Can carbon dioxide be bad if it is into your circulation?!

In high enough doses yes it can even be fatal. Your body needs oxygen to function. When you inhale air the oxgen gets absorbed by the lungs and passed on to blood cells that then take the oxgen to your organs. They then pick up carbon as a waste biproduct. This is carried back to the lungs and each time you exhale, you breathe out small amounts of CO2.

Now if you don't get rid of this CO2, if it stays your body and builds up to high enough levels, your blood cells try to pick up the CO2 over the oxygen it actually needs. In short, you essentially suffocate.

you'll die within the hour.