Just wanted to report that here where the air quality index is 170 “unhealthy”, I am seeing 0 PM 2.5 right now with a DIY cube fan with 1 inch filters running on low since 2 pm, and fresh air ventilation turned off. It does spike up when I open a door to the outside and comes back down over a few minutes. First time using it.
Hi @framistat, thank you for sharing this! Would you mind sharing some photos and resources? Just in case people who are experiencing the same issue can make the DIY fan.
Please take care!
Well, I am not being allowed to link to any resources here. Do a search on “clean air crew box fan filters” and you should find it.
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You see the sudden dropoff at about 2 pm, toward the right side of the graph, when I turned the fan on.
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Thank you again for sharing. If you have anything else to share, please feel free to share here with our community. I believe there will be more and more people who are affected by this wildfire find this helpful.
Hope everyone stays safe.
Just be aware, if your home is air sealed and you turn off fresh air ventilation, CO2 can rise to unacceptable levels. Mine rose to 1131 as of this morning, so I turned it back on - CO2 is dropping slowly while PM2.5 is creeping up. It’s going to be a balancing act.
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That’s interesting. So when your fresh air ventilation is on (I assume that it is a whole-home ventilation system), PM2.5 creeps up because the indoor pressure is getting lower, and then the outdoor air can easily get inside? Or is there something else involved in this case?
This is positive pressure whole home ventilation, bringing outside air in. lowering CO2 but raising PM2.5 when there is wildfire smoke. Running ventilation is necessary in any air sealed home to keep CO2 from rising too high. The cube fan provides additional filtration to lower PM2.5.
It’s a setup from 2007, if I knew then what I know now, all this would have been done differently.
BTW the gaps in the charts are when the wifi is turned off overnight.
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We see 1100 to 1200 CO2 indoors most of the year (when windows are closed) . . . and don’t worry much. When it’s 5F outside, I’m darn well NOT opening a window!
The smoke did give me a “trace” of where we were getting contaminated air in, though . . . Had a space with no return and an open vent dumping air outside, and drawing smoke in a bathroom vent (smelled like a campfire in there) allowing me to correct the situation and keep the smoke out! (And I have higher MERV filtes inbound . . . the MERV11 I have now (best available locally) won’t get indoor AQI much below 80 . . . )
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You may need an ERV. FWIW I’ve opened a window at that temp for 15-20 minutes at a time, it’s fine.
There is a study showing decreased decision making performance at those levels.
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I also sit around 1200 with 4 people in the house. If it goes over 2000 I do something.
Keeping my HVAC fan running on medium overnight keeps bedrooms from spiking over 1800 with doors closed when sleeping.
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That sounds scary though. I live in an area where we don’t regularly have big wildfires, but there are things like a smog season from around November to March. My apartment room is not well sealed (as usual for residential buildings here), and during the smog season, it is quite challenging for my air purifier to keep PM2.5 below 20-30 μg/m³ (around 70-90 US AQI) when the exhaust fan is on.
This isn’t typical here either, nor are the fires local. Canada is burning, and this is blowing in across Lake Superior . . . I’t happened on occasion (Canadian forest mismanagement), but never this bad. Outdoor AQI peaked at a bit over 1200, and it looked like milk out the window. Far better now (still in the 200’s outdoors) but with the MERV 14 filter and constant fan, I’ve been able to maintain an indoor of 30 or so and CO2 of 1000 (outdoor is about 450 at the moment.) Normally we are one of the cleanest places on the planet . . . .
Did the outdoor CO2 change when the fire was at its peak, or was it still around 450ppm?
CO2 really didn’t change . . . If anything, it was a bit lower - closer to 425. What we got is mostly smoke and fine particulates. (The fires are still ongoing - the wind direction is what determines if we get this or not.)
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That sounds kind of similar to what happens in the area I live in. Sometimes wildfires or even intentional burning (in Southeast Asia, it’s usually for agricultural purposes) occur in other areas, but the smog can still travel somehow to the residential areas.
Today were are clear . . . outdoor AQI is 10, indoor is 5. CO2 outdoor is still 450 . . .
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Thanks for the update! Take care folks!