With summer vacation just underway, the next school year is the furthest thing from city kids’ thoughts. But some local elected officials and environmentalists are already worrying that the arrival of fall could mean dirty business for young lungs.

The Department of Education is expected to soon sign a three-year multi-million dollar contract to purchase fuel for its 5,000 school buses. Yet despite federal and state-funded recommendations to convert all buses to cleaner ultra low-sulfur diesel (ULSD), the Bloomberg administration is still considering a deal that includes regular diesel fuel.

“It’s lagging behind at the expense of kids’ health and development, and that’s gross negligence,” said City Councilmember Alan Gerson, who, along with Council members David Yassky and Eva Moskowitz, has been pushing for the switch.

The danger of diesel exhaust is well documented. A 2002 study released by the nonprofit Environment and Human Health Inc. revealed that the concentration of fine particulate pollution was 5 to 15 times higher aboard buses than outside them, a dramatic finding given that children nationwide spend about three billion hours riding to and from school each year. On any one trip, they may inhale up to 40 different chemical pollutants, which can cause asthma attacks, bronchitis, pneumonia, and premature death.

Recognizing the problem, the U.S. Environmental Protection Agency in 2001 mandated that all on-road vehicles convert to ultra low-sulfur diesel by 2006. NYC Transit, which runs the city’s bus system, was quick to take heed and has already switched all 4,700 of its diesel buses to ULSD.

The Department of Ed, however, with a particularly vulnerable ridership to protect, has been much slower to act. And it’s not for lack of funding. The New York Power Authority in 2001 offered the city $6 million to gas up 1,000 newer school buses with ULSD fuel and retrofit them with filtration devices which, while not needed to use the air-friendly fuel, could help cut emissions by 90 percent. Though the Power Authority has been negotiating with city education officials for months, urging them to work with their 50-plus bus contractors to upgrade, to date none of the 1,000 school buses have been retrofitted.

“We’re disappointed that it’s not been implemented sooner,” said Peter Barden, spokesperson for the Power Authority.

“This is absolutely critical,” said Craig Wilson, associate director of environmental health for the American Lung Association of New York. “We know that diesel exhaust poses extreme health threats to children. We urge the Department of Education to take the right step.”