MONTPELIER, Vt. (AP) – With minimal rush hour traffic and no big fossil fuel-burning power plants, Vermont is not usually considered ground zero in the debate over how to improve the nation’s air quality.

But Vermont, like neighboring states in the Northeast, is expected to move ahead by the end of the year with new and tougher California-style car emission standards. Effective for new vehicles sold beginning in the 2009 model year, the standards would regulate the greenhouse gas carbon dioxide for the first time.

Carbon dioxide is believed to be a leading cause of global warming. Climatologists have warned that if allowed to continue, rising temperatures caused by human activity – like driving – will cause melting glaciers, rising sea levels, droughts and other big problems.

But before the draft California rules even take effect, auto dealers and manufacturers have sued in both state and federal courts to block them. That has left some states in the Northeast – like Massachusetts and New York – pushing ahead to adopt the California rules, while others – like Vermont – try to decide what to do.

“Is it appropriate at this time, given the amount of litigation over the new California standards, to adopt the California standards?” asked Tom Torti, secretary of Vermont’s Agency of Natural Resources. “We’re having quite an internal debate about that.”

Maine is in a similarly tentative situation, Jim Brooks, director of that state’s air quality division, said in a recent interview. “We’re gearing up, looking over potential rule-making language. The decision whether to go forward will probably be made later this summer.”

One option will not be standing still. Federal law requires states either to adopt the California standards – and keep pace with them – or adopt a more relaxed federal standard. That’s so car makers only have to produce two types of vehicles: those that meet the California standards and those that do not.

All the states need to make a decision soon. Those that want to stay up to speed with the California rules need to have their own rules in place by the end of the year, because federal law gives automakers two years to adapt to such changes and the new California rules are scheduled to take effect in 2009.

“There is the issue of timing,” said Frank Stevenson, a supervisor in the Rhode Island Department of Environmental Management’s air quality division. He said Rhode Island, too, is in the process of deciding what to do. But he added, “We would probably want to make our decision such that we would have ours (rules) in place by the end of the year as well.”

Vermont was one of the early northeastern states – following closely on New York’s and Massachusetts’ heels in 1998 – to adopt California standards for other pollutants, such as sulfur dioxide and particulate matter. The rest of the New England states, except New Hampshire, and New Jersey also use the current California emission standards.

Mike Fitzgerald, supervisor of mobile source planning in New Hampshire’s environmental agency, confirmed that even without having adopted the California standards, his state gets the cleaner cars anyway because that’s what moves through the region’s car distribution networks.

“We generally seek legislative direction in terms of the control measures and types of programs we would implement to reduce emissions in the state,” Fitzgerald said. The California rules – existing or new – haven’t generated much interest among New Hampshire lawmakers, he said.

Regulating carbon dioxide emissions would get states into new and legally dicey territory. The federal Environmental Protection Agency has ruled that carbon dioxide, or CO2, is not a pollutant of the type that can be regulated under the Clean Air Act. That finding is the subject of a court battle, too.

The Washington-based Alliance of Automobile Manufacturers and a group of car dealers in California have cited that EPA rule in their federal lawsuit seeking to block the new California rules. They also argue that the only way to cut CO2 emissions is to reduce the amount of fuel burned, and that states are pre-empted in federal law from regulating fuel economy.

“This legislation would impose a $3,000 surcharge on every new vehicle sold with no identifiable health or environmental benefits,” said the Alliance’s Eron Shosteck. He said individual states could not affect global warming. “If you want to address climate change as an issue, it has to be done on a national or even international basis.”

Steve Hinchman, a lawyer in the Maine office of the Conservation Law Foundation, who has been tracking the emissions issue, said other estimates have put the costs of the new technologies needed to reduce vehicle CO2 emissions at about $1,000 a vehicle.

Hinchman said the technologies needed to meet the California standards already exist, and that many of the more fuel-efficient cars on the road today would pass the new California rules.

He added that any increased cost would be more than offset by fuel savings of about a third. While the extra expense results in a slightly higher monthly payment on a car loan, fuel savings would mean “consumers would be saving money in the first week they owned the car.” Someone who paid cash would see savings in about three years, Hinchman said.