[mnw21cam]

It's incredible how quickly CO2 can build up inside a room. I'm also in a small village, and CO2 is 420ppm-ish outside. In my home office right now with the window open but no through flow, it's 1800ppm. If I close the window, it'll head off the scale of my CO2 monitor, above 5000ppm. Now that definitely is in the realm of cognitive impairment. I need some better ventilation.

[sideshowb]

Fair. My appropriate point of comparison (if I wasn't currently nitrogen drunk) should in fact have been mountains <1000m. Which I also love, but they don't have that clear headed altitude feeling.