AIR-BORNE

The COVID-19 pandemic now casts a long shadow on any topic that remotely touches on science and epidemiology and government health policy.

So it is for Air-Borne: The Hidden History of the Life We Breathe, from science writer Carl Zimmer. The book starts out by retelling one of the first "super-spreader" events of COVID-19 in the United States. From there it offers a critical perspective on the policy steps and missteps that ensued as governments all over the world took their cue from the World Health Organization and America's Center for Disease Control to shape a response to the pandemic.

But the book isn't about COVID-19 specifically. The pandemic merely provides a convenient and relatable jumping off point for the book's real topic of inquiry: what do we mean when we say that pathogens are airborne?

To the layman, that certain diseases can be transmitted through the air appears to be a reasonable proposition. After all, we remind children to practice good hygiene by covering their mouths when coughing or sneezing, precisely to avoid spreading respiratory diseases. Yet from a scientific perspective the concept of airborne diseases is arguably just a 20th-century vintage, largely because so much effort has been dedicated to debunking the notion that something in the air––miasma––causes us to get sick. Perhaps the most celebrated example of this was the work that John Snow did during the 1854 Broad Street Cholera Outbreak to demonstrate that it was a contact with a specific water pump and not "miasma" that was causing cholera to spread; after the pump was rendered unusable by removing its handle, cases of infection began to subside.

Thus it came to pass that the scientific consensus was that diseases spread through physical contact. Over time, however, new generations of scholars would look into this and subsequently challenge the orthodoxy, most prominent among them the husband and wife tandem of William Wells and Mildred Weeks. At a time when scientists were beginning to study to what extent biological matter existed in the air, Wells and Weeks conducted pioneering experiments to demonstrate the effectiveness of ultraviolet light in curtailing the spread of diseases like measles and chicken pox. Together with his collaborator Richard Riley, Wells would subsequently demonstrate at the Loch Raven medical facility in Maryland that tuberculosis was indeed airborne—the first study of its kind to do so definitively.

For all that, however, the scientific establishment did not immediately embrace the idea that diseases could be airborne. Or to put it differently: just because this happened to be true for tuberculosis did not mean it was true for other afflictions. After all, science dictates that this has to be (dis)proven.

The struggle of the scientific community to embrace the science of airborne disease is explored at length in Air-Borne.

Part of the problem was that there was a misreading of the results from the work of Wells et al. Their key finding was that diseases could be transmitted by either of two ways: either through respiratory "droplets" that come into direct contact with an uninfected person, or if the respiratory "droplet "nuclei" were to travel through the air for uninfected persons to breathe in. The difference between the two would be size: droplets are bigger, and therefore can only travel, shall we say, spitting distance from an infected person and could also dry out, whereas droplet nuclei are smaller and evaporated and could therefore travel and be carried through the air over longer distances. Although Wells never specified it as such, it somehow came to be understood that "droplets" referred to particles of 5 microns in size—and that became the accepted definition of droplets for better or worse.

On interpretation, therefore, as to the reason why it took so long for policymakers to accept that COVID-19 was airborne was because they were just following the science. Based on the technical definition it seemed there was insufficient empirical or clinical studies to demonstrate that the virus was transmitted through droplet nuclei. In this, the coalition of doctors who inferred that this was indeed the case based on available evidence were ultimately proven correct.

Author Zimmer makes excellent work of taking readers through the history of our understanding of the aerobiome and of the debates surrounding it in Air-Borne. The book highlights the the complicated ways that science works and evolves, and more importantly the many reasons why it sometimes does not. The idealized view of science as an objective and dispassionate process rooted in discovery, experimentation and the falsifiability of hypotheses is put under a microscope with its limitations laid bare. Yes, the secular trend is that good science almost always get things right eventually. But it is in the short term that science is affected by the human element: ego and politics, to name a few, also hold sway.

An interesting, if somewhat technical, dive into the history of the science of "air-borne" disease. Naturally it spends a lot of time on Covid, which was pretty interesting and informative about the (outwardly mystifying) back and forth over whether masks were effective and why. Fascinating to see just how unsettled the scientific consensus was about airborne transmission until even recently.

Beyond Covid, the book takes us all the way back to the miasma vs. germ theory of disease. I also thought it was interesting to learn how the backlash against miasma theory hampered proper understanding of airborne disease transmission (basically, once germ theory was scientifically established, any suggestion that germs could be airborne was thought of as mired in backward miasmatic thinking and often dismissed). The pendulum of scientific consensus in action.

Fascinating and informative exploration of our air and our health
In Air-Borne, Carl Zimmer examines the subject of aerobiology, the science of airborne life. This sounded to me like an interesting subject but not an especially controversial one. Was I wrong! The topic of life, especially disease-causing germs, in the air has been extremely controversial, and I was surprised at how long the controversies continued, even continue today during the COVID epidemic.
Zimmer covers the broad history of our investigation of life in the air and the MANY people who played a role in that investigation, such as Charles Darwin and Charles Lindbergh. One of the many things that surprised me a bit was how recently the scientific method began to be used.
Once we learned a bit about how germs can spread via the air, it is not surprising that countries would use the knowledge to develop weapons of biological warfare to kill the enemy with disease rather than guns and bombs, and this sobering topic is also covered.
Finally, Air-Borne looks at a very current example of aerobiological controversy, COVID infection and the disagreements about how it spreads and how to treat and prevent it. To mask or not to mask, that is the question.
The science in Air-Borne is not the only thing to enjoy. Readers are introduced to the many researchers like who studied (and fought over) how germs spread. I was surprised and a bit abashed that I was not at all familiar with important people like William and Mildred Wells, who did seminal work on airborne contagion and air hygiene, or the 19th-century German naturalist Christian Gottfried Ehrenberg, who made the first systematic survey of microorganisms and gave a name to one group he classified: bacteria! I laughed out loud at the christening of a balloon to be used for research involving spores at high altitudes; they used liquid air instead of champagne! There are also nonscientists like the Skagit Valley Chorale singers in Washington state who demonstrated that COVID-19 can be spread through the air---by singing.
It has been a long time since I read such a fascinating book. As I was reading it, I kept wanting to stop to share tidbits with my husband, but I restrained myself, because he will certainly want to read the book, and I do not want to spoil his fun!
I received an advance review copy of this book from NetGalley and Dutton.

Carl Zimmer’s book Airborne: The Hidden History of the Life We Breathe is an always informative, often fascinating, and at times worrying look at humanity’s long speculation and exploration of what is in the air around us and what we breathe besides the life-giving oxygen we need.

Zimmer covers a lot of ground here, going back to ancient civilizations and the idea of “miasma” or “bad air,” an explanation of sickness that held sway for centuries until being rivaled in the 14th century by the opposing idea that “diseases such as plague were caused by contagion — a poison that grew inside the sick and then spread to the healthy.” A speculative theory strengthened by the invention of the microscope in the 17th century, which enabled people to see microorganisms. Those who argued these organisms were the cause of disease became known as “contagionists.” They started to gain more credence with Louis Pasteur’s development of germ theory and British surgeon Joseph Lister’s use of carbolic acid to kill the theorized germs, greatly reducing post-surgical deaths due to infection/gangrene, as well as John Snow’s famous tracing of a cholera outbreak to a single water pump (removal of the pump handle led to the end of the outbreak). Even as miasmatists continued to argue against germ-caused disease, a group known as “sanitarians”, led by Florence Nightingale, took up the cause of trying to decrease germs in the environment and air.

Final proof of germs as the cause of disease came in the last 1800s when Robert Koch was able to isolate the microorganism behind anthrax and use it to infect mic, then did the same for tuberculosis. With germs firmly established, scientists began looking at transmission and also their presence in the air, even enlisting help from Charles Lindbergh to collect air samples during his many flights.

Thus the new science of aerobiology began in the 20th century, headlined particularly by plant pathologist Fred Meier and the husband-wife team of William and Mildred Wells, who despite their progress were attacked by other scientists for their conclusions and recommendations (the Wellses were also not helped by their notorious difficulty to work with or administer). The field fell into disrepute for a while, but the potential use of chemical and biological weapons, as well as the increased urbanization and population density that led to easier transmission of disease, brought it back. The rise of SARs and COVID have, as Zimmer does an excellent job of detailing, lent the field even more importance even as (again, vividly shown by Zimmer) the scientists themselves often disagreed with each, such as how far Covid germs would travel in a sneeze or cough for instance (or even, early on, if Covid was even airborne at all).

All of this is conveyed thoroughly, clearly, and often vividly, as with the details of Lindbergh’s flights, germ warfare experiments in America, Germany, Russia, and Japan, the highly detailed photographs depicting how far sneezes and coughs travel (you really don’t want to know), and more. Honestly, I didn’t feel I needed all the details Zimmer covers (mostly regarding the relationships between people but sometimes in other areas as well), but I certainly can’t fault him for his commitment to thoroughness. He has a good eye for the fascinating detail whether it’s visual, an engineering spec, and the sort of detail that perfectly captures an individual’s personality.

Air-borne is an excellent bit of science history that brings up right up to date to today and cautions us about avoiding the mistakes of the past if we want to do a better job than we have against the diseases that plague us.

Always an immediate request when I see Carl Zimmer. I first heard him on RadioLab, and have been obsessed with his work ever since. The way he narrates dry, and heavy topics is always so captivating. Air-Borne continues with that pattern with topics in air, Covid-related and just in the air we breathe.

Air-borne: The Hidden History of the Life We Breathe, by Carl Zimmer (February 25). The fascinating and little-known story of our atmosphere, told by a consummate storyteller. The air we breathe is absolutely essential to life on earth, and yet most of us pay it little attention. Award-winning science writer Carl Zimmer gives us a comprehensive but highly accessible look at mankind’s millennia-long attempts to understand the invisible envelope that surrounds our planet.

[This is one of four books on my recommended reading list. The post will go to around 8.7k readers on Jan 27. Also to BlueSky and X. Thank you for the ARC.]

I loved this book. At times it reads more like a thriller than science. It is also a great history of science book with excellent pacing and fluid writing. The explanations of the science are great and topical; the book brings the reader right up-to-date. Although the book covers a lot more than aerosols and droplets, the book did a great job of discussing this. The book answered so many of my questions. This book is well worth reading. Thank you to Netgalley and Dutton for the advance reader copy.