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Comment by immibis | Hacker News Reader

IIRC 1000 is where it starts having easily detectable negative effects on human cognition, which means it has less easy to detect negative effects on human cognition at numbers lower than that.

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If you own a CO2 sensor you know that even at 5000 it’s not “easily detectable”… I know what is said about cognitive abilities and CO2 but I guess that’s hard to feel yourself. Moreover I doubt those results. Humans start to die at 10%, that’s (if I’m not mistaken) 100.000 ppm.

Ive had a CO2 sensor for years, take it with me usually. In the beginning I was quite shocked, but I’m starting to doubt all the bad things said about CO2 over 1000-1500 ppm now…

Air you breathe out is around 40 thousand ppm (and higher during exertion), and the air in the lungs isn't completely replaced every breath - I doubt there's much measurable difference at the actual alveoli at the levels we're talking about. You'll probably get more of a difference if you're breathing deeper and faster, or just got up to get a coffee or similar.

And interestingly there are studies that show that breathing in air up to 3% co2 (30k ppm) "did not substantially impair either cognitive and motor performance" [0]

[0] https://www.tandfonline.com/doi/epdf/10.1080/10803548.2007.1...

High CO2 most definitely impairs cognitive performance as shown in many studies, and also backed up by substantial personal experience.

Double blind personal experience?

I've found the same. And thinking it through, I can't come up with a mechanism for how a few more CO2 molecules bopping around in a sea of nitrogen and oxygen changes anything about how my lungs exchange the CO2 in my body with air around me. These counts are ppm, nothing!

If there's twice as much CO2 in the air, twice as much CO2 goes from the air into your blood.

CO2 enters the blood in the body, it comes out of the lungs. If you breath too hard you loose too much CO2 and your blood pH will go up. That’s why you breathe into a bag when hyper ventilating, to keep that precious CO2 in.

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