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In-depth survey report: control technology for dowel drilling in concrete.

Echt A; Mead K; Kovein R
Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, EPHB 347-14a, 2011 May; :1-24
Background: Workplace exposure to respirable crystalline silica can cause silicosis, a progressive lung disease marked by scarring and thickening of the lung tissue. Quartz is the most common form of crystalline silica. Crystalline silica is found in several construction materials, such as brick, block, mortar and concrete. Construction tasks that cut, break, grind, abrade, or drill those materials have been associated with overexposure to dust containing respirable crystalline silica. Highway construction tasks that can result in respirable crystalline silica exposures include breaking pavement with jackhammers, concrete sawing, milling pavement, cleanup using compressed air, and dowel drilling. Dowel drilling machines are used to drill horizontal holes in concrete pavement so that dowels can be inserted to transfer loads across pavement joints. NIOSH scientists are conducting a study to assess the effectiveness of dust control systems sold by dowel drill manufactures by measuring exposures to workers operating dowel drills with and without dust controls installed. This site visit was part of that study. Assessment: NIOSH staff visited the E&B Paving site at the Columbus, Indiana municipal airport on August 17, 24, and 25, 2010 and performed industrial hygiene sampling which measured exposures to respirable dust and respirable crystalline silica among two workers that operated dowel drills to drill holes in a new concrete runway. The NIOSH scientists also monitored the wind speed and direction at the site, and collected data about the work process in order to understand the conditions that led to the measured exposures. Results: Air sampling for respirable dust and crystalline silica showed that on two of the three days, both workers were exposed to respirable quartz at concentrations that exceeded the NIOSH Recommended Exposure Limit of 0.05 mg/m3. The air sampling also showed that on one day, both workers were exposed to respirable dust in excess of the OSHA Permissible Exposure Limit for respirable dust that contains greater than 1 percent quartz, and that one worker's exposure exceeded that limit on a second day (the OSHA Permissible Exposure Limit varies depending upon the percent quartz measured in the dust). Conclusions and Recommendations: The concentrations of respirable dust and respirable crystalline silica measured during dowel drilling indicated that the potential for overexposure exists when no dust controls are used. The measured exposures indicate that dust controls should be installed on the dowel-drilling machines. In the absence of dust controls, respirators should be used to reduce exposures. NIOSH recommends (and it is mandated by OSHA where the use of respirators is required) that respirators in the workplace be used as part of a comprehensive respiratory protection program. The program should include written standard operating procedures; workplace monitoring; hazard-based selection; fit-testing and training of the user; procedures for cleaning, disinfection, maintenance, and storage of reusable respirators; respirator inspection and program evaluation; medical qualification of the user; and the use of NIOSH-certified respirators.
Region-5; Control-technology; Engineering-controls; Construction; Construction-equipment; Construction-industry; Construction-materials; Construction-workers; Machine-operation; Machine-operators; Equipment-design; Equipment-operators; Respirable-dust; Dusts; Dust-collection; Dust-collectors; Dust-control; Dust-control-equipment; Control-equipment; Control-systems; Concretes; Road-construction; Road-surfacing; Hydraulic-equipment; Measurement-equipment; Silica-dusts; Silicosis; Quartz-dust; Respiratory-system-disorders; Lung-disease; Pulmonary-system-disorders; Lung-disorders; Exposure-assessment; Cutting-tools; Grinding-equipment; Air-quality-measurement; Air-sampling; Air-sampling-equipment; Sampling; Exposure-levels; Exposure-limits; Permissible-limits; Respirators; Hazardous-materials; Work-practices; Respiratory-protective-equipment; Emission-sources; Exhaust-ventilation; Ventilation-equipment; Airports; Author Keywords: Highway, Street, and Bridge Construction; silica; crystalline silica; dowel drill; concrete; respirable dust; rock drill
National Institute for Occupational Safety and Health, Division of Applied Research and Technology, Engineering and Physical Hazards Branch, Mail Stop R-5, 4676 Columbia Parkway, Cincinnati, OH 45226-1998
7631-86-9; 14808-60-7; 65997-15-1
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Field Studies; Control Technology
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National Institute for Occupational Safety and Health
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division