MIG FumeThe MIG welding of carbon and alloy steel is the largest application of the process. Particulate fume is made up of discrete solid particles, normally complex oxides and silicates of metals, which are generally under 0,5 microns in diameter. This falls into the "respirable" size range meaning that the particles can be breathed in and reach the lungs. By far the most important source of particulate fume, when welding on clean plate, is the welding consumable, the carbon or alloy steel filler wire, and to a lesser extent, the parent plate. During transfer across the MIG welding arc, some of the volatilised filler metal will react with the active components, CO2 and O2, in the shielding gas and others which escape from the gas shield, will react with oxygen in the surrounding atmosphere to give particulate fume. It has also been demonstrated that spatter can contribute up to 30% of the particulate fume. Gaseous fume comprises pollutant gases mixed in the air around the welding station and so can easily enter the lungs. Gaseous fume often has as its source a reaction between ultraviolet radiation generated by the electric arc and the atmosphere surrounding the arc. It can also be formed by the action of a welding arc on some welding fluxes, and on coatings or contaminants on the plate surfaces.
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