WASHINGTON, D.C.: In a challenge to California's push for cleaner transportation, the U.S. House of Representatives voted this week to revoke the Environmental Protection Agency's 2023 approval of the state's plan to phase in more zero-emission heavy-duty trucks.

Lawmakers also voted to roll back an EPA waiver granted in December for California's "Omnibus" low-NOx regulation covering heavy-duty highway and off-road vehicles and engines.

A separate vote is expected, blocking California's landmark goal to ban the sale of new gasoline-only vehicles by 2035—a policy already adopted by 11 other states. The EPA issued a waiver for that plan under the Clean Air Act last December.

Whether Congress can legally overturn these waivers remains unclear. In March, the Government Accountability Office said the waivers fall outside the scope of the Congressional Review Act, which only requires Senate majority approval.

California officials pushed back firmly. "CARB will continue its mission to protect the public health of Californians impacted by harmful air pollution," a California Air Resources Board spokesperson said, calling the votes a violation of the CRA and legal precedent cited by the GAO and Senate Parliamentarian.

Republican Representative John James argued that the rules would drive up vehicle and goods prices, saying they would "force costly transitions to electric trucks, driving up prices for goods and disproportionately burdening working families and truckers across the country."

Under a 2020 executive order from Governor Gavin Newsom, California aims to make all medium- and heavy-duty vehicle operations zero-emission by 2045 "where feasible," moving away from diesel-fueled trucks.

CARB reports that although trucks over 14,000 pounds represent just three percent of vehicles on the road, they contribute over 50 percent of nitrogen oxides and fine particle diesel pollution. The NOx rule aims to slash emissions by 90 percent and is projected to deliver US$23 billion in public health benefits.

Transportation accounts for 29 percent of U.S. greenhouse gas emissions—the largest share—while heavy-duty vehicles alone make up 23 percent of that total.