Respirable Crystalline Silica Standards and Resources Important Update

This webpage gives an overview of standards to control employee exposures to respirable crystalline silica (RCS), which can cause silicosis, lung cancer, and other serious health effects.

May 21, 2024

On December 14, 2023, the Occupational Safety and Health Standards Board approved Cal/OSHA's Emergency Temporary Standard (ETS) on Respirable Crystalline Silica (RCS). This ETS affects employees working in general industry under California Code of Regulation, Title 8, section 5204. It includes important revisions to protect workers engaged in high-exposure trigger tasks (cutting, grinding, polishing, clean up, etc.) involving artificial stone and natural stone containing more than 10% crystalline silica. The ETS goes into effect on December 29, 2023.

For occupational exposure to respirable crystalline silica in construction industry, refer to Title 8 section 1532.3.

On December 14, 2023, section 5204 was amended on an emergency temporary basis to address additional employee protection requirements that go into effect on December 29, 2023. This emergency standard is temporary, and Cal/OSHA is working on creating a permanent version. Check the Cal/OSHA Training and Safety Awareness Events webpage frequently for related free training opportunities.

These changes apply to California workers occupationally exposed to RCS, except:

  • Construction work covered under section 1532.3.
  • Agricultural operations covered under section 3436.
  • Exposures that result from the processing of sorptive clays

Emergency Silica Standard - What Employers Need to Know: Executive Summary

Emergency Silica Standard: Information for Employers

Emergency Silica Standard: Information for Workers

Silica General Industry Exposure Control Model Plan

Section 5155 requires all employers to protect employees from exposures that exceed the "permissible exposure limit" (PEL) for respirable crystalline silica. NOTE: Construction employers and certain other employers properly using exposure control methods provided in Table 1 of section 1532.3 for particular construction tasks are not required to verify that employee exposures are at or below the PEL.

Section 1532.3 applies to occupational exposures in construction, except where exposures will remain below the "action level" under any foreseeable conditions.

Section 5204 applies to all occupational exposures except construction work, agricultural operations, and exposures from the processing of sorptive clays. In addition, section 5204 does not apply in the following situations:

The PEL for respirable crystalline silica is 50 micrograms per cubic meter (µg/M3) of air. This is the maximum concentration of respirable crystalline silica in air, as an eight-hour time-weighted average, to which an employee may be exposed.

The action level for respirable crystalline silica is 25 micrograms per cubic meter (µg/M3) of air. This is the concentration of respirable crystalline silica in air, as an eight-hour time-weighted average, at or above which employers must assess employee exposures, as prescribed in sections 1532.3 and 5204, and conduct medical surveillance, as prescribed in section 5204.

The broad categories of requirements are as follows:

Broad Categories of Requirements Section 1532.3 Section 5204
Methods of exposure control or compliance 1532.3(c) or (d)(3) 5204(a)(3) or (f)
Exposure assessments 1532.3(d)(2) 5204(d)
Respiratory protection 1532.3(e) 5204(g)
Housekeeping 1532.3(f) 5204(h)
Restricted or regulated areas 1532.3(g)(1)(D) 5204(e)
Written exposure control plans 1532.3(g) 5204(f)(2)
Medical surveillance 1532.3(h) 5204(i)
Communication of respirable crystalline silica hazards to employees 1532.3(i) 5204(j)
Recordkeeping 1532.3(j) 5204(k)

In general, the requirements in section 1532.3 are more protective than most of the requirements in section 1530.1. However, section 1530.1 contains certain requirements not found in section 1532.3. Construction employers covered by section 1530.1 must still comply with those requirements, found in the following subsections:

  • Subsection 1530.1(d)(1) requires procedures to ensure that dust reduction systems maintain their effectiveness for dust reduction throughout the work shift.
  • Subsection 1530.1(e) contains additional training topics, not included in section 1532.3, for employees and supervisors.

Section 5155 the PEL for respirable crystalline silica (50 micrograms per cubic meter (µg/M3) of air) is in effect. Employers not using exposure control methods provided in Table 1 of section 1532.3 for particular construction tasks must ensure that employee exposures are at or below the PEL.

Section 1532.3 is in effect.

Section 5204 is in effect, except as follows:

  • For all covered industries, requirements in subsection 5204(i)(1)(A) for medical surveillance go into effect on June 23, 2020, for employees who will be exposed to respirable crystalline silica at or above the action level for 30 or more days per year. Currently, medical surveillance requirements only apply to employees who are exposed to respirable crystalline silica above the PEL for 30 or more days per year.
  • For hydraulic fracturing operations in the oil and gas industry, requirements in subsection 5204(f)(1) for engineering controls, to limit exposures to or below the PEL, go into effect on June 23, 2021. Until that date, employers must:
    • Use work practice controls to reduce and maintain employee exposures to respirable crystalline silica at or below the PEL, unless the employer can demonstrate that such controls are not feasible.
    • Where work practice controls are not sufficient to reduce employee exposure to or below the PEL, use work practice controls to reduce employee exposure to the lowest feasible level and supplement them with the use of respiratory protection.
    • See Emergency Temporary Standard on Respirable Crystalline Silica for General Industry (5204) section

Additional ETS and silicosis reporting resources for employers and workers:

February 2025