Homemade Air Filters Are More Effective Than You Might Think, Public Health Scholars Say
Photo by Stephanie S. Cordle
While they look a bit like a last-minute high school science projects, the odd gadgets that students were making all last week in the School of Public Health Building get anything but a failing grade at enhancing indoor air quality.
Known as Corsi-Rosenthal boxes, they’re just an everyday box fan that sucks air through furnace filters capable of capturing viruses and other particles from the air. Add some cardboard and tape, and each costs only about $65 to make, compared to several hundred dollars for similarly effective commercial air filtering devices.
The device was designed by a college engineering dean and an air-filter manufacturing company CEO soon after the start of the pandemic; the idea to build them at Maryland and distribute them to the community came from Dr. Don Milton, a professor of environmental health and director of the Public Health Aerobiology, Virology and Exhaled Biomarker Laboratory (PHAB Lab), who’s using a portion of the funds that he received from becoming an MPower professor last fall to pay for the supplies.
Milton has long been a leader in getting people to understand air hygiene; his expertise in the tiny suspended particles known as aerosols has been instrumental to our understanding of how COVID-19 is spread.
“The inspiration is really that I think we need to be offering clean air out to the community, getting people to understand that when we talk about layers of protection, one of the layers of protection that we can do—that doesn't require necessarily wearing masks, and it can continue after we take our masks off—is cleaning the air,” Milton said. “These Corsi-Rosenthal boxes are a way of cleaning the air and doing so pretty efficiently.”
Students from the Global Public Health program in College Park Scholars, as well as those taking classes with SPH Professors Stephen Thomas and Kate McPhaul, began building the boxes last Tuesday in small groups, ultimately constructing more than 30, with more building scheduled this today and tomorrow.
Students from Thomas’ “Fearless Ideas” class, meeting for the first time in person at the event on Friday, were eager to apply what they’ve been studying so far this semester.
“We learned in class that the COVID virus lingers in the air for a while if someone with COVID came into a room,” said Karmen Macchiagodena, a senior studying public health science.
Thomas, who specializes in research that engages with community members in Prince George’s County and elsewhere, jumped at the opportunity to have his students get involved in constructing the devices.
“These boxes will be given away to the local neighborhood businesses, like barbershops and beauty salons, where people have to share air, the local schools and to churches, and to even the homes of our students,” he said.
He said hopes his students will feel more at ease, knowing there’s something tangible they can do to aid in the fight against the pandemic.
When they leave UMD, before they’re distributed around the community, they’ll make a pit stop at the College Park Academy, where middle school students will help beautify them with stickers and other decorations.
“We're excited to get our kids some more hands on projects again,” said Steven Baker, middle school principal at the school. “With the two years of pandemic here, we haven't had a lot of these opportunities … for our kids to get their hands dirty again, just getting back into science projects and things like that.”
The boxes are an imperfect solution, Milton said. Though more affordable and in some ways more effective than their store-bought counterparts, they’re not much more energy-efficient.
“When we start thinking holistically about climate change, our carbon footprint, and making indoor air cleaner and safer, we need to do all of these things at the same time,” Milton said.
Still, the Corsi-Rosenthal boxes are a step in the right direction.
“What we're trying to do with getting all of the students engaged with it is get people to feel that we can have safe, clean, indoor air, sanitary air,” Milton said. “The big revolution of the 21st century in public health is going to be breathing sanitary air indoors.”
Maryland Today is produced by the Office of Marketing and Communications for the University of Maryland community on weekdays during the academic year, except for university holidays.
Faculty, staff and students receive the daily Maryland Today e-newsletter. To be added to the subscription list, sign up here:Subscribe