The vote directs Cal/OSHA to initiate emergency rulemaking and, on a parallel track, to convene two advisory committees to study implementation. The board will need to vote again before any prohibition is adopted into regulation. Cal/OSHA staff and the board's own evaluation had concluded that removing engineered stone from the distribution chain would be the fastest and most cost-effective way to address the silicosis epidemic among fabrication workers.

Board member Derek Urwin, a UCLA chemistry professor, said "control measures are not working, and it's not the fault of the workers" during deliberations. Board chair Joseph M. Alioto Jr. and industrial hygienist Nola Kennedy joined Urwin in the unanimous vote.

The vote came after extended public testimony from physicians, industrial hygienists, fabrication workers with advanced silicosis, and industry representatives. The California Department of Public Health has confirmed more than 560 silicosis cases among the state's stoneworkers since 2019, with at least 31 deaths and nearly 60 lung transplants. Roughly 75% of those cases have been confirmed in the last three years, and state public health officials project approximately 1,000 additional cases in California over the next two years.

Industry representatives opposed the measure, arguing that the engineered stone material itself is not the problem but rather fabrication shops that fail to follow existing wet-cutting, ventilation and respiratory protection requirements. Major manufacturers, including Cambria and Cosentino, had proposed an industry-led fabricator certification program and stepped-up enforcement as an alternative to a fabrication prohibition.

Matt Thurston, regional director of Cosentino North America, told the board that banning the product to compensate for failed enforcement was irresponsible, and said many shops already fabricate engineered stone safely and in compliance with the existing emergency temporary standard.

Cal/OSHA adopted an emergency temporary standard targeting engineered stone fabrication in December 2023 and has since opened more than 140 inspections of fabrication shops, assessed roughly $1.8 million in penalties, and issued stop-work orders at 26 shops where dry-cutting or inadequate respiratory protection was observed, according to agency presentations to the board earlier this year.

If California ultimately adopts a fabrication prohibition through the rulemaking process, it would become the first U.S. state to do so. Australia adopted a similar prohibition on engineered stone in 2024.

The Standards Board's next monthly meeting is scheduled for June 18 in Sacramento.