Homemade air purifiers can filter air faster, making them an affordable alternative to more expensive commercial products.

and a box fan to draw air through the filters and toward the ceiling. Because the components are relatively inexpensive, the CR Box is a fraction of the cost of a HEPA air filter. As Corsi highlights ...

Tests conducted over 2,500 hours indicated that the CR Box worked as well as or even better than some of the most expensive HEPA filters.