... unless you are using a 15 Lb. ABCD fire extinguisher on a tiny electrical fire in a small hall closet that's about 2x3x4 in size.
I suspect that's why I have a cough, even to this day, and that was nearly 20 years ago. I caught the blow-back of the extinguisher full in the face. It got the fire out at least (along with making a giant mess!)
Then there was the some time contractors were doing some questionable work with a heat gun in one of our data centers and 'accidentally' tripped the pre-action system for the room. At least we found out that they didn't get the system drain properly setup, which resulted in the data center's sub-floor almost getting flooded. There were Words Spoken, I'm certain.