Occupational Safety and Health Administration OSHA

OSHA Fact Sheet

OSHA's Proposed Crystalline Silica Rule: General Industry and Maritime

OSHA is proposing two standards to protect workers from exposure to respirable crystalline silica-one for general industry and maritime, and the other for construction-in order to allow employers to tailor solutions to the conditions in their workplaces.

About 320,000 workers are currently exposed to respirable crystalline silica in general industry and maritime workplaces. Some of the affected industries are shown below.

Number of Workers Exposed to Respirable Crystalline Silica in Selected General Industry/Maritime Sectors
Industry sector

Number of workers currently exposed

Number of workers currently exposed above proposed PEL

Asphalt Roofing Materials



Concrete Products



Cut Stone



Dental Laboratories









Porcelain Enameling









Ready-Mix Concrete






Structural Clay Products



Support Activities for Oil and Gas Operations



Source: OSHA Directorate of Standards and Guidance

The proposed rule is expected to save nearly 700 lives and prevent 1,600 new cases of silicosis per year once the full effects of the rule are realized. Of these, over 130 lives would be saved and over 540 cases of silicosis would be prevented among general industry and maritime workers.

Major Provisions of the Proposed General Industry/Maritime Standard

The proposed standard for general industry and maritime includes provisions for employers to:

  • Measure the amount of silica that workers are exposed to if it may be at or above an action level of 25 μg/m3 (micrograms of silica per cubic meter of air), averaged over an 8-hour day;
  • Protect workers from respirable crystalline silica exposures above the permissible exposure limit (PEL) of 50 μg/m3, averaged over an 8-hour day;
  • Limit workers’ access to areas where they could be exposed above the PEL;
  • Use dust controls to protect workers from silica exposures above the PEL;
  • Provide respirators to workers when dust controls cannot limit exposures to the PEL;
  • Offer medical exams-including chest X-rays and lung function tests-every three years for workers exposed above the PEL for 30 or more days per year;
  • Train workers on work operations that result in silica exposure and ways to limit exposure; and
  • Keep records of workers’ silica exposure and medical exams.

Examples: Dust Control Methods

In most cases, dust controls can be used to limit workers’ exposure to silica. Examples of effective dust controls are shown below. These technologies are widely available and already commonly used by many employers.

Wet methods

This worker is using a saw with a built-in system that applies water to the saw blade. Wet methods are a common way to limit the amount of dust that gets into the air.

Wet methods


This worker is grinding castings in a foundry. The work is done in a ventilated booth that draws air away from the worker so he doesn’t breathe the dust created by the grinding. This method can be used in material handling (such as bag dumping), mixing operations, rock crushing, and other dust-producing activities.



This worker is using an enclosure while abrasive blasting dental castings in a dental laboratory. Enclosures create a barrier between the worker and the source of exposure. This can be done by methods such as:

  • Enclosing an operation in an airtight housing;
  • Covering conveyors and transfer drums used to move silica-containing materials so that silica dust doesn’t get in the air; or
  • Separating workers from the activity, such as when workers are in enclosed cabs.


Additional Information

You can learn more about OSHA’s proposed rule, including opportunities to participate in development of the rule, by visiting OSHA’s Silica Rulemaking webpage at www.osha.gov/silica.



This is one in a series of informational fact sheets highlighting OSHA programs, policies or standards. It does not impose any new compliance requirements. For a comprehensive list of compliance requirements of OSHA standards or regulations, refer to Title 29 of the Code of Federal Regulations. This information will be made available to sensory-impaired individuals upon request. The voice phone is (202) 693-1999; teletypewriter (TTY) number: (877) 889-5627.

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For Assistance, contact us. We can help. It's confidential. OSHA, Occupational Safety and Health Adminstration. U.S. Department of Labor. www.osha.gov (800)321-OSHA (6742)
U.S. Department of Labor
www.osha.gov (800)321-OSHA (6742)

DSG FS-3682 08/2013

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