Remember, galvanized metal contails lead, which volatalizes when heated (aka welded). Lead accumulates in the fatty tissues of the body and can never be flushed by the body. Causes all kinds of reproductive and nervous system problems with prolonged exposure....hence ....unleaded gasoline.
Good idea whenever working with chemicals...thinners, paints, bondo, welding, to be upwind of the vapors. There is probably stuff that we breath that will be found to be carcinogenic 5 years from now!!!!!, or make valuable parts of your anatomy fall off or sumsuch!!
Tim