California's attorney general, joined by officials from 16 other states and multiple cities, is opposing a U.S. Environmental Protection Agency proposal to weaken emissions standards for semi-trucks and other heavy-duty vehicles. The rule, unveiled in July 2026, would harm air quality and public health, they argue.
The proposal would significantly increase nitrogen oxide (NOx) emissions, which form smog and cause respiratory illnesses. The EPA proposal would shorten emission warranties for heavy-duty vehicles from 10 years to 5 years for model year 2027 and later, resulting in an additional 36,000 tons of NOx emissions annually, according to the EPA's own calculations. The proposal would also delay implementation of stricter standards from 2027 to 2030.
"The EPA's harmful rule is not only illegal, but it would put public health at risk by contributing to dangerous air pollution with serious health impacts. These impacts are especially concerning for communities of color and low-income communities, which too often bear a disproportionate share of pollution and its health consequences," said California Attorney General Rob Bonta.
The coalition argues the proposed rule violates the federal Clean Air Act, undermines states' ability to meet federally mandated air quality standards, and fails to account for health consequences. They are urging the EPA to withdraw the proposal immediately.