Welding Galvanized Metal & Metal Fume Fever
Galvanized steel is coated with zinc to stop rust. When you weld, torch-cut or plasma-cut it, the zinc boils off as a thick white fume of zinc oxide. Breathing it can cause metal fume fever, a flu-like illness that many welders know as “the shakes.”
- Welding
- Construction
- Fabrication
Symptoms
Symptoms usually start 4 to 12 hours after exposure, often in the evening after work:
- Fever, chills and shaking
- Muscle and joint aches, headache and tiredness
- A sweet or metallic taste, dry throat and cough
- Nausea and chest tightness
It usually goes away in 1 to 2 days. Workers sometimes build short-term tolerance during the week and get sick again after a weekend away, which is why it’s been called “Monday morning fever.”
It isn’t harmless
- Getting sick means your exposure was too high. The same work may be exposing you to other metals in the fume.
- Repeated episodes are a sign your controls aren’t working.
- See a doctor if you have trouble breathing, chest pain, a high fever, or symptoms that last more than 2 days. Tell them what you were welding. Other lung conditions can look like metal fume fever.
Copper, magnesium and some other metal fumes can also cause it. OSHA’s limit for zinc oxide fume is 5 mg/m³ averaged over 8 hours.
Know your coating
Not every coating is zinc. Old paint may contain lead, and some coatings and platings contain cadmium or chromium, which are far more dangerous. Find out what’s on the metal before you heat it. See Lead and Hexavalent Chromium.
Prevention
- Remove the coating from the weld area first, by grinding or with a chemical stripper, using dust controls and a respirator if needed.
- Use local exhaust, like a fume extractor with the hood close to the arc. General room fans aren’t enough. See Ventilation.
- Outdoors, work with the wind at your back or side, so it blows the plume away from you.
- Keep your head out of the plume. Position yourself so the smoke rises away from your face.
- Wear a respirator when the exposure assessment calls for one. A properly fitted respirator with particulate filters, or a PAPR under your welding helmet, can protect you. See Respiratory Protection.
- In confined or tight spaces, use local exhaust and supplied air as required.
The milk myth
Some welders believe drinking milk before or after welding galvanized metal prevents metal fume fever. There’s no good evidence that it works. Only reducing the amount of fume you breathe prevents it.
Before welding coated metal
- Coating identified: zinc, paint, lead, cadmium or other
- Coating removed from the weld zone where possible
- Fume extractor positioned close to the work
- Respirator on if required
- Head positioned out of the plume
Standards & references
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