Attention to Locomotives' Emissions Renewed

"Today, rail is simply cleaner than trucks," White said. "Nothing that has been said changes that."

Trucks emit more than three times as much soot as trains a year and well over twice as much nitrogen oxide, according to the EPA's most recent data. But locomotives' advantage in terms of pollution is expected to erode over time as diesel-powered trucks and buses meet new federal standards. By 2030, trains will emit almost twice as much soot as trucks: 25,000 tons to 14,000.

State and local environmental officials say they need tougher pollution curbs on trains as soon as possible to meet the federal air quality standards that will take effect in the next few years.

Kathleen A. McGinty, head of Pennsylvania's Department of Environmental Protection, said her state is having such a hard time achieving federal standards that it has begun regulating the design of portable gasoline containers to cut down on emissions.

"It really is a situation where we're trying to get blood from a stone," McGinty said. "Transportation is probably the toughest nut to crack, across the board, in terms of air pollution."

Pennsylvania has the fifth-most-extensive railroad network in the nation. McGinty said the proposed standards for train emissions are particularly important because train traffic will increase in the coming years. "For us, clean trains is a growth industry," she said.

Communities located near rail yards experience the highest level of pollution. One example is the Houston-Galveston area, where marine vessels and trains accounted for 41 percent of the region's off-road nitrogen oxide pollution in 2002, according to the Texas Commission on Environmental Quality.

"It will be difficult for Texas to attain the 8-hour ozone standard in some parts of the state unless cleaner engines are federally mandated," wrote Glenn Shankle, the commission's executive director, in a letter to the EPA.

Two years ago, the California Air Resources Board analyzed diesel pollution from the Roseville Rail Yard, the largest service and maintenance rail yard in the West, through which more than 30,000 trains pass each year. The study found that the cancer risk level for as many as 26,000 nearby residents averaged between 100 and 500 in a million, meaning that the exposure nearly doubled the lifetime cancer risk for these residents.

"They're breathing in this stuff all the time," said Diane Bailey, a scientist at the advocacy group Natural Resources Defense Council. Bailey added that many trains idle three-quarters of the time they are in rail yards, and that, compared with trucks and buses, locomotives are "lagging so far behind other diesel equipment."