from the link: "At high levels, the carbon dioxide itself can cause headache, dizziness, nausea and other symptoms. This could occur when exposed to levels above 5,000 ppm for many hours. At even higher levels of CO2 can cause asphyxiationas it replaces oxygen..CO2 poisoning, however, is very rare."
Comments
But it's great for making fossils.
https://youtu.be/KNvRLVBKn-I