Actual line printers were pretty quick and wouldn't have been running for long periods of time, and were likely to be tucked away in a back room somewhere. Now get a few 30-character-per-second DECWriters buzzing... And those were a vast improvement over the 10-CPS Teletypes that were the rage before video terminals were affordable.
A former coworker had a story from when he used to service those things. He was doing a cleaning and was tossing the solvent-soaked rags into a garbage can on the other side of the printer door. Someone came by and tossed a cigarette into the can - managed to blow out quite a few ceiling tiles. He was always a bit hard of hearing but I never determined if it was connected to this incident or not.