I once worked at the head end (where they make the bottles) of the Kerr Glass plant in Dunkirk, IN. It didn't have any ventilation at the machines or back end of the lehrer until shortly before i left it. I worked as utlity at the time, giving breaks to the machine operators and cleaning up messes of red hot glass.
Say a throw away Pepsi bottle, these were made at a rate of 90/minute, The gob would come down, sheared, then guided to the mold, once complete moved onto a conveyer belt in a single line, continue to a turnstile that would place them on another conveyor belt where a rake was that was timed to push them on to the lehrer belt which was a machine they went through for treatment to temper the glass.
If a machine shut down the molten glass would flow straignt through to the basement where it'd stack up in a large water trough and we'd use long steel hooks to grab a mass of still red hot but now emitting super heated steam out of the troughs into wheelbarrows when full we'd run down and dump into bins to recycle. You needed to push it fast enough so the steam didn't get in your face off of it, the glass was still red hot. When it came out of the glass furnaces it was over 2,000 degrees.
Now the turnstiles that move the bottles onto the leher feed belt would occasionally get out of time and might not be caught by someone right way so it would dumpt them on the floor at 90 bottles a minute. The thing about this is you are within ~6' feet of the lehrer opening which at the backend side was kept at ~1,800 degrees where the glass was moved into it. That cleanup was worse than working the pits. However they did finally put in some large ventilation tubes so you could go stand in front of before I left them.
I'd go home and I would literally feel my bones radiating heat feeling like I was being cooked from the inside out.