Figuring out which technology to use in schools should be simple, but it hasn’t always been easy, especially because of the influence of private companies.
After getting deluged by calls from sales representatives peddling various devices, Howard Taras, a medical consultant with the San Diego Unified School District, turned to scientists at the University of California at San Diego rather than take the companies’ claims at face value. He told me that Kimberly Prather, a professor of atmospheric chemistry at the university, where Taras is a faculty member, advised the school district to install MERV-13 filters in its centralized HVAC system and to add portable cleaners with HEPA filters to rooms where supplementation was needed. The district followed her advice, Taras told me. He said that many other school districts in the area, outmatched by the sales representatives, succumbed to the pitches and installed systems that did less.
Some school districts around the country, guided by scientists at nearby universities, constructed D.I.Y. portable filters using box fans, duct tape and MERV-13-rated filters, all of which can be purchased at hardware stores. These devices are called Corsi-Rosenthal boxes, after the engineers who designed them early in the pandemic: Richard Corsi, the dean of engineering at the University of California, Davis, and Jim Rosenthal. Multiple peer-reviewed studies show that the boxes can work just as well as, if not better than, many commercial HEPA filters, often at roughly a third of the cost.
Undergraduate students at the University of Connecticut built C-R boxes for less than $65 per unit, Marina Creed and Kristina Wagstrom, researchers at the university, told me. And in the Red Rock school district in Arizona, middle schoolers built the boxes, said Megan Jehn, an infectious disease epidemiologist at Arizona State University.
In contrast, New York City public schools, in addition to installing MERV-13 filters in HVAC systems and improving ventilation, bought more than 160,000 devices made by a company called Intellipure that were sold by a company called Delos Living. Gothamist reported that Delos Living paid hundreds of thousands of dollars for a firm to lobby city officials to buy the devices.