
life as well, and they did. And then there were
these explorers who got into sort of metal spheres that
were attached to giant balloons, and they went up to
the stratosphere, and so they took along with them probes
that Meyer had to see if life could survive up
in the stratosphere. And then on a second voyage, they
(23:55):
actually were able to catch stuff up there in the stratosphere.
Real kind of unbelievable to me is that by nineteen
thirty seven Meyer had done assembled so much dazzling work
that he was able to talk the government into creating
a whole new service in the government, a kind of
(24:17):
centralized lab for life in the air, and he was
going to head it. He coined the word for the
science that they were going to do, aerobiology. He came
up with that word in nineteen thirty seven with this plan,
and everything was looking great, and then he went on
his you know, sort of made voyage across the Pacific
in search of search of life and was never heard
(24:41):
from again. So I feel sometimes writing about these people,
there's there's a certain curse that hangs over aerobiology.
Speaker 1 (24:49):
I mean, I was shocked when that was like the
twist in the story, But then also it did feel
like fitting in a way like, of course this like
there's more things, Like you said, Befell, these people that
you know, you can't quite get their ideas and their
evidence to take hold in the public eye, I think,
in the public facing side of science. But as you
talk about the military side of things, this really did
(25:12):
gain hold. There was more interest in aerobiology and the
potential of air as a way to transmit disease and
how to protect ourselves from that. And I think it's
interesting to think about these two sort of lenses through
which people viewed aerobiology. You have Fred Meyer on the
one hand, who's just interested in the rich tapestry of
(25:32):
life in the air, and then you have more of
the US government interest at the time, in part shaped
by global politics, where it's like what about bioweapons, what
about biodefense, And how did that branch kind of grow
more or gain more interest than Meyer's side.
Speaker 2 (25:53):
Yeah, when World War two begins and then the United
States is starting to prepare to enter, there was a
serious concern that, you know, that Nazi Germany might be
developing biological weapons that it might use in battle. I mean,
(26:13):
it never have never been done before, but there was
this great fear for decades. They were in a fear
that someone might somehow deploy these these deadly germs against
soldiers or even civilians. So the US government actually started
to reach out to these aerobiologists. They would say, well,
what do you think, what do you think are the
what do you think are the risks that we face?
(26:35):
And so there was one aerobiologist named Ellen Stackman who
wrote a very long memo based a lot on the
work that he and Fred Meyer and others had been doing, saying, yes,
we could be attacked, and here's what could happen. So
I mentioned stem rust. So he said, you could imagine
someone dropping a stem rust bomb over our farms and
(26:58):
wiping out our food supply, and you know, they someone
like Stackman, who had, you know, been involved in World
War One, could see like what happens when an army
loses a food supply. Because Germany actually had its own
potato light, you know, this airborne disease that was devastating
to its food supply and that may have really tipped
the balance of the war. So he said, we need
(27:20):
to be aware of that. We need to have like
plant pathologists looking out for attack and so on. But
then it's quite amazing, like in writing, is like, we
have to explore developing our own weapons. It would be
remiss of us not to. It would be irresponsible for
us not to start building our own arsenal. You know.
It's kind of like the nuclear sort of logic, like, well,
(27:43):
if they're going to be building him, well we should
too as defense. And he had this He said, here's
how you could like go after Japan. You know they
have these rubber plantations for their tires for their vehicles. Well,
here's a MicroB you could drop on their rubber plantations
and wipe those out. He really thought a lot about this.
(28:04):
And there were other aerobiologists, William and Mildred Wells, a
husband and wife team who in the nineteen thirties had
been showing how people can spread diseases to each other
through the air. And William Wells in particular had developed
all sorts of really elegant devices to demonstrate how germs
(28:24):
can float in the air and also then to sort
of measure how much you would need an animal to
inhale to die. The military, you know, at Camp Dietrich,
they started building very similar devices they took secretly without
his awareness, They secretly started building these devices so to
(28:45):
figure out, well, how instead of saying, like, well, how
do we understand these airborne diseases to protect people? How
do we build better weapons? Like what's the minimum dose
we need of anthrax in the air to kill these mice?
And they did all this resent in a giant building
literally called the Aerobiology Building, and you know, the United States,
(29:05):
the Soviet Union and other countries you know, would go
on for decades to build huge stocks of biological weapons,
all firmly based on this new science of air biology.
Speaker 1 (29:17):
I mean, that is such an interesting aspect of this story,
where you have this acceptance of this idea of how
much the air can contribute to the spread of disease
and the potential there. So we have that happening in
the military side of things, what was happening in the
more public facing side of science and aerobiology with the Wellses.
Speaker 2 (29:38):
The Wells has come into the world of airbiology kind
of in a very peculiar, sort of sideways manner. You know.
William Wells, he gets a bachelor's degree at MIT and
Sanitation and he goes off to study typhoid and water
and he gets into studying how it is that oysters
actually can be really dangerous to eat because they filter
(30:01):
all the bacteria that caused typhoid, and you eat them
raw and you die. And so he's trying to figure
out how do I purify you oysters and so on,
and then he gets pulled into World War One. His
job is to clean the water for the soldiers, and
so he is protecting, you know, American soldiers by providing
clean water. But meanwhile they're dying of influenza, not a
(30:21):
waterborne disease, and it's not really clear how it's spreading,
but I think that the seeds were planted there that
they thought maybe this is airborne, despite that prevailing view
that diseases are not airborne. So he comes back from
the war. He's married Mildred Wells. She had gotten a
medical degree, but she didn't practice medicine. She was raising
(30:43):
their son who probably had some sort of psychiatric disorders.
Just judging from medical files, I was able to come
across later. They have a good run. In the twenties,
he continues studying oysters. He gets famous for being the
oyster Godfather because he's figuring out how to breed oysters.
And then the Great Depression comes and he's out of
a job. Mildred somehow gets a job studying the epidemiology
(31:06):
of polio, and she actually contributes to a book about it,
and she develops this idea that maybe polio is being
spread through the air. She doesn't really develop it a
lot in her writings, but it definitely influenced William Wells.
He gets a job at Harvard teaching. He's terrible at it,
like just I mean, I'm not making it up, Like
(31:27):
the dean of the school, bubble Galth says, this is
something that Wells does very badly, Like it's in writing,
and he in particular had a very difficult time with
communication and just he would get into arguments with people
or long long monologues. Mildred was really fierce herself. They
didn't make friends, and put it this way, They're brilliant,
(31:49):
but they alienated everybody. But at Harvard they start to
do some experiments that actually established some of the basic
ideas about airborne infection. In other words, that you know,
when you breathe, you are releasing droplets and some of
them have can have viruses or bacteria in them. They
can float around for hours, maybe days in the right conditions,
(32:12):
primarily in indoor spaces, and they even show that you
can use ultraviolet light to kill them in the air.
First they do this with, you know, with experiments on animals.
But then when they moved to Philadelphia, they put ultraviolet
lamps in a school and in nineteen forty there's an
(32:34):
outbreak of a disease we's been hearing a lot about recently, measles.
At the time, there was no vaccine, so people were
just very resigned to this terrible disease sweeping through The
Philadelphia school was substantially protected from this measle's outbreak by
these ultra violet lamps. And you know, this was not
stuff they did in secret. This was all heavily reported.
(32:57):
People were very excited. They were like, wow, we'd maybe
we don't have to worry about a new nineteen eighteen
flu pandemic again, because we know that influences airborne and
we have a way to protect ourselves from it. And
yet nobody knows who the Wells is are these days.
They just they crashed into obscurity later on, so you know,
(33:19):
they might not have died in a plane crash like
fred Meyer, but they had their own crash Nevertheless.
Speaker 1 (33:25):
That's another kind of mysterious disappearance of its own, Like
why this work that could have such profound implications for
public health just kind of went away, And I'm curious
to hear your thoughts on why that might be. You know,
was part of it any sort of taint that, like
the military's interest in bioweapons, Like was that part of it?
(33:46):
You mentioned, like antibiotics and vaccines and sort of the
decline is like we're winning the war against infectious disease.
What were some of the factors at play there?
Speaker 2 (33:56):
Yeah, I think there are many of these factors that
you mentioned that we're all play. I think that first
of all, epidemiology and trying to establish how diseases get
from one person another. It's just difficult science. You need
just the right opportunity and just the right conditions. You
need to design your experiments just right to get really clear,
(34:18):
compelling evidence. And so you know, if you're talking about water,
like let's say that sewage is flowing into a river
and a city is getting its drinking water supply just downstream,
and there are a bunch of typhoid cases like this
literally happened in Lowell, Massachusetts in the eighteen nineties. You
(34:38):
can you know, you can say like, hey, let's stop
getting our drinking water from there, shall we, and then
lo and behold the typhoid goes away, you know, like
so that there's a certain sort of control to that,
whereas the air is like it's very hard to control.
It's elusive, and while there is a lot of life
in the air, like it's it's dilute, you know. So
(35:02):
you might be breathing, you know, two thousand times a day,
hundreds of thousands of times a month, but you know,
it could just take one of those breaths for you
to take in COVID or what have you, and boom,
You've got an infection. So I'll just say it is
hard to study. But you know, on top of that,
I think there was this consensus that had really built
(35:23):
in and people were very reluctant to shift away from it.
So they just they would say, like, you need to
really really persuade me that diseases can be airborne. So
they really refused to look at good evidence. And yeah,
and I think with the with the biological warfare research,
it's arguable that a lot of the best evidence that
(35:44):
diseases are in fact, airborne was being done in secrecy, right.
It was being done you know, as classified research, and
some of that is still classified today. So instead of
being an open science, a science that was really like
focused on human health and you know, and understanding ecosystems,
a huge amount of effort in the air biology world
(36:06):
went into building weapons. And so maybe people thought like, well,
I suppose you could build a weapon that could really
create an airborne disease, but that you need human intervention
as opposed to just nature. So there were a lot
of different a lot of different reasons. But what's remarkable
is that even at the start of the COVID pandemic,
a lot of these assumptions and a lot of these
(36:28):
misunderstandings and so on that you can trace back a
century were still present in public health guidelines. Yeah, and
how and how public health organizations dealt with the COVID pandemic,
they were still in place, right.
Speaker 1 (36:46):
And the message was respiratory droplet transmission.
Speaker 2 (36:50):
Well, and that just to clarify what they were talking
about is like if someone is just a cough in
your face and like a big old drop of like
boom and just hits you in the face, that's what
they're talking about. Whereas what someone like William Wells was
talking about was saying, these tiny droplets that leave your
(37:13):
nose in your mouth just as you breathe or talk
or sing, and they can float. So those big droplets
they drop to the ground because they're so heavy, the
thinking was, But in fact, there's all these tiny droplets
which can themselves have covid viruses or influenza viruses or
you know, tuberculosis bacteria in them, and you know, they
(37:35):
can fill a room if it's not well ventilated. They
can fill a room like smoke. Think of those as viruses.
Speaker 1 (37:42):
And this is something that seemed to emerge during the
first Stars epidemic in two thousand and two two thousand
and three, with this idea that there was evidence for
potential airborne transmission of this virus. Why didn't we remember
those lessons? Is it just more of the same thing,
just the stickiness of this idea that airborne transmission is
(38:03):
a minor plays a minor role in the spread of
most respiratory pathogens, Like, why why didn't we remember that?
Speaker 2 (38:11):
Yeah, it would have been great if we had so.
In the SARS epidemic, what's really remarkable is that, you know,
as this coronavirus, another coronavirus was emerging as a human disease.
There were a few scientists who were getting dissatisfied with
the standard view held that these must be spread by
(38:32):
kind of you know, contact or very short range droplets.
They're like, no, this is like spreading. It seems like
it's spreading through like buildings. And they had to rediscover
William and Mildred Wells. Like these people were like, h
I keep seeing these references to William and Mildred Wells,
Like who are these people? Like nobody knew who they were.
(38:52):
And I talked to this one University of Hong Kong researcher,
a named Hugo Lee, who is just a you know
now is like a world expert on airborne and at
the time he was trying to help understand SARS and
he was like, h it looks like Wells has written
a book. Wells wrote a book in nineteen fifty five.
Nobody in Hong Kong had it, and the only place
(39:12):
he could find it was in one university library in
the United States, and he asked them to photocopy it.
This is like the early two thousands. They so they
photocopied the whole book for him and they mailed it
to him. And then so he gets this big stack
of photocopied pages and he starts reading it and he says, ah, okay,
now this is making sense. These are droplets, okay. And
(39:35):
it's crazy to think that he had to go to
these measures to discover what had been widely reported and
widely known in the nineteen thirties. You know that he
had to dig this back up, and thank goodness he did,
because then he did a lot of research on SARS
and really demonstrated how with the way he was spreading
through buildings and hospital wards and so on, it really
(39:56):
did look like it was behaving like what William and
Mildred Bells was talking about and airborne disease. The problem is,
among other problems, is that SARS, it's sort of a
good news band news thing. SARS was able to be
controlled and then eradicated because all you needed to do
(40:17):
is as soon as people showed symptoms, that's when they
started becoming infectious. So you just be real careful about
isolating people, you know, supporting them. Some of them died,
you know, about eight hundred people died of SARS worldwide,
but they rained it in and there is no stars anymore.
So it wasn't something that you could be sort of
steadying year in year out. It was just this one
(40:39):
terrible moment in history. And you know, there were these clues,
you know, these studies that said like, hey, maybe this
is airborne, but I yeah, I'd say that it didn't
really penetrate. You know, all the pandemic preparedness that came
afterwards was all based on this idea that it would
not be truly airborne.
Speaker 1 (41:00):
That shift did eventually happen during the COVID pandemic what
came to a head to then finally change the tides
to people realizing that airborne transmission is a real not
just a real possibility, but like at the forefront of
what is maybe spreading a lot of these cases.
Speaker 2 (41:17):
So there were people like Hugo Lee early in the
pandemic in early twenty twenty who would say, you know,
this seems to be spreading like an airborne disease, and
they were just being emphatically ignored by public health officials
or you know, people would just start brushing them off
or saying no, no, there's the evidence says otherwise. And
(41:40):
so this group of people, at first just you know,
just a couple dozen experts, they got together and they
tried to change the world health organizations the view on this,
who didn't budge. So then they went public. They started
trying to like gin up support. But it really took
like a whole string of outbreaks and studies on those
(42:03):
outbreak to really demonstrate it. I focus on one in
particular that struck a choir in Washington State where on
March tenth, twenty twenty, about sixty people gathered together one
night to sing, and they were being careful, they were
doing everything they were supposed to be doing, and no
(42:23):
one seemed to be sick, no one was coughing, but
there was an infected person who was breathing, and then
you know, over fifty people came down with COVID in
the next few days. It took time, unfortunately, to sort
of to become aware of these outbreaks and then for
these airborne advocates to say, like, hey, we're going to
investigate these as sort of cases of airborne spread, see
(42:46):
if we can test this hypothesis. And then eventually enough
evidence emerged that satisfied a lot of people, and then
the consensus shifted. I mean, I wouldn't you know, I'm
there are people who will still say like, no, I'm
not convinced, but you know, I would say like that
most certainly most scientific societies that are relevant to this
(43:08):
and so on, have all agreed that it's airborne. But yeah,
it took a long time.
Speaker 1 (43:15):
It did, and it does I think beg the question
of what could have been different if we had recognized
this before COVID. I mean not just before stars, but
just at least before COVID.
Speaker 2 (43:29):
If we had recognized it, there would be the at
least the opportunity to deal with the disease as an
airborne disease. You know, that takes a lot. I think
another reason for the slow take up of, you know,
recognizing this disease as airborne is that it's simpler to
(43:51):
deal with a disease that is just caused by short
range droplets or by contact. It is just it's a
simpler process. If it's all around you, as like a smoke,
then you've got to do different things. For one thing,
we might have made sure, really sure that we had
a real stockpile of protective equipment, which we didn't, so
(44:12):
you know, people were just desperately reusing N ninety five masks,
which is crazy. We could have invested in ventilation systems
in schools and other places. We could have had ultifilet
light in places where ventilation wasn't a good solution. I mean,
you know, these advocates of airborne disease that they were
(44:34):
saying in the summer of twenty twenty, like, we can
get kids back in school this fall if we take
airborne infection seriously, if every classroom has you know, at
least an air purifier or something. But you know, the
ventilation of schools, unfortunately, is terrible. So I think across
the board a lot of lives would have been saved
if we had immediately responded to COVID, recognizing the possibility
(44:58):
that it was airborne and acting on that.
Speaker 1 (45:01):
Has this recognition that not only airborne transmission of COVID
is a possibility, but just recognition of Wells's work overall.
The Wells work has that kind of revitalized the field
of aerobiology.
Speaker 2 (45:13):
Yes, it definitely has. And these scientists who felt like
they were just shouting into the wind, forgive the pun
they they really are trying to seize the moment our
whole research centers being built to study airborne transmission, and
they are trying to translate these findings into two real
(45:37):
meaningful policy that can protect people not just from new
diseases but from present ones. You know, measles, tuberculosis, influenza,
chicken box, like, there are lots of diseases that can
spread through the air at least to some degree. What
it hasn't led to has been real mandates. Like there's
no country anywhere yet that officially has standards in place,
(46:02):
you know, like if you're going to build a building,
this is what you have to do to keep the
air safe. Doesn't exist yet. If you walk into a building,
you kind of expect that, you know, there are building
standards about the rebar and the materials that they're used.
You know, you don't expect that they contain poisons that
(46:22):
are going to walk through the air and kill you
because there are standards, But there are no standards yet
for how to keep the air clear of pathogens. They've
suggested mandates, no one's taken them up quite yet.
Speaker 1 (46:37):
It'll be interesting to see what the future holds in
that regard as long as people are allowed to continue
to do basic research on this sort of thing.
Speaker 2 (46:47):
But which is an open question right now? An open question?
Speaker 1 (46:50):
Yeah, Well, I really enjoy chatting with you about this.
I loved your book Airborne. Everyone go check it out,
and thanks so much for taking the time to chat
with me today.
Speaker 2 (47:00):
Thanks been real pleasure.
Speaker 1 (47:23):
Huge thanks again to Carl Zimmer for taking the time to.
Speaker 2 (47:26):
Chat with me.
Speaker 1 (47:27):
This was such an eye opening conversation. If you enjoyed
today's episode and would like to learn more, check out
our website this podcast will kill you dot com, or
I'll post a link to where you can find Airborne,
The Hidden History of the Life We Breathe, as well
as a link to Carl's website where you can find
his other books and don't forget. You can check out
(47:48):
our website for all sorts of other cool things, including
but not limited to, transcripts, Quarantine and placib readA, recipes,
show notes and references for all of our episodes, links
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a first hand account form, and a music by Bloodmobile.
Speaking of which, thank you to Bloodmobile for providing the
(48:09):
music for this episode and all of our episodes. Thank
you to Leona Scuolacci and Tom Bryfocal for our audio mixing,
and thanks to you listeners for listening. I hope you
liked this episode and are loving being part of the
TPWKY book Club. A special thank you, as always to
our fantastic patrons. We truly appreciate your support so much. Well,
(48:33):
until next time, keep washing those hands.
Speaker 2 (49:00):
Foo
Hi, I'm Aaron Welsh and this is this Podcast Will
Kill You. Welcome to our newest episode in the tp
w k Y book Club series, where I get to
chat with authors about their latest books in science and medicine.
We have covered some great books so far this season
and in past seasons, and we've got plenty more excellent
(01:07):
books to add to your to read list throughout the
rest of this season. If you would like to see
the full list of books that we've covered so far,
as well as get a sneak peek of the books
that will be featured later this season, head over to
our website This Podcast will Kill You dot com, where
you'll find a link to our bookshop dot Org affiliate account.
Under the extra tab, there you'll see several TPWKY lists,
(01:31):
including a book club list. Check back on that list regularly,
as I'll be updating it throughout the season. As always,
we love getting your feedback, whether that's a topic request,
a suggestion for a book to feature in one of
these episodes, or just any other thoughts you have. You
can reach out to us via the contact dose form
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(01:54):
get into the meat of the episode Number one, Please rate, review, subscribe.
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(02:16):
By now, we are all fairly familiar with the concept
of the microbiome, the community of microbes that live in
a particular environment, such as your gut, or your skin,
or maybe even inside your belly button. But how many
of you have heard of the aerobiome. We don't often
think of the air as a medium teeming with microbial life,
(02:38):
but as Carl Zimmer demonstrates in his latest book Airborne,
The Hidden History of the life We breathe, that may
be a critical oversight. In this book Club episode, award
winning science writer Carl Zimmer joins me to discuss the
long neglected science of aerial life and the public health
implications of this research. Many of you may recall the
(03:02):
debate that sprung up seemingly out of nowhere in the
first couple of years of the COVID pandemic, when scientists
couldn't seem to agree on whether the virus was transmitted
via respiratory droplets or whether it was airborne. Why this
distinction mattered and how the issue grew so contentious is
just part of what Zimmer covers in Airborne. By placing
(03:25):
this debate in the broader context of the history of
aerial biology, he draws a line from the early days
of germ theory to the pioneers of this emerging field,
from the height of biowarfare research to a Washington State
choir in the first weeks of the COVID pandemic. Linking
together these disparate stories from the history of science, Zimmer
(03:48):
presents a revelatory picture of a scientific field you didn't
know existed. How might the COVID pandemic have been different
if we acknowledged the airborne potential of this virus earlier?
What lessons can we draw from this oversight to apply
to future outbreaks? What even lives in the air, and
(04:08):
why does it matter? We get into all of these
questions and so many more. According to a quick Google search,
we breathe about twenty two thousand breaths a day, breaths
that we don't often think about, but after this episode,
you'll have a newfound respect for those breaths and the
invisible airborne life all around us.
Speaker 2 (04:31):
I am very.
Speaker 1 (04:32):
Excited to be bringing this episode to you, so let's
just take a quick break and get started. Carl, thank
(05:01):
you so much for joining me today.
Speaker 2 (05:03):
Thanks for having me.
Speaker 1 (05:04):
I have long been such a fan of your work,
and I really especially appreciated your latest book, Airborne, which
tells us really fascinating story of discovery, dismissal, and then
ultimately kind of redemption in the end. To start us off,
can you give us this big picture view of what
the story that you explore in your book and what
(05:25):
inspired you to write about it.
Speaker 2 (05:27):
The story is about the air and how humanity has
slowly come to appreciate the fact that it's alive. In
other words, we really are walking around on the floor
of a giant, living ocean that is filled with trillions
upon trillions of organisms, thousands of different species, a few
(05:51):
of which we can see, you know, we can, you know,
see a goose flying overhead, but for the most part,
it's totally invisible to us. And I guess I say
this the seed of this book came about during the
COVID pandemic. I was working at the New York Times,
and I, along with my colleagues, we were just trying
(06:11):
to write as fast as we could about this totally
new disease. And you know, it was challenging because scientists
themselves are trying to figure out what exactly this disease
is like. And one of the biggest sumbling points, one
of the areas with the most debate and uncertainty, was
(06:31):
how it spreads. You had people telling you on TV
to wipe down your groceries. I know I did, and
just you know, keep your distance from people, and you know,
you'll be fine. Then there were other there were scientists,
a small number of scientists at first, who were saying,
we think this might be airborne. World Heart Organization explicitly
(06:52):
saying COVID is not airborne, and you know, it took
a couple of years, and then world health organizations that yeah,
it's airborne. And I just thought, why was that so hardy?
And the scientists themselves said to me, like, well, you
need to understand the history. One scientist said, you know,
(07:13):
history set us up. And so that led me down
this path to discover this whole history of this science
of the life in the air, which is called aerobiology.
Speaker 1 (07:23):
Yes, and as you discussed, you know this, we're living
underneath this ocean of all of these different organisms. This
the aerobiome. What can you tell me about the aerobiom
Like who's up there? Who's floating around besides the geese
that we.
Speaker 2 (07:38):
See, well, all sorts of things. The numbers are kind
of crazy. I mean, actually you have to write them
down and double check them because I'm like, did I
get that right? Because they're just so I'll just give
you one example. So insects. Okay, so you know you
presumably seen you know, some dragonflies flying by, or maybe
(08:00):
like a little swarm of mayflies or what have you.
I mean, it's not unusual to see an insect in
the air, but scientists have long suspected that that maybe
large numbers of insects flying long distances high in the air,
thousands of feet in the air. The problem is you
can't see them, and so scientists have invented technology st
(08:21):
barring radar and tuning it so that you can detect
insects that are in large numbers that are way up
in the air. Lo and behold, there are a lot
of insects up there. And just to give you one example,
and there's a study that came out last year and
from China where just in a small region of China,
they set up some radar systems to look up and
(08:41):
over the course of a year they recorded nine point
four trillion insects just in that place.
Speaker 1 (08:50):
I can't comprehend that.
Speaker 2 (08:51):
Yeah, yeah, right now, these numbers are incomprehensible. When you
get to fungi, you walk around in a forest trail,
you see some mushrooms. You think you know what fungi are,
but you really don't, because they're everywhere. They're on everything,
and they make a living by sending their spores into
the air. I mean they have adapted beautiful like little
(09:13):
cannons and other devices to get their spores up high
enough so that the air can carry them away and
then they can go all the way up to the stratosphere.
Fungi loan they lift up about a trillion trillion spores
every year.
Speaker 1 (09:29):
Again, I can't I don't know what that means even
right right.
Speaker 2 (09:33):
What do you do with that? The you know they're
back also bacteria, viruses, algae like and again they probably
comprise thousands tens of thousands, maybe millions of species. You know,
we've barely begun to sample this habitat, this living habitat
in the air called the aerobiome.
Speaker 1 (09:53):
And I love how you describe it as an ecosystem
of visitors. You know, this is a for most of
these species. This is a transitory period. If you take
one you know, cubic meter of air or something wherever
it is, how often that changes just within a second,
within a minute, within a day, it's completely different.
Speaker 2 (10:12):
Yeah, it really depends for the individual organism on how
high they get up initially, you know, and what the
air conditions are like when they get lofted into the air.
The oceans, for example, every time a wave breaks, there
are lots of tiny droplets that rise up, and some
(10:35):
of them have bacteria, viruses, other marine organisms in them. Now,
if there's enough of a breeze, they may get carried
up and maybe they fall right back down after you know,
a few seconds. But it is possible for them to
go up and then keep going up, and then eventually
they get so high that they're just riding along long
(10:57):
distance waves and they can actually go thousands of miles,
so they can be floating for days. You know eventually
they will land. I mean, it's just a matter of time.
But because there's so many things coming up all the time,
it's always a very lively space. So like the clouds,
for example, every cloud you look at is alive. It's
(11:18):
it's got you know, trillions of bacteria something something on
the order of that. And you know the bacteria, there
are signs that they might be growing in the clouds,
and that means that they are eating the clouds. So
you know, it's a different way to look at the
sky and think about what's up there.
Speaker 1 (11:39):
Let's take a short break, and when we get back,
there's still so much to discuss. Welcome back everyone. I've
(12:03):
been chatting with Carl Zimmer about his latest book Airborne,
The Hidden History of the life We breathe. Let's get
back into things. Which certain types of pathogens are more
likely to be airborne? Do they share certain evolutionary history
or drivers that might make them more likely to be airborne.
Speaker 2 (12:21):
That's a really good question, and I honestly, I don't
think anybody has a good answer for you. Yet. Part
of the challenge is it's hard to really carefully study
airborne disease if you're talking particularly about pathogens. Now, certainly
there are some very familiar pathogens that are clearly we
(12:43):
know are airborne, but that's by no means an exhaustive list.
There probably are lots of other things that we are
not appreciating fully yet. But just to give a couple examples,
the biggest infectious disease killer by far is tuberculosis. It's
caused by bacteria, and those bacteria are totally airborne. In
other words, they really can't infect people in any other
(13:07):
way other than people releasing little droplets that float out,
not just you know, maybe when they cough or sneeze,
but even when they're just breathing, they are going to
release droplets, some of which have tuberculosis bacteria in them.
These are so good at being airborne that they actually
(13:28):
manipulate us. They actually have adaptations to sort of essentially
tickle our airway to get us to cough more, because
that gets them out and gets them into the air,
propels them and then they can float off and infect
someone else, and they make the droplets make their way
into the very finest tips of our airway endings. In
the lungs, the lvoli and that's where the bacteria can grow.
(13:49):
So tuberculosis kills over a million people a year. But
you know, it's also a huge threat to in terms
of pathogens. It's also a huge threat to our crops.
So there are lots of disease is, particularly fungi that
spread through the air in part or entirely. I write
a lot about a kind of fungus called rust, which
(14:11):
can just you know, it can endanger the food supply
of whole countries if it really breaks out seriously. So
I'm just giving you two examples, but there's a long list.
And you know, is there something about airborne pathogens that
you know they all have in common? I would say
they're rugged in the sense that they can survive being
(14:34):
floating around in the air. It's not easy to be
a pathogen floating around out in the air. It's hard.
And there's some viruses that don't last very long when
they're exposed air. Other viruses can last a really long time,
and it might be that they sort of they have
adaptations that let them kind of use the chemicals inside
(14:55):
of those droplets that come out of our lungs to
sort of shield themselves from the elements.
Speaker 1 (15:01):
This respiratory droplet versus airborne debate, you know, as you say,
really took center stage during COVID as we all remember,
and kind of, like you it seemed baffling, like why
is this so controversial? Why is this something that we're
so resistant to the idea of this being airborne, especially
when it seemed like, you know, this research had been
(15:21):
going on for quite some time. And before we get
into how that controversy started in the germ theory myasthma debate,
what role did people think the air played in diseases
before germ theory.
Speaker 2 (15:35):
So if you go all the way back to say Hippocrates,
in the sort of the world of Western thought in particular,
there was this idea that obviously, you know, air is
essential to us. The Greeks considered it, you know, one
of the main elements we obviously we need to breathe.
But people couldn't really say why. And yet there was
(15:57):
sort of a sinister dark side to the atmosphere. And
you know, like I mean, we've all, I suppose we've
all had that experience walking around. It's you know, today
here in Connecticut, it's a beautiful sunny day. The air
feels very lovely, but you know there are also days
where you like, it smells really wrong, or there's a
there's a weird light in the sky because there are
(16:19):
wildfires someplace, and you know, like the the air is unpredictable.
And so Greeks had this idea that gods could visit
curses on them and they would call these miasthmas. And
Hippocrates said sort of took that name and applied it
to what do you call it, like corruptions of the air,
(16:39):
so that if you breathed in that air, you would
become sick. And there were different miasthmas for different diseases,
and even different species could get different diseases because they
had their own miasthmas, but they were all transformations of
the air itself. It had a certain explanatory power. I mean,
how was it that, you know, a bunch of people
in this same town all would get the same disease
(17:03):
around the same time. You can imagine, well, you know,
a breeze just came through and people all inhaled it
and then they all keeled over. But that explained plague,
and you know influenza, and you know malaria literally like
bad air, like that's what the disease name means. And
so it held on for a long long time until
(17:25):
people who had been discovering and studying microbes said no, wait,
we think these are responsible for these diseases. And it
was a very you know, it was a very long
slog I mean to us in hindsight, it seems obvious,
but you know, this was a battle that started around
seventeen hundred and lasted up until about nineteen hundred, so
(17:47):
about two hundred years of a long drawn out fight.
Speaker 1 (17:51):
It seems like a blink of an eye, like Louis
Pasture came in and solved everything, But it's not. That's
not what actually happened. But I think it's it's so
interesting to think about miasma and airborne transmission because they
seem like almost the same thing, right, Like, how was
that distinction made between microbes in the air causing disease
and miasma causing disease?
Speaker 2 (18:13):
There were a lot of confusing, seemingly contradictory pieces of
evidence flying around. So Louis Pasteur, who you mentioned it
was an architect of the germ theory disease. He actually
was the first person to really clearly demonstrate that there
were germs floating in the air. And people said at
(18:33):
the time when he was trying to persuade them of this,
that this was crazy. One journalists said, this is you
want to lead us into a world that's too fantastic
to believe. I love that line. But he would go
outside with flasks and he would catch bacteria. They would
fall down the long neck of the flask and fall
into sterile broth and start multiplying. And he did it
(18:56):
in Paris streets, he did it in farmland around France,
and the even climbed a glacier, which was my favorite
episode of this. And he actually initially said that he
thought that lots of diseases were caused by these floating germs,
by airborne germs, but it didn't really go that way,
and what happened instead was that as as scientists definitely
(19:22):
showed that the diseases were caused by germs. So, for example,
cholera not caused by miasma as the authority is claimed. Instead,
it was caused by Fibrio cholerae, like one particular bacteria,
and that particular bacteria spread in water, so you have
a water borne disease and then you have other bacteria
(19:42):
that get into food and contaminate food, so you have
food borne diseases. You have you know, bacteria that spread
through sex, sexually transmitted diseases, and on and on and on.
So it was like the germ theory disease was taking
one disease after another out of the air. Yeah, and
by the early nineteen hundreds you had very prominent public
(20:05):
health figures saying we don't need to worry about the
air anymore, like this should be a relief. The air
has been this specter of infection since Hippocrates. They literally
said this, and now you don't need to worry that.
I think that really did keep people from really thinking
very much about life in the air. And they also
(20:25):
didn't have very good technology for really measuring and capturing
life in the air. So that combination really did lead
to a real, very strong consensus starting in the early
nineteen hundreds that has endured for over a century.
Speaker 1 (20:41):
Let's take a quick break here, we'll be back before
you know it. Welcome back. I'm here chatting with Carl
(21:01):
Zimmer about his book Airborne, The Hidden History of the
Life We Breathe. Let's get into some more questions. There
were still some people that did remain intrigued by the
concept of, you know, living things that the aerobiome. And
I want to ask you about one of these, which
is Fred Meyer. How did he end up turning what
(21:22):
was first a hobby into this branch, this whole branch
of science.
Speaker 2 (21:27):
Yes, Fred Meyer is a really remarkable figure, and it's
kind of typical for early aerobiology figures completely forgotten, so
you know, I had to dig into archives to really
figure out what I could about his life. So I
had mentioned before about, you know how there are these
(21:48):
pathogens of plants, particularly of crops. So fred Meyer was
a plant pathologist. He worked at the US Department of
Agriculture ever since he was like twenty years old, was
just his lifelong employer, and he was part of this
tradition of studying diseases that affected crop like watermelon and
(22:08):
wheat and so on. And they were very comfortable with
the idea of airborne disease because there are these spectacular
crop failures, like you know, the the Great Irish Famine
that was caused by potato blight that in part was
airborne that organism. So by the early nineteen hundreds, plant pathologists.
(22:28):
They knew that things moved through the air, they just
didn't know how far they could go or high they
could go. And so eventually fred Meyer says, like, I
am going to try to figure out how high and
far I can go to catch them. And this was
something that his bosses did not want him to do,
so he just did it on the side on his
(22:49):
off hours, and it's kind of spectacular. He would he
would jump into planes, these open cockpit cockpit biplanes, and
you know, he'd have these petra dishes stuck on to
handle wooden handles, and he would just basically be waving
his arms around out of a flying plane in the clouds,
and the pilots would just be totally baffled by him.
(23:11):
But he'd bring these prejudicies back to his lab and
he would grow stuff. He was catching things. So then
he started looking for opportunities to send more sophisticated devices
higher and farther. So, for example, Charles and n. Lindberg,
they flew in ninety thirty four across the North Atlantic
over Greenland, and he talked them into trying to catch
(23:35):
life as well, and they did. And then there were
these explorers who got into sort of metal spheres that
were attached to giant balloons, and they went up to
the stratosphere, and so they took along with them probes
that Meyer had to see if life could survive up
in the stratosphere. And then on a second voyage, they
(23:55):
actually were able to catch stuff up there in the stratosphere.
Real kind of unbelievable to me is that by nineteen
thirty seven Meyer had done assembled so much dazzling work
that he was able to talk the government into creating
a whole new service in the government, a kind of
(24:17):
centralized lab for life in the air, and he was
going to head it. He coined the word for the
science that they were going to do, aerobiology. He came
up with that word in nineteen thirty seven with this plan,
and everything was looking great, and then he went on
his you know, sort of made voyage across the Pacific
in search of search of life and was never heard
(24:41):
from again. So I feel sometimes writing about these people,
there's there's a certain curse that hangs over aerobiology.
Speaker 1 (24:49):
I mean, I was shocked when that was like the
twist in the story, But then also it did feel
like fitting in a way like, of course this like
there's more things, Like you said, Befell, these people that
you know, you can't quite get their ideas and their
evidence to take hold in the public eye, I think,
in the public facing side of science. But as you
talk about the military side of things, this really did
(25:12):
gain hold. There was more interest in aerobiology and the
potential of air as a way to transmit disease and
how to protect ourselves from that. And I think it's
interesting to think about these two sort of lenses through
which people viewed aerobiology. You have Fred Meyer on the
one hand, who's just interested in the rich tapestry of
(25:32):
life in the air, and then you have more of
the US government interest at the time, in part shaped
by global politics, where it's like what about bioweapons, what
about biodefense, And how did that branch kind of grow
more or gain more interest than Meyer's side.
Speaker 2 (25:53):
Yeah, when World War two begins and then the United
States is starting to prepare to enter, there was a
serious concern that, you know, that Nazi Germany might be
developing biological weapons that it might use in battle. I mean,
(26:13):
it never have never been done before, but there was
this great fear for decades. They were in a fear
that someone might somehow deploy these these deadly germs against
soldiers or even civilians. So the US government actually started
to reach out to these aerobiologists. They would say, well,
what do you think, what do you think are the
what do you think are the risks that we face?
(26:35):
And so there was one aerobiologist named Ellen Stackman who
wrote a very long memo based a lot on the
work that he and Fred Meyer and others had been doing, saying, yes,
we could be attacked, and here's what could happen. So
I mentioned stem rust. So he said, you could imagine
someone dropping a stem rust bomb over our farms and
(26:58):
wiping out our food supply, and you know, they someone
like Stackman, who had, you know, been involved in World
War One, could see like what happens when an army
loses a food supply. Because Germany actually had its own
potato light, you know, this airborne disease that was devastating
to its food supply and that may have really tipped
the balance of the war. So he said, we need
(27:20):
to be aware of that. We need to have like
plant pathologists looking out for attack and so on. But
then it's quite amazing, like in writing, is like, we
have to explore developing our own weapons. It would be
remiss of us not to. It would be irresponsible for
us not to start building our own arsenal. You know.
It's kind of like the nuclear sort of logic, like, well,
(27:43):
if they're going to be building him, well we should
too as defense. And he had this He said, here's
how you could like go after Japan. You know they
have these rubber plantations for their tires for their vehicles. Well,
here's a MicroB you could drop on their rubber plantations
and wipe those out. He really thought a lot about this.
(28:04):
And there were other aerobiologists, William and Mildred Wells, a
husband and wife team who in the nineteen thirties had
been showing how people can spread diseases to each other
through the air. And William Wells in particular had developed
all sorts of really elegant devices to demonstrate how germs
(28:24):
can float in the air and also then to sort
of measure how much you would need an animal to
inhale to die. The military, you know, at Camp Dietrich,
they started building very similar devices they took secretly without
his awareness, They secretly started building these devices so to
(28:45):
figure out, well, how instead of saying, like, well, how
do we understand these airborne diseases to protect people? How
do we build better weapons? Like what's the minimum dose
we need of anthrax in the air to kill these mice?
And they did all this resent in a giant building
literally called the Aerobiology Building, and you know, the United States,
(29:05):
the Soviet Union and other countries you know, would go
on for decades to build huge stocks of biological weapons,
all firmly based on this new science of air biology.
Speaker 1 (29:17):
I mean, that is such an interesting aspect of this story,
where you have this acceptance of this idea of how
much the air can contribute to the spread of disease
and the potential there. So we have that happening in
the military side of things, what was happening in the
more public facing side of science and aerobiology with the Wellses.
Speaker 2 (29:38):
The Wells has come into the world of airbiology kind
of in a very peculiar, sort of sideways manner. You know.
William Wells, he gets a bachelor's degree at MIT and
Sanitation and he goes off to study typhoid and water
and he gets into studying how it is that oysters
actually can be really dangerous to eat because they filter
(30:01):
all the bacteria that caused typhoid, and you eat them
raw and you die. And so he's trying to figure
out how do I purify you oysters and so on,
and then he gets pulled into World War One. His
job is to clean the water for the soldiers, and
so he is protecting, you know, American soldiers by providing
clean water. But meanwhile they're dying of influenza, not a
(30:21):
waterborne disease, and it's not really clear how it's spreading,
but I think that the seeds were planted there that
they thought maybe this is airborne, despite that prevailing view
that diseases are not airborne. So he comes back from
the war. He's married Mildred Wells. She had gotten a
medical degree, but she didn't practice medicine. She was raising
(30:43):
their son who probably had some sort of psychiatric disorders.
Just judging from medical files, I was able to come
across later. They have a good run. In the twenties,
he continues studying oysters. He gets famous for being the
oyster Godfather because he's figuring out how to breed oysters.
And then the Great Depression comes and he's out of
a job. Mildred somehow gets a job studying the epidemiology
(31:06):
of polio, and she actually contributes to a book about it,
and she develops this idea that maybe polio is being
spread through the air. She doesn't really develop it a
lot in her writings, but it definitely influenced William Wells.
He gets a job at Harvard teaching. He's terrible at it,
like just I mean, I'm not making it up, Like
(31:27):
the dean of the school, bubble Galth says, this is
something that Wells does very badly, Like it's in writing,
and he in particular had a very difficult time with
communication and just he would get into arguments with people
or long long monologues. Mildred was really fierce herself. They
didn't make friends, and put it this way, They're brilliant,
(31:49):
but they alienated everybody. But at Harvard they start to
do some experiments that actually established some of the basic
ideas about airborne infection. In other words, that you know,
when you breathe, you are releasing droplets and some of
them have can have viruses or bacteria in them. They
can float around for hours, maybe days in the right conditions,
(32:12):
primarily in indoor spaces, and they even show that you
can use ultraviolet light to kill them in the air.
First they do this with, you know, with experiments on animals.
But then when they moved to Philadelphia, they put ultraviolet
lamps in a school and in nineteen forty there's an
(32:34):
outbreak of a disease we's been hearing a lot about recently, measles.
At the time, there was no vaccine, so people were
just very resigned to this terrible disease sweeping through The
Philadelphia school was substantially protected from this measle's outbreak by
these ultra violet lamps. And you know, this was not
stuff they did in secret. This was all heavily reported.
(32:57):
People were very excited. They were like, wow, we'd maybe
we don't have to worry about a new nineteen eighteen
flu pandemic again, because we know that influences airborne and
we have a way to protect ourselves from it. And
yet nobody knows who the Wells is are these days.
They just they crashed into obscurity later on, so you know,
(33:19):
they might not have died in a plane crash like
fred Meyer, but they had their own crash Nevertheless.
Speaker 1 (33:25):
That's another kind of mysterious disappearance of its own, Like
why this work that could have such profound implications for
public health just kind of went away, And I'm curious
to hear your thoughts on why that might be. You know,
was part of it any sort of taint that, like
the military's interest in bioweapons, Like was that part of it?
(33:46):
You mentioned, like antibiotics and vaccines and sort of the
decline is like we're winning the war against infectious disease.
What were some of the factors at play there?
Speaker 2 (33:56):
Yeah, I think there are many of these factors that
you mentioned that we're all play. I think that first
of all, epidemiology and trying to establish how diseases get
from one person another. It's just difficult science. You need
just the right opportunity and just the right conditions. You
need to design your experiments just right to get really clear,
(34:18):
compelling evidence. And so you know, if you're talking about water,
like let's say that sewage is flowing into a river
and a city is getting its drinking water supply just downstream,
and there are a bunch of typhoid cases like this
literally happened in Lowell, Massachusetts in the eighteen nineties. You
(34:38):
can you know, you can say like, hey, let's stop
getting our drinking water from there, shall we, and then
lo and behold the typhoid goes away, you know, like
so that there's a certain sort of control to that,
whereas the air is like it's very hard to control.
It's elusive, and while there is a lot of life
in the air, like it's it's dilute, you know. So
(35:02):
you might be breathing, you know, two thousand times a day,
hundreds of thousands of times a month, but you know,
it could just take one of those breaths for you
to take in COVID or what have you, and boom,
You've got an infection. So I'll just say it is
hard to study. But you know, on top of that,
I think there was this consensus that had really built
(35:23):
in and people were very reluctant to shift away from it.
So they just they would say, like, you need to
really really persuade me that diseases can be airborne. So
they really refused to look at good evidence. And yeah,
and I think with the with the biological warfare research,
it's arguable that a lot of the best evidence that
(35:44):
diseases are in fact, airborne was being done in secrecy, right.
It was being done you know, as classified research, and
some of that is still classified today. So instead of
being an open science, a science that was really like
focused on human health and you know, and understanding ecosystems,
a huge amount of effort in the air biology world
(36:06):
went into building weapons. And so maybe people thought like, well,
I suppose you could build a weapon that could really
create an airborne disease, but that you need human intervention
as opposed to just nature. So there were a lot
of different a lot of different reasons. But what's remarkable
is that even at the start of the COVID pandemic,
a lot of these assumptions and a lot of these
(36:28):
misunderstandings and so on that you can trace back a
century were still present in public health guidelines. Yeah, and
how and how public health organizations dealt with the COVID pandemic,
they were still in place, right.
Speaker 1 (36:46):
And the message was respiratory droplet transmission.
Speaker 2 (36:50):
Well, and that just to clarify what they were talking
about is like if someone is just a cough in
your face and like a big old drop of like
boom and just hits you in the face, that's what
they're talking about. Whereas what someone like William Wells was
talking about was saying, these tiny droplets that leave your
(37:13):
nose in your mouth just as you breathe or talk
or sing, and they can float. So those big droplets
they drop to the ground because they're so heavy, the
thinking was, But in fact, there's all these tiny droplets
which can themselves have covid viruses or influenza viruses or
you know, tuberculosis bacteria in them, and you know, they
(37:35):
can fill a room if it's not well ventilated. They
can fill a room like smoke. Think of those as viruses.
Speaker 1 (37:42):
And this is something that seemed to emerge during the
first Stars epidemic in two thousand and two two thousand
and three, with this idea that there was evidence for
potential airborne transmission of this virus. Why didn't we remember
those lessons? Is it just more of the same thing,
just the stickiness of this idea that airborne transmission is
(38:03):
a minor plays a minor role in the spread of
most respiratory pathogens, Like, why why didn't we remember that?
Speaker 2 (38:11):
Yeah, it would have been great if we had so.
In the SARS epidemic, what's really remarkable is that, you know,
as this coronavirus, another coronavirus was emerging as a human disease.
There were a few scientists who were getting dissatisfied with
the standard view held that these must be spread by
(38:32):
kind of you know, contact or very short range droplets.
They're like, no, this is like spreading. It seems like
it's spreading through like buildings. And they had to rediscover
William and Mildred Wells. Like these people were like, h
I keep seeing these references to William and Mildred Wells,
Like who are these people? Like nobody knew who they were.
(38:52):
And I talked to this one University of Hong Kong researcher,
a named Hugo Lee, who is just a you know
now is like a world expert on airborne and at
the time he was trying to help understand SARS and
he was like, h it looks like Wells has written
a book. Wells wrote a book in nineteen fifty five.
Nobody in Hong Kong had it, and the only place
(39:12):
he could find it was in one university library in
the United States, and he asked them to photocopy it.
This is like the early two thousands. They so they
photocopied the whole book for him and they mailed it
to him. And then so he gets this big stack
of photocopied pages and he starts reading it and he says, ah, okay,
now this is making sense. These are droplets, okay. And
(39:35):
it's crazy to think that he had to go to
these measures to discover what had been widely reported and
widely known in the nineteen thirties. You know that he
had to dig this back up, and thank goodness he did,
because then he did a lot of research on SARS
and really demonstrated how with the way he was spreading
through buildings and hospital wards and so on, it really
(39:56):
did look like it was behaving like what William and
Mildred Bells was talking about and airborne disease. The problem is,
among other problems, is that SARS, it's sort of a
good news band news thing. SARS was able to be
controlled and then eradicated because all you needed to do
(40:17):
is as soon as people showed symptoms, that's when they
started becoming infectious. So you just be real careful about
isolating people, you know, supporting them. Some of them died,
you know, about eight hundred people died of SARS worldwide,
but they rained it in and there is no stars anymore.
So it wasn't something that you could be sort of
steadying year in year out. It was just this one
(40:39):
terrible moment in history. And you know, there were these clues,
you know, these studies that said like, hey, maybe this
is airborne, but I yeah, I'd say that it didn't
really penetrate. You know, all the pandemic preparedness that came
afterwards was all based on this idea that it would
not be truly airborne.
Speaker 1 (41:00):
That shift did eventually happen during the COVID pandemic what
came to a head to then finally change the tides
to people realizing that airborne transmission is a real not
just a real possibility, but like at the forefront of
what is maybe spreading a lot of these cases.
Speaker 2 (41:17):
So there were people like Hugo Lee early in the
pandemic in early twenty twenty who would say, you know,
this seems to be spreading like an airborne disease, and
they were just being emphatically ignored by public health officials
or you know, people would just start brushing them off
or saying no, no, there's the evidence says otherwise. And
(41:40):
so this group of people, at first just you know,
just a couple dozen experts, they got together and they
tried to change the world health organizations the view on this,
who didn't budge. So then they went public. They started
trying to like gin up support. But it really took
like a whole string of outbreaks and studies on those
(42:03):
outbreak to really demonstrate it. I focus on one in
particular that struck a choir in Washington State where on
March tenth, twenty twenty, about sixty people gathered together one
night to sing, and they were being careful, they were
doing everything they were supposed to be doing, and no
(42:23):
one seemed to be sick, no one was coughing, but
there was an infected person who was breathing, and then
you know, over fifty people came down with COVID in
the next few days. It took time, unfortunately, to sort
of to become aware of these outbreaks and then for
these airborne advocates to say, like, hey, we're going to
investigate these as sort of cases of airborne spread, see
(42:46):
if we can test this hypothesis. And then eventually enough
evidence emerged that satisfied a lot of people, and then
the consensus shifted. I mean, I wouldn't you know, I'm
there are people who will still say like, no, I'm
not convinced, but you know, I would say like that
most certainly most scientific societies that are relevant to this
(43:08):
and so on, have all agreed that it's airborne. But yeah,
it took a long time.
Speaker 1 (43:15):
It did, and it does I think beg the question
of what could have been different if we had recognized
this before COVID. I mean not just before stars, but
just at least before COVID.
Speaker 2 (43:29):
If we had recognized it, there would be the at
least the opportunity to deal with the disease as an
airborne disease. You know, that takes a lot. I think
another reason for the slow take up of, you know,
recognizing this disease as airborne is that it's simpler to
(43:51):
deal with a disease that is just caused by short
range droplets or by contact. It is just it's a
simpler process. If it's all around you, as like a smoke,
then you've got to do different things. For one thing,
we might have made sure, really sure that we had
a real stockpile of protective equipment, which we didn't, so
(44:12):
you know, people were just desperately reusing N ninety five masks,
which is crazy. We could have invested in ventilation systems
in schools and other places. We could have had ultifilet
light in places where ventilation wasn't a good solution. I mean,
you know, these advocates of airborne disease that they were
(44:34):
saying in the summer of twenty twenty, like, we can
get kids back in school this fall if we take
airborne infection seriously, if every classroom has you know, at
least an air purifier or something. But you know, the
ventilation of schools, unfortunately, is terrible. So I think across
the board a lot of lives would have been saved
if we had immediately responded to COVID, recognizing the possibility
(44:58):
that it was airborne and acting on that.
Speaker 1 (45:01):
Has this recognition that not only airborne transmission of COVID
is a possibility, but just recognition of Wells's work overall.
The Wells work has that kind of revitalized the field
of aerobiology.
Speaker 2 (45:13):
Yes, it definitely has. And these scientists who felt like
they were just shouting into the wind, forgive the pun
they they really are trying to seize the moment our
whole research centers being built to study airborne transmission, and
they are trying to translate these findings into two real
(45:37):
meaningful policy that can protect people not just from new
diseases but from present ones. You know, measles, tuberculosis, influenza,
chicken box, like, there are lots of diseases that can
spread through the air at least to some degree. What
it hasn't led to has been real mandates. Like there's
no country anywhere yet that officially has standards in place,
(46:02):
you know, like if you're going to build a building,
this is what you have to do to keep the
air safe. Doesn't exist yet. If you walk into a building,
you kind of expect that, you know, there are building
standards about the rebar and the materials that they're used.
You know, you don't expect that they contain poisons that
(46:22):
are going to walk through the air and kill you
because there are standards, But there are no standards yet
for how to keep the air clear of pathogens. They've
suggested mandates, no one's taken them up quite yet.
Speaker 1 (46:37):
It'll be interesting to see what the future holds in
that regard as long as people are allowed to continue
to do basic research on this sort of thing.
Speaker 2 (46:47):
But which is an open question right now? An open question?
Speaker 1 (46:50):
Yeah, Well, I really enjoy chatting with you about this.
I loved your book Airborne. Everyone go check it out,
and thanks so much for taking the time to chat
with me today.
Speaker 2 (47:00):
Thanks been real pleasure.
Speaker 1 (47:23):
Huge thanks again to Carl Zimmer for taking the time to.
Speaker 2 (47:26):
Chat with me.
Speaker 1 (47:27):
This was such an eye opening conversation. If you enjoyed
today's episode and would like to learn more, check out
our website this podcast will kill you dot com, or
I'll post a link to where you can find Airborne,
The Hidden History of the Life We Breathe, as well
as a link to Carl's website where you can find
his other books and don't forget. You can check out
(47:48):
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but not limited to, transcripts, Quarantine and placib readA, recipes,
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Speaking of which, thank you to Bloodmobile for providing the
(48:09):
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you to Leona Scuolacci and Tom Bryfocal for our audio mixing,
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liked this episode and are loving being part of the
TPWKY book Club. A special thank you, as always to
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(48:33):
until next time, keep washing those hands.
Speaker 2 (49:00):
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Current and classic episodes, featuring compelling true-crime mysteries, powerful documentaries and in-depth investigations. Special Summer Offer: Exclusively on Apple Podcasts, try our Dateline Premium subscription completely free for one month! With Dateline Premium, you get every episode ad-free plus exclusive bonus content.
On Purpose with Jay Shetty
I’m Jay Shetty host of On Purpose the worlds #1 Mental Health podcast and I’m so grateful you found us. I started this podcast 5 years ago to invite you into conversations and workshops that are designed to help make you happier, healthier and more healed. I believe that when you (yes you) feel seen, heard and understood you’re able to deal with relationship struggles, work challenges and life’s ups and downs with more ease and grace. I interview experts, celebrities, thought leaders and athletes so that we can grow our mindset, build better habits and uncover a side of them we’ve never seen before. New episodes every Monday and Friday. Your support means the world to me and I don’t take it for granted — click the follow button and leave a review to help us spread the love with On Purpose. I can’t wait for you to listen to your first or 500th episode!