How to make your own at-home fan filter

SEATTLE — Editor’s note: The video above and story below were originally published in August 2018.

“I’m sensitive to smoke, particulate matter in the air and it just sucks,” said Mike Bjork.

Bjork, a civil engineer, rigged a homemade box fan filter a month ago in his Wallingford apartment before the smoke blew in.

He changed the filter on Monday and took a picture showing how much gunk had accumulated in a month's time.

“The proof is there. You can see it. It’s incredible,” Bjork added.

With the air so thick outside, KIRO 7 asked the Puget Sound Clean Air Agency about DIY filter fans. Air quality forecaster Erik Saganic says they do work at filtering particles.

“We start to see benefits quickly, within 15 minutes,” Saganic said.

Saganic showed KIRO 7 how easy it is to make your own. All you need is a box fan and a filter rated Merv 13 or higher.

“What happens is you have these arrows on the filter, you want to make sure you follow the flow. Because if the fan is blowing this way, you want to put it on the back and sucks it up by itself,” Saganic explained. “And that's all you need to do, enjoy clean air.”

He even took out a particle counter to show how it works.

It started out at 13,000 particles which is unhealthy and goes to show how smoky air still makes its way indoors. Three minutes later, the number of particles went down by almost half.

Meanwhile, Bjork showed KIRO 7 how he pushes his filter fan up against an open window so he can still have fresh air circulate in his bedroom. He uses cardboard and pushes his desk to make a seal.

Though Saganic doesn’t recommend keeping any windows open while the filter fan is running, Bjork says, without AC in his apartment, he has no choice.

“I’ve been breathing easier the last few nights versus going out and walking around. It’s helped,” Bjork added.