Was learning oxy/acetlyene welding, I could smell something burning. I lifted my goggles and asked is anyone smelled something burning, no one noticed anything, so back to welding I went. A minute later, I could REALLY smell something burning. I lifted my goggles again, and it was the front of my shirt. Some slag had settled in a fold and was smoldering. It was almost to the point of ignition, but I was safely able to extinguish it. I also had longjohns underneath which quite possibly insulated the heat so that I did not notice it as quickly.
Fire is a very dangerous situation, and it can happen fast. It is very important to always have your wits about you and keep very aware of your surroundings. Keep a fire extinguisher handy and probably the fire departments number as well.