title: Physicochemical Characterization of Aerosol Generated in the Gas Tungsten Arc Welding of Stainless Steel.
abstract: OBJECTIVE
  Exposure to stainless steel (SS) welding aerosol that contain toxic heavy metals, chromium (Cr), manganese (Mn), and nickel (Ni), has been associated with numerous adverse health effects. The gas tungsten arc welding (GTAW) is commonly applied to SS and produces high number concentration of substantially smaller particles compared with the other welding techniques, although the mass emission rate is low. Here, a field study in a workshop with the GTAW as principal welding technique was conducted to determine the physicochemical properties of the airborne particles and to improve the understanding of the hazard the SS welding aerosols pose to welders.
  
  
  METHODS
  Particle number concentration and number size distribution were measured near the breathing zone (50cm from the arc) and in the middle of the workshop with condensation particle counters and electrical mobility particle sizers, respectively. Particle morphology and chemical composition were studied using scanning and transmission electron microscopy and energy-dispersive X-ray spectroscopy.
  
  
  RESULTS
  In the middle of the workshop, the number size distribution was unimodal with the geometric mean diameter (GMD) of 46nm. Near the breathing zone the number size distribution was multimodal, and the GMDs of the modes were in the range of 10-30nm. Two different agglomerate types existed near the breathing zone. The first type consisted of iron oxide primary particles with size up to 40nm and variable amounts of Cr, Mn, and Ni replacing iron in the structure. The second type consisted of very small primary particles and contained increased proportion of Ni compared to the proportion of (Cr + Mn) than the first agglomerate type.
  
  
  CONCLUSIONS
  The alterations in the distribution of Ni between different welding aerosol particles have not been reported previously.
authors.affiliation: 1.Fine Particle and Aerosol Technology Laboratory, Department of Environmental and Biological Sciences, University of Eastern Finland, PO Box 1627, 70211 Kuopio, Finland; mirella.miettinen@uef.fi.
authors.forename: Mirella
authors.initials: M
authors.lastname: Miettinen
authors.affiliation: 1.Fine Particle and Aerosol Technology Laboratory, Department of Environmental and Biological Sciences, University of Eastern Finland, PO Box 1627, 70211 Kuopio, Finland;
authors.forename: Tiina
authors.initials: T
authors.lastname: Torvela
authors.affiliation: 2.SIB Labs, University of Eastern Finland, PO Box 1627, 70211 Kuopio, Finland.
authors.forename: Jari T T
authors.initials: JT
authors.lastname: Leskinen
mesh_terms: D000336:Aerosols / Q000009:adverse effects / Q000032:analysis* / Q000737:chemistry; D000395:Air Pollutants, Occupational / Q000009:adverse effects / Q000032:analysis; D000075322:Heavy Metal Poisoning; D006801:Humans; D019570:Inhalation Exposure / Q000032:analysis; D053758:Nanoparticles; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis*; D010316:Particle Size; D011041:Poisoning; D013193:Stainless Steel / Q000032:analysis* / Q000737:chemistry; D014414:Tungsten / Q000032:analysis; D014896:Welding / Q000295:instrumentation / Q000379:methods*
chemical_list: D000336:Aerosols; D000395:Air Pollutants, Occupational; D013193:Stainless Steel; D014414:Tungsten
keywords: chemical composition; morphology; nanoparticles; occupational exposure; transmission electron microscopy; tungsten inert gas (TIG) welding; workplace air