The Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) issued a hazard alert related to workers’ exposure to respirable crystalline silica during hydraulic fracturing.
The alert follows the July 31, 2013, publication of NIOSH findings in the Journal of Occupational and Environmental Hygiene that showed, at all 11 hydraulic fracturing sites tested, the concentration of silica in the air workers breathe exceeded the permissible exposure limits set by OSHA. The journal is published jointly by the American Industrial Hygiene Association and the American Conference of Governmental Industrial Hygienists.
Researchers measured the silica levels of more than 100 personal-breathing-zone samples at hydraulic fracturing, or fracking, sites in five states. They discovered that in some cases the samples exceeded OSHA’s limits by a factor of 10 or more.
“Occupational exposure to respirable crystalline silica is a well-established hazard in mining, sandblasting, foundry work, agriculture and construction, but not for oil and gas extraction work, which includes hydraulic fracturing,” NIOSH said. “To our knowledge, this represents the first systematic study of work crew exposures to crystalline silica during hydraulic fracturing. Companies that conduct hydraulic fracturing using silica sand should evaluate their operations to determine the potential for worker exposure to respirable crystalline silica and implement controls as necessary to protect workers.”
Crystalline silica is a common mineral in the Earth’s crust, most commonly found as sand, used to make everyday materials such as concrete, brick and glass, according to OSHA.
Breathing certain amounts of silica can cause lung cancer or the lung disease silicosis. Silica has also been linked to other diseases, including tuberculosis, chronic obstructive pulmonary disease, kidney disease and autoimmune disease.
It is used in building materials, manufacturing, and in commercial and industrial products. In construction, silica is found in cement, asphalt, roofing tiles, masonry board, sandstone, limestone, granite, building facings, gypsum board and bricks. Products and materials containing silica are used in residential, commercial, industrial, road and bridge construction.
Fracking has long been used to extract oil from depleted wells. It is now being used across the country to tap previously unreachable oil and natural gas locked within deep rock formations. Large volumes of water and sand are pumped into a well at high pressure to fracture shale and other tight formations, allowing oil and gas to flow into the well. Large quantities of silica sand are used during the fracking process. Sand is delivered in trucks and then loaded onto sand movers, where it is transferred via conveyer belt and blended with other hydraulic fracturing fluids before high-pressure injection into the drilling hole. Transporting, moving and refilling silica sand onto and through sand movers, along transfer belts and into blender hoppers can release silica-containing dust into the air, OSHA said.
Workers Exposed to Silica
In cooperation with oil-and-gas-industry partners, NIOSH collected 116 full-shift air samples at 11 hydraulic fracturing sites in five states (Arkansas, Colorado, North Dakota, Pennsylvania and Texas) to determine the levels of worker exposure to silica at various jobs at the worksites.
Many air samples showed that silica levels for workers in and around the dust-generation points were above defined occupational-exposure limits.
Of the 116 samples collected:
- Forty-seven percent showed silica exposures greater than the calculated OSHA limit.
- Seventy-nine percent revealed silica exposures greater than the NIOSH limit.
- Nine percent showed silica exposures 10 or more times the OSHA limit, with one sample more than 25 times the limit.
- Thirty-one percent showed silica exposures 10 or more times the NIOSH limit, with one sample more than 100 times the limit.
NIOSH found that sand mover and blender operators and workers downwind of these operations had the highest silica exposures. Workers upwind and not in the immediate area of sand movers also had exposures above the NIOSH limit, possibly from the dust created by traffic at the site. Worker and area samples collected in enclosed but nonfiltered cab vehicles were above the limit, even when workers spent most of the day in the cab. Worker and area samples collected in enclosed vehicles with air conditioning and filtration had silica exposures below the limit.
Recommendations to Protect Workers from Overexposure to Silica
A combination of engineering controls, work practices, protective equipment and product substitution where feasible, along with worker training, is needed to protect workers who are exposed to silica during hydraulic fracturing operations, OSHA said.
Some of those protective measures include:
*Monitoring the air to determine worker exposures to silica. If air samples reveal levels above OSHA’s permissible exposure limit, employers are required to take actions to reduce worker exposures.
*Improving engineering controls and safe work practices. Engineering controls and work practices provide the best protection for workers and must be implemented first, before respiratory protection is used, OSHA said.
*Providing respiratory protection when it is needed. When engineering and work-practice controls are not possible, or while they are being implemented, or when they do not reduce silica exposures below OSHA limits, employers must provide workers with respirators. Whenever respirators are used, the employer must have a respiratory protection program that meets the requirements of OSHA’s respiratory protection standard. This program must include proper respirator selection, fit testing, medical evaluations and training.
*Providing training and information to workers about the hazards of silica.
*Medical monitoring of workers exposed to silica. As part of its National Emphasis Program on Silica, OSHA recommends that employers medically monitor all workers who may be exposed to silica-dust levels at or above one-half the permissible exposure limit. The agency suggests that these tests be repeated every three years if the employee has less than 15 years of silica exposure, every two years if the employee has 15 to 20 years of exposure, and every year if the employee has 20 or more years of exposure.
Proposed Rule on Silica Expected Soon
OSHA’s proposal to comprehensively regulate silica is expected by September 2013.
“The proposed rule, which could be one of the most significant rulemakings in OSHA’s history, is expected to cut in half the permissible exposure limit for respirable silica dust and require a wide range of ancillary protective measures, including engineering controls, air and medical monitoring, restricted work areas, housekeeping mandates, respirator use, warnings, training and record-keeping,” explained Brad Hammock, a partner at Jackson Lewis and chair of the firm’s workplace safety & health practice group.
It is expected that the proposed rule will include a section on hydraulic fracturing.
Given the ubiquity of silica on jobsites, the proposed rule is expected to significantly affect employers, said Hammock. “If OSHA proposes to regulate silica like asbestos, reducing the exposure limit by 50 percent or more, widespread mandates for employers are in the offing.”
Roy Maurer is an online editor/manager for SHRM.
Follow him on Twitter @SHRMRoy.
AIHA Describes Requirements for ‘Silica-Competent Person’, SHRM Online Safety & Security, April 2013
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