[…] the literature on CO2s effects on cognition is extremely inconsistent. In some studies, relatively small increases in CO2 levels cause large impacts on cognitive performance. Other studies don’t find any cognitive impacts at all, even when CO2 levels are ten to one hundred times higher than atmospheric levels. We’re left with an extremely muddy picture of the relationship between CO2 levels and cognition.
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In other cases, the studies were performed on physiologically distinct populations. Many of the studies were done on people in specialized professions such as divers, astronauts, and naval submarine operators. Not only will members of these professions be much more physically fit than average (a naval submariner must pass the Navy Physical Readiness Test several times a year), but they’ll often have experience operating in environments of very high CO2. In nuclear submarines, CO2 levels may be at up to 5000 ppm for 90-day durations, and for short periods are allowed to be as high as 40,000 ppm, 100 times atmospheric levels. In spacecraft, CO2 levels are typically between 2000 to 5000 ppm, and may reach 10,000 ppm or above for short periods of time. This makes it hard to generalize findings on these sorts of subjects.
From the article:
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