California Plans to Ban Artificial Stone Containing More Than 1% Crystalline Silica
News related to:Cal/OSHA · 3 min read
California's Division of Occupational Safety and Health (Cal/OSHA) has unveiled a draft emergency regulation aimed at prohibiting the manufacture and fabrication of artificial stone containing more than 1% crystalline silica. The proposed rule, which could take effect as early as December 2026 or January 2027, is a significant step in the state’s efforts to address the ongoing silicosis epidemic among countertop fabrication workers.
The regulation follows years of scientific research, medical evidence, and advocacy by physicians, workers, and families affected by artificial stone silicosis. Earlier this year, the California Occupational Safety and Health Standards Board granted a petition submitted by over 600 physicians from the Western Occupational and Environmental Medical Association (WOEMA), urging the state to ban the fabrication and installation of artificial stone due to its severe occupational health risks.
Artificial stone, commonly used for kitchen and bathroom countertops, contains at least 90% crystalline silica by weight. Fabrication activities such as cutting, grinding, polishing, and edging release airborne nano-sized, high-surface area respirable crystalline silica dust. Medical and scientific research has increasingly linked exposure to artificial stone dust with accelerated silicosis, a progressive, irreversible, and fatal lung disease.
Cal/OSHA is accepting public comments on the draft emergency regulation through September 30, 2026. Following the public comment period, the proposal will be considered by the Cal/OSHA Standards Board. If approved at the Board's October or November meeting, the emergency regulation could become effective as early as December 2026 or January 2027.
The proposed regulation establishes a two-stage implementation process. Sixty days after the emergency regulation becomes effective, employers will no longer be permitted to purchase new artificial stone containing more than 1% crystalline silica for fabrication or manufacture. Employers will be allowed to continue fabricating inventory they purchased, contracted for, or possessed before the regulation's effective date during a limited transition period. All manufacture and fabrication of artificial stone containing more than 1% crystalline silica will be prohibited 180 days after the regulation becomes effective, regardless of when the material was acquired.
As a practical matter, if the regulation becomes effective in December 2026 or January 2027, California fabrication shops would have approximately six months to work through existing inventory before the prohibition is fully implemented.
"After reviewing scientific evidence, Cal/OSHA concluded that artificial stone is inherently dangerous and uniquely toxic. The agency's proposal reflects a growing recognition that existing control measures are not sufficient to prevent workers from developing silicosis. We commend Cal/OSHA for taking this important step and encourage the Standards Board to move quickly to finalize these protections."
California has documented hundreds of confirmed silicosis cases among countertop fabrication workers (644 as of today), many of whom developed the disease after relatively short periods of exposure. Researchers and regulators have found that artificial stone poses hazards distinct from natural stone products because of its exceptionally high silica content, the presence of nano-sized, high-surface area particles generated during fabrication, and the additional uniquely toxic blend of resins, dyes, glues, and heavy metals incorporated into the material.
The proposed regulation also reflects developments in other jurisdictions. Australia implemented a nationwide prohibition on artificial stone in 2024 after concluding that enforcement efforts and engineering controls could not adequately protect workers from crystalline silica exposure. Australian regulators reported that safer alternative countertop materials were, and have remained, widely available and that the transition away from artificial stone did not result in economic disruption.