Fight fire with filtration!

Air getting nasty? Use this DIY air filter during a wildfire or other event when the Air Quality Index (AQI) is hazardous to create a room in your home with better air quality.

Box fan, 20″
Air filter, MERV 13 grade, nominal size 20″×20″×1″
actual size 19½”×19½”×¾”
Elastic straps, 50% stretch, 1″ wide, about 40″ long (2) such as Amazon B07TBP5589
Sewing machine and thread

Illustrations by Rachel “McCrafty” Sadd

1. Sew the straps.
Loop the elastic and sew the ends together with a zig-zag stitch for strength. Make two loops about 18″ long.

2. Put the filter on the fan.
Place the MERV 13 filter on the back of the fan. Make sure the arrow markings on the filter are pointed toward the fan.

3. Strap it down.
Use the two elastic straps to hold the filter securely to the fan, one on each side. That’s it!

Tips for Your Clean Air Room
Use painter’s tape to seal around windows and door frames in older homes, and use a rolled-up towel or sheet at the bottom of doors. Inside your “clean air” room, don’t smoke or use candles, stoves, aerosol sprays, or vacuum cleaners.

DIY Kits
Wildfire smoke has had serious impacts in California and the West for the past several years, with under-resourced folks being the most severely affected. The Ace Makerspace community has partnered with Homies Empowerment to distribute 500 DIY air filter kits in Oakland to help manage poor air quality indoors. Learn more at and contribute at, or text “AIR4OAKLAND” to 44-321.

Photos by Sam Freeman