to each activity. A separate chart in Fig. 6 demon- strates the overall exposure during the same activities. In these figures, use of the cup grinder was noted to provide the highest expo- sure percentage relative to time, followed closely by the cone grinder. During a root cause
evaluation, detailed notes are collected from mul- tiple variables, including the specific positioning of the tools. Because of this, the data collected during cup and cone grinding can be broken down further, yielding information, for example, on specific cup grinding activities (Fig. 7). Tis investigation
Fig. 6. This pie graph shows the percentage of exposure (dust weight) per task during monitored chipping/grinding work.
in defining the inherent limitations of ventilation methods to fully protect workers from exposure. Tese findings also could provide direction for research and develop- ment efforts to improve the effectiveness of engineering measures to control exposures to air contaminants. Real-time exposure data also is used effec- tively as part of worker training programs. Workers can see from the real-time graphical data the impact specific work practices have on preventing spikes of elevated exposure.
shows that cup grinding on the top of the casting contributed a substantial portion of the employee’s exposure during use of the cup grinder. It was visually observed during the assessment that, when the cup grinder was used on the upper portions of the casting (the top and the upper edge), the grinding swarf produced often was not directed in an effective manner at the exhaust hood. Tis was due to the grinding surface of the cup grinder rotating on the casting surface being cleaned, dispersing the grinding swarf in all directions. Additionally, the exhaust of this tool was observed to disperse grinding dust in all directions. Subsequent engineering and work
Fig. 7. The graph shows the focused breakdown of measured exposure during specific tool use (cup grinder).
Tis article is based on paper 14-035 published in the 2014 AFS Transactions and presented at the 2014 AFS Environmental, Health and Safety Conference in Atlanta. Te AFS Transac- tions paper is an original work whose genesis was in the collaboration over many years between Eric Pylkas and Bob Scholz working together in TRC Environ- mental Corp.’s (formerly RMT, Inc.’s) industrial consultative effort in the field of health and safety.
While the collection of eight-
practice controls can be implemented with a defined goal of reducing expo- sure during specific tasks that have been shown to contribute significantly to overall exposure. Additionally, the real-time data can serve effectively as a baseline exposure to establish a metric by which to compare the effectiveness of implemented controls.
hour TWA compliance samples is well-suited for determining if work exposures are in compliance with OSHA standards, real-time exposure monitoring allows for a compre- hensive root cause analysis that can lead to effective and cost-efficient actions to lower worker exposures to air contaminants, such as respirable crystalline silica. Analysis of real-time exposure sampling data, as in the example of manually chipping and grinding castings with portable tools, can assist
ONLINE RESOURCE
OSHA is expected to present its pro- posed rule to reduce the permissible exposure limit to silica to the U.S. Office of Management & Budget in 2015. It reduces the respirable crystalline silica PEL from 100 to 50 µg/cu.m. A Silica Task Force created by the American Foundry Society (AFS) has been direct- ing the industry’s comments and discus- sions with OSHA in response to the agency’s proposed silica standard. Read more at
www.moderncasting.com and
www.afsinc.org/silica.
December 2014 MODERN CASTING | 37
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