Nearly 600 California workers have developed an incurable lung disease while making ‘quartz’ countertops since 2019; 65 needed lung transplants and 31 died

Nearly 600 workers in California’s engineered-stone countertop industry have been diagnosed with silicosis since 2019, due to the health risks posed by exposure to respirable crystalline silica during the cutting, grinding and polishing of artificial-stone slabs.

According to a report published August 12 in NEJM Evidence, the California Department of Public Health (CDPH) identified 592 cases of engineered-stone silicosis between January 2019 and June 2026. Of those workers, 65 underwent lung transplantation, and 31 died.

Silicosis is a progressive and incurable fibrotic lung disease caused by inhaling respirable crystalline silica. Engineered stone, also marketed as artificial stone or “quartz,” is produced by crushing natural quartz into fine powder and binding it with resins and pigments. The resulting material typically contains more than 90% crystalline silica. Workers can inhale hazardous levels of silica dust when slabs are cut, ground or polished.

First California case identified in 2019

California’s surveillance effort began after CDPH identified its first known case among a countertop fabrication worker in January 2019. The worker was diagnosed with silicosis at 32 years old and died of respiratory failure at 38. A subsequent workplace investigation found two additional cases among former employees at the same company, including another worker who had died. Screening of the company’s 43 current employees then identified five more cases.

CDPH later expanded surveillance using hospital discharge data, electronic case reporting and direct reports from clinicians and others. By June 2026, the department had identified 592 cases across the state. The cases were notable for the workers’ relatively young ages, short exposure periods, severe disease and rapid progression. Some workers also developed other silica-associated conditions, including autoimmune disease and tuberculosis.

The report found that the disease has had a particularly severe impact on affected workers. Among the 592 identified cases, 138 workers were referred for lung transplantation, 65 underwent transplantation, and 31 died. The median age at diagnosis among cases with available data was 46, while the median age at death was 52.

Safety rules have not eliminated exposure

The findings have already prompted regulatory action in California. The state Occupational Safety and Health Standards Board adopted an emergency regulation in 2023 that was made permanent in early 2025, strengthening existing silica protections. California Senate Bill 20 subsequently codified those regulations and expanded CDPH’s role in surveillance, outreach and education. Silicosis also became a mandatory reportable condition in California in 2025.

Yet the report says workers continue to face hazardous exposure. Water-based tools and ventilation systems designed to control silica dust can be expensive to install and maintain, and overexposure can still occur even when recommended controls are in place. Enforcement is another challenge.

In 2024, California’s occupational safety agency inspected only 85 of more than 1,300 countertop fabrication shops, according to the report. Of the shops inspected, 95% were found to be in violation of safety regulations.

Australia has already banned engineered stone

California is now considering an even stronger response. In May 2026, the Western Occupational and Environmental Medical Association petitioned the state to prohibit the fabrication and installation of engineered stone containing more than 1% crystalline silica. The California Occupational Safety and Health Standards Board granted the petition and directed Cal/OSHA to begin emergency rulemaking.

The proposed approach follows Australia, which banned the manufacture, import and fabrication of engineered stone in 2024. Following the ban, manufacturers began developing alternatives, including countertops made from amorphous silica, which carries a substantially lower risk of silicosis.

The report stresses that silicosis is preventable if exposure to silica dust is reduced or eliminated. It recommends stronger surveillance, active screening and greater involvement from clinicians, who can identify workers with occupational exposure, evaluate them for silicosis and report cases to public health authorities.