Metal fumes are byproducts of the welding of metals like lead, nickel, chromium, and mercury. Although invisible to the naked eye, metal fumes are generated when the filler rod or base metal gets vaporized during the various welding processes. They then condense as very fine particles.
Metal fumes are the byproducts of all processes involving:
- the manufacture of metallic materials such as galvanized metals (steel, brass, and other alloys)
- the application of rust preventative coatings onto steel
- alloying elements such as iron in steel manufacture
- the inhibition of foliage growth in marine environments
They are hazardous when inhaled and can lead to flu-like symptoms commonly referred to as "Metal Fume Fever." Apart from irritating or damaging the nose, throat, eyes, and lungs, prolonged exposure to metal fumes can lead to bronchitis, pulmonary edema, bone damage, and lung cancer. Measures for adequate control and maintenance have been introduced as a legal requirement under the Control of Substances Hazardous to Health (COSHH) Regulations.
OSHA has set the limit for exposure to welding fumes to an eight-hour TWA of 5 mg/m3 for these welding fumes, measured as total particulate in the welder's breathing zone. This limit applies to the total fume concentration produced during the welding of iron, mild steel, or aluminum. Additionally, it applies to the fumes generated by the welding of stainless steel, cadmium, or lead-coated steel, as well as other metals like copper, nickel, or chrome that are considerably more toxic and are to be kept at or below the levels required by their respective PELs.