Silica FAQ

  1. Why did OSHA issue a new crystalline silica rule?
  2. How will the crystalline silica rule protect workers’ health?
  3. What is the new permissible exposure limit (PEL)?
  4. What industries will be affected by the rule?
  5. How can silica exposures be controlled to keep exposure at or below the PEL?
  6. What is Table 1: “Specified Exposure Control Methods When Working with Materials Containing Crystalline Silica”?
  7. When must employers comply with the standard for general/industry and maritime?
  8. When must employers comply with the standard for construction?
  9. Will states with OSHA-approved programs adopt the standards?

Why did OSHA issue a new crystalline silica rule?

OSHA’s previous permissible exposure limits (PELs) for silica were outdated, inconsistent and did not adequately protect worker health. The previous PELs were based on studies from the 1960s and earlier that did not reflect more recent scientific evidence showing that low-level exposures to silica cause serious health effects, including lung cancer. In the 45 years since the previous PELs were established, the U.S. National Toxicology Program, the International Agency for Research on Cancer, and the National Institute for Occupational Safety and Health have all identified respirable crystalline silica as a human carcinogen. Previous construction and shipyard PELs were based on an old method of measuring worker exposures to silica that is not used today. Those previous limits are inconsistent, allowing permissible levels for construction and shipyards to be more than twice as high as levels in general industry. The revised rule will reduce the risk of disease among workers who inhale respirable crystalline silica and provide the same protection for all workers covered.

How will the crystalline silica rule protect workers’ health?

The new rule requires that employers use engineering controls − such as ventilation and wet methods for cutting and sawing crystalline silica-containing materials − to reduce workers’ exposure to silica dust. Once the full effects of the rule are realized, OSHA expects it to prevent 600 deaths a year from silica-related diseases – such as silicosis, lung cancer, other respiratory diseases and kidney disease – and to prevent more than 900 new cases of silicosis each year.

What is the new permissible exposure limit (PEL)?

The PEL limits worker exposures to 50 micrograms of respirable crystalline silica per cubic meter of air (μg/m3 ), averaged over an eight-hour day. This level is the same for all workplaces covered by the standard (general industry/maritime and construction), and is roughly 50 percent of the previous PEL for general industry, and roughly 20 percent of the previous PEL for construction and shipyards.

What industries will be affected by the rule?

The main industries affected include:

  • Construction
  • Glass manufacturing
  • Pottery products
  • Structural clay products
  • Concrete products
  • Foundries
  • Dental laboratories
  • Paintings and coatings
  • Jewelry production
  • Refractory products
  • Landscaping
  • Ready-mix concrete
  • Cut stone and stone products
  • Abrasive blasting in: -Maritime work -Construction -General industry
  • Refractory furnace installation and repair
  • Railroads
  • Hydraulic fracturing for gas and oil
  • Asphalt products manufacturing

How can silica exposures be controlled to keep exposure at or below the PEL?

  • Employers must use engineering controls and work practices as the primary way keep exposures at or below the PEL.
  • Engineering controls include wetting down work operations or using local exhaust ventilation (such as vacuums) to keep silica-containing dust out of the air and out of workers’ lungs. Another control method that may work well is enclosing an operation (“process isolation”).
  • Examples of work practices to control silica exposures include wetting down dust before sweeping it up or using the water flow rate recommended by the manufacturer for a tool with water controls.

Respirators are only required when engineering and work practice controls cannot maintain exposures at or below the PEL.

For construction, the standard includes Table 1, a list of common construction tasks along with exposure control methods and work practices that work well for those tasks and can be used to comply with the requirements of the standard.

What is Table 1: “Specified Exposure Control Methods When Working with Materials Containing Crystalline Silica”?

Table 1 is a flexible compliance option that effectively protects workers from silica exposures. It identifies 18 common construction tasks that generate high exposures to respirable crystalline silica and for each task, specifies engineering controls, work practices, and respiratory protection that effectively protect workers. Employers who fully and properly implement the engineering controls, work practices, and respiratory protection specified for a task on Table 1 are not required to measure respirable crystalline silica exposures to verify that levels are at or below the PEL for workers engaged in the Table 1 task.

OSHA developed Table 1 in response to stakeholders in the construction industry, who indicated the need for guidance and a standard that is different than a standard for general industry. Among the concerns of construction industry stakeholders were the impracticality of exposure monitoring based on short duration of task and constantly changing conditions, such as weather, job sites and materials.

When must employers comply with the standard for general/industry and maritime?

For all operations in general industry and maritime, other than hydraulic fracturing operations in the oil and gas industry:

  • Employers are required to comply with all obligations of the standard, with the exception of the action level trigger for medical surveillance, by June 23, 2018.
  • Employers are required to offer medical examinations to employees exposed above the PEL for 30 or more days a year beginning on June 23, 2018.
  • Employers are required to offer medical examinations to employees exposed at or above the action level for 30 or more days a year beginning on June 23, 2020.

For hydraulic fracturing operations in the oil and gas industry:

  • Employers are required to comply with all obligations of the standard, except for engineering controls and the action level trigger for medical surveillance, by June 23, 2018.
  • Employers are required to comply with requirements for engineering controls to limit exposures to the new PEL by June 23, 2021. From June 23, 2018 through June 23, 2021, employers can continue to have employees wear respirators if their exposures exceed the PEL.

When must employers comply with the standard for construction?

Employers are required to comply with all obligations of the standard (except methods of sample analysis) by September 23, 2017.

Employers are required to comply with methods of sample analysis by June 23, 2018.

Will states with OSHA-approved programs adopt the standards?

Yes. States with OSHA-approved state plans have six months to adopt standards that are at least as effective as Federal OSHA standards. Many state plans adopt standards identical to OSHA, but some state plans may have different or more stringent requirements.