which exceed the assigned protection factor for the typical type of respirator (half-face elastomeric or filtering face-piece) used by the workers at the sites visited. As part of the study, NIOSH identified seven primary points of dust generation and developed control recommendations that included both passive and active controls. The NIOSH team also described nine possible interventions to control dust, including

  • consideration of Prevention through Design2 on future versions of sand moving equipment that has built in dust control;
  • use of remote operations to keep workers out of areas of high dust concentrations;
  • substitution of sand with ceramic or other proppant materials;
  • installation of active controls such as the NIOSH-designed minibaghouse retrofit assembly (technology to reduce amount of dust released), over the thief hatches (access ports over sand movers), and consideration of enclosed sand transport mechanism such as a screw augur retrofit assembly to replace belt transport of sand;
  • use of enclosures around bottoms of sand movers (such as stilling or staging curtains) and the dragon tail (end of the sand belt) on sand movers;
  • minimizing the distance that sand falls from the dragon tail;
  • use of end caps on fill nozzles on sand movers;
  • use of amended water for dust control on site; and
  • implementing an effective respiratory protection program.

Mr. Esswein reiterated that NIOSH determined that respirable crystalline silica is a significant occupational health hazard associated with hydraulic fracturing; diesel particulate is also a likely occupational health hazard.

Discussion

Following the presentation from Mr. Esswein, Roundtable members started the discussion by asking about silica exposures at mines during the loading and unloading of trucks. Mr. Esswein noted that NIOSH’s assessment was limited to evaluating exposures only at oil and gas sites, not any further upstream. Nsedu Witherspoon inquired about exposures to pregnant workers and Mr. Esswein replied that he only saw two female oil and gas workers, and the NIOSH team did not evaluate their exposures. Bernard Goldstein asked about a 2008 article showing an increase in injuries per shale gas well and asked about the status of injuries. Dr. Goldstein went on to comment on integrating workers’ health and

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2 Prevention through Design is a NIOSH-led effort to address occupational safety and health needs in the design process to prevent or minimize the workrelated hazards and risks (http://www.cdc.gov/niosh/topics/ptd [accessed May 30, 2013]).



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