A DIY air purifier that costs under $100 to make is taking America’s classrooms by storm

This story is from January 2022

In the midst of lockdown due to COVID-19, many people looked for new hobbies to pass the time, from gardening to working out to baking bread. During winter break, Shiven Taneja also began a new project, hoping to help his community. In Mississauga, Canada, COVID-19’s fifth wave was coming in, along with the rapidly-spreading variant Omicron. Rapid tests and booster shots were in short supply and Taneja wanted to find another way to reduce people’s risk of catching the virus.

So the 14-year-old began building an DIY air purifier and soon ended up delivering his creations around his neighborhood. “Anxiety levels were rising again, and over my winter break, I had the time. So I felt like, why not just do it?

Shiven Taneja
Image Credit: Kavita Taneja | CBC

Teen Builds DIY Air Purifiers for His Community

Online, Taneja learned about an air purifier system constructed to reduce aerosol particulates. He realized he could build these models by himself at a fraction of the price of a HEPA purifier, which can range from hundreds to thousands of dollars. On Boxing Day, he posted an offer to build this filter for anyone interested. He delivered his first purifier to the Canadian Fencing Academy in Oakville. “They DM’d me on Twitter and they said this is perfect,” Taneja says. [1]

Kyle Foster co-owns the academy with his wife, Lisa Huzel, who is also “a physician with a double specialty in respirology and critical care who has been dealing with COVID on the front line since the beginning of the pandemic,” Foster says in an emailed statement. “She of course understands the importance of air flow and proper filtration especially in enclosed areas.

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Soon, Taneja’s DIY project became a booming business. He sold them for $150 each to cover the cost of the materials. Then more requests arrived. He had sold 30 or so by January. Many requests came from seniors or other individuals who are immunocompromised.

He initially planned to build the air purifier for his family but then he realized he could help his community. “Elderly people may not be able to build these because, well, when I bought the materials and then I built it… It’s a lot of bending down, and it might be really difficult for them,” Taneja says. “So I thought I can just build it. And also, they might not be able to afford the HEPA filters.” [2]

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The Corsi-Rosenthal Box

The design he used is called the Corsi-Rosenthal box, named after two friends who invented it in 2020. Richard Corsi, dean of the College of Engineering at the University of California-Davis, was discussing his idea of a DIY air purifier on Twitter. Jim Rosenthal, the CEO of a Texas-based air filtration company, read the tweets and set to work on a prototype. The Corsi-Rosenthal box is a box fan with high-grade (MERV-13) filters taped around it. Taneja needed only a fan, four filters, duct tape, and a cardboard box to use as a base. Once completed, the Corsi-Rosenthal box can reduce particulate spread in whichever room it’s in. 

Most notably, its design instructions are free. “We decided to make it open source so anybody could use the design,” says Rosenthal. “The amazing part of it is, by doing that, we wound up getting so much more support and so many more people involved and trying to help.

This support included scientists and engineers eager to test the velocity of the filter. “We’ve had universities test it,” says Rosenthal. “UC Davis has a peer-reviewed paper (in which) they tested it and found that it did better than the HEPA air cleaners that they compared it to.[3]

HEPA purifiers can remove at least 99.7% of particles from the air, even particles containing the virus, according to recent experiments. However, a C-R box contains a larger fan and can reach more air although it could only remove 60–80% of particles. “All you care about in the end is the total rate at which the air is cleaned,” says Joseph Fox. He’s the chair of the indoor air quality advisory group with the Ontario Society of Professional Engineers. “So, what the C-R box lacks in efficiency, it makes up for in airflow.” [4]

We need this in all schools

This economical DIY air purifier can become a potential long-term option for offices, companies, and schools. “We need this in all schools to protect our kids,” says Kimberly Prather, aerosol expert and atmospheric chemist at the Scripps Institution of Oceanography. She added that the C-R boxes “also reduce flu asthma, allergies, and other respiratory health issues.” She suggests optimizing the Defense Protection Act to build 40 million of these air purifiers to place in every school in America.

Taneja, now 15, is interested in building robots, and has joined his local Robotics team. He has always been fascinated by engineering, having already tinkered with 3D printers, Popsicle sticks, and motors. He hopes to go into the STEM field in the future. 

Keep Reading: Here’s How This DIY Couple Converted a School Bus Into a Gorgeous Home


  1. “Mississauga youngster builds DIY air purifier for Oakville business.The Star. Mansoor Tanweer. January 14, 2022
  2. “Meet the Ontario teen building DIY air purifiers for seniors and small businesses.CBC. January 10, 2022
  3. “Characterizing the performance of a do-it-yourself (DIY) box fan air filter.” Aerosol Science and Technology. Rachael Dal Porto,Monet N. Kunz,Theresa Pistochini,Richard L. Corsi, Christopher D. Cappa. April 5, 2022
  4. A DIY air purifier that costs under $100 to make is taking America’s classrooms by storm.” Fortune. Carolyn Barber. September 15, 2022