Sarah Zhang writes:

When London vanquished cholera in the 19th century, it took not a vaccine, or a drug, but a sewage system. The city’s drinking water was intermingling with human waste, spreading bacteria in one deadly outbreak after another. A new comprehensive network of sewers separated the two. London never experienced a major cholera outbreak after 1866. All that was needed was 318 million bricks, 23 million cubic feet of concrete, and a major reengineering of the urban landscape.

The 19th and early 20th century saw a number of ambitious public-health efforts like this. The United States eliminated yellow fever and malaria, for example, with a combination of pesticides, wide-scale landscape management, and window screens that kept mosquitoes at bay. One by one, the diseases that people accepted as inevitable facts in life—dysentery, typhoid, typhus, to name a few more—became unacceptable in the developing world. But after all this success, after all we’ve done to prevent the spread of disease through water and insects, we seem to have overlooked something. We overlooked air.

This turned out to have devastating consequences for the beginning of the coronavirus pandemic. The original dogma, you might remember, was that the novel coronavirus spread like the flu, through droplets that quickly fell out of the air. We didn’t need ventilation or masks; we needed to wash our hands and disinfect everything we touched. But a year and half of evidence has made clear that the tiny virus-laden particles indeed linger in the air of poorly ventilated areas. It explains why outdoors is safer than in, why a single infected person can super-spread to dozens of others without directly speaking to or touching them. If we are to live with this coronavirus forever—as seems very likely—some scientists are now pushing to reimagine building ventilation and clean up indoor air. We don’t drink contaminated water. Why do we tolerate breathing contaminated air?

It’s not just about COVID-19. The scientists who recognized the threat of airborne coronavirus early did so because they spent years studying evidence that—contrary to conventional wisdom—common respiratory illnesses such as the flu and colds can also spread through the air. We’ve long accepted colds and flus as inevitable facts of life, but are they? Why not redesign the airflow in our buildings to prevent them, too? What’s more, says Raymond Tellier, a microbiologist at McGill University, SARS-CoV-2 is unlikely to be the last airborne pandemic. The same measures that protect us from common viruses might also protect us from the next unknown pathogen. [Continue reading…]