MILFORD — They’re sometimes called “zombie trucks,” and their franken bodies — old high-polluting diesel engines concealed by new exteriors — cruise I-95 and other highways spewing emissions that exceed federal vehicle standards.

In the last hours Scott Pruitt was administrator, the Environmental Protection Agency decided last week not to enforce an existing annual cap on these vehicles, also known as “glider kits,” through the end of 2019. The move could lead to an increase in freight trucks that emit up to 55 times the air pollution that vehicles with modern emissions controls do, according to a study by the EPA itself.

Connecticut Attorney General George Jepsen is currently in communication with other states about this change, said Jaclyn Severance, spokesman for the attorney general’s office. Connecticut and 11 other states filed comments with the EPA in January against lifting regulations on these trucks, which they called “a pollution menace.”

A New England trucking throughfare, Connecticut environmentalists and lawmakers on Thursday decried the end of the Obama-era cap, which limited truck manufacturers to producing 300 gliders per year.

“It’s a sad day that the Trump administration has done this,” said state Sen. Paul Doyle, a Wethersfield Democrat who is running for attorney general. He held a news conference at the I-95 Northbound rest stop in Milford to highlight the issue. Connecticut’s next attorney general should oppose such deregulation, he said.

“It is incumbent upon us all to make sure we are doing everything we can to improve our air quality and not make it worse,” said state Sen. Gayle Slossberg, a Democrat from Milford.

Even the president of the Connecticut Motor Transport Association was not thrilled.

“Our industry for the past 10, 12 or more years, we’ve been at the table with the EPA,” Joe Sculley, the trucker association’s president, said in an interview Thursday. “Our industry feels we had great dialogue with the government on (emissions). We got, kind of, where we wanted to be, and then it’s unraveling a little bit.”

Zombie truck manufacturers built these trucks to skirt modern emissions standards. An estimated 10,000 glider trucks were sold in the U.S. in 2015, or about 4 percent of new heavy-duty truck sales, according to EPA figures. Without the cap, production could return to that level.

Most Connecticut-based trucking fleets opt to buy new trucks with modern emissions controls, Sculley said. Zombie trucks are sometimes purchased by individuals running their own small trucking operations or those who contract with larger fleets.

“Some people who use them are still skeptical of these new emission controls on these (new) trucks functioning properly,” Sculley said. They might worry that the controls will break, resulting in maintenance costs and time off the road for their truck, and opt to purchase a vehicle with an old diesel engine.

Connecticut has the third best electric vehicle infrastructure in the state, said Martha Klein, chapter chair of the Connecticut Sierra Club. The state and country need to put more electric vehicles on the road — not diesel, she said.

“When you have the technology to control human-harming and climate-harming pollution, what you do is you control it,” she said.

emunson@hearstmediact.com; Twitter: @emiliemunson