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How to make a DIY air filter out of a box fan to protect against covid

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Covid is not going to go away in the foreseeable future. Vaccinations, rapid testing, and proper masking are important ways to protect against getting sick and spreading the virus.

So is better indoor air quality.

As we enter Year 4 of this pandemic, with new variants emerging, I want to be able to get together more often — and safely. with family and friends. I want to host regular sour cherry pie dinners, like the one I’ve made for other health reporters after we’ve worked remotely — virtually 24 hours a day — for over a year.

And I want to feel safe at work, where, like most reporters, I don’t have my own office. I can’t just close the door to keep germs away from colleagues. Or open the windows for fresh air.

So, as someone who likes to take control of seemingly uncontrollable situations, I decided to build my own DIY portable air filter.

Generating internal cleaning air at home and at work reduces everyone’s risk of becoming ill from airborne pathogens such as those that cause covid-19 and the flu.

While I’m pretty good at following recipes, I’m not very confident in my ability to create things from scratch. Not even with Legos when my son was little. Forget Ikea furniture.

But I decided to give this Corsi-Rosenthal Box a try. because we would be reuniting with many loved ones heading into the new year.

The Corsi-Rosenthal Box is named after its two inventors, who were looking for an economical way to build something that would perform the same functions as more expensive air purifying devices. They came up with the idea in August 2020, five months after the coronavirus pandemic.

Richard Corsi, dean of the College of Engineering at the University of California at Davis, and Jim Rosenthal, CEO of Tex-Air Filters, teamed up to create the inexpensive, easy-to-assemble air filter using materials found in hardware stores or online. The box uses four common household air filters on the sides – the kind you use in a home HVAC system – a 20-inch fan on top, cardboard, scissors and tape to hold it all together.

It is important to get the right kind of filters. Filters must have a MERV-13 rating, which refers to the filter’s ability to capture particles of a specific size.

When the fan is turned on, air is drawn through the four sides of the box. Filters trap contaminated particles, allowing clean air to flow into the middle of the box and be pushed back into the room through the fan. The fan only needs to be plugged into a normal electrical outlet. The boxes not only reduce the spread of pathogens such as the coronavirus, but also reduce other particles such as those generated by wildfires, as well as dust and pollen.

The box removes all kinds of other pollutants, such as “allergens, tiny particles created by chemical reactions to ozone, or cleaning chemicals,” said Don Milton, professor of environmental and occupational health at the University of Maryland School of Public Health, who created the name of the box.

In a small office — 10 feet by 10 feet by 10 feet — a box could reasonably achieve a clean air delivery rate of around 300 to 400 cubic feet per minute, according to Rosenthal. In other words, with the fan down, about a third of the air passes through the device every minute, or the equivalent of all the air in that office in about three minutes. How often the filters need to be replaced will depend on usage.

Of course, if people can afford a good HEPA air filter, go ahead and buy one, Rosenthal said. “Just make sure it’s a HEPA and doesn’t have ‘extra’ features like ionizers,” he says. told me.

But a good HEPA cleaner costs between $300 and $600.

Supplies to make a filter box cost me $127: $30 for the 20-inch box fan, about $90 for a pack of four Merv-13 filters (20 x 20 x 1), and $7 for a large roll of duct tape. (Note to the accountant who approves my expenses: I bought enough supplies for two boxes, one to practice at home so I don’t look like an idiot building one for the first time in this Washington Post video.)

Scientists at the National Institute for Occupational Safety and Health tested the effectiveness of DIY air filtration units, including the Corsi-Rosenthal Box, in reducing exposure to respiratory aerosols, and their study found that the DIY units “reduced exposure to aerosols by up to 73% depending on design, filter thickness and fan airflow.”

Another recent study, by Brown University and the Silent Spring Institute, a Massachusetts nonprofit that conducts breast cancer research, found that the boxes significantly lowered the concentration of indoor air pollutants. The Corsi-Rosenthal boxes were installed in 17 rooms on the Brown campus last year to fight COVID-19 and to study the boxes’ effectiveness in removing particulate matter from the air. The researchers collected samples of the concentration of indoor pollutants in the rooms from October to November 2021, before the pits were installed, and from February to March 2022, when the pits were in operation.

Results showed that the boxes reduced a type of synthetic chemical known as PFAS by 40 to 60 percent. The chemical is used in products such as cleaning products, textiles and wire insulation. Phthalates, a group of pollutants commonly found in building materials and personal care products, were reduced by 30 to 60 percent.

The boxes are so popular that people have posted photos on social media showing off their creations. decorated with Halloween cat ears, or suspended from chandeliers in fluorescent colors, and even incorporating lighting as part of the scenography of a music production.

AN 10th grade robotics enthusiast in Mississauga, Ontario, created a public step by step guide in English, French and Spanish and made 122 boxes for people in the Toronto area. The student, Shiven Taneja, won second place in a award that Corsi created last year to honor individuals who help protect others.

School systems in the US, Canada and Indonesia built them for classrooms. Several major universities, including the University of Connecticut, Arizona State University and the University of California at San Diego and Davis have also built them, according to Corsi, who received 600 applications when he asked people to send in photos of boxes they built in the year. past. .

At the University of Maryland, sophomore Ella McCloskey is using the boxes to teach students about the importance of air quality and ways to minimize the spread of disease. The university distributed more than 100 free boxes to barbershops, funeral homes and churches in suburban Maryland.

Some students took the boxes home to their families. Others found them too big for tiny dorms and put them in student lounges where they study and socialize.

I was nervous about making this box because I’m not a helpful person. The hardest part was making sure the masking tape didn’t stick to itself. The most time-consuming part was cutting the cardboard — use the box the fan came in — to make the base and a cover that goes over the top of the fan to improve efficiency. It took me about two hours as I kept checking the videos online to make sure I was doing everything correctly.

Finishing it gave me great satisfaction and comfort for the next encounters. My niece, who is undergoing cancer treatment, gave a thumbs up emoji when I sent a picture of the finished box. (She texted back to say that a close friend of hers also built one and takes it to my niece’s house every time she visits.) Other family members were baffled when I placed the box in the dining room during dinner. of Christmas Eve.

At work, the box blocks foot traffic near my desk. But the colleagues sitting next to me are grateful for the cleaner air. Fan hum also drowns out the loudspeakers.

An editor saw the box and wanted to make one for her. Of course, I immediately offered to build her a Senior editor if she bought the supplies.

PS Making pie crust is more difficult.