| Description |
In the exposure history of a welder, two important questions are, "What do you weld on?" and "Do you weld in a confined space?" The most commonly used welding processes are shielded metal arc (stick welding), metal inert gas (MIG welding), tungsten inert gas (TIG welding), oxy-fuel welding, and submerged welding. In stick welding, the shielding gas evolves from the flux coating of the electrode; in MIG and TIG welding, the inert gas is provided directly. The most commonly welded metals are mild steel, stainless steel, and aluminum. Stick welding on stainless steel produces higher hexavalent chromium exposure than MIG or TIG welding. Welders are at increased risk for the following acute conditions: pulmonary edema from welding in a confined space; photokeratitis of the eyes from UV exposure; and metal fume fever from welding copper or zinc coated metals. [Burgess, p. 167-204] Welding fume comes mainly from the filler metal and flux (if used); the contribution of the parent metal is relatively minor. Coatings on the surface of the parent metal may be significant inhalation hazards. [Hendrick, p. 470] Stick welding is the preferred method in the construction industry; it is less sensitive to the wind than MIG or TIG welding. [PMID 17963139] Advantages of stick welding: welding in all positions; inexpensive; and can be performed by unskilled welders. [PMID 12645092] Most welding is on mild steel. About 5-20% is on stainless steel. A few percent is on aluminum and other metals. Welding fume is classified as a possible human carcinogen. [IARC] The welder may be exposed to dangerous concentrations of cadmium fume, phosgene, nitrogen dioxide, and ozone. Each of these four agents can cause delayed pulmonary edema. See OSHA Technical Links: http://www.osha.gov/SLTC/weldingcuttingbrazing/index.html. |
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