A new study entitled "The effects of CO2 inhalation in patients with chronic post-traumatic stress disorder (PTSD)", published in the journal European Psychiatry, examines the link between the "psychometric effects of CO2 on panic anxiety and PTSD symptoms in subjects with PTSD."
I can't access the entire paper, but there is previous research linking getting too much carbon dioxide (and at the same time not getting enough oxygen) with anxiety disorders (especially in children).
What does all of this suggest? Nothing conclusive.
But it does lead us to remember one key word: