I am going to preface this post with the warning that breathing any fumes ,even the forge exhaust, is not a good thing. Shop safety and respirators are a must if you want a long and healthy life.
I will also set the record straight about Jim paw-paw Wilson's death from "zinc poisoning" as it is often stated. Jim was burning the coating off galvanized pipe in a tightly closed up shop - with no ventilation or respirator - with a case of the flu - and totally messed his lungs up by breathing the fumes over several hours. It wasn't the zinc that killed him. His death is often stated as "zinc poisoning", or "complications of metal fume fever" in some posts, but to put it in graphic words, he drown in the fluid that was weeping out of his destroyed lungs. It was pneumonia that killed him. Jim was a great guy, and knew better than to do what he did....but did it anyway. His example ( bad one) should be well noted by all.
That said, I read all the time posts where someone says, "Don't use galvanized, the fumes are toxic". ( often followed by a reference to paw-paw)
Galvanized steel is just regular steel with a coating of a zinc compound. If you look up zinc, you will find all sorts of info on ZINC POISONING. Especially for animals, some of which which are highly susceptible to zinc ( IIRC, dogs and birds).
Zinc poisoning is caused by the over absorption of metallic zinc into the body, which can play hell with your metabolism. You need zinc to live, but not too much of it. Zinc poisoning in humans is extremely rare.
Many metal parts in electronics and other industrial uses are CADMIUM plated, and cadmium fumes can kill you.
When you grind the zinc off of steel, you create zinc dust and may breathe metallic zinc. That is certainly not good. Breathing zinc dust can possibly cause zinc poisioning.........so grinding it off must be done carefully and all dust cleaned up ( which is pretty hard to do in most workshops). A P100 filter should be worn at all times when the grinding is in progress, and kept on until all dust is removed. Even with this warning, understand that zinc is a very active metal, and readily combines with oxygen to form zinc oxide ( or other compounds) and the amount of metallic zinc absorbed by grinding a few inches of galvanizing off a weld joint is most likely going to be minute ,unless you are working in an industrial situation doing it day in and day out.
When you weld or heat galvanized metal it creates a white fuzzy dross and a white smoke. This is not zinc...it is zinc oxide. Zinc oxide is not absorbable in any real way.....or every life guard in California would be dead by now.
If you breath enough of it it can make you feel bad, but is not going to kill you. This is called "ZINC SICKNESS" ...not zinc poisoning. Another name is "METAL FUME FEVER".
Zinc sickness is caused by breathing too much zinc oxide fumes and makes you feel nauseous and headachy. If you were breathing smoke, grain dust, or many other airborne particulates, similar symptoms may result.
The treatment for zinc sickness is fresh air, a glass of milk, and a good nights sleep. It is not fatal.
Good ventilation with a fan blowing the fumes away prevents it, as well as wearing a P100 particulate respirator. Zinc oxide is not an organic compound, and does not require special organic filters.
The long and short of this post is that 90% of all people think that zinc welding fumes are deadly...but that is not the case. Same story goes for MOP and Abalone, which are often posted as giving off deadly cyanide gas. MOP and other shells are calcium carbonate, and similar compounds....which is probably in your toothpaste. There is no cyanide in shells. Apricot pits have cyanide.
