Duke researchers develop calculator to examine risk of airborne transmission in classrooms

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Kasibhata's calculator looks at a classroom setting and takes into account how many faculty and students would be in the classroom, how many sessions would be held in the classroom and the size of the classroom. This is unique because the calculator is able to look at a variety of different settings and variables, including the use of air purifiers.

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These are not all the parameters that influence the spread of the coronavirus in the classroom, Kasibhatla said. The calculator looks at what behaviors are more likely to increase the risk of infection.

Using masks, social distancing and practicing good hygiene are also known to be a good way to lower the risk of infection, he said.

The calculator was first only going to be used to look at classrooms on Duke University's campus. Now Kasibhatla and his associates are in discussion with Durham Public Schools about using the tool to look at classrooms there.

Kasibhatla said there is increasing evidence that the virus is able to be expelled in small particles. Kasibhata and other atmospheric scientists say that the coronavirus can stay airborne for much longer than the Centers for Disease Control and Prevention and the World Health Organization scientists say.

Scientists with the CDC and the WHO say that particles larger than 5 microns fall out of the air after they have been exhaled and don't pose a risk to others, according to Kasibhatla.

"We know that’s not true," Kasibhata. "It’s only particles larger than 100 microns or 50 microns that fall out pretty quickly, the rest can actually stay airborne for quite awhile."

Kasibhata used this knowledge when creating the calculator.