That era saw the rise of well-ventilated “Nightingale pavilions,” named after Florence Nightingale, who popularized the design in her 1859 book, Notes on Hospitals. As a nurse in the Crimean War, she saw 10 times more soldiers die of disease than of battle wounds. Nightingale began a massive hygiene campaign in the overcrowded hospitals, and she collected statistics, which she presented in pioneering infographics. Chief among her concerns was air. Notes even laid out exact proportions for 20-patient pavilions that could allow 1,600 cubic feet of air per bed.

Each pavilion was a separate wing, radiating from a central corridor. And it had large windows that faced each other, which allowed a cross breeze to blow between the beds. The windows stayed open no matter the weather. There were stories, Kisacky told me, of hospitals in winter where “the patients are closing the windows, and the nurses are opening them. And the doctors come and knock the glass out to make sure they stay open.” In some pavilions, a central fireplace heated the room, so that contaminated air rose out of the ward via the chimney effect. That heat might have been nice in the winter but “they would run fires in the fireplaces in August to keep the air moving,” Kisacky said. “You wouldn’t want to be the patient in the bed closest to that.”

The pavilion-plan hospitals formalized the fear of “bad air” in hospital design, but the idea is much older. The Greek physician Hippocrates warned in the fifth century B.C. that bad air was the cause of pestilence. People in the Middle Ages believed some version of this too. The word miasma, which dates to the 17th century, comes from the ancient Greek for “pollution.” In the 19th century, the fear of outbreaks fueled new sanitation campaigns to rid cities of miasma.