VIDEO: Build a DIY home air purifier for about $20

SEATTLE -- Smoke-filled, unhealthy air is back in Western Washington and will be sticking around for several days.

To keep the air inside your home healthy, you could buy a High-Efficiency Particulate Air (HEPA) purifier for $800. Or you could build one yourself for about $20 using a fan and a furnace filter.

Meteorologist Katie Boer explains how researchers from the University of Michigan came up with this easy life hack that can reduce 90% allergens inside your home.