EPA plans to rewrite truck pollution rules, but it’s unclear how much stricter they’ll get

A truck exits the 710 Freeway at East Alondra Boulevard next to an apartment complex in Compton. The U.S. Environmental Protection Agency plans to update emissions standards for heavy-duty diesel trucks in an effort to reduce smog-forming pollution.
A truck exits the 710 Freeway at East Alondra Boulevard next to an apartment complex in Compton. The U.S. Environmental Protection Agency plans to update emissions standards for heavy-duty diesel trucks in an effort to reduce smog-forming pollution.
(Don Bartletti / Los Angeles Times)

The U.S. Environmental Protection Agency announced Tuesday that it would begin rewriting smog rules for heavy-duty trucks, but offered little clarity on how much the initiative would seek to slash or strengthen regulations and whether it might conflict with California’s efforts to develop its own stricter emissions limits.

EPA officials said they would start work to revise truck pollution standards to lower nitrogen oxide emissions while also removing requirements industry has complained are costly and burdensome. The agency provided few specifics on what changes could ultimately result from the “Cleaner Trucks Initiative,” but said it plans to propose new rules in early 2020.

“This initiative will help modernize heavy-duty truck engines, improving their efficiency and providing cleaner air for all Americans,” acting EPA Administrator Andrew Wheeler said.


“We are under no regulatory or court-ordered requirements to launch this initiative,” Wheeler added. “We are doing it because it’s good for the environment.”

Environmentalists, who have long pressed the EPA to adopt rules slashing emissions from diesel trucks, were surprised given the Trump administration’s nearly two-year push to weaken environmental protections, including those aimed at reducing other sources of health-damaging air pollution.

“In this one instance there’s an admission by the EPA that their job is to deal with nitrogen oxides that hurt the health of Americans and children,” said Amit Narang, regulatory policy advocate for the group Public Citizen. “If they really believe that, they should also immediately stop the other deregulatory actions.”

The move was welcomed by state and local air quality regulators, who have also pushed for tighter limits and say reining in big rig emissions is one of the biggest obstacles to clean air in Southern California and other areas of the country that do not meet federal health standards.

It remains unclear if the EPA would include more stringent emissions limits or anything as strict as the 90% reduction in nitrogen oxide pollution California air quality officials say is necessary to clean smog to health standards. Millions of Californians breathe air that exceeds federal limits for ozone and fine-particle pollution, which is linked to asthma, heart disease and thousands of early deaths each year.

EPA officials referred to the truck pollution initiative as both a “deregulatory” and “regulatory” action, and presented it in the context of dozens of regulation-slashing actions completed or under development by the Trump administration. Agency officials would not say whether the rule would ultimately include a toughening of tailpipe emissions limits on trucks.


Wheeler said part of the initiative would be “to cut unnecessary red tape while simplifying certification and compliance requirements.” In the nearly two decades since the agency’s truck pollution rules were last overhauled, requirements have been added in piecemeal fashion, he said, resulting in “overly complex and costly requirements that do little to actually improve the environment.”

Bill Wehrum, the EPA’s assistant administrator for air and radiation, said it does not have an emissions reduction target in mind because it is at the beginning of the rule-making process. He suggested the update could involve changes to address known shortcomings in vehicle emissions-testing methods that fail to capture high pollution generated by real-world driving conditions.

Wehrum said there may be ways to reduce emissions “without even changing the number, the numeric value of the standard.”

Trucks remain the No. 1 source of smog-forming pollution in Southern California.

Ozone pollution exceeded the federal health limit of 70 parts per billion in the South Coast air basin that spans Los Angeles, Orange, Riverside and San Bernardino on 141 days this year as decades of progress fighting smog has faltered in recent years.

California is already developing its own, more stringent nitrogen oxide emissions standards for trucks, raising the possibility that they could conflict with the proposal by the federal government. The state Air Resources Board is currently testing vehicles as it develops new rules it expects to consider for adoption by the end of next year.

Air Resources Board spokesman Stanley Young said nitrogen oxide pollution from heavy-duty trucks “is a huge problem both as a precursor to ozone and fine particles, and also as a greenhouse gas. And the total emissions from this source are growing.”


“We are pleased that the agency is moving forward to address the next generation of new heavy-duty engines,” Young said.

Wehrum said the agency would work with California in drawing up the new truck pollution standards, and an EPA spokesman said “we are committed to setting a single, 50-state standard.”

If California chooses to impose stricter emissions rules than the EPA, however, it may need a waiver — a situation that could set up another state-versus-federal legal battle.

In another recent move that has spawned a legal fight, under Trump the EPA has proposed freezing greenhouse gas emissions standards for passenger cars and trucks at 2020 levels while taking away the authority to adopt stricter rules by California and about a dozen other states that adhere to its standards.

“We’d want to make sure this isn’t going to be used as a device to set weak standards and then deny a future California request to set its own more aggressive standard,” said Frank O’Donnell, a longtime clean-air advocate and former president of the nonprofit Clean Air Watch. “It could become a mirror image of the passenger vehicle battle.”

EPA officials said heavy-duty trucks account for an increasing share of the nation’s smog-forming emissions and will be responsible for one-third of nitrogen oxide pollution from transportation by 2025. Officials said they’ve heard from industry groups and states saying it was time to update rules.


“This new rule will provide manufacturers with additional regulatory certainty and contribute to the cleaner environment we’ve promised to help deliver,” said Ross Eisenberg, vice president for energy and resources policy for the National Assn. of Manufacturers.

In 2016, more than 20 state and local air quality agencies, including several in California, sent petitions urging the U.S. Environmental Protection Agency to adopt tougher tailpipe emissions standards for heavy-duty trucks.

In the closing days of the Obama administration, the EPA responded to the petitions by acknowledging “a need for additional NOx reductions from this category of vehicles and engines, particularly in areas of the country with elevated levels of air pollution” and said it intended to move forward with rules that would take effect in 2024.