Corsi–Rosenthal Box

COVID-19 is primarily transmitted through the air, and superspreading events are generally associated with indoor gatherings where the virus is allowed to accumulate in the air. In response, and on recommendations of infectious disease researchers, engineers began to consider how improved ventilation may reduce risk of infection by reducing the amount of virus in indoor air. but there had never been an attempt to apply such a design to reduce the airborne load of viruses. In August 2020, Richard Corsi, an environmental engineer and the incoming Dean of Engineering at the University of California, Davis, spoke with Wired reporter Adam Rogers about an idea he had for combining multiple store-bought filters with a box fan to improve the efficiency of home-made air filter designs. Corsi tweeted that Rosenthal really deserved the credit, and that he preferred the name Corsi–Rosenthal Box. == Design ==

The Corsi–Rosenthal Box design consists of four The units can be assembled in around 15 minutes, last for months, and cost between US$50 and $150 in materials. == Efficacy ==

Airborne virus particulates range in size from 1 to 50 micrometres (μm). Rosenthal used his HVAC company's testing equipment to run an informal test of the design, in which he found that around 60% of 1 μm particles were removed by the system, and almost 90% of 10 μm particles were removed. Based on the cost of their design, this output amounted to $0.08 per CADR, or roughly ten times cheaper than commercial air purifiers, with quieter operation. Researchers have expanded studies of these citizen science filtration units to evaluate their efficacy for reducing the levels of airborne volatile chemicals (VOCs); Dodson and colleagues showed the units reduced PFAS and phthalates. == Safety ==

A 2021 study by Underwriters Laboratories found that attaching filters to a box fan in a do-it-yourself configuration did not present a fire hazard from increased heating of the fan motor windings. == Uses ==

in 2022 Corsi–Rosenthal Boxes have been used in schools to reduce risk of COVID-19 transmission, sometimes also functioning as a STEM lesson with students learning about the science of air filtration and constructing the boxes themselves. At the university level, engineering students are also running tests on the units. Homeless shelters and daycare facilities have also used Corsi–Rosenthal Boxes to mitigate COVID risk. Corsi–Rosenthal Boxes have also seen use in the 2023 wildfire season in North America, especially as smoke pollution caused hazardous air quality conditions across heavily populated areas in the Eastern United States. == See also ==