NSI supports strong worker protections while calling for science-based exposure limits, clearer definitions and regulations focused specifically on artificial stone
The Natural Stone Institute (NSI) urged the California Occupational Safety and Health Standards Board to revise its standard regulating the use of engineered stone by incorporating clearer, science-based exposure limits that would better protect workers and distinguish engineered stone from natural stone.
The Oberlin, Ohio-based group submitted public comment on September 30 in response to OSHSB Petition 609 proposed by the CAL OSHA Board.
The proposed standard would prohibit the fabrication and manufacture of artificial stone containing more than 1% crystalline silica. The proposal follows California Occupational Safety and Health Standards Board Petition 609, which seeks additional protections for workers exposed to respirable crystalline silica during the fabrication and installation of engineered stone products.
In comments submitted September 30, NSI emphasized its support for protecting workers from preventable silicosis while recommending that the state’s final regulations be based on scientific evidence, clearly distinguish artificial stone from natural stone and provide employers with requirements that can be consistently implemented and enforced.
“The Natural Stone Institute greatly values worker safety and the critical need to protect employees from preventable silicosis caused by airborne respirable crystalline silica,” NSI CEO James A. Hieb, CAE, said in the organization’s comments. NSI also called for science-based research and exposure data to be considered as California develops its final regulations.
Among its recommendations, NSI asked Cal/OSHA to make clear that the proposed standard applies specifically to artificial stone slabs and panels. NSI also recommended that the definition of artificial stone should be revised to explicitly state that “natural stone, fired ceramic and porcelain slabs, tiles and panels not be regulated as artificial stone.”
NSI additionally recommended removing the terms “quartz” and “cuarzo” from proposed signage requirements, arguing that the terms could be misinterpreted as referring broadly to the naturally occurring mineral quartz, which is used in numerous materials and industries.
The Institute also raised questions about a proposed 3 micrograms per cubic meter (μg/m³) Artificial Stone Action Level. NSI asked Cal/OSHA to provide the research or medical evidence supporting 3 μg/m³ as a documented safe exposure level and noted that the proposed threshold is close to laboratory minimum reporting levels, potentially increasing the possibility of measurement error.
NSI also questioned a proposed respiratory protection requirement calling for respirators with an assigned protection factor (APF) of 10,000 in certain circumstances. NSI characterized that requirement as excessive and argued that respirator selection should instead be based on known exposure risks. NSI said the APF 1,000 protection available under current regulations should provide protection at exposure levels well above those recorded in Cal/OSHA visits and consultations.
Other recommendations submitted by NSI include:
- Clarifying what documentation and records businesses must maintain to demonstrate compliance, including situations in which documentation is unavailable from the original product supplier.
- Narrowing language defining the “Artificial Stone Action Level” so it applies to work performed on artificial stone containing more than 1% crystalline silica rather than a broader “variety of materials.”
- Clarifying what constitutes “minor on-site adjustments” during installation. NSI cautioned that ambiguous language could unintentionally encourage high-exposure fabrication tasks to be performed in the field, where assessment and enforcement may be more difficult.
NSI said it intends to remain engaged in the rulemaking process as California considers additional protections for workers exposed to respirable crystalline silica.
“NSI looks forward to continuing its role to advocate for employee safety, education, and resources to support both workers and employers,” Hieb wrote. NSI makes many of these resources available to the public on its website at https://www.
