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.
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 exposed to respirable crystalline silica at the evaluated sites.
In addition to silica hazards, the Hazard Alert identifies a number of additional safety hazards during hydraulic fracturing, including being struck by moving equipment, poor lighting, being caught in pinch points, falling from heights, being struck by high-pressure lines, fires or explosions, and working in confined spaces.
The Hazard Alert advances a number of measures to protect workers from exposure to silica, including a combination of engineering controls, work practices, protective equipment, training, and even product substitution. The Hazard Alert identifies short-term work practices and procedural changes that can be implemented quickly, including:
- Mandating the capping of unused fill ports (e.g., cam lock caps) on sand movers;
- Reducing the drop height between the sand transfer belt and T-belts and blender hoppers;
- Limiting the number of workers, and the time workers must spend in areas where dust and silica levels may be elevated, and consider ways to perform dusty operations remotely to completely remove employees from these areas; and
- Applying fresh water to roads and around the well site to reduce the dust.
The Hazard Alert recommends additional control options for hydraulic fracturing operations involving equipment changes as follows:
- Enclosing points where dust is released;
- Where possible, using enclosed cabs or booths;
- Using local exhaust ventilation to collect silica-containing dusts and prevent dust escape; and
- Replacing transfer belts with screw augers on sand movers in new designs or retrofits.
When engineering and work practice controls are not feasible or when they do not reduce silica exposures below OSHA PELs, the Hazard Alert directs employers to provide workers with respirators. Likewise, monitoring of the air at the active worksite is identified as an important way to assess which workers or worker tasks may result in exposure to excessive levels of respirable crystalline silica.
What This Means to You
The Hazard Alert is not a standard or a regulation, and it creates no new legal obligations. The General Duty Clause of the Occupational Safety and Health (OSH) Act, however, requires employers to provide their employees with a workplace free from recognized hazards likely to cause death or serious physical harm. NIOSH made safety and health in the oil and gas extraction industry an explicit priority focus area in 2005 by creating the National Occupational Research Agenda (NORA) Oil and Gas Extraction Council. The NIOSH Field Study and newly issued Hazard Alert are an extension of that continued and focused interest. Likewise, the issuance of the Hazard Alert continues the trend of increased federal focus and federal regulatory involvement concerning hydraulic fracturing.
1. OSHA is responsible for worker health and safety and sets enforceable standards for occupational health and safety whereas NIOSH is responsible for conducting research and making recommendations for the prevention of work-related disease and injury to other federal agencies such as OSHA. NIOSH cannot establish enforceable standards for worker and health and safety.
2. The study has not yet been released to the public.
3. OSHA's legally enforceable calculated Permissible Exposure Limit (PEL) for quartz is currently set at 10 milligrams per cubic meter of air (mg/m3). The PEL is calculated based on a formula using an eight-hour time-weighted average exposure to respirable dust.
4. NIOSH's Recommended Exposure Limit (REL) is a non-mandatory, recommended occupational exposure limit, currently set at 0.05 mg/m3.
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