DIY Air Cleaner to Reduce Wildfire Smoke Indoors Infographics

Learn the steps you can take to create a do-it-yourself (DIY) air cleaner in an emergency, if portable air cleaners are not available or affordable. Two designs are available a basic design and a beyond the basics design.

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On this page:

• Beyond the Basic Design
• How to Make a DIY Air Cleaner Shroud

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Beyond the Basic Design

• Download the Beyond the Basics Design infographic (pdf) (1,751 KB).
• Text version of the Beyond the Basics Design infographic.

Text Version of the Beyond the Basic Design Infographic

DIY Air Cleaner to Reduce Wildfire Smoke Indoors: Beyond the Basic Design

Good

Basic Supplies:

• 20" x 20" x 1" or 4" air filter
  • Suggested rating: MERV 13
• 20" x 20" box fan
  • Only use certified fans with UL or ETL markings (2012 model or newer)
• 2p" x 20" cardboard shroud
  • cutout the size of the fan blades
• clamps or Duct Tape or Bungee Cord 

Better

Additional Supplies: 

• Two - MERV 13 air filters
• Triangle cardboard cutout for base on top

Best

Additional Supplies:

• Four or five - MERV 13 air filters
• If using five filter design, use left supports (e.g., blocks) to allow airflow through bottom.

Ways to Improve Effectiveness:

• Add a cardboard shroud
  • No cost improvement
• Use thicker filters
  • 4" rather than 1" MERV 13 filters
• Use multiple filters 
  • 2-5 filter design

Key Reminders

• Only use certified fans with UL or FTL markings
  • 2012 model or newer
• Keep extra filters on hand
• Replace filters when dirty

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How to Make a DIY Air Cleaner Shroud Infographic

• Download the How to Make a DIY Air Cleaner Shroud Infographic (jpg)
• Text version of the How to Make a DIY Air Cleaner Shroud Infographic.

Text version of the How to Make a DIY Air Cleaner Shroud Infographic

How to Make a DIY Air Cleaner Shroud

Adding a shroud to a do-it-yourself air cleaner can significantly improve its filtration performance.

Materials: Scissors, string, a pencil or pen, a box fan, sturdy cardboard (like the box the fan came in), and duct tape. Be sure the fan is unplugged. Select a box fan manufactured in or after 2012.

1. Tie a string to a pen or pencil.
2. Holding the pencil at the edge of the fan blade, extend the string to the center of the fan, and cut the string at that point.
3. Draw an ‘X’ connecting opposite corners of the cardboard. Hold the string at the center (intersection) and draw a circle.
4. Using the drawing as a guide, cut out the circle from the center of the cardboard.
5. Attach the shroud to the front of the fan with duct tape to seal it to the fan.