One weird trick to reduce CO2 levels in your home!

Now that we’ve been working from home for *checks watch* 18 months, we decided to check the carbon dioxide levels after hearing some coworkers had measured levels that were kind of high, which can lead to headaches and whatnot.

The general guidance for CO2 is that it should be less than 700 ppm above the outside level, which is an indication that fresh air is getting cycled in enough. From an absolute level, more than 1000 ppm over a while can lead to drowsiness, etc. (here’s a news article that cites the 1000 ppm threshold – primary sources from the EPA are harder to read, like this PDF…)

The first few days, the lowest our meter got was 900 ppm (first thing in the morning) and most days it would get up to 1050-1100 or so when the kids got home. One weekend day after we had been exercising and then had our gas oven for an hour it got up to 1500 ppm!

This was kind of surprising. Our house is fairly new, and we tend to work in the living room (where the CO2 meter is), which is a pretty open space. And the A/C is able to keep things cool, so it’s not like ventilation is terrible. We did notice that the outdoor level was around 400 ppm, which is on the high side.

Totally coincidentally, one of our smoke detectors started going off on the way to bed (because this always happens at night 🙄), and after taking it down, we thought it might have been set off by dust. Right next to that smoke detector was a giant A/C intake vent, which was incredibly dusty. (I don’t think it’s been cleaned in the 3.5 years we’ve lived here…)

So David vacuumed it the next day. And after the dust settled, the CO2 levels in our house dropped by 100-150 ppm!

My guess is that changing out the A/C filter in the attic would help a bit too, but I was surprised a dusty intake vent had such a big impact!