The reduction in sulfur content, which is classified as a "fine particle," has energy experts fearing a spike in diesel prices as pipelines and refineries face increased spending and logistic issues in producing and transporting the new fuel.

But health experts say it will lower health costs for Americans, who since the 1980s have suffered through a surge in asthma, a respiratory disease that often targets the young and the elderly.

"We know that fine particle pollution is the most lethal air pollutant, tied to a whole range of health problems," said Frank O'Donnell, president of Clean Air Watch, a non-profit environmental watchdog.

The law, which was passed in 1997 during the Clinton presidency and affirmed by the current Bush administration, is expected to prevent the premature deaths of 8,300 people per year, along with about 5,500 cases of chronic bronchitis and more than 360,000 asthma attacks, according to Environmental Protection Agency estimates.

Plus, the new standard will help prevent 1.5 million lost work days, 7,100 hospital visits and 2,400 emergency room visits for asthma each year, the EPA said.

"In other words, the ultra-low-sulfur diesel fuel is one of the most positive and significant public health protection moves from the EPA in years," said O'Donnell.

KEEPING YOUNG LUNGS HEALTHY

While the new regulation will reduce sulfur emissions directly related to the fuel, it will also enable pollution controls which can remove 90 percent of diesel soot.

"The real benefits come when additional pollution control technologies are added to engines, either during manufacture through retrofitting of existing vehicles and off-road equipment," said Robert Laumbach, assistant professor of environmental and occupational medicine at Rutgers University in New Brunswick, New Jersey.

Not only is asthma the nation's most common chronic disorder, it targets children and elderly. While children make up only 25 percent of the population, they represent 40 percent of all asthma cases. And the disease has far outpaced the population, growing 70 percent from the mid-1980s to the mid-1990s.

School buses are major sources of pollution, and children who ride them face 5 to 15 times as much particulates inside the buses compared with outside, studies show.

Laumbach said New Jersey recently passed a law that requires retrofitting of school buses and municipal vehicles is scheduled to go into effect over the next few years.

"This should result in more rapid health benefits, especially for children who ride school buses, who are among the most heavily exposed population," he said.

OLD VULNERABLE AS WELL

Hospital admissions among the over-65 population due to heart failure increased every time particulate pollution increased, studies show.

"Most of these admissions occurred the same day as the rise in fine particle concentration, which suggests a short lag time between the change in pollution and the subjects' response," said Francesca Dominici of Johns Hopkins University in Baltimore, Maryland, and lead author of a four-year study of Medicare enrollees.

The study was presented, along with other testimony, on Wednesday in Philadelphia, Chicago and San Francisco by an advisory panel asking the EPA to follow their recommendations for setting a new more stringent annual limit on soot pollution.

But the EPA decided against implementing the recommended levels of 13 or 14 micrograms of particulates per cubic meter of air, keeping the current level of 15 micrograms per cubic feet to the dismay of the advisory panel.

According to information from the American Lung Association, the EPA proposal would cut premature deaths to about 3,600. But this number would be cut by almost half using the expert panel recommendations.