Los Angeles smog woes worsen as U.S. EPA threatens to reject local pollution plan

Smog hangs in the air as the sun sets on the downtown Los Angeles skyline.
Smog hangs in the air as the sun sets on downtown Los Angeles in October 2023.
(Luis Sinco / Los Angeles Times)

The U.S. Environmental Protection Agency is preparing to reject California’s plan to curb air pollution in Los Angeles, a consequential move that could result in stiff economic sanctions and federal regulatory oversight of the nation’s smoggiest region.

Despite having the strictest air pollution rules in the nation, Southern California has never complied with federal health standards for ozone, the lung-searing gas commonly called smog. Because of this, state and local air regulators are required to submit plans to the EPA detailing how they intend to reduce pollution and comply with federal standards.

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California air regulators acknowledge that the region still needs to reduce smog-forming nitrogen oxides by more than 100 tons per day in order to achieve the 1997 standard for ozone.

However, the South Coast Air Quality Management District proposal calls on the federal government to make most of those cuts — at least 67 tons per day — arguing that some of the largest sources of smog-forming emissions are federally regulated, such as ships, trains and aircraft. Local air quality officials lack the jurisdiction to regulate mobile sources of emissions, and can only control stationary sources, such as industrial facilities.


In a recent draft response, the EPA has proposed rejecting California’s plan, declaring “states do not have authority” under the Clean Air Act or the Constitution to order the federal government to reduce pollution.

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In a pointed response, local air officials claimed the EPA was responsible for the damaging health effects of Los Angeles area smog, because it has failed to offer solutions to curb emissions from “sources that they know are beyond our control.”

“U.S. EPA’s draft decision is disheartening,” read a statement from the air district. “South Coast AQMD intends to comment on this new proposal and take all appropriate actions in hopes that this decision does not become final. More importantly, U.S. EPA will need to answer the millions of residents, especially children, who have asthma, lung disease and other illnesses associated with air pollution that continue to suffer.”

The EPA has until July 1 to decide whether to finalize the rejection. If the state and local air regulators fail to submit a plan that the EPA finds acceptable within that time, the federal government could withhold billions of dollars in highway funding, place strict requirements on new permits and even impose a federal plan to curb smog.

The EPA has disapproved of the air district’s plans several times in the past, but the region has managed to avert potential sanctions.

The proposed denial is the latest confrontation between Southern California air regulators and the Biden EPA — two unlikely adversaries who have clashed for nearly two years over how to solve the region’s long-standing issues with smog.


It has also highlighted the complex nature of regulating pollution in the region where at least three entities have authority — the local air district, which oversees smokestack emissions; the California Air Resources Board, which governs in-state vehicles; and the EPA, which handles interstate and international travel.

However, some environmental advocates say the dilemma is a collective failure by every level of government.

Adrian Martinez, a senior attorney with Earthjustice, said the conflict follows years of repeated delays and deadline extensions, when all three environmental agencies were capable of cutting more emissions.

“The plan to meet our clean air standards relied on these faith-based assumptions that we’ll figure out how to reduce the pollution at a later time. And what ended up happening is we never figured it out,” Martinez said.

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Historically, Southern California has been plagued by smog, which forms when the region’s persistent sunlight interacts with vehicle exhaust and smokestack emissions. The region’s mountainous terrain confines this toxic haze over the region, rather than allowing it to disperse.

Although there has been significant progress over the last several decades through the development of cleaner vehicle engines and pollution controls for industry, the region’s smog remains the worst in the country.


Since 1997, nitrogen oxides have decreased 70% in the air basin. The majority of those emission reductions are the result of stricter vehicle standards imposed by the state, and locally imposed regulations on industry, according to the South Coast air district.

As emission reductions have stalled and aircraft emissions have risen, the air district has found itself under increasing pressure to force the EPA’s hand. According to estimates, even if Southern California eliminates emissions from all building and industrial sources, it wouldn’t be enough to meet federal standards.

The air district has sued the EPA for violating the Clean Air Act, arguing it was impossible for the region to comply with federal smog standards without massive cuts from federal sources. The move was intended to compel the EPA to adopt new regulatory strategies that would curtail pollution from ports, railyards and airports. The air district later settled the case.

For its part, the Biden administration last year adopted tighter vehicle emission standards, including for heavy-duty trucks, which is expected to reduce smog.

But these federal requirements still pale in comparison to rules in California — the only state that can implement its own vehicle emission standards with federal approval.

“We acknowledge that there are sources of air pollution in South Coast that the air district and CARB do not have the regulatory authority to control,” an EPA spokesperson said in a statement. “EPA has made it a very high priority to help reduce mobile source emissions through rulemaking and leveraging unprecedented federal funding ... wherever possible.”


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The EPA is accepting public comments on its proposed disapproval of the regional smog plan until March 4.

If the EPA finalizes this disapproval, California will have 18 months to obtain the federal agency’s approval for a new plan. By failing to meet that deadline, the federal government would require some newly permitted businesses to reduce twice as many tons of smog-forming as they emit.

Six months later, if the deadline still hasn’t been met, the Federal Highway Administration is required to impose a moratorium on highway funding (with exceptions for mass transit and public safety).

No more than two years after final disapproval, the EPA must enforce a federal implementation plan to achieve federal smog standards.