Community Outreach Specialist, Yajaira Ramírez Sigala, delivers Corsi-Rosenthal boxes to community partners.
Community Outreach Specialist, Yajaira Ramírez Sigala, delivers Corsi-Rosenthal boxes to community partners. Photo credit: Heather Riden

The Corsi-Rosenthal Box: DIY Box Fan Air Filter for COVID-19 and Wildfire Smoke

En español

The Corsi-Rosenthal Box is a homemade air cleaning system that  can reduce indoor exposure to airborne particles that contain the virus that causes COVID-19. It can also reduce the levels of other particles in the air, such as dust or wildfire smoke. These filters are being used in homes and schools, and can be an affordable temporary solution for a variety of agricultural settings, including office spaces and break rooms.* While they are not HEPA air cleaners, recent testing at UC Davis and elsewhere has shown that the box can be more effective than HEPA air cleaners.  

Corsi-Rosenthal Air Filter Box
Photo by CC-BY al.hu.

Materials

The Corsi-Rosenthal Box is made of a simple box fan, which should be oriented upward so that it is blowing air toward the ceiling. The fan is connected to a “box,” which is made of four MERV-13 filters and a cardboard base attached with duct tape.

How long can the Corsi-Rosenthal Box be used? 

The lifetime depends on how long it is used each day and how dusty the environment is where it is placed. A Corsi-Rosenthal Box used several hours per day will last longer than one running continuously. 

In many cases, a system operating on low for a portion of a day may last as long as 5 to 6 months. If operated on higher flows and longer durations in a dusty location, the system might only last a month or two.

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* The Corsi-Rosenthal box is not a substitute for high-quality masks. Use of this, or any other air cleaner should be a supplement not a substitute for wearing a mask. Use of a high-quality mask, particularly N95 and KN95, is the most effective way to protect your respiratory system.