The South Coast Air Quality Management District (South Coast AQMD) approved amendments to Rule 1146.2, a regulation aimed at significantly reducing emissions of nitrogen oxides (NOₓ) from large water heaters, small boilers, and process heaters used across commercial and industrial facilities in Southern California. The changes will require many new and existing residential and commercial buildings in the region to transition to zero-emission water heaters, boilers, and other gas-fired equipment. The requirement begins in 2026 for certain units in new buildings and extends through 2033 for larger units and existing buildings.

The action, taken as Agenda Item 26 during the board’s June 7, 2024 meeting, clears the way for stronger emission limits while determining that no new environmental review is required under the California Environmental Quality Act (CEQA). Instead, the board found that the amended rule falls within the scope of the previously certified 2022 Air Quality Management Plan (AQMP) Environmental Impact Report.

The change is likely to bring a significant reduction in NOx emissions, which occur with the fossil fuel combustion processes that also release carbon emissions. It is also part of a growing effort to reduce the use of natural gas-fired appliances. In 2021, the Bay Area AQMD passed a rule to phase out gas heaters starting in 2027. In 2022, the California Air Resources Board (CARB) adopted a proposal to ban the sale of all new natural gas-fired space heaters and water heating appliances by 2030.

Rule 1146.2

Rule 1146.2 applies to combustion equipment with a rated heat input of up to 2 million British thermal units per hour, commonly found in restaurants, apartment buildings, hospitals, manufacturing facilities, and other commercial operations. These units are a notable source of NOₓ, a pollutant that contributes to smog formation and is linked to respiratory and cardiovascular health impacts.

Under the proposed amendments, South Coast AQMD would move toward zero-emission standards for covered equipment as cleaner technologies become commercially available. New installations would be required to meet a zero-parts-per-million NOₓ emission limit once those technologies are deemed feasible. Existing equipment would be subject to phased-in requirements tied to the age of the unit, allowing operators time to plan for replacements or retrofits rather than facing immediate compliance deadlines.

The amendments to Rule 1146.2 are part of a broader strategy by South Coast AQMD to meet federal and state air quality standards in the South Coast Air Basin, which includes Los Angeles, Orange County, and portions of Riverside and San Bernardino counties. The region has long struggled with some of the worst ozone pollution in the nation.

Final adoption and implementation timelines will depend on subsequent board actions and determinations regarding technology availability.