New to this forum, so just came across this thread, and thought it appropriate for me to enter this reply.
In 1968, as an 18 year old fresh out of H.S. I was employed by the Fisher Body Division of Oldsmobiles Lansing Michigan plant, where my first 5 years were spent working in the 'Arc Booth' welding and brazing on the Olds 88 and 98 (B&C body) production line. (Olds first hired me at 16, but thats another story)
In particular relationship to this thread, one position that I held was mig welding the galvanized trunk floor pans, which required leaning far into the trunks. Normal production in those days was in the range of 300-350 bodies per shift.
Although we were provided with large overhead mounted fans to dissipate the fumes,there were no masks, in the course of welding, our disposable welding shields would become permanently coated with a white deposit from the zinc welding fumes, progressively obstructing vision, so the shields were normally replaced twice daily, at starting time and 4 hours latter after lunch break.
I was on this trunk welding job for several months, until problems with my sinuses bleeding, got me transferred to a different position. That was 36 years ago, and I'm still around,
and I still do a lot of welding, That said, I still fear there may ultimately be long effects on my health from exposure.......