COMPARISON OF METALWORKING FLUID MIST EXPOSURES FROM MACHINING WITH DIFFERENT LEVELS OF MACHINE ENCLOSURE

This research investigated the efficacy of machine enclosures in reduc ing employee exposures to metalworking fluid mist. Four hundred fifty- five personal samples from automotive machining and grinding operation s collected over six years were divided into three groups based on the type and extent of enclosure and local exhaust ventilation. The sampl e groups were (1) machining equipment with original equipment manufact urer (OEM) total enclosures and local exhaust ventilation, (2) machini ng equipment with partial or retrofit enclosures and loca I exhaust ve ntilation, and (3) machining equipment with little or no enclosure. Th e results of the Mann Whitney U test of the three data sets indicated that the employees operating equipment with OEM enclosures had signifi cantly lower exposures than employees operating equipment that had eit her of the other two control methods. There was no difference between the exposures of operators of equipment with retrofit enclosures compa red to operators of equipment without enclosures. The median exposure for operators of equipment with OEM enclosures was 0.71 mg/m(3), about half that found with the other two control methods. Each of the data sets was compared to exposure criteria; 100% of the exposures associat ed with OEM enclosures were below 1.0 mg/m(3), and 900/a of the exposu res were below 0.5 mg/(3). The other two methods were not as effective as OEM in reducing exposure to below these criteria. These results in dicate that OEM enclosures provide the most effective control of metal working fluid mist exposure.