PORTLAND – State transportation officials want to ban trucks and buses from the left lane of Maine’s three-lane highways in an effort to meet federal air quality standards.

The Maine Turnpike Authority is widening a 30-mile section of the highway between York and Scarborough to three lanes in each direction. Work is scheduled to conclude next year.

Turnpike officials believe Maine is the only one of 14 states on the East Coast lacking a third-lane restriction on heavy-duty trucks and buses.

While some states implemented bans for safety reasons, the turnpike authority hopes it will earn federal air quality credits.

The turnpike authority has to earn a certain number of credits to mitigate any harmful impact the widening project could have on air quality.

Failure to do so would jeopardize the project, as well as federal funding for other state transportation improvement projects, said Daniel Paradee, spokesman for the turnpike authority.

An engineering firm hired to identify possible mitigation measures found nitrogen oxides pollution levels above a limit set by the U.S. Environmental Protection Agency.

The turnpike authority then developed a list of projects that could earn air quality credits. The list included improvements to park and ride lots, construction of new lots, and the creation of a highway advisory radio station.

The lane restriction rule, which would satisfy 18 percent of the required number of credits, was also on the list.

“There were very few available options capable of producing the number of air quality credits needed,” said Paul Violette, executive director of the turnpike authority.

An EPA model estimates that vehicles in the left lane are moving approximately 3 mph faster than vehicles in the middle and right lanes and are generating more nitrogen oxide emissions.

“According to their models, if trucks are in the right lane, they’re likely going to be going slower. If they’re going slower, they’re creating less pollution,” Paradee said.

The plan is viewed skeptically by truckers.

“I think it’s stupid,” said Mark Armstrong, a trucker who transports seafood between Seattle and New England. “We’re the ones with appointments to make and schedules.”

But Old Orchard Beach Councilor Joseph Kline, who commutes to Boston each day, believes trucks in the third lane are a safety problem.

“They create a problem with visibility, especially when you have two trucks trying to pass each other and being unable to see for more than a mile,” he said.

The state Transportation Department and turnpike authority will hold a public hearing on the proposed change Tuesday at the Holiday Inn Express in Saco.