HEPA vs DIY Air Filter for Smoke, Dust, Pollen, Dander

A low cost way to filter the air in your house to be clean and free of smoke, dust, pet dander, bacteria and pollen. I highly recommend these 3M Filtrete MERV 13 filters: https://amzn.to/47MKb70 20" x 20" x 1” (2 Pack 1900) or https://amzn.to/45se4If (3 pack 2200). They have great air flow and do a better job of filtering smoke out of the air than other brands I've tried.

To also remove odors, add this activated charcoal filter material which you can cut and fit to your box fan for about $5 each: https://amzn.to/2U2pS1v
To filter pollen, dust, mold, etc. but not smoke, these are cheaper: https://amzn.to/2MOhC3x 20" x 20" x 1” (MERV 8) Filters are only $5 each for a pack of 6.
Or you can get a washable/reusable filter, and some of these can be cut to fit a round fan. Here's a selection: https://amzn.to/2Zidk7t

True HEPA filter units, from $60 to $800, that also remove odors: https://amzn.to/2nhCmEJ
This HEPA filter also kills germs with UV light for a fair price: https://amzn.to/2mLhvsN

A low cost 20" Comfort Zone CZ200A 3 speed fan: https://amzn.to/2l4MBLC
Black 20" fan with good reviews: https://amzn.to/2mJFCrS
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Here’s the Merv equivalent filter rating chart shown at 2:41 in this video:
MERV FPR MPR Filters out Micron Size
1-4 4 300 Dust, Lint, Pollen over 10
5-8 5 600 + Mold, Dust Mites 3-10
9-12 7 1000 + Exhaust, Pet Dander 1-3
13+ 10 1500 + Smoke, Bacteria 0.3-1
HEPA filters all the above 0.3
Charcoal + Odors, Chemicals
Wood Smoke particles are 0.2 to 3.0 microns
Check the description or label on the filter - they often show a chart.
FPR is used by Home Depot & Honeywell, MPR is used by 3M

An easy homemade DIY box fan air purifier works for allergies, smoke, home or shop dust, and can be very helpful if you're sick. Video shows how to filter wildfire smoke or smog out of the air entering your home and create good air flow. Choosing an air purifier filter: chart of Merv ratings vs FPR and MPR with Micron size, Merv 13 vs a HEPA filter air cleaner. Keep the air in your house clean and sweet smelling, even when there's forest fire smoke, air pollution or pollen outside, or pets, dust and mold inside.

Online air quality index tools:
US - select state for local reports: https://www.airnow.gov/
Canada - animated forecast maps include the US & wind patterns: https://weather.gc.ca/firework/

During the unhealthy air from Washington and BC forest fires in August 2018, and again in 2022 from the Bolt Creek fire 3 miles away, it was such a relief to have clean smoke-free air in our house to breathe, like an oasis. Going outside even for 10 minutes my eyes, nose and throat were irritated. When the weather got hot, I filtered the air coming into our house by putting a Merv 13 filter with a fan in the window to bring cool air into the house early in the morning when it was cooler outside than inside, then closed it up during the hot part of the day and ran our air conditioner.