Attention to Locomotives' Emissions Renewed
Monday, August 14, 2006
For years, government scientists who measure air pollution assumed that diesel locomotive engines were relatively clean and emitted far less health-threatening emissions than diesel trucks or other vehicles.
But not long ago, those scientists made a startling discovery: Because they had used faulty estimates of the amount of fuel consumed by diesel trains, they grossly understated the amount of pollution generated annually. After revising their calculations, they concluded that the annual emissions of nitrogen oxide, a key ingredient in smog, and fine particulate matter, or soot, would be by 2030 nearly twice what they originally assumed.
That means that diesel locomotives would be releasing more than 800,000 tons of nitrogen oxide and 25,000 tons of soot every year within a quarter of a century, in contrast to the Environmental Protection Agency's previous projections of 480,00 tons of nitrogen dioxide and 12,000 tons of soot.
The new findings have put pressure on the government to crack down further on diesel engine emissions, a long-standing goal of Bush and Clinton administration officials. Bill Wehrum, the EPA's acting assistant administrator for air and radiation, said recently that his agency hopes to issue draft regulations by the end of the year or early next year for trains and ships that would reduce nitrogen oxide and particulate matter emissions "on the order of 80 to 90 percent."
Research has linked soot and smog to premature heart attacks, as well as to lung disease and childhood asthma, leading environmental activists to argue that the government has no choice but to impose tighter rules on locomotives.
"This is compelling evidence that EPA should move aggressively to clean up this major source of soot and smog," said Frank O'Donnell, who heads the advocacy group Clean Air Watch. "More than 150 million Americans live in areas that violate public health standards for one or both of these pollutants, and a lot of them live near major rail lines. Millions will probably continue to breathe dirty air in the future unless we reduce public exposure to train pollution."
In 2000, Clinton administration officials required manufacturers of trucks and buses to reduce their nitrogen oxide and soot emission by more than 90 percent by 2030; four years later, the Bush administration put the same requirements on off-road equipment used in construction, farming and heavy industry.
The EPA announced two years ago that it was drafting rules to clean up trains and marine vessels: Any rule would likely force manufacturers to redesign their engines and install controls on trains' exhaust.
"It's a real priority for us," Wehrum said in an interview. "This is a standard we want to get done, and we want to get it done as soon as possible."
The EPA's revised diesel pollution estimates highlight the extent to which shifting scientific data can lead to changes in federal regulations, according to Daniel C. Esty, a Yale environmental law and policy professor.
"This new information shows the environmental realm is very dynamic, and you've got to update your regulations to make them consistent" with the new calculations, said Esty, who worked in the EPA under President George H.W. Bush.
According to Association of American Railroads spokesman Tom White, diesel trains are three times as fuel efficient as trucks, having reduced their fuel consumption by 70 percent over the past 25 years, and emit a third of the pollution trucks release when transporting the same weight over a comparable distance.