On March 25, 2016, the Occupational Safety and Health Administration (OSHA) published in the Federal Register its final rule on occupational exposure to respirable crystalline silica.

U.S. Secretary of Labor Thomas E. Perez announced the rule at the International Masonry Institute in Bowie, Maryland. “The new rule will substantially reduce the permissible exposure limit, setting it at 50 micrograms per cubic meter of air. That’s half the current exposure limit for general industry and five times more stringent than the current exposure limit for construction,” Perez said. “The rule provides remarkable flexibility to employers, small businesses and large businesses alike, as they implement this standard . . . . I think this demonstrates that we’re listening to employers, that we’re not imposing one-size-fits-all approaches, and that we want to make our rules as practical as possible. Practical solutions, that’s what we are all about.”

What Stayed the Same From OSHA’s Proposed Rule? 

  • Permissible Exposure Limit. As Secretary Perez emphasized in his remarks, the final rule maintains the proposed rule’s uniform permissible exposure limit (PEL) of 50 micrograms of respirable crystalline silica per cubic meter of air (μg/m3) (calculated as an 8-hour time-weighted average), applicable to all affected industries. For the construction industry, the new PEL significantly drops the PEL from an earlier standard of 250 μg/m3 to 50 μg/m3. For maritime and general industries, the rule lowers the PEL from 100 μg/m3 to 50 μg/m3.
  • Action Level. OSHA kept the proposed rule’s Action Level of 25 μg/m3 intact. A sample at or above the Action Level triggers the requirements for periodic exposure assessments and requires employers to conduct additional assessments at least every six months until they fall under the Action Level for two consecutive monitoring assessments, taken at least seven days apart.
  • Exposure Assessment Threshold Triggered by the Action Level. Employers must conduct an initial exposure assessment whenever an employee may reasonably be expected to be exposed at or above the Action Level.
  • Medical Surveillance and Testing for Tuberculosis. The final rule retains virtually all the medical surveillance provisions of the proposed rule, but now requires health care providers and specialists to prepare two reports: one for the employee, and one for the employer. It also retains the requirement to test for tuberculosis, as well as the requirement to maintain Social Security numbers on employee records.

What Changed from the Proposed Rule? 

  • Scope. According to an OSHA Fact Sheet on the crystalline silica rule, the new silica exposure standard now excludes tasks that involve “low exposures,” i.e., exposures below the Action Level “under any foreseeable conditions.” Employers must have evidence to support this exception.”
  • Implementation Dates. The rule gives the construction industry a one-year grace period for compliance with the rule after its effective date. General industry and maritime employers receive a two-year grace period. The fracking industry received a two-year grace period, but was also given a five-year grace period to implement engineering controls to limit exposures above the new PEL.
  • Medical Surveillance Triggered by Exposures at or Above the Action Level. The new rule now triggers medical surveillance provisions when employees are exposed to silica at or above the Action Level (25 μg/m3) for 30 or more days per year. The proposed rule had triggered medical surveillance when an expected exposure was at or above the PEL (50 μg/m3) for 30 or more days per year. The final rule for construction “requires that medical surveillance be made available to employees who are required by the standard to use respirators for 30 or more days per year.”
  • Expanded Table 1 now Available for Infrequent Tasks in General and Maritime Industries. The final rule allows general industry and maritime employers to utilize the new, expanded version of Table 1 if the task performed is indistinguishable from the construction task listed and is not “performed regularly in the same environment and conditions.”

OSHA’s final rule adds even more tasks and methods for controlling exposures to Table 1. New tasks include:

  • handheld power saws for cutting fiber-cement board;
  • rig-mounted core saws and drills;
  • dowel drilling rigs for concrete;
  • small drivable milling machines;
  • large drivable milling machines;
  • heavy equipment and utility vehicles used to abrade or fracture silica-containing materials (e.g., hoe-ramming, rock ripping) or used during demolition activities involving silica-containing materials; and
  • heavy equipment and utility vehicles for tasks such as grading and excavating, but not including demolishing, abrading, or fracturing silica-containing materials.

New methods for control include:

  • wet methods to apply water at flow rates sufficient to minimize release of visible dust;
  • handheld grinders that must be operated outdoors for uses other than mortar removal, unless certain additional controls are implemented;
  • wet methods option for the use of heavy equipment and utility vehicles for tasks such as grading and excavating, but not including demolishing, abrading, or fracturing silica-containing materials; and
  • the use of wet methods when employees outside of the cab are engaged in tasks with heavy equipment used to abrade or fracture silica containing materials (e.g., during hoe-ramming or rock ripping) or used during demolition activities involving silica-containing materials. 
  • Ban on Dry Sweeping Lifted. According to the Fact Sheet, “[t]he final standards allow for use of compressed air, dry sweeping, and dry brushing where other cleaning methods are not feasible.”
  • Compressed Air Cleaning Permitted in Certain Circumstances. The rule still prohibits cleaning silica off of clothes or surfaces with compressed area, unless the employer uses a ventilation system that effectively captures the dust cloud created by the compressed air, and no alternative method is feasible.
  • Ban on Employee Rotation Lifted. The well-intentioned, but overbroad ban on employee rotation was removed from the final rule.
  • Protective Clothing Provisions Removed. “The final rule does not include requirements for use of protective clothing to address exposure to respirable crystalline silica.”
  • Mandatory Regulated Areas and Written Exposure Control Plans. The proposed rule gave employers an option of creating either demarcated “regulated areas” or “written access control plan[s]” for areas where employees might be exposed to silica in levels above the PEL. The new rule requires regulated areas and a written exposure control plan, but provides no alternative for a written access control plan. Construction industry employers must also assign a competent person (“a designated individual who is capable of identifying crystalline silica hazards in the workplace and who possesses the authority to take corrective measures to address them”) to implement the plan. The final rule for construction requires a written exposure control plan to “include procedures used to restrict access to work areas, when necessary, to minimize the numbers of employees exposed to respirable crystalline silica and their level of exposure.”
  • Signage for Regulated Areas. Employers must post signs with mandatory language at all entrances to regulated areas:






  • More Medical Surveillance Paperwork. The final rule requires health care providers and specialists to prepare two reports for the medical surveillance program: a detailed report for the employee and a less-detailed report for the employer. Employees may consent to their employers’ receiving additional medical information from health care providers and specialists. Permitting employees to give such consent seems designed to cut out the employer as a middleman between an employee and the employee’s health care provider, but the rule still dictates that employers ensure that health care providers and specialists furnish employees with their reports within 30 days of an examination. Sample forms and reports are included in a non-mandatory Appendix B.
  • No Round-Robin Testing Requirement for Labs. Labs analyzing air samples no longer are required to participate in round-robin testing with at least two other independent labs every six months. All lab requirements have been moved to a new Appendix A.
  • Digital Radiography Allowed. In response to concerns raised by the health care industry, OSHA allowed chest x-rays to be recorded on either film or digital radiography systems.
  • Sorptive Clay Exposure excluded. The final rule excepts from its coverage exposures resulting “from the processing of sorptive clays” (e.g., sealants for landfills, kitty litter, and other consumer and industrial products).

Key Takeaways

OSHA’s final rule on occupational exposure to respirable crystalline silica makes some concessions to employers, such as removing the ban on dry sweeping and certain provisions related to protective clothing, but the core provisions of the rule as it was originally proposed in 2013 have remained relatively unchanged. Labor unions applauded the final rule as long overdue; industry groups, such as the National Association of Manufacturers, expressed disappointment that OSHA rejected their concerns about the feasibility of the rule. OSHA responded to feasibility concerns by building in longer grace periods before the rule takes effect.

Congressional action to limit the effect of the silica rule is unlikely, given that President Obama would certainly veto any such measure. Litigation to halt or overturn the rule is likely, however, and OSHA’s nearly 1,600 pages of comments and analysis on the final rule will be invoked to help defend the rule in court. For now, employers have one, two, or five years to weigh their options and plan compliance efforts.

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