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Q: Is CO2 Hazardous?

A: CO2 is hazardous in the same way that water is hazardous.

Just like water, CO2 is in your body all the time. You exhale both CO2 and water with every breath.

Just like water, the problem is not with the presence of CO2, but with its concentration. If you are surrounded by water you can drown. Similarly, if you are  surrounded by too much CO2, for example in an unventilated or confined space, you won’t be able to breath.

The bottom line: Like water, CO2 is not hazardous except in unusual circumstances.

Feel free to keep breathing.


SCUBA divers need to be aware of hypercapnea because they breathe air in an unnatural way. Diving medicine specialists have studied how hyperventilation can sometimes lead to increased CO2 in the blood and its symptoms.




In Italy carbon dioxide naturally seeping out of the ground can accumulate in high enough concentrations to pose a health hazard. Click on the icon to the left link to an assessment of Italian seeps by researchers in the United Kingdom.