LAS CRUCES – When Heath Haussamen contracted COVID-19 in August 2021 he thought he had a relatively minor case. Flu-like symptoms were the worse it got for him. But for over a year he suffered from fatigue, breathlessness and mental fog.

Haussamen, a longtime Las Cruces resident, said his family followed masking and social distance measures, but his and his girlfriend’s children were in a split living situation: His daughter spends half her time at her mother’s home while the other child does the same.

Ultimately, this negated the idea of creating COVID “bubbles” with only close family.

“Both of them are going back and forth to other houses and we realized pretty quickly that you can mask in places like stores and it’s irrelevant if kids are going back and forth and can bring (the virus) into your house,” Haussamen said.

The family started looking for solutions that better fit their situation and landed on air filters. The idea was to bring a machine into the home which turns over air in a room more often than without, filtering viruses, dirt and other particles out of the air leaving it healthier to breath.

Commercial air filters are available for homes, businesses and schools, but can get expensive. Through social media, Haussamen came across a do-it-yourself option – the Corsi–Rosenthal Box.

What are box-fan air filters?

The Corsi-Rosenthal Box is a simple air filter that is made out of five furnace filters and a box fan. The filters form five sides of the box while the fan itself is added as the last side. Rather than pushing air out to cool a room, the fan is turned inward to suck air in and through the filters.

Any particulate matter in the air is caught on the filters and removed from the air in the room.

Environmental engineer Richard Corsi and Tex-Air Filters CEO Jim Rosenthal came up with the concept in late 2020, about six months after the COVID-19 pandemic led to shutdowns and stay-at-home orders across the country.

Such boxes have been used before, particularly in areas affected by wildfires. However, this design was perfected during the COVID-19 pandemic.

The box requires five MERV13 furnace filters, a box fan, cardboard and duct tape. All materials are available at local hardware stores. The project can cost up to $100 compared to commercial air purifiers which can cost hundreds of dollars. Filters should then be changed every six months.

How reliable are homemade box fan air filters?

Research is still ongoing on the efficacy and efficiency of the Corsi-Rosenthal box, particularly related to long-term use. However, the Centers for Disease Control and Prevention released a study Feb. 3, 2023, in which experts tested the box design, along with a second design developed by Ford Motor Company and Lasko Products, in a mock classroom.

Researchers found use of a DIY air filtration unit reduced aerosol exposure up to 73% – unit design, filter thickness and airflow are factors that altered the amount of exposure.

Megan Jehn, epidemiologist and professor in the School of Human Evolution and Social Change at Arizona State University, said there are other scientists in the field who have compared the Corsi-Rosenthal box to commercial HEPA filters because of the volume of air the DIY boxes are able to draw through the filters.

Jehn said these filters are able to turn over the air in a given space three to six times per hour. Air change rate quantifies the number of times in an hour the volume of air in a room is replaced or recirculated. This is important to maintain healthy breathable air indoors.

“For health reasons, we would like to be able to turn over the volume of air in a room three to six times every hour,” Jehn said. “Most schools right now that we have seen are probably in the .5 to maybe 1.5 (air changes per hour) range, so still pretty far away from meeting those recommended health-based standards.”

For comparison, hospitals maintain a standard of 12 to 15 or more air changes per hour, depending on the individual hospital.

Jehn said researchers were able to put air quality sensors in a classroom and show that the DIY filters reduce the volume of particles in the air based on size.

She said many schools internationally are showing interest in the box filters due to its ease of use and cost, but also the opportunity it gives students to learn about their environment.

“I like it because kids can do it themselves, right? Fifth graders can build these, third graders can build them. They can take ownership of it,” Jehn said. “It’s a STEM activity.”

Jehn’s research group at ASU recently worked with Red Rock Elementary in Arizona on a school-wide initiative where students built a Corsi-Rosenthal box for every classroom.

“They really took ownership of their own box and their classroom. And then you know, in the fall, when the new kids come in, that's the first thing they'll do is they'll get to build and decorate their box, and it'll be for their specific classroom," Jehn said. "And then they're integrating into the curriculum. So kids are learning about decision making and health and topics like environmental justice and engineering."

Jehn said her group has provided 40 boxes to hundreds of schools and others are interested in integrating the project into class curriculum, including organizations outside of schools such as Girl Scout Troops and nonprofit organizations.

ASU is also working with schools by installing sensors for research documenting the longer term health impact boxes have, cost analysis and environmental impacts the boxes have on landfills through changing filters.

While Las Cruces Public Schools has not embraced the DIY box filters as a district-wide project, one middle school has. Mesilla Valley Leadership Academy, an experiential middle school within LCPD, introduced the boxes at the start of the 2022-2023 school year.

Lily Haussamen, 11, Heath Haussamen’s daughter, was homeschooled during the pandemic and saw her father contract the virus. The family built several boxes for their home and friends, and worked through the trials and errors of the project.

Before she started sixth grade at MVLA, the father-daughter pair came up with the idea of building the boxes at school. They presented the idea to the school principal and were given the go ahead.

“I didn't do anything after that except buy the materials and drop them off at school. Lily led her teacher and her class, she talked them through how to build them,” Heath Haussamen said. “Lily really took it and ran with it.”

MVLA students have what is called My Time – an elective period where students get to choose from a handful of class options ranging from science-related topics to music to art. Tracie Mikesell teaches a class called Sustainable Hippie Hive and decided to integrate the box filters into her first My Time of the semester.

"We talk about recycling, we take care of the fish in the front, we weed," Mikesell said. "We talk about different things that affect the environment like fires … there being too much carbon in the atmosphere and how in New Mexico we really need to be conscious of our water usage."

About nine students took the four-week class and built box filters the first week of school.

"Despite all the science we have behind COVID now and things like that, a lot of people still get hurt from it and these (filters) help stop that because they stop the spread a lot," Lily Haussamen said. "So just helps keep people a little safer."

Reese Grandjean, 12, said she has allergies and thought the boxes would be a good idea to help filter pollen out of the air. She and Alexander Sheridan, 11, said the boxes were not difficult to make, just time consuming.

"There was a really big learning curve where you were learning how to put the tape on exactly and if you didn't align the air filters, they wouldn't work. Just anything, slight thing ... you would have to restart," Grandjean said.

Boxes are in just about every room at the school, including the cafeteria and front office. The school is also now including replacement supplies in its budget.

The first filter replacement for the school’s boxes is coming up, and Mikesell said her students are hypothesizing which rooms will have the dirtiest filters. MVLA is not collecting data on what impact the boxes have overall on air quality or student health.

"I think that it's amazing what middle schoolers can do when you give them the freedom and that they feel like they have a purpose," Mikesell said. "They've really felt like they were making a contribution to the school and so they were very proud of their filters and they are starting to care more about the environment and they start talking about it more. And so those are the things that I think really motivate them."

While the box filters do not keep people from contracting COVID-19 or other viruses, they do reduce the probability people will come into contact with the virus particles. More research is needed to determine whether this solution will have an impact on reductions in asthma and fewer school absences due to respiratory illness.

Leah Romero is the trending reporter at the Las Cruces Sun-News and can be reached at 575-418-3442, LRomero@lcsun-news.com or @rromero_leah on Twitter.

This story was produced in partnership with KRWG as part of the Southern New Mexico Journalism Collaborative, which is covering the COVID-19 rebuild with a solutions-based lens. As a disclosure, Diana Alba Soular, the SNMJC editor involved in this project, is a friend and former colleague of Heath Haussamen, who was interviewed for the story.