In one of the heavy structural steel fabrication plant, one bay was used to spray paint steel girders, diaphrams, columns, etc. The bay was around 25000 sq.ft. with two large sliding doors on each end of the bay. To cure paint sprayed on the steel, there were two dozens or so side wall mounted radiant natural gas heaters which were also vented into the bay. These heaters were about 20ft off the ground and we had a dozen ceiling fans to spread the heated air that accumulated between the fans and the roof. For my duration of employment about 12 years before retiring we never had any health problem or injuries related to lack of ventilation, fires or explosion from combustible vapors. A word about the paint bay as it should not be viewed as a spray painting booth which has different NFPA and OSHA requirements.