Welding joins metal pieces by intense heat where consumable electrodes are frequently applied to improve the assembly of the larger parts. Fume arises from the base metal and in particular from electrodes. Welding fume is a complex mixture of metals, gases, and other compounds. In addition, it comprises very small particles, including ultrafine matter. The exposure of welders is dependent on several factors, including the welding process itself, workplace characteristics, and protective measures.
Protect Yourself Against Welding Fumes.
“Several hazards have been associated with exposure to welding fume particles.”
These hazards are related to the high concentrations of aerosolized fine and ultrafine metal and metal oxide particles that are generated by the welding arc. The heat generated by the arc melts the electrode, which is transferred to the welding pool in the form of superheated metal droplets. Spatter particles are also formed. The spatter particles and the heated metal droplets produce high concentrations of supersaturated metal vapors that then nucleate to form solid particles. As these particles cool to ambient temperatures, they undergo condensation and coagulation, which leads to the formation of chain aggregates and agglomerates.
Welders work in numerous settings that range from outdoor, open, well-ventilated spaces (e.g., construction sites) to confined, poorly ventilated spaces (e.g., crawl spaces, ship hulls, and pipelines). The close proximity of the welder to the arc exposes the operator to high concentrations of metal fumes); therefore, exposure studies usually measure fume concentrations in the welder’s breathing zone . In recent years, researchers have placed increasing emphasis in studying the effects of exposure to specific fume constituents such as manganese, chromium, nickel, and other volatilized chemical species, and searching for ways to minimize exposure .
A large amount of effort has also been placed in the development of exhaust ventilation systems to remove the welding fumes. Some of these ventilation systems include extraction torches, local exhaust ventilation, and welding booths with built-in exhaust walls. In spite of these options, for practical or economic reasons, welding processes often occur in open spaces with no engineering controls, where nearby workers engaged in other tasks may also be exposed to the fumes. This situation may be particularly prevalent in construction or manufacturing facilities where workers in multiple stations share the same large, open work area. Although, in general, efforts are made to shield the arc and to protect nearby workers from ultraviolet light exposure, often little is done to contain and prevent exposure from the fumes. This results not only in exposure of the welder to the welding fumes, but also in secondhand exposure of nearby workers.