ITHACA, N.Y.—Hallie Snowman, an Ithaca High School science teacher, has a mission: increase ventilation in classrooms to reduce the chance of COVID-19 spread, especially during this winter’s Omicron variant surge.

Included in its reopening preparations, Ithaca City School District’s Board of Education allotted $300,000 for building remediations to repair deficient or outdated HVAC and air filtration systems. Despite this, Snowman felt that an extra layer of protection was necessary, and she set out to continue to improve the working and learning environments within IHS.

“As a science teacher I’ve been following the pandemic really closely,” she said. “The experts are all saying ‘ventilation, ventilation, ventilation’ as an additional layer of protection in schools, and even though our school updated its ventilation the summer before last with some pandemic money, with the Omicron surge and hospitals filling up I just wanted another layer of protection to reduce classroom spread.”

Snowman already knew that there could be more ventilation within her classroom thanks to a CO2 monitor installed in there which indicated more than a thousand parts-per-million when students were in the room. After doing some research and discovering an easy DIY air filtration system called a Corsi-Rosenthal box, she began constructing them with money out of her own pocket.

The template used to build the boxes. (Photo provided by Hallie Snowman)

Corsi-Rosenthall boxes, or CR boxes, were designed by two engineers that wanted to provide a cheap way for people to improve their air quality in whatever space they were in, whether that be a classroom, home, office or business.

The boxes cost less than $100 and an hour to build, and Snowman has made 12 herself to date, while also educating other teachers at the school about why they are beneficial and may want one in their room.

Materials for Corsi-Rosenthal boxes. (Photo provided by Hallie Snowman)

There has been no communication between the Snowman and the district about the project, and though she said she was a little nervous about pushback, she decided she could apologize later because she felt an obligation to do her part in combating potential spread of COVID within schools, and reducing strain on healthcare systems was important to her. The district did not respond to a request for comment.

“I just started building them and putting them in classrooms. Then I decided to start a GoFundMe to get more money to build more,” she said. The GoFundMe, found here, has raised $3,460 out of its $5,000 goal.

Though it began as a solo project, students are beginning to get involved. “This week I started building them in my classroom as part of a science lesson on ventilation, so it’s involved in that way. Kids have also approached me about building more in their free time as well,” she explained.

“This box is something that anyone can build to increase air quality in their homes and classrooms and businesses, so really I just want to get the word out about them,” she said.

Zoë Freer-Hessler

Zoë Freer-Hessler is the digital editor/reporter for the Ithaca Voice. Joining in November 2021, she has covered a wide range of topics related to local news. She can be reached at,...