Hazard of ultraviolet radiation emitted in gas tungsten arc welding of aluminum alloys

Ultraviolet radiation (UVR) emitted during arc welding frequently causeskeratoconjunctivitis and erythema. The extent of the hazard of UVR varies depending on thewelding method and conditions. Therefore, it is important to identify the levels of UVRthat are present under various conditions. In this study, we experimentally evaluated thehazard of UVR emitted in gas tungsten arc welding (GTAW) of aluminum alloys. The degree ofhazard of UVR is measured by the effective irradiance defined in the American Conferenceof Governmental Industrial Hygienists guidelines. The effective irradiances measured inthis study are in the range 0.10–0.91 mW/cm² at a distance of 500 mm from thewelding arc. The maximum allowable exposure times corresponding to these levels are only3.3–33 s/day. This demonstrates that unprotected exposure to UVR emitted by GTAW ofaluminum alloys is quite hazardous in practice. In addition, we found the followingproperties of the hazard of UVR. (1) It is more hazardous at higher welding currents thanat lower welding currents. (2) It is more hazardous when magnesium is included in thewelding materials than when it is not. (3) The hazard depends on the direction of emissionfrom the arc.