Yep.
Can high CO2 cause headaches?
Moderate to high levels of carbon dioxide can cause headaches and fatigue, and higher concentrations can produce nausea, dizziness, and vomiting. Loss of consciousness can occur at extremely high concentrations.Apr 1, 2016
Carbon dioxide levels and potential health problems are indicated below:
250-350 ppm: background (normal) outdoor air level 350-1,000 ppm: typical level found in occupied spaces with good air exchange 1,000-2,000 ppm: level associated with complaints of drowsiness and poor air 2,000-5,000 ppm: level associated with headaches, sleepiness, and stagnant, stale, stuffy air; poor concentration, loss of attention, increased heart rate and slight nausea may also be present. >5,000 ppm: This indicates unusual air conditions where high levels of other gases also could be present. Toxicity or oxygen deprivation could occur. This is the permissible exposure limit for daily workplace exposures. >40,000 ppm: This level is immediately harmful due to oxygen deprivation.
So I ventilate the room with a fan to outside.
These stoves, if you read the doc linked above, produce CO levels well below the regulated limits by the law. They are labelled CO free. And again, the room is ventilated, and there is a CO2 detector that switches off the stove. Anytime there is CO, there is a lot more of CO2, thus it would trigger the automated shut off safely.