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In-Depth Survey Report: Mixing Mortar
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2017/04/01
[PDF-598.54 KB]
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Alternative Title:In-Depth Survey Report: Mixing Mortar, International Union of Bricklayers and Allied Craftworkers Southern Ohio-Kentucky Regional Training Center, Batavia, Ohio
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Description:Background: This is the report of a field study to evaluate respirable dust and respirable crystalline silica exposures associated with the task of mixing mortar. In data presented in the Preliminary Economic Analysis for the Notice of Proposed Rulemaking for Occupational Exposure to Crystalline Silica [OSHA 2013], two results of less than the limit of detection (12 microg/m3) and 18 microg/m3 were reported for workers who primarily mixed fresh mortar and delivered it to other bricklayers. However, anecdotal reports from bricklayers indicated that the task could be dusty. This study was conducted to collect additional exposure data on mortar mixing. Assessment: Task-based personal breathing zone and area air samples for respirable dust and respirable crystalline silica were collected while an apprentice bricklayer and instructors at the training center cleaned the mixer and while the apprentice bricklayer mixed a batch of lime mortar and a batch of type N mortar. Results: In samples collected over 12 to 17 minutes, personal breathing zone sampling results for quartz ranged from less than the limit of detection while the mixer was cleaned to 0.11 mg/m3 while lime mortar was mixed. That result is a value between the limit of detection and the limit of quantitation, which is considered a trace amount with limited confidence in its accuracy. Personal breathing zone results for respirable dust ranged from less than the limit of detection when Type N mortar was mixed to 7.8 mg/m3 while the mixer was cleaned. Conclusions and Recommendations: Mixing either lime mortar or Type N mortar for eight or more hours a day could generate sufficient worker exposure to require the use of an air purifying respirator that is at least as protective as a filtering facepiece respirator or half-mask respirator with N-95 filters. The respirator user must be trained and fit-tested, and the respirator must be used as part of a comprehensive respiratory protection program in accordance with the OSHA silica standard [81 Fed. Reg. 16285 (2016)]. Air sampling to characterize full-shift exposures to mortar mixing with a variety of mixes and mixing technology would determine the extent to which mortar mixing on job sites is a concern and if engineering controls should be developed for mortar mixers.
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DOI:10.26616/NIOSHEPHB35818a
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Pages in Document:1-10
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NIOSHTIC Number:20049946
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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 358-18a, 2017 Apr; :1-10
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Federal Fiscal Year:2017
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Peer Reviewed:False
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Resource Number:EPHB-358-18a
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