Originally Posted by AiredAle
CO2 is an acid gas, which is why it burns your nose. It is also not quite odorless, but has an acrid sorta smell. Don't overdo it, don't want you pitching headfirst into the freezer and knocking over the fermenters.
You're right in stating that CO2 is an acid gas (it's better to consider it an acidic gas, but technically by itself it is an acid gas), but it is also a tasteless, odorless, colorless gas. Ever smell dry ice? I have and it didn't burn my nose. There is some other fermentation by-product giving it that bite and I was just curious if anyone knew.