The environmental findings of a combined occupational hygiene and medical study of exposure to airborne contaminants from a welding process are reported. Twenty-five welders worked separately for 1 day each on similar tasks (assembling mild steel dock blocks, using general purpose rutile welding rods) in an enclosed area with 5-11 air changes per hour but without local extraction. Breathing zone samples of total fume and of respirable fume were taken by means of personal samplers with lapel-mounted sampling heads; air drawn from the breathing zone by pipeline was sampled for NOx, NO2, CO and O3 either by Draeger tube or by continuous recording instruments. Fume was also drawn from the breathing zone by a sampling line and a semi-quantitative continuous record obtained using a paper tape monitor.Total fume concentrations in the breathing zone exceeded the TLV on 19 of the 25 days, but the average concentrations of iron, zinc, manganese and copper did not exceed their respective TLVs. Average gas concentrations were well below the TLVs. Although the task and the working conditions were held steady, the exposure patterns were complex and variable. Fume concentrations both over working time and corrected to 8 h varied more than twenty-fold. The pattern of peak concentrations was also extremely variable. These variations were associeted with differences in work pattern and posture; some men worked continuously in the plume from the welding operation, others only occasionally entered it or always stayed clear. No single day or part of a day could have been sampled and taken to be representative of all days or all exposures. It is clear that occasional sampling of a few welders in a group may give little indication of long-term individual or group exposure. There is need for a simple, easily worn and reliable sampling package for measuring concentrations of gases and fume in the breathing zone of welders. © 1977 Copyright Controller HMSO, London.
