Corsi-Rosenthal Box DIY air purifier works for COVID, studies say


This fall, lecturers and fogeys have been sharing pictures on social media of do-it-yourself air purifiers that they’ve made for lecture rooms to assist defend youngsters from COVID-19 transmission.

But do these low-cost purifiers really work?

According to researchers, they do.

They’re known as Corsi-Rosenthal Boxes, a DIY air purifier that was first conceived of in the summertime of 2020 by two air filtration specialists, Richard Corsi and Jim Rosenthal.

Since then, their effectiveness has been backed up by scientists, studies and an organization that makes air filters.

Studies have proven that poor air flow is related to a lot increased unfold of COVID-19. But many buildings in Canada, together with faculties and workplaces, are nonetheless not outfitted with correct air flow programs or HEPA purifiers.

Unlike HEPA purifiers, which might price from $200 to upwards of $500, a Corsi-Rosenthal Box may be made for round $100 with supplies that may be bought at any ironmongery store.

A York University engineering professor who has been carting his Corsi-Rosenthal Box with him throughout campus this previous week says he heard about them on social media in mid-2021.

“Some ventilation engineers were talking about them and they seemed like a practical and easy way to get more clean air into schools and into my home,” James Andrew Smith informed in an e mail.

“I don’t believe that we’re doing enough for clean air,” he added, saying that he feels higher in regards to the danger stage in his classroom when he makes use of the DIY air purifier together with different measures.

The packing containers additionally appear to have longevity.

“This guy behind me just turned eight months a couple days ago,” Corsi mentioned in a Twitter video Monday, referring to his personal Corsi-Rosenthal Box buzzing away previous his shoulder. “Still doing its job, still lowering inhalation-dosed aerosol particles, including virus-laden respiratory aerosol particles. It’s not rocket-science, folks.”



There are variations, however the primary Corsi-Rosenthal Box is made of 4 air filters, one field fan and a few cardboard, all taped collectively to make a dice. A University of California, Davis tutorial specifies to make use of MERV-13 filters.

The field fan ought to have the airflow pointing outward, and all edges needs to be sealed with duct tape. The ultimate sixth facet of the dice needs to be closed off with cardboard or perhaps a fifth air filter.

To make the filter extra environment friendly, it’s also possible to reduce a circle out of a chunk of cardboard and tape it overtop of the outward face of field fan to cut back backflow.

The concept behind the Corsi-Rosenthal configuration is that the air that enters the field will probably be passing by means of a number of filters for purification, and the sealed dice implies that solely filtered air will then be blown out into the room by the fan.

Studies point out that whereas it received’t be capable to filter out fairly as many particles as a HEPA filter can, a Corsi-Rosenthal Box can cycle the air in a room at a charge that typically outstrips HEPA purifiers, eradicating viral particles from the air at a fraction of the price.

A research printed in March within the journal Aerosol Science and Technology, which included Corsi as considered one of its authors, discovered that the packing containers had been in a position to rapidly filter a complete room at a a lot sooner charge than the HEPA purifiers.

When wanting on the “cost-per-unit-air-cleaned,” the research mentioned that “the DIY air filter is approximately one-tenth the initial cost of a commercially available HEPA-based air cleaners.”

3M, an organization that makes air filters, mentioned in a February press launch that their scientists had studied Corsi-Rosenthal Boxes and that the DIY concept works.

“Indoor air is shared air,” Kelsey Hei, a 3M Filtrete model engineer, mentioned within the launch. “Many viruses like COVID-19 are airborne and can become highly concentrated in poorly ventilated spaces. I’m heartened to see so many people advocating for the importance of clean air, especially in schools.”

Another research printed in September within the journal Science of the Total Environment checked out 9 totally different configurations of DIY air purifiers and in contrast them to 3 HEPA purifiers.

The research discovered that the DIY choices, together with a single filter with a field fan, Corsi-Rosenthal Boxes, and a variation on them that makes use of three filters and two field followers in a dice, had been all comparable or higher than HEPA purifiers by way of the pace during which they filtered the air.


When it turned clear that COVID-19 was unfold by means of airborne transmission, scientists started to emphasise the significance of fine air flow as a instrument to gradual transmission.

An Italian research printed final March that checked out greater than 10,000 lecture rooms discovered that environment friendly air flow programs had been in a position to scale back transmission of COVID-19 in faculties by greater than 80 per cent.

Infections had been a lot decrease within the 316 lecture rooms that had been outfitted with a mechanical air flow system, in comparison with these with out them. When the air flow programs cycled to utterly change the classroom’s air with new air 2.4 instances an hour, infections had been lowered by 40 per cent. If they changed the air six instances an hour, the infections had been lowered by 82 per cent, the research discovered.

With few public well being measures nonetheless in place for again to highschool, lecturers have been more and more turning to instruments just like the Corsi-Rosenthal Box to make their lecture rooms safer.


As college students returned to lecture rooms this fall, lecturers and fogeys took to social media to share pictures of their Corsi-Rosenthal Boxes. On Twitter, the hashtag #CorsiRosenthalBox consists of quite a few inventive designs aimed to be kid-friendly.

One person primarily based in Manitoba posted a photograph of a Corsi-Rosenthal Box for his son’s classroom that had been upgraded to appear to be a robotic, with googly eyes, antennae and arms.

Other designs utilized large eyes, brightly colored paints and quite a lot of animal ears to rework the packing containers into pleasant creatures.

In Quebec, dad and mom and lecturers have posted a petition calling for Jean-Francois Roberge, Minister of Education, to permit them to offer Corsi-Rosenthal Boxes to their kids’s faculties, saying citizen initiatives have “come up against strong administrative resistance.”

“Installing homemade air purifiers, known as Corsi-Rosenthal cubes, is an effective and inexpensive way to improve air quality in indoor spaces,” the outline reads.

The petition, began final month, has greater than 1,600 signatures.

At York`s Lassonde School of Engineering, Smith says that carting round a Corsi Rosenthal Box has spurred questions and curiosity from college students.

“How much do I care about my students? Enough to build them a wheeled #CorsiRosenthalBox to bring to class,” he tweeted Monday.

Smith and different college members have been calling for the Dean’s Office of York’s Lassonde School of Engineering to fund and distribute moveable air purifiers to college members, however up to now, these motions have been denied.

“Personally, I think that they’re a no-brainer,” Smith informed “They’re easy to install, easy to operate, aren’t nearly the controversial topics that vaccines or masks are. They make the air cleaner for smog, smoke, dust… they’re just generally a great idea.”

These packing containers are being utilized in lecture rooms throughout the globe.

In November 2021, the Brown University School of Public Health in Rhode Island launched a challenge to construct Corsi-Rosenthal Boxes for lecture rooms and research them, and have since put in packing containers in quite a few lecture rooms and scholar lounges.

Oliver Patrick, a county councillor within the U.Ok., began a GoFundMe final month to offer Corsi-Rosenthal Boxes for faculties in his district, stating that he was involved in regards to the lack of public well being measures in place in his area.

“I want to make sure we do as much as we can to make sure school is as safe as possible for children,” Patrick wrote.

The California Department of Public Health listed Corsi-Rosenthal Boxes as a advisable choice for lecture rooms in a February bulletin for enhancing air high quality in faculties to struggle COVID-19. 


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