The massive growth of cities in the 19th century also sparked the creation of bigger and more elaborate public buildings, which meant the creation of bigger and more elaborate ventilation systems in new museums, prisons, and courthouses. “There are new types of buildings being invented to respond to urbanization,” Alistair Fair, an architectural historian also at Edinburgh College, says. This was a time of innovation in ventilation too. In these complicated buildings, simple windows and chimneys would no longer do. Instead, intake vents were installed, as were ducts that wove through the walls and floors.
A famous example is the Palace of Westminster, in London, whose construction began in 1840. The building’s architect consulted with a doctor, David Boswell Reid, and Reid suggested extensive revisions to the architectural plan to improve ventilation. The two iconic towers of Westminster—the Victoria Tower and the one that holds Big Ben—are both also ventilation towers that helped draw warm, stale air out of the buildings. Reid further insisted on an expensive third tower, the Central Tower, for the sole purpose of ventilation. The ventilation system as a whole, which also included mechanical fans, valves, and a series of air chambers in the basement, accounted for a quarter of the building’s costs. Physically, too, “that system, when it was completed, took up about a quarter of the entire building,” said Schoenefeldt, who has extensively studied historical ventilation in Westminster.
The system’s physical remnants are still in the building, now unused. Even in the 19th century, the building’s ventilation did not always work as designed—Reid was a doctor, not an engineer, after all—but the principles of his designs were influential. “The Palace of Westminster was, at the time, the technologically most sophisticated building constructed in Europe,” Schoenefeldt told me. Its ventilation system inspired those in the era’s new museums, concert halls, and courthouses.
By the late 19th century, scientists were developing the beginnings of germ theory. John Snow had drawn his famous map of a cholera outbreak, which he traced to a single water pump. Louis Pasteur had shown that organisms cannot spontaneously generate in sterilized broth. And Robert Koch had identified the microorganisms that cause tuberculosis, cholera, and anthrax. But germ theory did not immediately do away with the importance of fresh air. “Early understandings of the germ, which emphasized its ubiquitous presence in air and water and its hardiness outside the body, neatly harmonized with already accepted modes of protection,” Nancy Tomes, a science historian at Stony Brook University, writes in The Gospel of Germs. The shift, like most paradigm shifts in science, was gradual.
For hospitals, the pavilion style continued into the 1930s, Annmarie Adams, an architectural historian at McGill University, told me. The 1918 flu pandemic struck at a time when germ theory was taking hold but people still recognized the importance of air. Even in modern hospitals today, where hand-washing and disinfection are paramount, the flow of air remains tightly controlled. Infectious patients are put in negative-pressure rooms, which contaminated air cannot escape. Immunocompromised patients are put in positive-pressure rooms, where contaminated air cannot enter. If anything, the flow of air is controlled in ever more sophisticated ways.