In-depth survey report: control technology for crystalline silica exposures in construction: exposures and preliminary control evaluation at various sites for Bricklayers Local #9, Pittsburgh, Pennsylvania.
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, ECTB 247-12, 2000 Feb; :1-21
Respirable silica exposures were measured while workers were using grinders to remove old mortar during a building renovation. Respirable silica exposures ranged from 1.0 to 3.0 mg/m3 grinding mortar, well in excess of the NIOSH Recommended Exposure Limit of 50 ug/m3. A preliminary evaluation of available engineering controls revealed that control measures ineffectively control the dust generation by the grinding operation. Control measure evaluated included two ventilated shrouds for grinding and the application of water to the grinding wheel. Testing on one ventilated shroud was terminated because dusty air, which was likely to contain and excessive amount of respirable crystalline silica, was emitted from the back of the grinder. A 30-minute exposure measurement resulted in a measured exposure of 9 mg/m3 of respirable crystalline silica. A commercially available grinder was tested which also emitted much dust. A wet grinding device resulted n a respirable dust concentration of 0.3 mg/m3 for a one hour sampling period. Apparently, wet grinding can suppress dust emissions. However, the use of water wit an electric grinder raises concerns about electrical shock hazards for the operator.
Region-3; Respirable-crystalline-silica; Particulates; Dust-exposure-evaluation; Respirator-fit-testing; Wet-grinder
Field Studies; Control Technology
NTIS Accession No.
National Institute for Occupational Safety and Health