Respirable crystalline silica consists of particles small enough to reach deep into the lungs. Repeated exposure can cause silicosis, an irreversible and potentially fatal lung disease.
California identified 592 engineered-stone workers with silicosis between January 2019 and June 2026. According to the California Department of Public Health, at least 65 of these workers received lung transplants and 31 died. The median age at diagnosis was 46, and the median age at death was 52.
The number and severity of these cases show how quickly engineered-stone silicosis can progress when exposure is not adequately controlled. California’s permanent respirable crystalline silica standard establishes specific requirements for employers performing high-exposure work with artificial stone and certain natural stone products.
Employers that cut, grind, drill, polish, finish, or clean up these materials should review their operations under California Code of Regulations, Title 8, Section 5204. Written procedures, wet tools, and respirators must be supported by effective implementation and exposure monitoring that shows whether workers are adequately protected.
Who Does the New Silica Standard Cover?
Section 5204 applies to general-industry operations where employees may be exposed to respirable crystalline silica. Its requirements include specific protections for employees working with artificial stone, also called engineered stone, composite stone, or quartz, and natural stone containing more than 10% crystalline silica by weight.
Exceptions:
- Construction (§1532.3), agriculture (§3436), and sorptive-clay processing remain under their own rules.
- Objective-data exemptions below the 25 µg/m³ action level still apply—but not to “High-Exposure Trigger Tasks” (HETTs), meaning any cutting, grinding, drilling, polishing, or cleanup that disturbs artificial stone (> 0.1 % silica) or high-silica natural stone.
What Got Tougher in the Permanent Silica Standard
Regulated Areas:
ETS (2023): Required for high-exposure trigger tasks; provisional signage allowed.
Permanent Rule (2025): Signage text locked in—must warn of “permanent lung damage that may lead to death,” displayed in both English and Spanish.
Engineering Controls
ETS (2023): Running water “where feasible.”
Permanent Rule (2025): Continuous water flow or full submersion mandated; employer must document that flow rate is adequate for dust suppression.
Respiratory Protection
ETS (2023): Loose-fit PAPR allowed if exposure < Action Level.
Permanent Rule (2025): Tight-fit PAPR with HEPA/N-R-P 100 filters is the default; downgrade only after semi-annual sampling shows exposure < Action Level.
Medical Surveillance
ETS (2023): Baseline exam plus annual follow-up.
Permanent Rule (2025): Baseline, then every three years; immediate follow-ups required for high-exposure workers (HETT or > PEL results).
Silicosis Reporting
ETS (2023): “Prompt” reporting language.
Permanent Rule (2025): 24-hour deadline to notify Cal/OSHA and CDPH of any confirmed case.
Dry sweeping/air blow-off—banned outright.
Employee rotation—no longer an acceptable exposure control.
Eight Core Silica Exposure Duties for Employers
- Written Exposure-Control Plan – List all materials/tasks by silica content. Include air-monitoring records and engineering-control schematics.
- Exposure Assessment & Air Monitoring – Initial sampling plus 12-month repeat cycle; HETT work may trigger 6-month or 3-month cycles.
- Engineering Controls – Continuous-water tools, submerged cutting, water-jet, or local exhaust with HEPA filtration.
- Regulated-Area Management – Barricades or tape, plus bilingual danger signage.
- Respiratory-Protection Program – PAPR (HEPA/N100/R100/P100) minimum; fit-testing per §5144.
- Housekeeping Rules – Wet cleanup or HEPA vac only; no dry sweeping, no compressed-air blow-off.
- Medical Surveillance & Medical Removal Protection – Baseline exam, chest imaging as needed, and 3-year cycle; wage retention up to 6 months if removal required.
- 24-Hour Silicosis/Cancer Reporting & Recordkeeping – Confirmed cases reported within 24 hours; all sampling & medical records kept 30 years.
Penalties and Shut-Down Risk
Cal/OSHA’s 2025 penalty schedule caps a serious citation at $25,000 and a willful/repeat at $162,851. The minimum penalty for willful violations is $11,632.
But the real hammer is the Order Prohibiting Use (OPU). Inspectors spotting dry cutting or missing water-feed can tape off your saw on the spot. In 2024, more than a quarter of inspected shops were shut down until they fixed violations.
A Practical Roadmap to §5204 Compliance
Gap Analysis
- Map tasks where employees may be exposed against §5204 requirements
- Flag dry processes and inadequate water-feed tools.
Engineering Upgrades
- Budget for new wet saws, water-recycling systems, or downdraft HEPA tables.
- Verify flow rates meet manufacturer specs for dust suppression.
Engage a Qualified Person
- Exposure monitoring may have to be conducted by a third-party “qualified person,” such as a Certified Industrial Hygienist (CIH).
Finalize Written Exposure Control Plan & Training
- Implement exposure control plan
- Conduct bilingual, task-specific training; refresh annually.
Medical Program Contract
- Partner with an occupational clinic familiar with silicosis diagnostics and Cal/OSHA’s 24-hour reporting portal.
California Is Considering Further Restrictions
California may impose additional restrictions on engineered-stone fabrication and installation. In May 2026, the California Occupational Safety and Health Standards Board began an expedited rulemaking process that could prohibit the fabrication and installation of artificial stone products containing more than 1% crystalline silica.
Cal/OSHA held an advisory meeting in July 2026 to gather stakeholder input on possible regulatory language. That meeting did not establish a prohibition, effective date, or final rule. Stone fabricators should continue complying with Section 5204 and monitor the rulemaking process for further developments.
Frequently Asked Questions
“We’re below the Action Level—do we still need regulated areas?”
Yes, for any HETT. The regulated-area requirement is task-based, not exposure-based.
“Can I just rotate employees?”
No. Rotation is explicitly prohibited as an exposure control.
“Is a loose-fitting PAPR ever okay?”
Only if semi-annual sampling proves exposures < 25 µg/m³, and even then you need written justification and medical clearance.
Confirm That Silica Controls Are Working
Written programs and installed equipment do not, by themselves, demonstrate that workers are adequately protected. Wet methods can be compromised by insufficient water flow, poor maintenance, production changes, or inconsistent use. Respirators may provide less protection than expected when they are improperly selected, fitted, worn, cleaned, or stored. Dust and slurry can also become airborne again when cleanup and waste-handling practices are inadequate.
Employers need to evaluate the work as it is actually performed. Representative personal exposure monitoring can identify higher-exposure tasks, test the effectiveness of engineering and work-practice controls, and show where corrective action is needed.
FACS industrial hygienists can help stone fabricators identify silica-generating tasks, assess employee exposures, evaluate engineering controls and respiratory-protection programs, update written exposure-control plans, provide training, and conduct follow-up monitoring.
To discuss silica exposure assessment and control with a FACS industrial hygienist, contact FACS or call us at (888) 711-9998.