Interesting account - I sort of remember that incident with that gas cloud. So yeah - concentrating it into a pipeline that might leak.... And I’m guessing Paladin2 isn’t talking about an extra 10 to 100 ppm of CO2 in the air as being “toxic”.
CO2 is not toxic in the normal sense, but high concentrations should be avoided.
One’s exhalations are about 4% CO2, well above the nominal 0.04% average atmospheric concentration.
I wouldn’t want to be next to a natural gas pipeline if it burst either. Thankfully U.S. pipelines are built a little better than Cameroon pipelines.