DIY Box Fan Air Purifier

Cheapest and incredibly effective air purifier. If you have wildfire smoke it can clear out a 100sqft room in under 10 minutes.

Supplies

1 box fan
1 20x20 air filter
Duct tape

Step 1: Get a Box Fan and a Filter

Shouldn't cost more than $40. You can get a box fan for under $20 online and a 6 pack of 20x20x1 air filters is currently $30 on Amazon. You just need one filter but with really bad air you're going to want to replace the filters up to once a week.

Step 2: Duct Tape Filter to Fan

It's really that simple. Just duct tape it on. The filter will have an arrow along the edge to show which way the air flow is supposed to go. So many sure that arrow points with the flow of the fan. Based on your fan you may have to tape to front or back. Either will work as long as you have the filter pointing the correct way. You'll know it's working as you see the filter getting dirty over time!

Step 3: You're Done! Turn It On!

We live in an area that can get really bad wildfire smoke days. A box fan filter can clear out a small closed room from 100+ aqi down to good below 20 levels in 10 minutes. For our house on really bad air days we'll have 3 of these running throughout the house to keep the air clean.