Estimation of regional pulmonary deposition and exposure for fumes from SMAW and GMAW mild and stainless steel consumables.

The particle size distributions and bulk fume densities for mild steel and stainless steel welding fumes generated using two welding processes (shielded metal arc welding [SMAW] and gas metal arc welding [GMAW]) were used in mathematical models to estimate regional pulmonary deposition (the fraction of each fume expected to deposit in each region of the pulmonary system) and regional pulmonary exposure (the fraction of each fume expected to penetrate to each pulmonary region and would be collected by a particle size-selective sampling device). Total lung deposition for GMAW fumes was estimated at 60% greater than that of SMAW fumes. Considering both the potential for deposition and the fume specific surface areas, it is likely that for equal exposure concentrations GMAW fumes deliver nearly three times the particle surface area to the lungs as SMAW fumes. This leads to the hypothesis that exposure to GMAW fumes constitutes a greater pulmonary hazard than equal exposure to SMAW fumes. The implications of this hypothesis regarding the design of future health studies of welders is discussed.