"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.