mg/m3). In plant C, considerably higher concentra-'
tions of fumes were found in the welders' breathing
zone (mean 3-5 mg/m3; range 1 0-9 1 mg/m3) than in
that ofthe welders' assistants (mean 0-8 mg/m3; range
0 2-1 9 mg/m3) who only occasionally stayed at the
welding posts. Mean fume concentrations in plants B
and D amounted to 3 2 mg/m3 and 1-3 mg/m3
respectively.