California Enacts Reactive Chemical And Methyl Methacrylate Controls Under Senate Bill 883

California approved Senate Bill 883 on 27 September 2026 as Chapter 658. The enacted law adds building-permit safeguards for certain new reactive chemical storage facilities and specific treatment of methyl methacrylate (MMA).

New-Facility Permit Conditions

A city or county may not approve a building permit for a new reactive chemical storage facility where an explosion, including thermal runaway, could cause injury or death beyond the property boundary unless three conditions are met:

• A backup cooling or other contingency system is approved by the Unified Program Agency.
• The application demonstrates that the facility is not adjacent to a home.
• The city council or county board provides public notice and an opportunity to comment.

The permit definition covers stationary sources with a reactive-substance process, excluding facilities exempt under Government Code section 53091(d). The act sets no numerical distance for adjacency.

Qualifying approvals must be notified to the Office of Emergency Services and OEHHA. At the next revision of the emergency operations plan or equivalent document, the local authority must designate a lead hazardous-materials response department. OEHHA must also consider the specified facilities in disadvantaged-community assessment under Health and Safety Code section 39711.

Inspections Have A Separate Scope

Section 25404.7 requires inspections at least every three years for facilities meeting its own definition. This includes accidental-release-programme coverage and CalEPA reactive-substance designation and minimum-threshold conditions. It is narrower than the building-permit definition. Results go to CalEPA, the State Fire Marshal and the Office of Emergency Services.

The enacted inspection definition cites section 22532, while the act's regulated-substance definition appears in section 25532. This cross-reference requires clarification; the inspection rule cannot safely be described as automatically covering every facility subject to the permit safeguards.

MMA Threshold And Environmental Review

The law adds MMA to the regulated-substance definition, requires CalEPA to adopt a state threshold quantity and removes the specified section 25534 exemption for sources storing or using MMA. It sets no numerical threshold itself and does not ban MMA.

The advanced-manufacturing CEQA exemption is unavailable for specified new facilities or significant expansions or modifications involving MMA at or above the adopted threshold. This removes one exemption, rather than every CEQA exemption or automatically requiring an environmental impact report.

The permit safeguards and emergency-plan duties do not expressly depend on MMA threshold rulemaking. The specified CEQA exclusion does, while inspection coverage has its own designation and threshold conditions.