Corsi–Rosenthal Box

The Corsi–Rosenthal Box is a do-it-yourself air purifier built from four or five HVAC particulate filters forming a cube, with a box fan drawing air through them. A 2022 UC Davis study found the five-filter design's clean air delivery rate was between 600 and 850 cubic feet per minute, depending on fan speed, at roughly one-tenth the cost of commercial air purifiers. Engineers Richard Corsi and Jim Rosenthal created the design during the COVID-19 pandemic to reduce airborne viral particles indoors. The units can be assembled in about 15 minutes and cost between US$50 and $150 in materials.