A high-quality HEPA air purifier can eliminate nearly all the smoke, dust or allergen particles from the air in a room—but a $30 contraption can eliminate about 90 percent. It’s worth a try if you need to clean your indoor air on the cheap.
To build the purifier, you just need:
A 20-inch box fan (about $15-20 new, or perhaps you have one lying around)
A 20-by-20 inch furnace filter that’s rated MERV-13, FPR 10, or MPR 1500-1900 (also about $15-20)
Tape to attach the two
In this video, Jeffrey Terrell, director of the University of Michigan Health System’s Michigan Sinus Center, demonstrates how the DIY purifier compares to an $800 factory model. It’s not quite as good, but a lot better than nothing.
Once you build a system like this, you can put it in a bedroom or wherever you need your air to be cleanest. This type of filter will capture particles as small as 1/3 of a micron in size, which is good enough for many allergens and a lot of the particles from wildfire smoke. No filter can protect against carbon monoxide or irritating gases, though, so make sure you’re protecting yourself in every way possible.