A report in NEJM Evidence identifies 592 confirmed silicosis cases among California workers who fabricated engineered-stone countertops from January 2019 through June 2026. At least 31 workers have died, and 65 required lung transplants. The study, Silicosis Epidemic Among Workers Fabricating Engineered Stone (Quartz) Countertops in California, 2019–2026, was reported on August 20, 2026.
David Michaels of George Washington University led the study with co-authors from the California Department of Public Health, UCLA and UCSF. The findings focus on workers fabricating engineered stone, also described as quartz countertop material, and on the silica-dust exposure created during cutting, grinding and polishing.
Separately, California's Occupational Safety and Health Standards Board voted 3–0 on May 21, 2026 to direct Cal/OSHA to draft an emergency temporary standard toward a prohibition on fabrication and installation of engineered stone containing more than 1% crystalline silica. The Board directive begins drafting work; it is not a prohibition already in force.
Report findings
The report covers the January 2019–June 2026 period and identifies confirmed disease among California engineered-stone countertop workers. The 592 confirmed cases, at least 31 deaths and 65 lung transplants are separate reported figures. They describe the human consequences associated with the occupational exposure addressed in the study, rather than a product-performance measure.
The article appeared in NEJM Evidence and names David Michaels as lead author. Its co-authors include contributors from CDPH, UCLA and UCSF. For procurement and specification teams, the report places a defined California worker-health record alongside the material choices made for countertops and related fabrication work.
Reported case figures
- 592 confirmed silicosis cases among California engineered-stone countertop workers.
- At least 31 workers have died.
- 65 workers required lung transplants.
- Case-identification period: January 2019–June 2026.
Michaels said: Hundreds of workers have been sickened making quartz countertops, a product we do not need, especially when a safer alternative is available. The statement is attributed to the study's lead author and addresses the countertop-fabrication setting described in the report.
Material and exposure
Engineered stone, often called quartz, is made by crushing natural quartz into fine powder and binding it with polyester resins and pigments. The material typically contains over 90% crystalline silica. During cutting, grinding and polishing, the material releases fine silica dust. That dust causes silicosis, an incurable lung disease.
The material description is important because an engineered-quartz surface is not simply a label for a visual finish. Its quartz powder, resin and pigment composition is part of the exposure issue described in the report. Buyers considering engineered quartz surfaces can keep the material category distinct from the controls and working methods used during fabrication.
The report's focus is engineered-stone countertop workers in California. It does not convert every stone material into the same category. For teams examining other material paths, the comparison of natural stone and sintered porcelain provides a relevant lower-silica alternative context.
California standards action
WOEMA petitioned California's Occupational Safety and Health Standards Board to prohibit fabrication and installation of engineered stone containing more than 1% crystalline silica. On May 21, 2026, the Board voted 3–0 to direct Cal/OSHA to draft an emergency temporary standard toward that ban.
The distinction between a Board directive and an operative restriction matters in project communications. The locked record says the Board directed drafting of an emergency temporary standard; it does not say that a ban has taken effect. The developing California action is covered in California ban progress.
For a buyer, the immediate factual reference points are the case report, the material's typical crystalline-silica content and the May 21 Board vote. Those points can be recorded without representing the proposed standard as an already-effective requirement.
What it means for buyers
Buyers, importers and specification teams can separate product selection from the fabrication exposure described in the report. A material discussion can identify whether an engineered-quartz surface is requested, while procurement conversations can ask how cutting, grinding and polishing will be handled in the relevant fabrication setting.
California projects should distinguish the existing report from the pending regulatory drafting direction. Contracts, product schedules and communications should not state that the proposed more-than-1%-crystalline-silica prohibition is already in force. They can instead identify the May 21, 2026 Board vote and the instruction to Cal/OSHA to draft an emergency temporary standard.
Where a specification allows choices, the reported material composition and California case record provide a basis for evaluating engineered stone alongside alternative material categories. The decision remains tied to the product requested and the fabrication work it entails, rather than to an unsupported claim about a future rule.
