In Portland, the policy requires school buses to turn off engines unless it’s 20 degrees or colder .

PORTLAND (AP) – Environmental Protection Agency Administrator Christie Whitman on Thursday praised efforts in Maine to reduce emissions from school buses, which she said travel 4 billion miles nationwide each year.

Standing in front of two gleaming buses, Whitman singled out the Portland School District for replacing old buses with newer models and reducing the amount of time buses spend idling their engines each day.

In addition, the school district is seeking to further reduce emissions by using ultra-low sulfur fuel in its 32 diesel buses and retrofitting buses with newer pollution controls or replacing them with ones that use alternative fuels, said Kevin Mallory, the school district’s transportation director.

“We know they’re the safest way to get kids to school. We also believe they can be healthier,” Whitman, surrounded by youngsters, said at a news conference outside the Reiche Elementary School.

The EPA has a $5 million congressional appropriation and another $20 million from a court settlement to help school districts across the country begin making changes to reduce school bus emissions, Whitman said.

In Maine, education and environmental agencies collaborated last year in sending letters to superintendents encouraging them to adopt policies to limit the amount of time buses spend idling.

In Portland, the policy requires school bus drivers to turn off their engines unless it’s 20 degrees or colder outside, Mallory said. Drivers also are not allowed to idle their engines while parked in front of schools.

The school district has even employed scheduling and routing software to keep buses moving efficiently to reduce idling time, Mallory said.

The goal nationwide is to reduce the average amount of time each school bus idles from an hour to 30 minutes a day by 2005, Whitman said. That alone would save 17 million gallons of fuel a year, she said.

By 2007, there is a mandate for new technology in diesel engines that will require ultra-low sulfur fuel. The EPA has set a goal of 2010 for retrofitting school buses purchased before 2007 with devices that reduce air pollution.

In Portland, the city will be applying for grants to pay for retrofitting the buses at a cost of $5,000 to $6,000 apiece, Mallory said.

Whitman’s visit to Maine came two days after the Bush administration proposed reductions greater than 90 percent in air pollution from diesel-powered farm, construction and other off-road equipment.

The changes would start with 2008 models, and all bulldozers, farm combines and other diesel-powered equipment not used on roads must have modern emission controls by 2014. Cleaner burning diesel fuel would be required by 2010.

Diesel engines represent a bigger problem than most people realize, accounting for a greater percentage of nitrogen oxide emissions than power plants in New England, said EPA spokesman Peyton Fleming.

Diesel engines account for 18 percent of nitrogen oxide emissions, compared to 10 percent for power plants, he said.

In Portland, the city used to have one of the oldest fleets of school buses in Maine, but its buses are now among the newest, Mallory said. The oldest bus in the fleet is a 1998 model.

But even the new buses won’t meet the new pollution guidelines without being retrofitted or replaced, he said.