Every breath you take

At the start of 2020, a small team of scientists tried and failed to convince public health organizations that Covid-19 was spread through the air we breathe.

- ROBERT SULLIVAN

Why they failed, and how they ultimately won, is the subject of Carl Zimmer's new book, Air-Borne.

Until 2020, explains Zimmer (a New York Times science columnist), scientists thought that respiratory diseases like Covid spread through droplets, and that these droplets had a limited range. Coughed up, they fell quickly to the ground — like "soggy raisins," to use the vivid if disgusting terminology of a 1990s health official speaking about tuberculosis. Thus the recommendation offered by the World Health Organization (WHO): "Maintain at least one meter (three feet) distance between yourself and other people, particularly those who are coughing, sneezing and have a fever."

Air-Borne shows us how the scientific community came to understand that Covid-19 transmission was less akin to shots from a gun, and more like smog in a valley. To explain, Zimmer takes us through the history of aerobiology, and in his detailed and gripping account, he ascribes the reluctance of both the Centers for Disease Control and the WHO to a bias born of an ancient battle between two factions known as "miasmatists" and "contagionists."

According to miasmatists, bad air destroyed health. In the Middle Ages, swamps meant fever. And when Benjamin Rush looked for the cause of 1793's deadly yellow fever outbreak in Philadelphia, he smelled bags of spoiled coffee: "Their sickness commenced with the day on which the coffee began to emit its putrid smell."