Forest Fire Smoke Home Prep

Forest fire smoke is something many people deal with these days(it sucks). When smoke moves in to your area, maintaining air quality in your home is very important. If stuff smells in our house we can go outside. If outside air is bad, we have to focus on maintaining our indoor air quality.

tl;dr list... (detailed info below)


We had very bad forest fire smoke move through our area back in 2020. Talking over 250 on the air quality index for multiple days. Peak at one point was 646.



These are steps we took, which we were successful with, to help maintain good air quality inside of our home.

I'm by no means a prepper, but statistically speaking, forest fire smoke can be in our future(looking at past summers with really bad days) so buying a few things, off season, while you have your pick of things in stock to stow away in a corner can be really helpful if smoke makes its way in to your area and the stores inventories are cleared out.

After we had a rough summer with smoke, I bought stuff after it was back in stock to have on hand. Better to have it and not need it vs need it and not have it. :)
For $100-200 you can have some good insurance for a situation where smoke comes in to your area again.

Close Fresh Air Intake
If you have a central air unit, you will most likely have a fresh air intake. This allows your furnace to pull in fresh air. You can close this when smoke is bad to help avoid bringing in smoke to your home. This will be on the 'return' side of your furnace. The lever to move the dampener also represents the position of the dampener itself. 


Air Scrubber
We built an air scrubber which helped a lot ( Washington Department of Ecology Air Scrubber Build Tutorial ). It continuously recirculates your air through the filter. We ran ours on high for five days and it was fine. We've got two fans now for two scrubbers in our house if needed. The forest fire smoke last summer sucked... not like you can go outside if your air indoors is in bad shape as well so take care of it for you and your loved ones! Also consider buying stuff for family and maybe kindly remind your neighbors. $40 worth of stuff to make a scrubber can make a world of difference. Especially if you don't have central air to clean your air. Build multiple scrubbers for your home.



This was after five days running this scrubber in our downstairs hallway. Even after 12 hours of running, it already had a smoke mark.



Furnace Central Air Filter
Regarding MERV ratings... the CDC recommends MERV 11-14 for forest fire smoke. ( jump to page 14(printed number 8) here: CDC guide (link - site).

"The higher the MERV rating, the higher particle removal efficiency of the filter. Only MERV 11 filters and above are specifically tested for their ability to remove the smaller (0.3µm) particles. MERV 11 filters must achieve at least 20% efficiency for 0.3µm particles, while MERV 13 and above require at least 50% efficiency for 0.3µm particles."

"Forest fire smoke consists predominantly of particles 0.4-0.7 micron" (https://depts.washington.edu/wildfire/resources/pubhealthguide.pdf)

So I went with MERV 11 (20x20x1 Filtrete Micro Allergen Air Filter Merv 11 by 3M) and these specific ones are rated to remove 41% of 0.3µm particles which is getting near the MERV 13 rating of 50%. Reason I mention this is you will see MERV 13 mentioned a lot in documents but check the actual percentage. It's not an all or nothing rating. The 41% of the MERV 11 for my scrubbing filters is good especially considering the air will pass through it multiple times while recirculating.

The MERV 11 rating on our central air furnace filter (Honeywell 20x20x4 part no FC100a1011) is lower though. 25% efficiency for those particulates for our particular filter so not as good as the 50%+ of a MERV 13 but with our scrubbers running, we'll be in good shape. Also, when you run a MERV 13 in your furnace, you'll have more back pressure and lower throughput. Better filtration with a MERV 13 but if the weather is warm, that's less cooling in your home. Something to consider.

Closing Up Bathroom/Laundry Room Exhaust Vents
We also put bags over our bathroom vents to block outside air from coming in that way.



Use Garage Side Door To Preserve AQ In Home

We were also entering and exiting our home through the side garage door so we went through two doors to go in and out of our house to minimize outdoor air coming in. The garage acts like a buffer.

If you don't have central air in your home to filter the air, a few of these scrubbers go a long way to cleaning up the air in your home.

Also ponder suggesting or buying scrubber materials and/or an adequate central air filters for family that may not consider it. They'll thank you when they need it! $30 for peace of mind.