|
The other responses are duly cautious, but several are a bit off the mark. Galvanized steel is coated with thin layer of zinc. This forms a sacrificial anode which prevents corrosion of the steel. When you weld the galvanized material, the zinc is vaporized and/or oxidized. If you breath the fumes, you inhale zinc and zinc oxide. Enough of this can give rise to fairly unpleasant flu-like symptoms know as "welder fever" or "metal fume fever". Zinc itself is not a deadly poison. It is, in fact, an essential mineral and you can buy bottles of it in the vitamin section of any pharmacy or grocery store. The fever symptoms are due to an "overdose" of zinc, but the body excretes the excess and there is no lasting damage or soft tissue accumulation as with lead. Zinc oxide is a lung irritant, causing coughing and perhaps asthma-like symptoms
in severe cases. Recovery from such events is generally complete within 24 to 48 hours, and permanent lung damage is rare. Unpleasant, yes, "bad for you", yes, but perhaps no worse than firefighters face all the time and hardly in the same league as phosgene gas. The vaporized zinc makes for a fairly nasty looking mess near the surface of the weld. With appropriate technique, one can avoid entrapping the zinc within the weld and thereby weakening the weld. Some measure needs to be taken to replace the corrosion protection lost in the region of the weld, such as paint or cold galvanizing compound. Safety is always important, but it is equally important to understand what you are dealing with. Galvanized steel can be cut or welded just fine. Just try not to breath the fumes. (Lead, cadmium, and chromium, also used in metal plating, are another matter entirely and much more problematic).
| 
