> - Cognitive effects show up well over 1000 ppm. "Well over" is as little as 1500ppm. Definitely at 2500ppm. Reaching those numbers in poorly ventilated build

> - Cognitive effects show up well over 1000 ppm. "Well over" is as little as 1500ppm. Definitely at 2500ppm. Reaching those numbers in poorly ventilated buildings is easy. > - Current atmospheric concentration is around 417 ppm. People mostly work indoors, so atmospheric concentration is not comparable. > maybe then I would worry about this but probably worry about ocean acidification before cognitive decline. True, you can always improve individual ventilation in rooms and houses until maybe 700-800ppm in the atmosphere, and at that level I would also worry about other things (ecosystem collapse, major weather events, fires and air pollution).