The Biden administration is moving to enact stringent new emissions regulations for large trucks that have been operating for more than a decade under standards environmentalists complain are too lax.

The U.S. Environmental Protection Agency proposed Monday to cut nitrogen oxide emissions from heavy-duty trucks by roughly 90% below current standards beginning as soon as 2027. 

“These new standards will drastically cut dangerous pollution by harnessing recent advancements in vehicle technologies from across the trucking industry,” EPA Administrator Michael Regan said in a statement. 

The proposed regulations have drawn pushback from the industry that says it is already facing a shortage of drivers and is rushing to unkink a supply chain crunch and is wary about anything that would drive up costs.

“We look forward to working with EPA to ensure that the final version of today’s rule is practical, technically feasible, cost-effective,” Jed Mandel, president of the Truck and Engine Manufacturers Association, said in a statement.

Heavy-duty trucks account for a disproportionate share of pollution from nitrogen oxide, a poisonous gas that contributes to smog. The trucks, which the U.S. government estimates represent 5% of registered vehicles and 9% of miles traveled, account for 37% of total nitrogen oxide emissions emitted by vehicles traveling at highway speeds, according to the International Council on Clean Transportation. 

The agency said it’s also planning in the near future to update greenhouse-gas emission rules for trucks. 

Read more: Truckers Say This Is Worst Time for Biden Emission-Cutting Plan

Sierra Club President Ramón Cruz said the EPA’s proposal “falls short of what environmental justice communities have been demanding,” but he said “there is opportunity for the EPA through its regulatory process to hear directly from advocates on what the science requires.”

“A strong federal rule that is bold in cleaning up dirty diesel trucks is essential for the Biden administration to deliver on its climate and environmental justice commitments,” Cruz said in a statement.

The new rules won’t become effective until after a public comment period. They follow a separate effort by President Joe Biden to require automakers to produce fuel-efficient fleets of cars, SUVs and pickup trucks that average 52 miles (84 kilometers) per gallon by 2026. Biden also announced last year a target that half of all vehicles sold in the U.S. would be capable of emissions-free driving by the end of the decade.

But the government is playing catch-up on regulating truck emissions: That’s due, in part, to the different nature of big rigs that haul tons of freight and have their own regulatory yardsticks.

Read more: Robot Trucks Get U.S. Tests, Raising Self-Driving Safety Stakes

Congress has authorized the regulation of car pollution since the 1970s, but the first standards for greenhouse gas emissions from trucks were issued in 2014 and the first two years were voluntary. The most recent nitrogen oxide emission rules for trucks took effect in 2007 and 2010. The Biden administration is hoping to synchronize the nitrogen oxide and greenhouse gas emission rules so both take effect in 2027. 

The EPA said Monday it’s proposing two regulatory options for more stringent nitrogen oxide emission rules for trucks, including one that would include a jump in federal standards in 2027 and a second increase in 2031 and one that would immediately jump to full implementation in 2027. The agency estimates the second option would achieve less nitrogen oxide emissions reductions than the first one. 

Separately, the Biden administration announced plans to spend $1.1 billion in the 2022 fiscal year on expanding the U.S. Department of Transportation’s Low- and No-Emission Transit Vehicle Program and $372 million on the agency’s Bus and Bus Facilities Program. The White House said the money would be used to help state and local governments purchase U.S.-built electric transit buses and other cleaner models. The money is coming from the bipartisan infrastructure bill passed by Congress in November.