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Comment by breput | Hacker News Reader

tl;dr: No

A suggestion from someone who has built three different CO2 monitors - don't chase the numbers. 420/800/1200 ppm has no meaningful difference, and if you don't have a good way to calibrate your CO2 sensor, such as a pure nitrogen environment or taking your sensor outside at least weekly and forcing a calibration, you can easily be 500 ppm out of true.

I suspect that you probably feel more clear-headed outside because there is wind and nature and distractions that aren't an LED screen.

That said, I think an interesting experiment would be to use a CO2 scrubber to remove carbon dioxide, instead of trying to overpower it with more oxygen. Otherwise, just get a tank of oxygen and face mask and see how it works for you.

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> 420/800/1200 ppm has no meaningful difference

That claim contradicts the results of the NIEHS study "Is CO2 an Indoor Pollutant?"[1], which has found that "Relative to 600 ppm, at 1,000 ppm CO2, moderate and statistically significant decrements occurred in six of nine scales of decision-making performance."

[1] https://web.archive.org/web/20160305212909/http://ehp.niehs....

Yeah, that matches up with my experience.

Thank you for the reply! I've had two different CO2 monitors and feel like I definitely notice a difference between when the level is 1000 and when it's 400-600. In fact both my girlfriend and my father have noticed the difference in "stuffiness" when I have the windows open vs closed, and that was in separate houses/apartments. But I think I pay way closer attention to it than most other people.

"I suspect that you probably feel more clear-headed outside because there is wind and nature and distractions that aren't an LED screen."

I definitely agree that those things make a difference in how I feel, but I think that the CO2 makes a difference even at those lower levels. I'll say this: if I drink coffee, I can power through it / not notice it. But if I'm not using caffeine, I'm a lot more sensitive to it.

"I think an interesting experiment would be to use a CO2 scrubber to remove carbon dioxide"

Thank you for that idea! I didn't know a CO2 scrubber was a thing, so this is exactly the kind of thing I was hoping to get from the HN crowd.

The sense of stuffiness can be due to humidity, mold, or probably just various household smells.

If your sensors are able to do remote logging, you can do your own double blind test and cover up the displays for a week and log what you feel like the CO2 level might be, and then at the end of the week compare it to the logged levels.

Either way, you might consider an air exchanger - either commercial or homemade[0] that can efficiently move air from outside to inside, without much heat loss.

[0] https://www.loudawson.com/17884/how-to-build-air-cross-flow-...

Good ideas. "Air exchanger" is another thing I'd never heard of before. And I've written down the idea to do an experiment: I think maybe what I could do is cover up my Aranet4 CO2 monitor's front screen with some tape, take it with me to different venues around where I live, write down what I think the CO2 level is at that venue, and then look at the logs afterwards.

Can recommend Panasonic ERV/HRV. With it air in my office is better than the air outside: CO2/O2 levels are practically the same, but on the way in air gets filtered.

Thank you for the tip!

I used to use this window-mounted model from PuriFresh: http://www.purifresh.com/erv.html Having fresh indoor air in the winter was amazing.

Unfortunately my current home has non-standard windows so it doesn't fit anywhere. If you are in the Boston area I'd be glad to gift it to you.

Wow, thank you for the tip! I'm going to look into the Purifresh, that sounds like exactly the kind of thing I'm looking for. Unfortunately I'm not in the Boston area but thank you for the offer!

Does your place, by any chance, have paint that isn't made out of non-toxic materials? I recently moved and went back to the old place after a few days, noticing how much different the air was. The new place had certified paint used and it was quite noticable.

I'm not sure, but this CO2 issue is something I've noticed in many different situations, including just being in a car with air recirculation turned on. Once I became attuned to CO2 I started noticing its effects everywhere. It's similar to how, once I experienced my first major earthquake (Washington DC in 2011) I suddenly started noticing all of the very minor quakes that happen all the time but that most people never notice.

In the higher end of co2, 1000+ I definitely notice and will get more tired and less able to concentrate. Definitely buy a good meter and not the cheapest on Amazon. Aranet is pretty reliable for me but the calibration does slip over time and you hinted at, although not weekly.

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