California’s permanent silica rule adds task-based safeguards

October 7, 2026

California’s enhanced general-industry silica protections became permanent on February 5, 2025. Section 5204 retains the 50 micrograms per cubic meter permissible exposure limit as an eight-hour time-weighted average while imposing additional duties for defined high-exposure trigger tasks. The current displayed text makes task classification central to applicability.

APT’s California permanent silica standard tracker record identifies the high-exposure task requirements and their site exceptions.

Identify the task and the material together

The trigger definition covers specified work on artificial stone containing more than 0.1 percent crystalline silica by weight and other silica-containing products, including natural stone, containing more than 10 percent. It includes specified handling and cleanup of resulting wastes and dust. The definition also contains a task exception that requires supporting representative sampling.

The high-exposure trigger-task requirements have exceptions for quarries, mines, and concrete and cement manufacturing facilities. That exception should not be described as a general exemption from every silica duty under section 5204 or from other applicable standards.

Sampling duties continue for covered trigger tasks

Section 5204 requires scheduled monitoring for covered high-exposure trigger tasks regardless of expected exposures or objective data. Monitoring for those tasks cannot simply stop after a result below the action level; the rule requires qualified-person sampling at least every 12 months, with more frequent monitoring where its provisions require it.

The rule also sets task-specific requirements for controls, respiratory protection and medical surveillance. Their exceptions and alternatives need to be read with the relevant subsection before choosing a site procedure.

APT’s practical interpretation is to document the task, material composition and applicable exception alongside the sampling plan. The permanent-rule history separates the February 2025 adoption from the earlier emergency rulemaking. Later discussion drafts must be tracked separately from this operative text.

Find related developments in the industrial hygiene regulatory tracker.