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Regulation 11 Rule 18: Reduction of Risk from Air Toxic Emissions at Existing Facilities - 2025 Amendments (Draft)

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Learn about the Air District's development process for amendments to Regulation 11, Rule 18, which would update and improve the Rule 11-18 Facility Risk Reduction Program that reduces health risks from toxic emissions from existing local facilities.

Find out about the status and anticipated timeline of the rule development process. Information on hearings, workshops, and other events is provided below, along with supporting documents and materials.

The Air District recently held a public workshop and public comment period on draft amendments to Rule 11-18. To view or download the documents, please click on the links below or visit the “Documents” section at the bottom of this webpage.

A recording of the public workshop and copies of the public comments received on the draft amendments to Rule 11-18 can be found in the 'Events' table and 'Comments' tables below.


Background

Regulation 11: Hazardous Pollutants, Rule 18: Reduction of Risk from Air Toxic Emissions at Existing Facilities (Rule 11-18) is designed to ensure that facilities emitting toxic air contaminants do not pose unacceptable health risks to nearby residents, workers, or students. Rule 11-18 targets existing high-impact facilities and requires them to implement Risk Reduction Plans (RRPs) which reduce risks through emissions reductions or Best Available Retrofit Control Technology for Toxics (TBARCT). (See the Facility Risk Reduction Program webpage for additional information, and see the Rule 11-18 Risk Reduction Facilities webpage for lists of facilities affected by the rule.)

The Air District is developing amendments to Rule 11-18 to address long-standing concerns about implementation delays, particularly in completing Health Risk Assessments (HRAs), and advance strategies in the Path to Clean Air Community Emission Reduction Plan (PTCA CERP), which call for increased efficiency and transparency in Rule 11-18 implementation. To accomplish this, Rule 11-18 amendments will proceed in two phases:

  • Phase 1 (current): focused on procedural improvements and implementation efficiency;
  • Phase 2 (future): focused on evaluating and potentially increasing rule stringency.

The Air District published a Rule 11-18 Concept Paper and draft updated Rule 11-18 Implementation Procedures (IP) document in December 2023. The Concept Paper was the initial step in the process of developing amendments to Rule 11-18 to improve procedures and implementation efficiency (Phase 1). The Air District accepted public comments on these documents, and also held a virtual public workshop in February 2024 to discuss and gather comments on these items. See the Facility Risk Reduction Program webpage for these documents and additional information.

Draft Rule Amendment Package

The Air District published the draft rule amendment package (including the draft rule amendments, draft Rule 11-18 Implementation Procedures, and Preliminary Staff Report) detailing the draft changes to improve program implementation and efficiency in August 2025. The draft amendments to Rule 11-18 include a number of key procedural changes, including requirements for facilities to submit their own preliminary HRAs for Air District review, correction, and approval; the establishment of detailed steps and timeline for HRA and RRP processes; and other amendments to improve clarity and efficiency. Staff has also developed draft amendments to the Rule 11-18 Implementation Procedures, which includes aligning with the draft amended rule language; improving clarity and readability; and defining the role, scope, and process for the Dispute Resolution Panel (DRP).

The Air District held a public comment period on these materials through October 13, 2025, and conducted a virtual public workshop on October 2, 2025. A recording of the workshop is available in the 'Events' table below. The Air District will review and consider all input received during the comment period and public workshop toward further development of these amendments. The Air District is currently assessing the need for revisions before preparing Proposed Rule Package that will proceed to a public hearing before the Board of Directors.

Further information on the development of amendments to Rule 11-18 will be provided on this page. To receive future updates on the amendment process for Rule 11-18, please sign up to the 'Reg 11 Rule 18' email list on the main Rule Development page.

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Last Updated: 10/16/2025