title: Respirable silica dust suppression during artificial stone countertop cutting.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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-m(3) 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 69.6 mg m(-3) mass and 44.6 mg m(-3) quartz. There was a statistically significant difference (α = 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.
authors.affiliation: Department of Occupational and Environmental Health, University of Oklahoma College of Public Health, 801 NE 13th Street, Oklahoma City, OK 73104, USA.
authors.forename: Jared H
authors.initials: JH
authors.lastname: Cooper
authors.affiliation: Department of Occupational and Environmental Health, University of Oklahoma College of Public Health, 801 NE 13th Street, Oklahoma City, OK 73104, USA David-Johnson@ouhsc.edu.
authors.forename: David L
authors.initials: DL
authors.lastname: Johnson
authors.affiliation: Department of Occupational and Environmental Health, University of Oklahoma College of Public Health, 801 NE 13th Street, Oklahoma City, OK 73104, USA.
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Phillips
mesh_terms: D000395:Air Pollutants, Occupational / Q000032:analysis; D003252:Construction Materials; D004391:Dust / Q000032:analysis*; D004867:Equipment Design; D006801:Humans; D019570:Inhalation Exposure / Q000032:analysis / Q000517:prevention & control*; D016273:Occupational Exposure / Q000517:prevention & control*; D011791:Quartz / Q000032:analysis; D012822:Silicon Dioxide / Q000032:analysis*; D014691:Ventilation; D014867:Water
chemical_list: D000395:Air Pollutants, Occupational; D004391:Dust; D014867:Water; D011791:Quartz; D012822:Silicon Dioxide
keywords: countertop cutting; engineering controls; respirable silica