DIY filter systems improve air quality in classrooms

As students return to classrooms and the cold and flu season begins, researchers are exploring methods to enhance indoor air quality and lower the risk of airborne disease spread. A study published in ACS ES&T Air examined the performance of DIY air filters, referred to as Corsi-Rosenthal Boxes, in university classrooms. These cost-effective filters demonstrated a significant 61% reduction in airborne particles during class sessions while creating minimal noise and proving to be more budget-friendly than commercial portable air purifiers.

Misti Zamora, the lead author of the study, emphasized that indoor air quality plays a crucial role in student health and academic achievement, as students spend most of their day in classrooms. Poor ventilation can lead to the accumulation of harmful particles like infectious respiratory aerosols, dust, mold spores, and pollen, creating an unhealthy environment.

While commercial portable air purifiers can effectively clean the air, they are expensive, with the smallest units starting at approximately $140 each, making them unaffordable for many school districts.

The Corsi-Rosenthal (C-R) Box, a low-cost DIY alternative, consists of a box fan, four high-quality pleated air filters that cost around $60 in total, along with cardboard and duct tape. Previous research had shown the effectiveness of C-R Boxes in removing airborne pollutants, but few studies had investigated their performance in active, occupied classrooms. To address this gap, researchers Marina Creed, Kristina Wagstrom, Zamora, and their team conducted this study focusing on university classes.

The researchers built two C-R Boxes and tested them during 59 class sessions involving 14 to 30 students in a rectangular room. They initiated both boxes 10 minutes after the classes started and ran the fans at a low setting for the remaining 50-minute period. The results revealed that the boxes successfully reduced airborne particulate concentrations by an average of 61% by the end of the class.

The particle removal was consistent throughout the room, and noise levels remained between 46-55 decibels, posing no disruption to the learning environment. Moreover, the cost of these DIY filters was significantly lower than that of commercial portable air purifiers, which could cost five to 10 times more to achieve the same level of clean air.