Seeing Science: Breathe Easier

Wildfires are increasing in size and intensity across the Western United States and with them come a new seasonal threat: smoke. The hazardous gases and particulate matter set aloft by large fires pose health risks, particularly for those with cardiovascular and pulmonary diseases. But how can you protect yourself when commercial air filters and cleaners are in short supply? A team of three Portland State mechanical and materials engineering students and alumni, advised by faculty member Elliott Gall, came up with a solution that won $10,000 and the Environmental Protection Agency’s 2021 Cleaner Indoor Air During Wildfires Challenge. Their device—dubbed “the Cocoon”—uses materials found around the house or easily purchased for less than $45. “The design was intentionally simple,” said student Warren Gunn. “We wanted it to be low-cost, simple to make and use, and accessible to everyone.”

Here are the elements they used to assemble the Cocoon:

• Box Fan: A standard 20-inch box fan does the trick.
• Fastener: During the competition, Matthew Moore ’20 and students Gunn and Brett Stinson used a ratchet strap (available from hardware stores) to tightly seal the fabric’s edge to the fan. They’ve also had success in the lab using daisy-chained zip-ties.
• Washable fabric tube: They created a 4-foot-long tube with a 20-inch diameter by sewing together a length of cotton batting (with help from Gall’s mother-in-law). They’re testing a range of fabrics now to see if some might capture particulates even more effectively.
• Rubber bands: The team folded the far end and secured it with rubber bands to create the closed part of the “sock.”

Competition field testing showed the Cocoon accomplished a clean air delivery rate of 125 cubic feet per minute of particle-free air, equivalent or greater to many commercially available room-scale air cleaners.