Worker exposures to total chromium, hexavalent chromium (VI), sulfuric acid and alkaline dust at electroplating operations and worker exposures to trichloroethylene (TCE) and methyl chloroform (MCM) at degreasing operations in eleven small industrial plants were evaluated. Appropriate local exhaust ventilation systems for both operations were designed and recommended.
Results of the study are summarized as follows ;
1. Out of 134 measurements for airborne hexavalent chromium concentrations, seven were exceeding the Korean occupational health standard of 50 ㎍/㎥ and 45 were exceeding the NIOSH standard of I ㎍/㎥. With an exception of one measurement, concentrations of total chromium were below the Korean standard of 500 ㎍/㎥.
2. Worker exposures to chromium were closely related to the existing control methods at the electroplating operations. Local exhaust systems, partial coverage of the tank surface, and antifoaming agents on liquid surface were adopted as control methods.
3. With an exception of one sample, airborne concentrations of sulfuric acid and alkaline dusts were below the applicable occupational health standards.
4. Three plants indicated that airborne concentrations of TCE and MCM were exceeding the Korean standards. Other plants showed lower concentrations than the standards. It should be noted that, generally, the activities and workloads on the day of surveys were less than normal.
5. Since the most existing ventilation systems did not satisfy the ACGIH criteria, the ventilation systems should be improved. Some examples for designing appropriate ventilation systems are presented.
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