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OSHA Amends Existing Standards for Occupational Exposure to Respirable Crystalline Silica

Summary:  This news alert discusses the Occupational Safety and Health Administration's (OSHA) final rule for worker exposure to respirable crystalline silica.  The rule significantly lowers the existing permissible exposure limits for silica and requires employers to undertake a series of protective measures that were not required under OSHA’s existing standards.  These new requirements are broadly applicable to  industries in the General Industry, Construction, and Maritime sectors and are expected to cost over $1 billion annually  to implement.

On March 25, 2016, OSHA issued a final rule amending its existing standards for exposure to respirable crystalline silica.[1] The final rule seeks to comprehensively protect workers exposed to respirable crystalline silica by lowering the permissible exposure limit (PEL) to 50 micrograms per cubic meter of air as an eight-hour time weighted average and requiring employers to implement protective measures that include exposure assessment, exposure control, respiratory protection, medical surveillance, hazard communication, and recordkeeping.  The rule contains two standards, one for General Industry and Maritime and one for Construction, that are tailored to the circumstances found in those sectors.  These standards take effect on June 23, 2016, and under the compliance schedules therein, employers will have one to five years to comply with most requirements.

The implications of OSHA’s final rule on affected employers are significant, as the new PEL for respirable crystalline silica is 50 percent of the previous PEL applicable to general industry, and 20 percent of the previous PEL applicable to construction and shipyards.  Moreover, employers will be required to implement a series of protective measures that were not required under OSHA’s existing standards.  OSHA has estimated that approximately 676,000 workplaces in over 30 major industries will be affected by the new standards and that annualized costs of compliance will exceed $1 billion.  Affected industries include hydraulic fracturing, construction, shipyards, railroads, and manufacturing industries.


OSHA first adopted standards for workplace exposure to respirable crystalline silica in 1971 as one of 425 permissible exposure limits for air contaminants.[2]  The original silica PELs were approximately 100 micrograms per cubic meter for general industry and 250 micrograms per cubic meter for construction and shipyards.  These original PELs were not accompanied by additional protective measures.  OSHA now believes that the formula used to determine the general industry, construction, and maritime PELs has been “rendered obsolete by respirable mass (gravimetric) sampling.”[3]

In 1974, the National Institute for Occupational Safety and Health (NIOSH) recommended that the PEL for crystalline silica be reduced to 50 micrograms per cubic meter time weighted across a 10-hour workday over a 40-hour workweek.   NIOSH also recommended that the PEL be supplemented by protective measures, such as exposure monitoring and medical surveillance.  The same year, OSHA issued an Advance Notice of Proposed Rulemaking based on NIOSH’s recommendations, but never issued a proposed or final rule.[4]

Over the following decades, OSHA forecasted an eventual rulemaking through planning committees designed to review the frequency and severity of silica exposure, Special and National Emphasis Programs to increase enforcement of the OSHA standards, and public education campaigns to prevent worker illness.  These efforts culminated in OSHA’s publication of a Notice of Proposed Rulemaking on September 12, 2013.[5]  OSHA accepted public comments until February 11, 2014.[6]  After holding 14 days of public hearings and reviewing more than 2,000 comments, OSHA issued its final rule on March 25, 2016.[7]

Key Provisions of OSHA’s Final Rule

Permissible Exposure Limit

For the first time in decades, OSHA lowered the exposure limit to silica dust, setting it at 50 micrograms per cubic meter of air as an eight hour time-weighted average in all industries covered by the rule.[8]  In the final rulemaking, OSHA determined that under the existing PELs, employees “are at an increased risk of lung cancer mortality and silicosis mortality and morbidity” and an “increased risk of death from other nonmalignant respiratory diseases including chronic obstructive pulmonary disease (COPD), and from kidney disease.”[9]  After evaluating the evidence received during the rulemaking process, OSHA “determined a PEL of 50 mg/m3 is appropriate because it is the lowest level feasible for all affected industries.”[10]  However, OSHA further noted that while the PEL is technically feasible for most operations in industries affected by the rule, “it will be a technological challenge for several affected sectors and will require the use of respirators for a limited number of job categories and tasks.”[11]

The new PEL is five times lower than the existing limit for construction (250 micrograms) and half of the existing limit for general industry (100 micrograms).

Construction Standard

Under the new Construction Standard, employers are required to limit worker exposures to silica by using a control method set forth in “Table 1” of the Standard or by measuring workers’ exposure and independently deciding which dust controls work best to limit exposure to the PEL.  

Table 1 pairs common construction tasks with dust control methods determined to be effective by OSHA.

Employers who forego the control methods in Table 1 must:

  • Measure the amount of silica workers are exposed to if it may be at or above 25 micrograms averaged over an eight hour shift;

  • Protect workers from silica exposures above the PEL of 50 micrograms averaged over an eight hour shift;

  • Implement dust controls to protect workers from silica exposures above the PEL; and

  • Give workers respirators when dust controls cannot limit exposures to the PEL.

In a departure from OSHA’s proposed rule, OSHA will exclude exposures where worker exposure will remain below 25 micrograms per hour as an eight hour time-weighted average.

General Industry and Maritime Standard

Under the new General Industry and Maritime Standard, employers must:

  • Measure the amount of silica workers are exposed to if it may be at or above 25 micrograms averaged over an eight hour shift;

  • Protect workers from silica exposures above the PEL of 50 micrograms averaged over an eight hour shift;

  • Limit workers’ access to areas where they may be exposed above the PEL;

  • Use dust controls to protect workers from silica exposures above the PEL; and

  • Give workers respirators when dust controls cannot limit exposures to the PEL.

In a departure from the proposed rule, OSHA will exclude exposures where the employer provides objective data demonstrating that that exposure will remain below 25 micrograms per hour as an eight hour time-weighted average.

All Employers Subject to the Rule

Under the final rule, General Industry, Construction, and Maritime employers must:

  • Establish and implement a written exposure control plan to be implemented by a competent person;

  • Restrict housekeeping practices that expose workers to silica when feasible alternatives are available;

  • Offer medical exams every three years for workers required by the standard to wear a respirator 30 days or more per year;

  • Train workers on ways to limit exposure during work operations; and

  • Keep records of workers’ silica exposure and medical exams.

Implementation Schedule

Industries must comply with the rule’s requirements consistent with the following deadlines:

  • Construction: June 23, 2017

  • General industry and maritime: June 23, 2018

  • Hydraulic fracturing: June 23, 2018 for all provisions except Engineering Controls, which have a compliance date of June 23, 2021.


The most significant implication of the new rule will be the need to reduce worker exposures by half for general industry and by five times for the construction industry.  Employers may need to make substantial investment in new technologies in order to satisfy the lower PELs. 

Employers may also need to increase supervisor training and purchase additional personnel equipment to satisfy the rule’s additional protective provisions.  In addition, diligent recordkeeping will be required to keep track of workers’ silica exposure and medical exams.  Because of these significant and far-reaching implications, it is expected that petitions for review of the final rule will be filed with a federal appeals court.

[1] 81 Fed. Reg. 16286 (Mar. 25, 2016).

[2] 36 Fed. Reg. 10466 (May 29, 1971).

[3] 81 Fed. Reg. 16286 (Mar. 25, 2016).

[4] 39 Fed. Reg. 44771 (Dec. 27, 1974). 

[5] 78 Fed. Reg. 56273 (Sept. 12, 2013). 

[6] 79 Fed. Reg. 4641 (Jan. 29, 2014).

[7] 81 Fed. Reg. 16286 (Mar. 25, 2016).

[8] Id.

[9] Id.

[10] Id.

[11] Id.

© 2020 Beveridge & Diamond PC National Law Review, Volume VI, Number 91


About this Author

Mark N. Duvall Chemicals Regulation Attorney Beveridge & Diamond Washington, DC

Mark has over two decades of experience working in-house at large chemical companies. 

His focus is product regulation at the federal, state, and international levels across a wide range of programs, and occupational safety and health.

He leads the firm’s Chemicals group. His experience under the Toxic Substances Control Act (TSCA) includes enforcement actions, counseling, rulemaking, advocacy, and legislative actions. Since the enactment of TSCA amendments in 2016, he has been heavily involved in advocacy, compliance activity, and litigation arising from EPA's implementation...

Jayni A. Lanham Environmental, Health, & Safety Attorney Beveridge & Diamond Baltimore, MD

Jayni draws on her experience with environmental, health, and safety (EHS) regimes to help clients assess risk, develop compliance strategies, and build strong legal and technical cases when faced with litigation or enforcement.

Jayni counsels companies in a variety of industries on regulatory compliance and represents them in litigation and enforcement proceedings related to a broad range of federal and state EHS laws. Jayni is a leader of Beveridge & Diamond’s Occupational Safety and Health group and has significant experience advising clients on compliance obligations relating to worker health and safety, providing advice following workplace incidents, helping clients prepare for and respond to government inspections, and defending against enforcement actions and related litigation.

Jayni entered the practice of environmental law because of her intersecting interests in law, policy, science, and technology. Her work involves considering historical factual and technical issues, managing complex parallel proceedings in both the criminal and civil regulatory arenas, and collaborating with subject matter experts to find creative solutions to her clients’ complex EHS issues.

Jayni values learning about her clients' operations and businesses and draws on her experience across many industries to help clients improve overall compliance, develop necessary corrective steps, build strong legal and technical cases to minimize liability, and achieve business goals.

Professional Involvement

Jayni maintains an active pro bono practice and has assisted individuals with civil litigation, immigration, and criminal expungement matters. One of Jayni’s notable pro bono cases involved the representation of a family that was displaced from its home for seven months because of a mercury spill. Jayni’s advocacy on behalf of the family enabled the family to obtain a favorable settlement for the family’s expenses and hardship during the cleanup of its home.

Before joining B&D, Jayni interned with the Maryland Office of the Attorney General at the State Highway Administration and the Maryland Department of the Environment. During law school, Jayni earned a certificate of Concentration in Environmental Law, served on the Maryland Law Review, and represented clients on a variety of environmental matters as a member of the University of Maryland Environmental Law Clinic.

Michael F. Vitris Environmental Litigation Attorney Beveridge & Diamond Austin, TX

Michael F. Vitris partners with clients to efficiently resolve complex civil and criminal environmental litigation.

He is an environmental litigator in the Austin office of Beveridge & Diamond, with a national practice defending companies in a wide variety of matters including environmental and mass torts, class actions, and federal citizen suits under the major environmental statutes. 

Mr. Vitris also leverages his past experience as an environmental attorney with the Texas Commission on Environmental Quality to help clients prevent environmental violations or favorably...