Covid Closed the Nation’s Schools. Cleaner Air Can Keep Them Open.

Published August 27, 2023 in the New York Times

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Scientists and educators are searching for ways to improve air quality in the nation’s often dilapidated school buildings.

…But scientists who study viral transmission see another lesson in the pandemic school closures: Had the indoor air been cleaner and safer, they may have been avoidable. The coronavirus is an airborne threat, and the incidence of Covid was about 40 percent lower in schools that improved air quality, one study found…

…Until recently, it wasn’t even clear to school officials how clean the air in school buildings should be. In May, however, the Centers for Disease Control and Prevention recommended that there should be five so-called air changes — the equivalent of replacing all the air in a room — per hour.

In June, the American Society of Heating, Refrigerating and Air-Conditioning Engineers, an influential standards-setting organization, published its first-ever requirements for “pathogen-free air flow” in buildings, including combinations of filtration and ventilation technologies that building managers can ratchet up during outbreaks.

“If I had to pick one place for pilot programs to invest money in layers for ventilation and filtration, school is the place to start,” said David Michaels, an epidemiologist at George Washington University who led the Occupational Safety and Health Administration during the Obama administration.

There are tentative signs of progress. A C.D.C. survey last year found that 70 percent of 420 schools nationwide had evaluated their ventilation systems, although many implemented only low-cost improvements, like opening doors or windows…