Prasad Kasibhatla in class fall 2020 with mask on

Calculating Classroom COVID Risks 

Nicholas School researchers have created an online calculator that can estimate the risk of airborne transmission of the COVID-19 virus in classrooms, cafeterias and other campus settings.

To use the model, you simply enter information about the room to be used, along with information about the number of students and duration of the class, into highlighted fields on the calculator’s webpage.  

Clickable “how to” pages help you answer questions that require technical knowledge, such as knowing a room’s ventilation rate. There’s even a link that explains how community infection rates – a required field – can be derived from current COVID case counts in your area.

Based on this information, the model calculates the risk that aerosol particles exhaled by someone with COVID are present in the room and could be inhaled by uninfected people. 

“The idea was to make it as easy as possible for teachers, administrators and students to assess the probable risk of COVID transmission from microscopic airborne aerosols containing the virus, which is a newly discovered route of infection,” said Prasad Kasibhatla, professor of environmental chemistry.

The actual risk may be higher than calculated if social distancing, mask use and hygiene protocols are not strictly adhered to, Kasibhatla stressed. And the calculator doesn’t measure the risk of COVID transmission by droplets or from contaminated surfaces, two other potential routes of infection.

“We can’t predict or eliminate all risks, but using our calculator can help schools zero in on which control measures – more ventilation? fewer people? shorter class durations? – might make the biggest difference,” he said.

John Fay, a lecturer in the Geospatial Analysis Program, Betsy Albright, assistant professor of the practice of environmental science and policy methods, and Bill Pan, Elizabeth Brooks Reid and Whitelaw Reid Associate Professor of Population Studies, helped develop the calculator.