Fumes are airborne particles small enough to be inhaled and are produced in all welding and cutting operations. They are a mixture of: gases from the surrounding air, shielding gas, metallic elements – from parent metals, coatings and welding fluxes, which are vaporised in the welding arc.
Welding fumes are generally at levels low enough to pose no great health risk. However, when the concentration of fume is high enough the welder will be exposing him/herself to both low oxygen levels and potentially toxic metals.
Even low concentrations of toxic metals in welding fume, may cause health problems to nasal passages, the lungs, blood, liver, kidneys and nervous system.
Certain substances are particularly dangerous, even in very low concentrations so, welders should be aware of the dangers associated with metals such as beryllium, cadmium, zinc and lead.
The table below an indication of the toxicity of some of the metals more commonly encountered by welding operators.
| Metal | Effect | Typical fume source | Ventilation |
| beryllium | A highly toxic, quick acting poison. A carcinogen. | copper based bearing alloys casting alloys |
glove box, fresh air supply |
| cadmium | A highly toxic carcinogen. Causes heart, lung and kidney damage | silver brazing alloys surface coatings |
glove box, fresh air supply |
| chromium | A carcinogen. Causes lung and skin disease, nasal irritation | chromium alloys stainless steel electroplating |
local exhaust |
| lead | Causes fatigue, nerve and kidney damage and high blood pressure | copper base casting lead based paints free machining steels |
local exhaust |
| copper | An irritant to nose and throat. Causes metal fume fever. | copper alloys and castings | local exhaust |
| nickel | Causes skin and respiratory irritation and kidney damage. A carcinogen. | nickel alloys stainless steel |
local exhaust |
| zinc | Causes metal fume fever | surface coatings bronze and brass |
local exhaust |
| aluminium | Causes irritation to nose and throat and chronic bronchitis | plates, castings extrusions |
local exhaust |
