Corsi-Rosenthal (CR) Box
The Corsi-Rosenthal (CR) box is a cost-effective, do-it-yourself air filter used to increase particle removal in indoor spaces. The CR box was developed in 2020 by Jim Rosenthal in response to COVID-19 and builds on Richard Corsi’s idea of using multiple filters and a box fan to improve the efficiency of homemade air filter designs. Composed of 4 HVAC filters, 1 box fan, duct tape, and cardboard, the CR box is an accessible solution that can be built using items found in most stores.
CR boxes have proven to efficiently filter out microscopic particles in the air by increasing airflow in enclosed spaces. Communities with a higher risk for wildfires are particularly vulnerable to air pollution that travels to indoor spaces, which is worsened by congestion in public areas without proper air circulation. Because of their low cost, CR boxes can be a swift solution in response to wildfire smoke.
Interested in building your own CR box? Check out the tutorial linked below for steps on how to build one:
How to Build a CR Box