Instructions to build a version of the DIY air cleaner are below in an image or download the PDF.
With cost and resource constraints in mind, our team developed an air cleaner that uses low-cost, common household fabrics as reusable filters that are then affixed to a box fan. Our solution, which has been shown to be effective during both field and environmental chamber testing, is akin to a “windsock”—this windsock creates a large surface area of filter material, enabling the box fan to move high flowrates of air through the fabric.
We've tested various iterations of this design and its effectiveness - you can find details in this study in the journal Science and Technology of the Built Environment. In short, the design shown here can realize a smoke PM2.5 CADR of ~100 cfm. This is strong enough to meaningfully improve air quality in a small volume of your home, like a bedroom with the doors and windows closed.
We call the air cleaner "the Cocoon", because it kind of looks like a cocoon and it's more concise than "the long fabric tube air cleaner you built from stuff you already had". But the result is in fact a long tube of fabric that can remove particulate matter with effectiveness comparable to some lower-cost commercial air cleaners (~100 cfm CADR). The idea for this current design is that this could help by offering a very low-cost stopgap measure until more effective air cleaning can be implemented.
Some other resources on the Cocoon to check out:
A story by NPR on building a Cocoon in LA during the 2025 wildfires
The US EPA press release on the design being selected a Phase II winner of the Cleaner Indoor Air During Wildfires Challenge
PSU coverage of the Cocoon