Workplace safety regulators say that workers in the hydraulic fracturing industry are at risk of serious health effects from respiratory exposure to silica.
The Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) issued a “hazard alert” after identifying respirable crystalline silica exposure as a health hazard to workers in hydraulic fracturing operations, where they use large amounts of silica sand in the process to stimulate oil and gas extraction.
Crystalline silica is a common mineral and the major component of sand.
Hydraulic fracturing or “fracking” is a process in which a mixture of water, chemicals and sand are pumped at high pressure into a well to fracture the surrounding rock formation and release oil and gas. The sand in the fracking fluid acts as a proppant, holding the fractures open so oil or gas can flow freely out of the rock and into the well bore. This process uses enormous amounts of sand. It is delivered to the site by truck, loaded into sand movers, then moved by conveyor belt to be blended with other ingredients into fracking fluid. This transfer of the sand can release large clouds of silica-containing dust into the air where workers may breathe it into their lungs.
NIOSH began an investigation of air quality at hydraulic fracturing sites in January 2010. In cooperation with oil and gas industry partners, the agency collected 116 full shift air samples at eleven sites in the states of Arkansas, Colorado, North Dakota, Pennsylvania and Texas.
Of the 116 samples collected:
- 47% showed silica exposures greater than the calculated OSHA PEL.
- 79% showed silica exposures greater than the NIOSH REL of 0.05 milligrams per cubic meter (mg/m3).
- 9% of all samples showed silica exposures 10 or more times the PEL, with one sample more than 25 times the PEL.
- 31% of all samples showed silica exposures 10 or more times the REL, with one sample more than 100 times the REL.
“Hazardous exposures to silica can and must be prevented. It is important for employers and workers to understand the hazards associated with silica exposure in hydraulic fracturing operations and how to protect workers,” said Dr. David Michaels, assistant secretary of labor for occupational safety and health in a release. “OSHA and NIOSH are committed to continuing to work with the industry and workers to find effective solutions to address these hazards.”
People who breathe silica into their lungs can develop lung cancer or a disease called silicosis that is characterized by inflammation and scarring of lung tissue around silica particles that reduces absorption of oxygen.
According to the hazard alert, silicosis is classified into three types:
- Chronic/classic silicosis, the most common type, occurs after 10–20 years of moderate to low exposures to respirable crystalline silica. Symptoms associated with chronic silicosis may or may not be obvious; therefore, workers need to have a chest x-ray to determine if there is lung damage. As the disease progresses, the worker may experience shortness of breath when exercising and have clinical signs of poor oxygen/carbon dioxide exchange. In the later stages, the worker may experience fatigue, extreme shortness of breath, cough, and, in some cases, respiratory failure.
- Accelerated silicosis can occur after 5–10 years of high exposures to respirable crystalline silica. It is similar to chronic silicosis, but progresses more rapidly.
- Acute silicosis occurs after only a few months or a few years following exposures to extremely high levels of respirable crystalline silica. Symptoms of acute silicosis include rapidly progressive and severe shortness of breath, weakness, and weight loss. Though much less common than other forms of silicosis, acute silicosis nearly always leads to disability and death.
Respiratory exposure to silica is also associated with diseases such as tuberculosis, chronic obstructive pulmonary disease (COPD), kidney and autoimmune disease.
“Through partnerships, both businesses and safety professionals are able to collaborate on assessing and managing occupational safety and health risks,” said NIOSH Director John Howard, M.D. “The recommendations for protecting workers in the hazard alert are practical, evidence-based and effective solutions to help support the safe growth of American-made energy.”