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Respirable silica dust suppression during artificial stone countertop cutting.

Cooper-JH; Johnson-DL; Phillips-ML
Ann Occup Hyg 2015 Jan; 59(1):122-126
Purpose: To assess the relative efficacy of three types of controls in reducing respirable silica exposure during artificial stone countertop cutting with a handheld circular saw. Approach: A handheld worm drive circular saw equipped with a diamond segmented blade was fitted with water supply to wet the blade as is typical. The normal wetted-blade condition was compared to (i) wetted-blade plus 'water curtain' spray and (ii) wetted-blade plus local exhaust ventilation (LEV). Four replicate 30-min trials of 6-mm deep, 3-mm wide cuts in artificial quartz countertop stone were conducted at each condition in a 24-m3 unventilated tent. One dry cutting trial was also conducted for comparison. Respirable cyclone breathing zone samples were collected on the saw operator and analyzed gravimetrically for respirable mass and by X-ray diffraction for respirable quartz mass. Results: Mean quartz content of the respirable dust was 58.5%. The ranges of 30-min mass and quartz task concentrations in mg m-3 were as follows - wet blade alone: 3.54-7.51 and 1.87-4.85; wet blade + curtain: 1.81-5.97 and 0.92-3.41; and wet blade + LEV: 0.20-0.69 and <0.12-0.20. Dry cutting task concentrations were 69.6mg m-3 mass and 44.6mg m-3 quartz. There was a statistically significant difference (a = 0.05) between the wet blade + LEV and wet blade only conditions, but not between the wet blade + curtain and wet blade only conditions, for both respirable dust and respirable silica. Conclusions: Sawing with a wetted blade plus LEV reduced mean respirable dust and quartz task exposures by a factor of 10 compared to the wet blade only condition. We were unable to show a statistically significant benefit of a water curtain in the ejection path, but the data suggested some respirable dust suppression.
Silica-dusts; Respirable-dust; Stone-processing; Quartz-dust; Dust-control; Dust-exposure; Control-methods; Engineering-controls; Control-technology; Author Keywords: countertop cutting; engineering controls; respirable silica
David L. Johnson, Department of Occupational and Environmental Health, University of Oklahoma College of Public Health, 801 NE 13th Street, Oklahoma City, OK 73104, USA
7631-86-9; 14808-60-7
Publication Date
Document Type
Journal Article
Email Address
Funding Type
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-T01-OH-008614; M102014
Issue of Publication
Source Name
Annals of Occupational Hygiene
Performing Organization
University of Oklahoma Health Sciences Center - Oklahoma City