While the blog post you linked to claims that the work finds "implausibly large effects", it doesn't clarify what the author finds implausible about them (and the author admits to only spending 30 minutes looking at the literature).
I would agree that the graphic in the PDF linked in this HN discussion, and in the paper referenced by the blog post you cited, uses alarmist labels (e.g., "dysfunctional" for performance scores at 25th percentile and below). However, the full version of the report, as linked by post, states that the percentiles are based on the reported scores from 20k other administrations of the test.
Therefore this report simply implies that some of the reported variation in some of the historical scores might be explained by variations in room CO2 concentrations. What's so implausible/impossible about that?
Disclaimer: I know several of the authors of this report, and have good regard for their scientific integrity, so my gut-level reaction to an undocumented accusation that their results are implausible, was skeptical.
The whole idea behind "breathing" is to regulate the CO2 in the blood at a very constant level. This is one of the strongest, fastest feedback loops in homeostasis. How are relatively small changes in environmental CO2 making their way into the bloodstream? Did they actually conduct blood tests to see if the test conditions were reflected in the subjects' physiology?
> The whole idea behind "breathing" is to regulate the CO2 in the blood
True, but two devil's-advocate what-ifs come to mind.
First, the system isn't so responsive to a lack of oxygen, and in many of the "low ventilation with people" scenarios, higher CO2 correlates with lower O2, because that's the conversion going on.
Second, might the body down-regulate mental resources as a response to chronically higher CO2 in the environment? As an adaptive or precautionary measure, helping keep that blood-concentration correct?
