South Coast AQMD Governing Board Adopts Warehouse Indirect Source Rule

On May 7, 2021 the South Coast AQMD Governing Board adopted Rule 2305, known as the Warehouse Indirect Source Rule (ISR). The rule requires warehouses greater than 100,000 square feet to directly reduce nitrogen oxide (NOx) and diesel particulate matter (PM) emissions, or to otherwise reduce emissions and exposure of these pollutants in nearby communities.

Warehouses are a key destination for heavy-duty trucks and have other sources of emissions like cargo handling equipment, all of which contribute to local pollution, including toxic emissions, to the communities that live near them. Emissions from sources associated with warehouses account for almost as much NOx emissions as all the refineries, power plants and other stationary sources in the South Coast Air Basin combined. Those living within a half mile of warehouses are more likely to include communities of color, have higher rates of asthma and heart attacks, and a greater environmental burden. The warehouse rule is expected to reduce smog-forming emissions by 10-15 percent from warehouse-related sources.

As part of the rule, warehouse operators will need to earn a specified number of points annually. These points can be earned by completing actions from a menu that includes acquiring and using natural gas near-zero and/or zero-emission on-road trucks, zero-emission cargo handling equipment, solar panels or zero-emission charging and fueling infrastructure and more. As alternatives to the points system, warehouse operators can prepare and implement a custom plan specific to their site or choose to pay a mitigation fee. Funds from mitigation fees will be used to incentivize the purchase of cleaner trucks and charging/fueling infrastructure in communities near the warehouse that paid the mitigation fee.

Starting January 1, 2022, existing warehouses will phase-in to the program over three years, beginning with the largest facilities first. In Los Angeles County, about 1,600 existing warehouses are expected to be subject to the rule, with about an equal number of additional warehouses located in the Inland Empire and Orange County.

South Coast AQMD staff is available to assist the regulated community and answer any questions through a hotline at 909-396-3140 and email at For more information, please visit 

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