I built a Corsi-Rosenthal Box! Here are my tips on building a Corsi-Rosenthal Box air cleaner for airborne pollution and pandemics.
#HowToBuild #CorsiRosenthalBox #tips #IAQ #AirPurifier #AirFilter #DIY
#corsirosenthalbox — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #corsirosenthalbox, aggregated by home.social.
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I keep reading about Corsi–Rosenthal boxes as DIY air purifiers that outperform all commercially available air purifiers.
You literally only duct-tape four HVAC filters together and slap any regular PC fan onto them.
US-Americans recommend the brand #Filtrete for MERV-rated HVAC filters, but in Europe that brand costs at least twice or thrice as much as in the USA.
Are there any equivalent affordable HVAC filters in Europe with a MERV rating of 8 or 13? Or do I simply have to swallow the additional cost because HVAC filters aren't as ubiquitous in Europe as they are in North America?
#DIY #CorsiRosenthalBox #CorsiRosenthal #HVAC #HEPA #MERV #AirQuality #AirPurifier #AirFilter
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RE: https://kolektiva.social/@DoomsdaysCW/116926218706587720
Tagging for #SolarPunkSunday. #OpenSource instructions for building your own #CorsiRosenthalBox out of a box fan and MERV filters.
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An Easy-to-Build #CorsiRosenthalBox Using Modular #PCFan Systems
Jim Rosenthal
October 21, 2023"The first Corsi-Rosenthal Box was built in August of 2020. It was presented as an #OpenSource' concept so that as many people as possible could have low-cost cleaner, safer indoor air. It is based on sound engineering principles, but it is really very simple. Use 4 (or 5) MERV 13 filters in a 'box' configuration with a box fan. The best thing is – it works! Consequently, many thousands have been made all over the world.
It has also been very enjoyable to see the continuous stream of ingenuity, creativity, and knowledge that has been expended to create a 'better' Corsi-Rosenthal Box. Much of this was out of necessity since many countries in the world do not have the same filters and fans as we have in North America. Many really smart and creative people have developed designs of the CR Box concept that work with the fans and filters available in their countries.
We have also had many people in North America who have contributed to the development of a “better mousetrap” of a DIY air cleaner. For effectiveness and low cost, it is very hard to beat the original box fan and “box” of filters design. But there have been many interesting modifications that have been shown to provide some real benefits. The most interesting of these is the use of PC fans to replace the box fan. The PC fans have the advantages of low noise and low energy usage but are not as economical or as easy to construct.
Here is another alternative – modular PC fan systems. A company by the name of AC Infinity (www.acinfinity.com) makes them. Their primary uses are for audio-visual cabinets and indoor horticulture. However, they provide low noise, high air flow and low power usage. In other words, they should work for Corsi-Rosenthal boxes. My initial tests confirm this conclusion. "
Note: I am not finding the fans on the AC Infinity website. I have found computer fans that can do the job on eBay and Amazon.
Learn more:
https://www.texairfilters.com/an-easy-to-build-corsi-rosenthal-box-using-modular-pc-fan-systems/#SolarPunkSunday #CleanAir #WildfireSmoke #WildfireHaze #AQI #AirQuality #WildfireSeason #Wildfires #DIY #CRBoxes
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I clearly need a long-term solution for maintaining my respiratory health when there's wildfire smoke. What are people doing? Anyone recommend specific respirators? (I don't particularly want to rely long term on being able to get a very specific type of filter if that's possible.)
Is the Corsi Rosenthal box the best thing for my house? Is there a permanent version I won't hate looking at? (I have basic Levoit purifiers.)
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In the Canadian Smokestream right now! Graph from #HomeAssistant, showing PM2.5 readings. Outside is from the nearest station reporting to #WAQI, inside from #IKEA Vindstyrka. At 8pm, I switched from washable HVAC filters to MERV10 disposables. Around midnight, turned on #CorsiRosenthalBox, full speed. (Same room as sensor.)
So, #hvac was doing ok, MERV10 improved it. The CR really made a big difference, and quickly, lowering the level about 2.5x. -
RE: https://social.ridetrans.it/@Andres4NY/116931466428900883
Tagging this thread for #SolarPunkSunday... Discussions about building one's own #CorsiRosenthalBox from folks who have built them. These ones use computer fans, which are a lot quieter than the box fans recommended in the original instructions by Corsi.
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#FFF 70 — Corsi-Rosenthal Box
The whole State of Michigan is getting hit with smoke from wildfires in Minnesota and Canada. It's a haze that looks like fog, but it smells like smoke. A family member sent this AQI from early this morning and it is quite alarming. Along the lake ours was 300 but inland is generally worse. Now the haze is much worse from yesterday also. I had dream group today and so was out driving in it. Since the A/C is out on the car, on the way there I kept the windows shut and the air […] -
RE: https://mastodon.nz/@oseiler/110597049520787620
Since CR boxes seem to be getting some attention again I'm still very happy with how these turned out
#CleanAir #CorsiRosenthal #CorsiRosenthalBox -
'Dangerous' air quality in Detroit, Minneapolis as thick wildfire smoke shrouds the sky for millions
Smoke from wildfires burning in Ontario have caused air quality to reach "dangerous" levels across Canada, and the northeastern and midwestern United States. And it could get worse before conditions improve.
By Brian Lada, AccuWeather meteorologist
Published Jul 15, 2026 11:50 AM EDT | Updated Jul 16, 2026
" Massive plumes of smoke are descending across parts of Canada and the United States, creating dangerous air quality and scenes reminiscent of the historic wildfire smoke outbreak from three summers ago.
" 'In 2023, a major fire outbreak in Quebec caused days of unhealthy air quality in the northeastern U.S.,' AccuWeather Vice President of Forecast Operations Dan DePodwin said. 'This event could cause similar levels of poor air quality in spots.'
"Air quality alerts have been issued for millions of people, including across all of #Connecticut, #Delaware, #Massachusetts, #Michigan, #NewHampshire, #NewJersey, #NewYork, #Ohio, #Pennsylvania, #RhodeIsland and #Wisconsin.
"Over 800 wildfires are currently burning across Canada, including dozens that are out of control across western #Ontario, the source of most of the smoke. 'Many of these fires may have been started by lightning,' AccuWeather Senior Meteorologist Brett Anderson said.
"On Wednesday, #Toronto had some of the worst air quality in North America, reaching 'very unhealthy' levels with an AQI of 220. #BostonMA was not far behind with an unhealthy AQI of 147.
" 'When the AQI climbs into the 150+ range for a full day outside, that’s in the ballpark of [smoking] 7 to 9 cigarettes,' Dr. Jonathan M. Tan, division chief of General Anesthesiology at Children’s Hospital of Philadelphia, told AccuWeather.
"Conditions deteriorated by Thursday morning, with widespread "dangerous" air quality across nearly all the Great Lakes region and into parts of the Northeast. Minneapolis and Duluth, Minnesota, as well as Detroit, were among the worst cities at daybreak Thursday, with AQIs over 340.
" 'Any exposure to the air, even for a few minutes, can lead to serious health effects on everybody,' Plume Labs said.
Avoid outdoor activities.' "#CanadianWildfires #CRBox #AirQuality
#WildfireSmoke #AQI #HEPAFilters #CorsiRosenthalBox #AirCleaners #Masks #ParticulateMatter #RespiratorMasks #StayIndoors #HazardousAir #AirQualityAlert -
Canadian #wildfire smoke turns air hazardous in the US #Midwest. Officials say stay inside
By TAMMY WEBBER and PHILIP MARCELO, July 16, 2026
NEW YORK (AP) — "Heavy, pungent smoke from #CanadianWildfires darkened skies in the U.S. on Thursday from the #GreatLakes to parts of the #EastCoast, reducing visibility for commuters and prompting warnings that air quality could make being outside dangerous.
"#Detroit’s air quality was among the worst in the world for major cities, as a lingering high pressure system trapped smoke from dozens of fires in Canada and northern Minnesota, said Steven Freitag, a National Weather Service meteorologist in Pontiac, Michigan.
" 'Sure enough, it arrived in force here and it’s really pretty extreme levels,' said Freitag, who noted that visibility in some areas was reduced to a half mile.
"Omar Mitchell wore a mask as he walked to his restaurant in Detroit. He said he urged his employees to do the same.
" 'It’s scary,' Mitchell, 50, said as he looked at the sky. 'You don’t know necessarily what the side effects may be. That’s days or months later.'
"Cities across the Great Lakes states registered air quality ranging from unhealthy to hazardous — which means it’s unhealthy for anyone, regardless of health conditions. Microscopic particles can lodge deep in the lungs and enter the bloodstream, leading to heart and lung problems and contributing to other long-term health issues.
"All of #Michigan and much of #Minnesota were under a hazardous #AirQualityAlert. In the Chicago area, air quality ranged from very unhealthy to hazardous.
"National Weather Service meteorologist Jake Petr said even if winds from the northwest clear skies as expected later this week, the smoky air could keep returning until the fires are out. That could take weeks or longer.
" 'Anytime we have something that could bring air from that region until the fires are over, it could conceivably dip back into the area,' Petr said.
"In #SaintPaulMN, the air was 'glowing yellow,' said Brent Williams, head of the soil, water and climate department at the University of Minnesota, who said the area 'could be looking at weeks to months of continued smoke and flare-ups off and on as the winds blow in different directions.'
"A study published this year found that long-term exposure to tiny particles from wildfire smoke contributed to an average of 24,100 deaths a year in the lower 48 states. Long-term exposure can make existing health problems worse and lead to a range of chronic and deadly health issues, including respiratory illness, cardiovascular and neurological diseases, and premature death."
https://apnews.com/article/canada-wildfires-smoke-us-ae4b2bd09a97919a081e26ede6a6d355
#CRBox #AirQuality #WildfireSmoke #AQI #HEPAFilters #CorsiRosenthalBox #AirCleaners #Masks #ParticulateMatter #RespiratorMasks #StayIndoors #ThanksBigOil
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Our Corsi-Rosenthal box is working well.
Overnight readings for air quality (based on AirNow.gov) in our community ranged from 480-680.
As of 7AM this morning, air quality is 455, which is considered Hazardous.
Inside our home, our air quality monitor says it's 54.
#AirQuality #AQI #CorsiRosenthalBox #Michigan #WildfireSmoke
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“Corsi-Rosenthal Box” sounds SO much more sci-fi than what it is.
It’s a clever and useful bit of engineering, but the name sounds like something Geordi would use to fix the Heisenberg Compensators, not a box fan duck-taped to some air filters.
https://engineering.ucdavis.edu/news/science-action-how-build-corsi-rosenthal-box
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How and When to Change the Filters in Your #CorsiRosenthalBox
by WCAHS September 18, 2023
"Corsi-Rosenthal Boxes provide excellent filtration of indoor air, especially for particles containing the virus that causes COVID-19 and wildfire smoke. After assembling and using your Corsi-Rosenthal Box, you may be wondering when and how to change the filters.
When to change the filters"The filters used in Corsi-Rosenthal Boxes generally have a lifespan between 1,000 to 4,000 hours of actual use time on the mid-flow setting. The range varies based on the size of the filter (one inch or two inches), frequency of use, and differences in the indoor environment in which it is being used. For example, it is best to change the filters nearer to 1,000 hours for a dusty indoor setting with carpeting and/or indoor pets. Changing the filters at approximately 4,000 hours is recommended for a relatively clean indoor environment without carpet.
"This filter change recommendation means that you could use a Corsi-Rosenthal Box on the mid-flow setting in an uncarpeted office, for example, for eight hours a day, five days per week and the filters would last for about 25 months. In contrast, a Corsi-Rosenthal Box used for six hours a day, five days a week in a breakroom adjacent to a workshop with people coming and going would need to have the filters changed after about eight months.
"Many people underestimate the life of the filter because they compare it to a filter in an HVAC system or assume that it needs to be changed because it looks dirty. The timeframe for changing the filters in a Corsi-Rosenthal Box is different from changing filters for an HVAC system because the filter width and the air speeds through the filters are different between an HVAC system and a Corsi-Rosenthal Box. In a Corsi-Rosenthal Box, discoloration means that the filter is working and does not necessarily mean that it is time to change the filter.
How to change the filters
- Switch the system off for at least six hours before removing the filters to limit exposure to newly deposited viruses.
- Take the box outside or to a large open area inside. Removing the filters may release a small amount of particles.
- It is recommended to wear a KN95 mask or better while changing the filters.
- Working one by one, cut each filter away from the fan and gently place it in a trash bag. Be careful to not shake or drop the filter as sudden movement can disperse dust and particles into the air.
- Follow this step again for all filters in your Corsi-Rosenthal Box. Change all filters the same day. Never use a combination of new and used filters in your Corsi-Rosenthal Box.
- Tie the bag tight and put it in the garbage. Wash your hands thoroughly with soap and water.
- Using new filters, you can now reassemble your Corsi-Rosenthal Box.Note: If the cardboard base is damaged or worn, you will need to replace the cardboard when replacing the filters in order to properly rebuild your Corsi-Rosenthal Box for maximum efficiency.
Summary
- The filters in Corsi-Rosenthal Boxes have a lifespan of 1,000 to 4,000 hours.
- Many people underestimate the lifespan of a filter.
- Although risk of exposure from discarding the filters is very low, precautions, such as wearing a KN95 mask or better, are recommended when changing filters.
- All filters should be changed at the same time."Source:
aghealth.ucdavis.edu/news/how-and-when-change-filters-your-corsi-rosenthal-box#CRBox #AirQuality #DIYAirFilters
#WildfireSmoke #AQI #HEPAFilters #CorsiRosenthalBox #AirCleaners -
Scientists Tested a DIY Air Cleaner – And It Beat Expensive Filters
By American Chemical Society, March 24, 2025
Excerpt: "As Corsi highlights during his presentation, he and his colleagues recently tested the durability and performance of #CRBoxes by installing units in four locations across the UC Davis campus. They ran them for 2,500 hours — the equivalent of two K-12 school years.
"The CR Box filters performed as well or better than comparable #HEPAFilters. The #DIY system was also more effective at clearing particles 1-3 micrometers in diameter than particles 0.35-1 micrometers. For a sense of scale, typical smoke particles are smaller than 1 micrometer, whereas dust and pollen are 0.5-3 micrometers.
"Although HEPA filters are more efficient at removing particles in a single pass than the HVAC filters used in the DIY system, Corsi explains, much more air passes through the CR Boxes, leading to more particles being removed from the air. Although the CR Boxes’ effectiveness diminished over time, they still performed better than new and more expensive HEPA air filters for the larger particle size and performed competitively with HEPA for smaller particles over the extended study period."
Read more:
https://scitechdaily.com/scientists-tested-a-diy-air-cleaner-and-it-beat-expensive-filters/#DIYAirCleaner #CorsiRosenthalBox #CorsiRosenthalBox #AirCleaners #AirFilters #DIY #WildfireSmoke
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How to Build a #CorsiRosenthalBox
Apr 15, 2022
"Richard L. Corsi, dean of the UC Davis College of Engineering, explains how to build a #CorsiRosenthal box. Dr. Corsi is an internationally recognized expert in the field of indoor air quality, with a specific interest in physical and chemical interactions between pollutants and indoor materials. His concept for a low-cost, accessible, and effective air cleaner, the Corsi-Rosenthal box, is now being used as an open-source do-it-yourself approach worldwide for reducing exposure to the #SARSCoV-2 virus, #WildfireSmoke and more."For step-by-step instructions, visit the website listed below.
Video:
https://www.youtube.com/watch?v=hIuH-2naozIWebsite:
https://engineering.ucdavis.edu/news/science-action-how-build-corsi-rosenthal-boxDoomsdaysCW
@DoomsdaysCW
How to Build a #CorsiRosenthalBoxApr 15, 2022
"Richard L. Corsi, dean of the UC Davis College of Engineering, explains how to build a #CorsiRosenthal box. Dr. Corsi is an internationally recognized expert in the field of indoor air quality, with a specific interest in physical and chemical interactions between pollutants and indoor materials. His concept for a low-cost, accessible, and effective air cleaner, the Corsi-Rosenthal box, is now being used as an open-source do-it-yourself approach worldwide for reducing exposure to the #SARSCoV-2 virus, #WildfireSmoke and more."For step-by-step instructions, visit the website listed below.
Video:
https://www.youtube.com/watch?v=hIuH-2naozIWebsite:
https://engineering.ucdavis.edu/news/science-action-how-build-corsi-rosenthal-box#CleanAir #DIY #DIYAirFilter #WildfireSmoke #WildfireHaze #AQI #AirQuality #WildfireSeason #Wildfires #MERVFilters #CorsiRosenthalBox #DIY #DIYAirFilters #OpenSource
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#DIY box fan filters – #CorsiRosenthal box
"Also known as a Corsi-Rosenthal box, this DIY method of building your own air filter with #MERV13 furnace filters and a box fan are an easy and cost-effective way to help clear indoor air from airborne virus particles, wildfire smoke, pollen, dust, and more!
If you can seal a box, you can build one (or 100!) of these!"
https://cleanaircrew.org/box-fan-filters/
#OpenSource #CleanAir #CleanAirCrew #WildfireSmoke #WildfireHaze #AQI #AirQuality #ClimateDiary #WildfireSeason #Wildfires
#HEPAFilters #CorsiRosenthalBox -
Written back when the #US #EPA cared about #CleanAir!
Do-It-Yourself #AirCleaners: Making Cleaner Air More Accessible
Published September 6, 2023
"Everyone should have the right to breathe clean air. However, during wildfires, the cost and availability of clean air technologies and reliable power sources can create challenges for people trying to protect their health from wildfire smoke. Recognizing these barriers, EPA and other health, environmental, and nonprofit organizations have provided instructions and materials for creating do-it-yourself (#DIY) air cleaners. DIY air cleaners are a more affordable and accessible alternative to commercial versions and can be constructed using a box fan and a high-efficiency home air filter. Securing the filter to the fan creates an effective, simple air cleaning system.
"This DIY solution filters out smoke particles and improves indoor air quality, but its use has raised key questions about the devices’ safety and effectiveness. EPA scientists and their colleagues are conducting research to answer these questions.
" 'This research was highly anticipated, particularly by EPA’s western regions, who have suffered from terrible wildfire smoke for years without the ability to recommend more affordable air filtering options to the public,' noted Meredith Bauer, Assistant Director of EPA Region 9’s Air and Radiation Division. 'It is important that we develop tools that allow everyone to protect themselves and their families when wildfire smoke is in the air.' "
Learn more [includes diagrams and instructions]:
https://www.epa.gov/sciencematters/do-it-yourself-air-cleaners-making-cleaner-air-more-accessibleArchived version:
https://archive.ph/6USXC#AirQuality #DIYAirFilters #WildfireSmoke #Northeast #WildfireHaze #AQI #AirQuality #ClimateDiary #WildfireSeason #Wildfires #HEPAFilters #CorsiRosenthalBox
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#AirQuality plummets in #Boston, #Toronto as thick wildfire smoke shrouds the sky for millions
Smoke from wildfires burning in Ontario have caused air quality to reach unhealthy levels across #Canada, and the northeastern and midwestern United States. And it could get worse before conditions improve.
By Brian Lada, Jul 15, 2026
Excerpt: "Toronto had some of the worst air quality in North America on Wednesday morning, reaching 'very unhealthy' levels with an AQI of 220. 'Health effects will be immediately felt by sensitive groups and should avoid outdoor activity,' Plume Labs said. 'Healthy individuals are likely to experience difficulty breathing and throat irritation.'
"In Boston, air quality reached 'unhealthy' conditions on Wednesday morning with an AQI of 147. Little improvement is expected in the city into Thursday. "
#WildfireSmoke #Northeast #WildfireHaze #Canada #NewEngland #AQI #AirQuality #ClimateDiary #WildfireSeason #Wildfires
#HEPAFilters #CorsiRosenthalBox -
This is what we do about it and IME it works well. After 5 years, I'm surprised by the number of folks I know that refuse to give it a try. https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box #corsiRosenthalBox #airquality
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I built a Corsi-Rosenthal Box! Here are my tips on building a Corsi-Rosenthal Box air cleaner for an airborne pandemic like COVID-19.
#HowToBuild #CorsiRosenthalBox #tips #IAQ #AirPurifier #AirFilter #DIY
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Bah. I had some bids in an auction for some HEPA grade 400cfm air filters, with an RRP of £3,995. I was hoping to pay about £25 each for two of them, but after a few days of being in the lead I got pipped to the post while on a work call.
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I built a Corsi-Rosenthal Box! Here are my tips on building a Corsi-Rosenthal Box air cleaner for an airborne pandemic like COVID-19.
#HowToBuild #CorsiRosenthalBox #tips #IAQ #AirPurifier #AirFilter #DIY
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Estudio italiano demuestra que un sistema de ventilación eficiente en el escenario escolar puede reducir los casos de #COVID19 en la escuela en más de un 80%.
#CleanTheAir #CovidIsAirborne #CorsiRosenthalBox
La divulgación de los estudios de esta índole es esencial para los sistemas educativos y la protección y cuidado preventivo de la salud de nuestros niños.
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#Yale #YaleClimateConnections #airquality #IndoorAir #co2 #ParticulateMatter #CorsiRosenthalBox #HEPA #filter
Jeff Masters 22.Dec.2025, YCC
Improving indoor air quality might save your life
https://yaleclimateconnections.org/2025/12/improving-indoor-air-quality-might-save-your-life/
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RE: https://mastodon.social/@paulbeckwith/115771889007772777
#FYI #PaulBeckwith video lecture and literature review
#airquality #IndoorAir #co2 #ParticulateMatter #CorsiRosenthalBox #HEPA #filterVentilate!
(Pro tip: Visit Germany, experts of Lüften =D)