Silica Exposure to Workers in Oil and Gas Hydraulic Fracking
Exposure to High Levels of Crystalline Silica
Silica exposure to workers is nothing new. Also hydraulic fracturing or “fracking” is nothing new either. What’s new is the number of workers exposed to high levels of crystalline silica as the oil and gas “fracking” industry has gone into high gear.
The use of a large volume of sand as a proppant—to “prop open” the fractured rock that allows oil and gas to flow more freely has gone from a few such locations to hundreds, if not thousands of well sites. (In 2012, there were 22,326 hydraulic fracking wells drilled or permitted).
The National Institute of Occupational Safety and Health (NIOSH) has estimated that as many as 1.7 million workers are exposed to crystalline silica each year.
OSHA has lowered the PEL to 50 ug/m3 and an Action Level of 25 ug/m3. The new Silica regulation is 29CFR1910.1053. The regulation is now in effect but there are extensions to the enforcement requirements for engineering controls to June 23, 2020, for the Oil and Gas Industry.
The process of preparing the proppant involves large quantities of sand that must be quarried, sized, cleaned, transferred, mixed, prepared, and injected into the wells which creates many stages where workers can be exposed to the crystalline silica-containing sand. These stages include quarries, sorters, trucks, roadways, conveyors, blenders, pump stations, and the well head. Each stage has its unique problems in controlling the dust and the workers’ exposures. OSHA Industrial Hygiene Surveys have resulted in over 60% of the workers in this multitude of tasks being overexposed to silica.
Many oil and gas wells are located in the Marcellus Shale Foundation in the Eastern Midwest (Pennsylvania, New York, Ohio, West Virginia and Maryland) and in Texas, Oklahoma, and North Dakota, but records indicate that hydraulic fracking wells are present in at least 17 states.
The health hazards of the crystalline forms of silica—if inhaled—is mostly due to the damage to lung tissue. The rigid sharp crystals cause lung damage, scarring, inflammation, and autoimmune disease. The resultant silicosis can cause irreparable damage resulting in COPD, lung cancer, and potentially death.
The work activities most likely to result in worker overexposure to silica are sand quarrying, sand mover vehicles, sand mover belts, sand mover conveyors, mixing/blending operators, at the well head, and even road construction personnel exposed to road dust.
The method for sampling of workers by an industrial hygienist is not difficult. There are a variety of sampling devices available—worn by the individual workers—that can collect respirable dust samples which can then be analyzed by an American Industrial Hygiene Association (AIHA) accredited laboratory. The sampling can cover a short term activity or a full work shift.
Methods of dust control and worker exposure control are more complex and varied.
Change to less dusty methods, ventilation, and substitution of less hazardous materials, equipment modification, wet methods of handling, enclosure, and finally respiratory protection (only recommended as an interim control method or as a supplement to other engineering or administrative controls).
Some technologies are emerging to better control dust at each stage of the proppant process but these technologies need to be monitored to confirm their ability to reduce worker exposure to silica and the prospect of developing silicosis, lung cancer, and the other diseases associated with the fracking process. It would be tragic to develop a substitute process that simply adds another health/safety hazard to the workers’ risks.