A new paper finds the performance of test-taking (cognitive, decision-making) “astronaut-like” subjects exposed to 5000 ppm CO2 was “similar to or exceeded” the performance of those exposed to baseline (600 ppm). This study follows up on a 2018 paper that determined submariners exposed to 15000 ppm CO2 performed just as well as subjects exposed to 600 ppm.
Those of us who own CO2 monitors know that indoor (bedroom) CO2 concentrations typically vary between about 600 ppm during the day and 1000 ppm overnight – the latter earning a frowny face air quality rating.
CO2 is a cognitively-impairing toxin?
In recent years there has been a push to create the impression carbon dioxide is a pollutant, or toxin. Consequently, there have been a few studies suggesting exposure to higher CO2 concentrations (~1500 to 2500 ppm) severely impair human cognitive and decision-making performance (Satish et al., 2012, Allen et al., 2016).
If true, this would be rather problematic for elementary school children, as they are routinely exposed to CO2 concentrations ranging between about 1500 and 3000 ppm in their classrooms (Corsi et al., 2002).
Driving alone in one’s vehicle could mean exposure to “3700 ppm … above outdoor [CO2] concentrations” (Satish et al, 2012), or about 4100 ppm.
This elevated-CO2-is-toxic-to-brain-functioning paradigm suggests the world’s highways are teeming with cognitively-impaired drivers.
2 new studies show elevated CO2 has no effect on cognitive performance
The results from a 2018 study (Rodeheffer et al., 2018) measuring the cognitive and decision-making performances of submariners exposed to elevated CO2 undermined the attempts to portray CO2 as a brain-function-impairing toxin.
In the study, subjects were exposed to 3 CO2 conditions: 600, 2500, and 15000 ppm.
The results indicated there were “no significant differences” in how the subjects performed for any of the CO2 exposure levels.
Image Source: Rodeheffer et al., 2018
A new study (Scully et al., 2019) assessing the capacity of elevated CO2 exposure to affect cognitive and decision-making performance appends the Rodeheffer et al. (2018) results.
This time, “astronaut-like” subjects were exposed to four CO2 gradients: 600, 1200, 2500, and 5000 ppm.
The results indicated there were “no clear dose-response patterns” evident for any of the exposure conditions.
In fact, the performance of subjects exposed to 5000 ppm slightly exceeded the performance of subjects exposed to 600 ppm CO2.
These results suggest the elevated-CO2-is-toxic-to-brain-functioning paradigm is not supported by real-world experiments.