Cal/OSHA Moves Toward Emergency Silica Restrictions for Engineered Stone
A proposed emergency regulation would prohibit fabrication of engineered stone containing more than 1% crystalline silica as California seeks to address silicosis among countertop workers.
- By Danielle Naidu
- Sep 28, 2026
California countertop fabricators could face new material restrictions, notification duties and exposure-control requirements under a discussion draft released by the California Division of Occupational Safety and Health (Cal/OSHA).
The recent discussion draft would add Section 5204.1 to the state's General Industry Safety Orders and amend existing silica requirements in Sections 5204 and 1532.3. Comments on the proposal are due Sept. 30 and may be submitted to the Cal/OSHA Research and Standards Branch.
Beginning 60 days after the emergency regulation's effective date, employers would be prohibited from manufacturing or fabricating artificial stone containing more than 1% crystalline silica by weight. The restriction would cover material used for countertops, backsplashes, walls, flooring, waterfall countertop edges and similar products made from slabs or panels.
Fabrication would include cutting, grinding, drilling, routing, polishing, finishing, joining and other processes used to transform artificial stone into a final or near-final product.
Employers would be required to notify workers verbally and in writing, in a language they understand, that manufacturing or fabricating covered materials is prohibited and dangerous to their health. Warning signs in English and Spanish would also be required at workplace entrances.
Prohibited manufacturing or fabrication would be considered an imminent hazard and could result in a Cal/OSHA Order Prohibiting Use. Employers would also have to maintain documentation showing that covered materials contain no more than 1% crystalline silica by weight. Materials without sufficient documentation would be treated as exceeding the limit.
A limited exception would apply to covered material that an employer purchased, contracted for or possessed before the regulation's effective date. Employers using the exception would have to comply fully with the existing silica standard, and all manufacturing or fabrication of the material would have to stop 180 days after the effective date.
The draft would also create a separate artificial-stone action level of 3 micrograms of respirable crystalline silica per cubic meter of air over an eight-hour time-weighted average. It would require wet methods to keep exposures below the applicable action level.
For high-exposure trigger tasks, employers generally would have to provide full-face, tight-fitting powered air-purifying respirators or other respirators providing an assigned protection factor of at least 1,000. Less-protective options would be permitted under specified conditions, including representative air sampling demonstrating that exposures remain below the applicable action level.
The proposal follows the California Occupational Safety and Health Standards Board's partial approval of Petition 609, which requested expedited restrictions in response to disabling and fatal silicosis among engineered-stone workers. OH&S reported on the board's decision to begin emergency rulemaking in May.
The discussion draft is not a final regulation, and Cal/OSHA has not announced an effective date.
About the Author
Danielle Naidu is assistant editor for Security Today, Campus Security Today, Occupational Health & Safety and Environmental Protection Online.