Crystalline Silica Exposures and OSHA’s Proposed New Rule

Posted by mpolkabla On October - 18 - 2013

DSCN0068The Federal Occupational Safety and Health Administration (OSHA) has recently submitted a proposed revision to its current regulatory standards on workplace exposures to crystalline silica (measured as respirable quartz).  This proposal seeks to lower the worker and workplace exposure limits to crystalline silica through its Permissible Exposure Limit (PEL) to 50 micrograms per cubic meter of air.  (or equivalent 0.05 milligrams per cubic meter of air).   If approved, (which is likely) this will significantly change OSHA’s general industry, maritime, and the construction standards by lowering the current standard by 200 %.  State standards will likely be short to follow as they are mandated to be “at least-as-stringent as” the Federal standards.  For example, California’s current equivalent standard for workplace exposures to respirable crystalline silica (quartz) is 0.1 mg/m3 (100 micrograms/m3).  These current California standards are listed in Title 8 CCR Section 5155.  In addition, the proposed rule will mandate required methods and procedures for controlling worker’s exposures to crystalline silica, in conducting medical testing/surveillance of workers, and in training workers about silica-related hazards on their work sites.

As Environmental Health and Safety professionals and Certified Industrial Hygienists already clearly understand the significant hazards associated with crystalline silica…  Inhalation of very small (respirable) crystalline silica particles puts those exposed at risk for developing silicosis (a debilitating lung disease), lung cancer, chronic obstructive pulmonary disease (COPD), and kidney disease.  What happens is that small particles of crystalline silica act like “tiny harpoons” which are readily breathed-in and penetrate and damage that smallest recesses of your lung cavities called the alveoli region.  Once there, they will cause tiny scar tissues and over time the scars build up and your lung capacity is depleted due to lack of elasticity.  Long-term effects of such exposures also may cause a host of lung diseases including pulmonary tuberculosis and lung cancer.

The primary hazardous form of crystalline silica are the very small particles, which exist at about 5 microns in size and smaller.   These are known as the “respirable” size of the airborne substance and is over 100 times smaller that ordinary beach sand that is encountered on beaches and in playgrounds.  However, the hazardous form of this material is also produced during many common work operations involving stone, granite rock, concrete, brick, cinder block, mortar and industrial sand.  Common construction site activities where crystalline silica exposures are encountered include tile cutting, jack hammering, concrete sanding/finishing, roof shingle (and cement siding) cutting, and sand blasting.  Even the common handling, transport, and movement of materials containing crystalline silica can result in airborne exposures, which exceed the noted Permissible Exposure Limits. Exposures are also very common in hydraulic fracturing (fracking) operations in the oil and gas industries.

What is significant is that crystalline silica levels in the environmental and workplace may exceed the OSHA Permissible Exposure Limit (PEL) even when visible dust is NOT seen by the naked eye.   For example, visible dust is understood to be visible in the air starting at a concentration of about 5 milligrams per cubic meter of air (5mg/m3).  In such an example, if this visible dust cloud was entirely composed of respirable crystalline silica, it would exceed the current Permissible Exposure Limit by over 50 times and the proposed standard by greater than 100 times.

At least 1.7 million US workers are exposed to respirable crystalline silica according to the National Institute of Occupational Safety and Health (NIOSH).  At the highest risk are those whose work involves sand blasting, or cutting, blasting, chipping, grinding, and sawing stone, brick or concrete.  OSHA estimates that the implementation of the proposed changes will save nearly 700 lives and prevent 1,600 new cases of silicosis per year, once the effects of the proposed rule are realized.  This proposed rule was submitted to the Office of Information and Regulatory Affairs (OIRA).  Public hearings for the proposal will be open for 90 days and are scheduled in early March of 2014.

As the Senior Certified Industrial Hygienist with BioMax Environmental, Mr. Michael A. Polkabla, CIH, REA has consulted with clients and successfully performed hundreds of workplace exposure assessments including crystalline silica since 1996.  Each industrial hygiene assessment we perform includes the development and implementation of an appropriate site-specific sampling plan to evaluate worker exposures in compliance with current regulatory standards.  Please contact us directly to discuss how we may assist you in the protection of your employees, staff, and workplace through proper assessment of conditions and development of prudent and feasible workplace controls and safety strategies.

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