Elevated exposures to respirable crystalline silica among engineered stone fabrication workers in California, January 2019-February 2020.

Background: Workers fabricating engineered stone face high risk for exposure to respirable crystalline silica (RCS) and subsequent development of silicosis. In response, the California Division of Occupational Safety and Health (Cal/OSHA) performed targeted enforcement inspections at engineered stone fabrication worksites. We investigated RCS exposures and employer adherence to Cal/OSHA's RCS and respiratory protection standards from these inspections to assess ongoing risk to stone fabrication workers.

Methods: We extracted employee personal air sampling results from Cal/OSHA inspection files and calculated RCS exposures. Standards require that employers continue monitoring employee RCS exposures and perform medical surveillance when exposures are at or above the action level (AL; 25 μg/m ); exposures above the permissible exposure limit (PEL; 50 μg/m ) are prohibited. We obtained RCS and respiratory protection standard violation citations from a federal database.

Results: We analyzed RCS exposures for 152 employees at 47 workplaces. Thirty-eight (25%) employees had exposures above the PEL (median = 89.7 μg/m ; range = 50.7-670.7 μg/m ); 17 (11%) had exposures between the AL and PEL. Twenty-four (51%) workplaces had ≥1 exposure above the PEL; 7 (15%) had ≥1 exposure between the AL and PEL. Thirty-four (72%) workplaces were cited for ≥1 RCS standard violation. Twenty-seven (57%) workplaces were cited for ≥1 respiratory protection standard violation.

Conclusions: Our investigation demonstrates widespread RCS overexposure among workers and numerous employer Cal/OSHA standard violation citations. More enforcement and educational efforts could improve employer compliance with Cal/OSHA standards and inform employers and employees of the risks for RCS exposure and strategies for reducing exposure.