The engineers at Ford’s Project Apollo team have found a cheap way to help mitigate the risks of Covid-19 transmission in indoor spaces. The “Scrappy Filtration” system just got the seal of approval in the scientific journal Physics of Fluids. The air purifier uses just a few parts and has been designed as a low-cost way to help people who need to be indoors, like school children. The system requires just a 20-inch box fan, a filter (one that is 4-inches thick and has a minimum efficiency reporting value of 13), and some cardboard. It’s a kit that, by design, can be assembled cheaply and easily. To ensure that underserved communities can make use of the air filter, though, Ford is donating 20,000 of them to school districts in Los Angeles, New York, and throughout southwest Michigan.