Application of End-of-Shift Respirable Crystalline Silica Monitoring to Construction

Details

• Journal Article:
  Application of end-of-shift respirable crystalline silica monitoring to construction
• Personal Author:
  Harper, Martin ; Wu, Chang-Yu ; Chien, Chih-Hsiang
• Description:
  A pilot project was conducted to determine the effect of common construction dusts as interferences in a new portable end-of-shift (EoS), direct-on-filter (DoF) sampling and analysis method for respirable crystalline silica (RCS), in this case quartz. The sampling and analysis system was developed by the Pittsburgh Mining Research Division of the National Institute for Occupational Safety and Health (NIOSH) for mineral dusts containing quartz in the mining environment. NIOSH provided training at their site for the investigators in this project. Construction dusts were prepared from plaster, drywall, cement and brick by grinding bulk materials to dust, aerosolizing the dust, and collecting the respirable fraction with high flow-rate respirable cyclones. Laboratory samples were generated by loading filters with different levels of commercial a-quartz powder (Min-u-Sil 5), and different levels of the interfering dusts, singly and in combination. Samples were analyzed by the EoS-DoF FTIR procedure and some samples then sent for confirmatory x-ray diffraction (XRD) analysis at Maxxam Laboratory. Although the results of this study show promise for future research, this pilot project does not reach a comprehensive conclusion regarding the suitability of the DoF-EoS FTIR procedure for RCS in construction dust in part because of two unexpected issues which arose during this study. Both issues were investigated and are important considerations for any future study. First, the two Certified Reference Materials (CRMs) from the National Institute of Standards and Technology (NIST), 1878a and 1878b, appear to give different results when used to calibrate XRD analysis of Min-u-Sil 5. This issue will require careful future study and may lead to authoritative recommendations regarding the use of these CRMs by researchers and commercial analytical laboratories. Second, attempting to apply materials in sequence to a filter gave poor variance in results, and a procedure using a single mixture addition was able to give much tighter variance and results more consistent with expectations. Unfortunately, resources available under the project did not allow the XRD analysis of this second sample set, although the samples have been retained in case resources become available in the future. The results from this second set of prepared samples and FTIR analyses were sent to NIOSH for statistical analysis. The results show that a) plaster and drywall dusts do not interfere substantially with the quartz measurement; b) cement does not interfere with the quartz measurement, but it does change the background absorbance of the filter; and c) in addition to having a substantial quartz content that has to be carefully evaluated in any study, brick dust may also contain an additional material, probably a silicate mineral, which interferes additionally with the quartz peak. In other words, the presence of cement leads to lower quartz values and brick leads to higher values. Overall, 83% of the quartz contents predicted from the averaged calibration data agreed within 50% of the adjusted nominal loadings. This result is encouraging given the high levels of interfering dusts. Samples loaded with smaller amounts of all four dusts in combination gave even better results, with all nine results within 25% of the adjusted nominal loadings. Both cement and brick could be correctable interferences once the identity of the interference is revealed, in the same way that correction is made for interfering mineral dusts in mines, and this is one of the further investigations suggested by this study. It also is important to further investigate the extent of the difference in XRD results from using NIST 1878a or NIST 1878b as the XRD calibration standards. A manuscript detailing the experience and results, as well as recommendations for further work has been accepted for publication. [Description provided by NIOSH]
• Subjects:
  Construction Industry Dust Occupational Health Quartz Safety Silicon Dioxide
• Keywords:
  Construction industry; Respirable dust; Silica dusts; Sampling methods; Analytical processes; Quartz dust; X-ray diffraction
• Source:
  Silver Spring, MD: CPWR-The Center for Construction Research and Training, 2020 Jun; :1-24
• Publisher:
  CPWR-The Center for Construction Research and Training
• Document Type:
  Text
• Funding:
  Production of this document was supported by cooperative agreement OH 009762 from the National Institute for Occupational Safety and Health (NIOSH)
• Genre:
  Report
• Place as Subject:
  Florida ; Maryland ; OSHA Region 3 ; OSHA Region 4
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  29 pdf pages
• NIOSHTIC Number:
  nn:20067607
• CAS Registry Number:
  Quartz (SiO2) (CAS RN 14808-60-7)
• Federal Fiscal Year:
  2020
• Performing Organization:
  CPWR - The Center for Construction Research and Training, Silver Spring, Maryland
• Peer Reviewed:
  False
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:25259b5594d6802966fadf2b20b5bdc05e7fd43c4351af76360b3b0f1582e4f97451e51ceb966cb4b1aa034ec109540ad752be2c9bd9c2df0e2cf9c102f1fafc
• Download URL:
  https://stacks.cdc.gov/view/cdc/147780/cdc_147780_DS1.pdf
• File Type:
  [PDF - 1.45 MB ]