The Bay Area Air District (the District) held a virtual workshop on July 10, 2025 discussing their plans to impose more standardized and stringent air permitting requirements for facilities that recycle metals or have metal shredding operations on-site after several air quality concerns resulting from recent fire incidents and the release of Light Fibrous Material (LFM) from nearby facilities. Most notably, this includes the replacement of the Emission Minimization Plans (EMPs) for facilities that recycle and shred upwards to 50,000 tons or more of metals by more standardized Best Management Practices (BMPs).

Gaps in the Existing Rule

The District is proposing to amend Regulation 6, Rule 4: Metal Recycling and Shredding Operations (Rule 6-4), originally adopted in 2013 to reduce particulate matter (PM) emissions from facilities processing over 1,000 tons of metal annually. The rule currently requires facilities handling more than 50,000 tons per year to implement EMPs. Facilities that are below these thresholds are exempt from permitting requirements. Currently, Rule 6-4 allows metal shredding facilities to tailor their EMPs to their operations and puts the responsibility of EMP development in the hands of the facility. Consequently, this has allowed facilities to uniquely tailor their EMPs which pose consistency issues across different metal processing facilities. In addition, the District discussed the need for regulatory visibility for unpermitted sources that are below the Rule 6-4 applicability thresholds.

During the workshop, the District addressed concerns from AB 617 communities that highlighted ongoing issues, including frequent fires, deposition of LFM, and elevated levels of volatile organic compounds (VOCs) beyond facility boundaries. The West Oakland Community Action Plan (WOCAP) and Path to Clean Air (PTCA) include strategies to pursue amendments to the existing rule to reduce emissions from metal recycling and shredding operations. Therefore, the proposed amendments will further reduce air emissions and enhance air monitoring.

Proposed Amendments

In response to the gaps identified in Rule 6-4, the District is proposing the following amendments:

• Replace flexible EMPs with enforceable emission standards via mandatory BMPs for all metal shredding equipment;
• Fenceline monitoring requirements; and,
• Expand registration and permitting requirements to include smaller facilities that are currently exempt.

These amendments will create a standardized requirement, improve the District’s enforceability and accountability, and increase visibility into facility operations.

Best Management Practices (BMPs)

The District is proposing the following BMPs for fugitive emissions (point and area sources), trackout and fire prevention.

BMPs for Fugitive Sources

The following BMP will be required to address fugitive emissions from point and area sources:

• Require enclosures or windscreens for processing operations and stockpiles;
• Activities must cease during high wind events; and,
• Water application to minimize PM emissions.

BMPs for Trackout Sources

The following BMPs will be required to address trackout-related emissions:

• Prohibition of trackout onto paved roadways, from any unpaved roadways onsite and during cleanup activities;
• Surfaces and roads for vehicle traffic must be paved;
• This includes sufficient maintenance such as regular cleaning and for the facility to minimize trackout activities where possible.
• Stabilization of any disturbed inactive sites; and,
• Speed limits and appropriate vehicle traffic signage requirements.

BMPs for Fire Prevention

The following BMPs will be required for fire prevention:

• Compliance with stringent depollution methodology for incoming feedstock and inspection requirements;
• Continuous monitoring to check for off-gassing of toxic and/or flammable gases from fire prone stockpiles;
• Implementation of a “shred-to-ground” schedule; and,
• Continuous watering during and outside of operational hours for highly flammable materials.

Registration

There are over 100 sites in the Bay Area that have metal scrapping operations and are unpermitted. Facilities that have a throughput of 1,000 tons of metal or less are exempt from Rule 6-4. This has allowed for scrap metal facilities that do not have an air district permit or a shredder to operate without the District’s knowledge. To increase visibility and promote accountability, the District is proposing to amend Rule 6-4 to require registration for previously exempt sources that handle scrap metals.

Fenceline Monitoring

California Assembly Bill 2581 (AB 2581) requires the local air districts to develop facility-wide monitoring requirements at metal recycling and shredding sites in consultation with the Department of Toxic Substances Control (DTSC) and the Office of Environmental Health Hazard Assessment (OEHHA) by January 2027. The bill requires the local air districts, in consultation with OEHAA, to establish threshold levels for pollutants such as lead, zinc, cadmium, nickel, and LFM. By July 1, 2027, local air districts must formally adopt these regulations and community notification will be established.

Metal recycling facilities are known sources of heavy metals and LFM, which can be released during shredding, handling, sorting, and fires. LFM, often referred to as “fluff,” can become airborne and travel beyond facility boundaries and deposit on nearby properties. Fenceline monitoring will provide opportunities for data collection to understand emissions from metal recycling and shredding facilities (which are typically difficult to measure and quantify) and establish clear thresholds. If thresholds are exceeded, public notification will be required and result in potential reduction measures. Therefore, the implementation of AB 2581 will improve emissions estimates, enhance public transparency and provide opportunities for further reduction measures.

Timeline

The District plans to release the draft rule by the end of 2025, hold public hearings and accept public comments in early to mid-2026. Interested parties can review the White Paper which is an initial study and gap analysis the District conducted of the existing Rule 6-4 and additional documents from the Virtual workshop when it becomes available on the District’s website.

If you would like to discuss the amendments to Rule 6-4 and how it may impact your facility, please contact Trinity Consultants’ Oakland office at 510.285.6351