How an open window can make a classroom safer from COVID-19

A New York Times simulation shows how proper ventilation and filtration in classrooms can make schools much safer from COVID-19 transmission. The visualization was created with input from healthy buildings expert Joseph Allen of Harvard T.H. Chan School of Public Health.

Published on February 26, 2021, and highlighted on the front page of the New York Times on March 17, the simulation shows how viral particles might travel from one infected student in a classroom under several scenarios—with no windows open, with one window open, and with a box fan in the window and an air cleaner in the room. Under the last scenario, viral concentrations are lowest, according to the simulation.

Allen, associate professor of exposure assessment science and director of the Healthy Buildings program, noted that it’s safest to position a fan so that it blows air out of a window, not in. “We don’t want to ever blow air across anyone’s face, not knowing who’s infected,” he said.

View the New York Times simulation: Why Opening Windows Is a Key to Reopening Schools

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Op-ed: Opening windows can make schools safer during pandemic (Harvard Chan School news)