The California Occupational Safety and Health Standards Board (OSHSB) reached the public comment deadline of September 30, 2026, for Cal/OSHA's draft emergency rule addressing engineered and artificial stone. Two major industry associations submitted distinct regulatory proposals on the standard, presenting alternative approaches to workplace silica controls and fabricator oversight.
The Natural Stone Institute (NSI) filed formal comments on OSHSB Petition 609 on September 30, 2026, seeking specific technical refinements to the proposed silica standard. On September 28, 2026, the International Surface Fabricators Association (ISFA) submitted a separate petition advocating statewide licensing for all California surface fabricators, backed by independent third-party audits.
For stone processors, countertop fabricators and architectural specifiers, the submissions outline how industry groups are responding to California's regulatory direction, which was previously examined in StoneTrades' coverage of the California Cal/OSHA draft engineered stone ban.
NSI comments on Petition 609 and material scope
NSI submitted its public comments on Petition 609 on September 30, 2026, as reported by StoneNews.eu on October 8, 2026. The association focused on differentiating natural geological stone from manufactured agglomerates to avoid unintended regulatory burdens on quarries and dimension stone shops.
NSI requested that Cal/OSHA explicitly exclude "natural stone, fired ceramic and porcelain slabs, tiles and panels" from the artificial stone definition. The distinctions between quarried stone and manufactured slabs are detailed in StoneTrades' natural stone vs engineered quartz B2B comparison, as well as analyses of the sintered stone market and natural stone impact.
James A. Hieb, CAE, CEO of NSI, emphasized worker protection in his statement: "The Natural Stone Institute greatly values worker safety and the critical need to protect employees from preventable silicosis caused by airborne respirable crystalline silica."
Signage, exposure thresholds and respiratory standards
NSI raised technical concerns regarding required facility signage. The institute asked Cal/OSHA to remove the terms "quartz" and "cuarzo" from mandatory warning signs, to avoid confusion with naturally occurring mineral quartz.
On occupational health thresholds, NSI called on Cal/OSHA to provide supporting research and medical evidence for the proposed 3 μg/m³ action level. NSI noted that a 3 μg/m³ threshold sits close to laboratory minimum reporting levels.
Regarding respiratory personal protective equipment, NSI asked the board to reconsider the proposed APF 10,000 respiratory protection requirement. NSI described APF 10,000 as excessive and argued that current APF 1,000 protections provide adequate safeguards for fabrication staff. In addition, NSI requested clarification on record-keeping protocols when supplier documentation is unavailable, and urged regulators to narrow the definition of "minor on-site adjustments" to prevent high-exposure cutting and grinding operations from shifting from controlled shops to construction job sites.
ISFA proposal for statewide fabricator licensing
The International Surface Fabricators Association petitioned the California Occupational Safety and Health Standards Board on September 28, 2026, as reported by Stone Update on September 30, 2026. ISFA proposed establishing mandatory state licensing for all California surface fabricators, regardless of the material processed.
Under ISFA's proposed framework, fabricators would be required to hold a location-specific license. Obtaining and maintaining the license would require independent audits conducted by ISO 45001 Lead Auditors, proof of active workers' compensation coverage, and verified submission of medical surveillance and air exposure monitoring reports. Operations would face immediate cessation upon an audit failure or official regulatory prohibition.
Laurie Weber, ISFA CEO, commented on the enforcement objective: "The record shows that most California shops have never been inspected. This petition gives the board a way to reach every one of them, for every material."
Feasibility program and procedural timeline
To demonstrate the operational viability of its licensing model, ISFA organized a six-month feasibility program covering about 300 California shops. The program deploys ISO 45001 auditors and includes air sampling protocols at no fewer than 45 fabrication locations across the state.
The public comment period for the ISFA petition runs from September 29 through November 13, 2026. ISFA has formally requested to present its proposal at the Standards Board meeting scheduled for November 19, 2026, in Monterey. Industry participants can review petition details through the information site CountertopLicensing.org.
What it means for buyers
- The proposed Cal/OSHA emergency rule and ISFA licensing model remain at the draft and petition stage, meaning neither framework is currently in force.
- Natural stone and porcelain organizations are actively seeking explicit exclusion from artificial stone rules, which would keep natural granite, marble and sintered panels separate from composite stone restrictions.
- Fabricators and suppliers shipping into California should prepare for mandatory exposure monitoring, third-party facility audits, and rigorous documentation of raw material silica content.
- Importers and trade contractors should maintain up-to-date safety data sheets (SDS) and silica percentages from primary slab suppliers, while tracking regulatory decisions following the November 19 board meeting in Monterey.
