Workplace exposure to submicron particle mass and number concentrations from manual arc welding of carbon steel.
Stephenson-D; Seshadri-G; Veranth-JM
Am Ind Hyg Assoc J 2003 Jul/Aug; 64(4):516-521
Particle emissions from manual shielded metal arc welding of carbon steel were sampled in a typical industrial maintenance and metal fabrication workplace environment. Particle number measurements over the size range from 14 nm to 10 microm using a scanning mobility particle sizer and an optical particle counter showed that welding produced an approximately lognormal particle mode with a 120 nm count median and a geometric standard deviation of 2.07. This study produced welding particle number concentrations on the order of 2 x 10(5)/cm(3) in the building air 8.5 m away from the welding. Workplace exposure samples were below the current 8-hour American Conference of Governmental Industrial Hygienists mass concentration threshold limit value of 5 mg/m(3). Submicron particles comprised 80% of the total aerosol mass collected by a cascade impactor during welding. The concentration of larger particles was indistinguishable from indoor background. Microscopy showed that the welding emissions are dominated by clusters formed from <0.1 microm primary spheres. These data on the particles resulting from aerosol transformation by natural dilution inside an industrial building can be compared with laboratory-scale studies of welding particulate. The particle number characteristics observed in this study are significant because toxicological hypotheses suggest that number or surface area may be a better metric than mass when evaluating the health effects of fine particles.
Arc-welding; Particulates; Metals; Welding; Steelworkers; Metal-workers; Metal-industry-workers; Industrial-exposures; Industrial-factory-workers; Industrial-emissions; Fabricated-plate-work; Particle-counters; Toxic-materials; Threshold-limit-values; Arc-welders; Nanotechnology;
Author Keywords: electron microscopy; occupational exposure; particle number; SMAW; welding
D. Stephenson, University of Utah, Rocky Mountain Center for Occupational and Environmental Health, 75 South 2000 East, Salt Lake City, UT 84112-5120
American Industrial Hygiene Association Journal
Rocky Mountain Center for Occupational and Environmental Health, Department of Family & Preventive Medicine, University of Utah, Salt Lake City, Utah