In-Depth Survey Report: Engineering Control of Silica Dust from Stone Countertop Fabrication and Installation [Stone Systems of Houston]

Details

• Personal Author:
  Echt, Alan S. ; Qi, Chaolong
• Corporate Authors:
  National Institute for Occupational Safety and Health. Division of Applied Research and Technology
• Description:
  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 materials, such as brick, block, mortar and concrete. Construction and manufacturing tasks that cut, break, grind, abrade, or drill those materials have been associated with overexposure to dust containing respirable crystalline silica. Stone countertop products can contain >90% crystalline silica and working with this material during stone countertop fabrication and installation has been shown to cause excessive exposures to respirable crystalline silica. NIOSH scientists are conducting a study to develop engineering control recommendations for respirable crystalline silica from stone countertop fabrication and installation. This site visit was part of that study. Assessment: NIOSH scientists visited the Stone Systems of Houston, TX on August 11-13, 2015. During the site visit, they performed industrial hygiene sampling which measured the short term task-based exposures to respirable dust and respirable crystalline silica of five workers who used handheld tools in the stone countertop fabrication process. The evaluated work tasks predominantly included polishing (i.e. "Polishers"), grinding (i.e. "Grinders") and surface lamination (i.e. "Laminators"). An engineering control measure that supplied water to the tools to suppress the dust at its source was used throughout the fabrication process. The NIOSH scientists also recorded detailed survey notes about the work process in order to understand the conditions that led to the measured exposures. Results: Air sampling for respirable crystalline silica showed that the short term respirable crystalline silica exposures ranged from 27.1 to 142.6 ug/m3 for the Polishers, and from 57.8 to 450.8 ug/m3 for the Grinders. The mean short term respirable crystalline silica exposures were 62.2 and 159.4 ug/m3 for Polishers and Grinders, respectively. It is apparent that the Grinders experienced considerably higher exposures than the Polishers. Excluding two outlier sampling periods, the Laminator's short term respirable crystalline silica exposure ranged from 48.0 to 119.0 ug/m3 with a mean of 90.8 ug/m3. However, the two outlier samples revealed that the Laminator experienced high exposures to respirable crystalline silica when performing the tasks of cleaning and drying the stones with compressed air, and initial grinding. The Grinders' respirable crystalline silica exposures were significantly higher than the Polishers' (p=0.0004). Conclusions and Recommendations: The results from the task-based samples in this survey revealed that wet grinding and wet polishing both granite and engineered quartz stone may still lead to overexposure to respirable crystalline silica. The exposure levels for wet grinding were especially concerning. Using a larger amount of water through a center water feed for the grinders may be the first choice for a future test of control technologies. Additional engineering control measures will be needed for these tasks to reduce the exposure to levels consistently below the NIOSH Recommended Exposure Limit (REL). Alternative ways of cleaning and drying stone countertops other than using compressed air need to be considered and implemented. In the absence of sufficient dust controls, respirators should continue to be used to reduce exposures, and the employer needs to make sure that the respiratory protection program follows the OSHA standard.
• Subjects:
  Construction Industry Construction Materials Dust Engineering Occupational Health Quartz Respiratory Protective Devices Safety Silicon Dioxide
• Keywords:
  Construction Construction Materials Construction Workers Control Technology Cut Stone And Stone Product Manufacturing Dust Control Dust Exposure Engineering Control Engineering Controls Humans Quartz Dust Respirable Crystalline Silica Respirable Dust Respirators Respiratory Protection Respiratory Protective Equipment Silica Silica Dusts Stone Countertop Stone Processing Stone Products

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• Series:
  Engineering and Physical Hazards Survey Reports
• DOI:
  https://doi.org/10.26616/NIOSHEPHB37511a
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Name as Subject:
  Stone Systems of Houston
• Genre:
  Field Study
• Place as Subject:
  Texas ; Houston (TX) ; OSHA Region 6
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  DART - Division of Applied Research and Technology ; EPHB - Engineering and Physical Hazards Branch
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-22
• NIOSHTIC Number:
  nn:20047713
• NTIS Accession Number:
  PB2016-102825
• Citation:
  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 375-11a, 2016 Mar ; :1-22
• CAS Registry Number:
  Quartz (SiO2) (CAS RN 14808-60-7)
• Federal Fiscal Year:
  2016
• Peer Reviewed:
  False
• NAICS and SIC Codes:
  327991 - Cut Stone and Stone Product Manufacturing - (NAICS)
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:f3c426444904ee981fccd529b3f665af8172454c5ace99c9448db89dd40769bad0b2d29ea7be7ce3a7ce3458eeac294095a36efdfb9b423ea27451b253db8f21
• Download URL:
  https://stacks.cdc.gov/view/cdc/175031/cdc_175031_DS1.pdf
• File Type:
  [PDF - 4.62 MB ]