Last year, OSHA promulgated a chemical-specific standard for Respirable Crystalline Silica (RCS) in the forms of quartz, cristobalite, and tridymite. Among other impacts of the standard, it lowered the Permissible Exposure Limit (PEL) significantly and established an Action Level (AL) at one-half the PEL that triggers various aspects of the standard. Medical surveillance is required if workers are exposed to greater than the AL for 30 days or more per year. This chemical-specific standard is different from the others in that it requires the use of objective data by employers to demonstrate compliance in industries or work environments known to carry the risk for exposure to RCS. This document focuses on the general industry standard, 29 CFR 1910.1053.
The standard incorporates a phased compliance approach within five years of the effective date, June 23, 2016. Most aspects of the standard become enforceable within next year in 2018. Medical surveillance is required for workers found to be exposed to RCS levels at or exceeding the PEL on that date; however, employers are allowed to delay surveillance activities for workers exposed to less than the PEL but at or more than the AL until 2020. Operations involving hydraulic fracturing have one more year, in 2021, to implement feasible engineering controls. This is likely due to ongoing partnership activities occurring between that industry and OSHA.
The previous PEL was based on epidemiological and toxicological research available prior to the publication of the 1968 ACGIH Threshold Limit Values (TLV's) that were incorporated into Subpart Z at the time of promulgation in the early 1970's. Much more has been learned about the effects of exposure to RCS in the 50 years since. The primary disease associated with exposure is silicosis, or a type of pneumoconiosis that results in chronic progressive obstructive pulmonary disease. Besides the obvious reduction in the quality of life among affected workers, the disease may result in lung cancer. Other diseases, such as those affecting the kidney or an increased susceptibility to tuberculosis are also known to be associated with exposure to RCS. OSHA estimates the exposure limit reduction along with medical surveillance will save 642 workers annually from these occupational diseases.