"Performance and Practical Considerations of Deploying Do-It-Yourself (DIY) Air Purifiers in Occupied Classrooms" ACS ES&T Air
As students return to school and cold and flu season begins, researchers are studying ways to improve indoor air quality and reduce the risk of airborne disease transmission. A study in ACS ES&T Air reports test results of do-it-yourself (DIY) air filters, known as Corsi-Rosenthal Boxes, in university class sessions. The units reduced particulate matter across the occupied classroom by 61%, produced minimal noise, and were more affordable than commercial portable air purifiers.
Corsi-Rosenthal Boxes are a safe, highly effective tool for improving indoor air quality without disrupting the learning environment." - Misti Zamora
Adapted from ACS ES&T Air 2026, DOI: 10.1021/acsestair.6c00143
"Indoor air quality in educational settings is a critical factor affecting student well-being and academic performance because children and school staff spend a large portion of their day inside classrooms," says Misti Zamora, corresponding author of the study. "When schools lack good ventilation, harmful particles like infectious respiratory aerosols, dust, mold spores, and pollen can build up, creating an unhealthy environment."
Commercial portable air purifiers clear airborne particles and help limit disease transmission. But they're expensive - with the smallest sizes starting around $140 per device - and many school districts can't afford them for every classroom. As a lower-cost, DIY alternative, researchers developed the Corsi-Rosenthal (C-R) Box , which combines a box fan, four high-quality pleated air filters (about $60 total), cardboard, and duct tape. Previous studies reported that the C-R Boxes effectively remove airborne pollutants, but few assessed their performance in active, occupied classrooms. So, Marina Creed, Kristina Wagstrom, Zamora and colleagues have been evaluating the system's effectiveness and practicality, and this study focuses on university classes.
The researchers built two C-R Boxes and tested them during 59 class sessions with 14 to 30 students in a rectangular room. They turned on both boxes 10 minutes after the classes began and ran the fans at a low setting for the rest of the 50-minute period. Results showed that the boxes:
- Reduced ultrafine, fine, and coarse particulate matter concentrations by 61% on average by the end of class.
- Produced 46 to 55 decibels of noise, comparable to a typical office environment.
- Moved air evenly around the rectangular classroom space.
- Removed airborne particles at similar rates at three places around the room.
To Zamora, the study suggests that "Corsi-Rosenthal Boxes are a safe, highly effective tool for improving indoor air quality without disrupting the learning environment. We showed that the clean air circulated around the entire room, meaning every student receives the protective health benefits regardless of where they sit."
"Commercial units can cost five to ten times more than these DIY air filters to provide the same amount of clean air," says Zamora. "This research proves that communities don't need to choose between clean air and their school budgets."
The study's authors are part of the University of Connecticut's Indoor Air Quality Initiative , which provides resources for schools and videos on how to build a DIY air purifier.
The authors acknowledge financial support, discounted materials, and/or donations of materials from the Balvi Filantropic Fund; Petit Family Foundation's Haley's Hope and Michaela's Miracle MS Memorial Fund; TexAire Heating and Air Conditioning; The Home Depot; and the University of Connecticut's Schools of Medicine, Engineering, and Nursing.
