Last week, the Occupational Safety and Health Administration (OSHA) proposed a rule to decrease the permissible exposure limits (PELs) for crystalline silica.  OSHA indicated that the inhalation of silica dust can increase workers’ risk of silicosis and other diseases.  Silica is commonly used as a proppant in hydraulic fracturing. 

The current PELs for crystalline silica are more than 40 years old and vary by industry.  OSHA concluded that these PELs were difficult to understand and not adequately protective of worker health.  The proposed PEL is 50 micrograms of respirable crystalline silica per cubic meter of air averaged over an 8-hour period and applies to all industries covered by the rule.

At fracking sites, silica sand is delivered by truck and typically transported by conveyor belt before it is blended with other fluids and injected into the well.  The resulting exposure of silica dust from these operations was recently identified by National Institute for Occupational Safety and Health (NIOSH) as a hazard for workers involved in fracking operations.

OSHA will accept comments on the proposed rule for 90 days after publication of the rule in the Federal Register.