Evaluation of silica exposures during dowel drilling
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Evaluation of silica exposures during dowel drilling

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    "Management from a dowel drilling company requested a NIOSH health hazard evaluation (HHE) concerning employee exposure to respirable crystalline silica during dowel drilling activities. Dowel drilling is one step in the process of repairing a road. The work on this HHE took place on a state road construction site. During our visit, we observed work processes and work practices, estimated the amount of water used to control dust, collected air samples for respirable crystalline silica and respirable dust, and collected bulk samples of the slurry produced from drilling to determine its silica content. Our air sampling showed that the drill rig operation led to concentrations of respirable crystalline silica above relevant occupational exposure limits; however, the drill rig operator was wearing appropriate respiratory protection. Concentrations of respirable dust were below relevant occupational exposure limits for all samples. The slurry bulk samples contained 10%-13% quartz. The drill rig operator was required to wear a respirator, but there was no written respiratory protection program, medical clearance, or annual respiratory training. However, the respirator was put on and taken off correctly, cleaned after each shift, and stored appropriately. Other health and safety issues we identified during our evaluation included leaving the slurry and dust on the drill rig to dry overnight, high visibility vests not being used consistently, stepping into the live traffic lane while filling and covering patches, and not having enough vehicle spacing in between crews. We recommended developing a written respiratory protection program, sending drill rig operators for medical respirator clearance, and providing employees training about respirator use and maintenance. We also made recommendations to address other health and safety issues we identified during our evaluation." - NIOSHTIC-2

    NIOSHTC no. 20058426

    Recommended citation: NIOSH [2019]. Evaluation of silica exposures during dowel drilling. By Grant MP. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Health Hazard Evaluation Report 2019- 0178-3368, https://www.cdc.gov/niosh/hhe/reports/pdfs/2019-0178-3368.pdf.


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