I had an CO2-related incident when I worked in a lab a few years back. We had a large freezer for dry ice. I was working by myself at night. I put on gloves and reached into the freezer to grab a few pieces of ice at the very bottom of the freezer. My feet were almost off the floor. Of course the freezer was completely filled with CO2 vapors. I instinctively took a deep breath while I was in there and started to black out. Luckily I pulled myself out before I did. I could have easily suffocated.
It would have been an embarassing way to die. They would have found me Monday morning with my feet sticking out of the top of the freezer. Knowing my boss he would have bitched about all the dry ice that I let evaporate.