Step 1: Choose a Design for your Cleaner

Pick one of these simple designs for your filter:

• Single Filter Design: Tape or attach one filter flat to the back of the fan. The Department of Ecology has made a simple video showing this method.
• Triangle Design: Use two filters taped with cardboard to form a triangle around the fan (video example from Confederated Tribes of the Colville Reservation)
• Cube Design: Use 4 or 5 filters to form a cube around the fan for better filtration (example)

Step 2: Gather Materials

• A box fan (made in 2012 or later) with a UL or ETL safety label.
• One or more high-efficiency air filters (MERV 13 or higher), the same size as your fan. Tip: you can buy air filters, which are made for HVAC units and furnaces, at most hardware stores, or you can order packs of them in many places online. It's good to purchase air filters in advance, since they can sell out during smoky weather.
• Cardboard, and a bungee cord, or tape to secure your filter to the fan. 

Step 3: Assemble Your Filter

• Attach the filter(s) to the intake side of the fan (where air enters)
• Make sure the arrow on the filter points in the same direction as air flow through the fan
• Seal the edges well with tape for best results
• Add a shroud (covering the corners of the fan’s front) if desired for better airflow

Step 4: Run the filter in Your Clean Air Room

• Place the filter in the room where you need cleaner air. In a smaller space, air will travel through the filter over and over capturing more particles each time.
• Run the fan on the highest setting as often as possible

Safety Tips

• Use only newer fans (2012+)—older ones can be a fire risk
• Don’t leave the fan on unattended or while sleeping if it’s an older model
• Avoid using extension cords or damaged fans
• Keep children supervised around the fan to keep them safe

Maintenance

• Replace filters when dirty or if they start to smell like smoke
• During heavy smoke events (when the air is 200 AQI or higher) filters might need to be replaced every few days, so have extra on hand.