no, it would actually take about 3cc's full of air, directly into a vein to kill you. its always safe practice to tap out the airbubbles till their at the tip of the needle and then push it out a little. and this is why you also aspirate when injecting. safety first.
Jayson-Just before you inject your gear, but when the syringe is in your body, you pull back on the plunger. You should get air bubbles if your not in a vein. If you are in a vein, you will get blood...if this happens, which is rare, just pull the pin out and inject elsewhere. This is how you avoid injecting into veins...do this at every injection.
no need to even tap to get those little air bubbles...just hold then needle towards the sky and push plunger until a bead or 2 of oil falls down the needles (this will actually lube the needle as well) and thats it..... aspiration however is important, even thought some people dont actually do it, but its a good habit to get into.