Late last week, federal officials from the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH)1 issued a hazard alert on Worker Exposure to Silica during Hydraulic Fracturing (Hazard Alert) identifying exposure to airborne respirable crystalline silica (silica) as a potential health hazard to workers conducting hydraulic fracturing operations.
The Hazard Alert follows results from a NIOSH Field Effort to Assess Chemical Exposures to Oil and Gas Extraction Workers (NIOSH Field Study),2 in which OSHA and NIOSH, along with oil and gas industry partners, have been investigating worker safety and health hazards in oil and gas extraction for more than two years. Exposure to silica, in the form of frac sand, during hydraulic fracturing has been the focus of the NIOSH Field Study to date. Excessive inhalation of silica can cause silicosis, an incurable, but preventable, lung disease.
Sources of Silica Dust
The NIOSH Field Study identified seven primary sources of silica dust exposure during hydraulic fracturing operations:
Dust ejected from thief hatches (access ports) on top of the sand movers during refilling operations while the machines are running (hot loading); Dust ejected and pulsed through open side fill ports on the sand movers during refilling operations; Dust generated by on-site vehicle traffic; Dust released from the transfer belt under the sand movers; Dust created as sand drops into, or is agitated in, the blender hopper and on transfer belts; Dust released from operations of transfer belts between the sand mover and the blender; and Dust released from the top of the end of the sand transfer belt (dragon's tail) on sand movers. NIOSH Findings
In cooperation with its industry partners, NIOSH collected 116 full shift air samples at 11 hydraulic fracturing sites in five states (Arkansas, Colorado, North Dakota, Pennsylvania, and Texas). Of the 116 samples collected, NIOSH determined that:
47 percent showed silica exposures greater than the calculated OSHA PEL.3 79 percent showed silica exposures greater than the NIOSH REL.4 9 percent of all samples showed silica exposures 10 or more times the PEL, with one sample more than 25 times the PEL. 31 percent of all samples showed silica exposures 10 or more times the REL, with one sample more than 100 times the REL. Based on these results, NIOSH concluded that an inhalation health hazard existed for workers...