Energy & Environment

Diesel in Distress

The workhorses of our economic life are churning out an exhaust that sickens and kills people.
by | April 2005

Tom Arrandale

Tom Arrandale is a GOVERNING correspondent.

Growing up in the 1950s, I spent hours running Lionel O-gauge model trains in my basement. So on a hot day last summer, I didn't mind being stuck at a railroad crossing gate and watching 4,000-horsepower Burlington Northern locomotives muscle coal-laden cars out of the local train yard. The reverie dispelled, however, when soot-laden smoke poured through my truck's open window. This small-town resident got a choking dose of the diesel exhaust that millions of Americans in more congested communities breathe into their lungs every day.

Diesel-powered vehicles and industrial gear are the workhorses in the country's daily economic life. They power garbage trucks, farm tractors, road scrapers, mining draglines, front-end loaders, backup generators and other machinery. But diesel engines can churn out smog- forming nitrogen oxide and unburned particles that carry metals, toxic chemicals and cancer-causing hydrocarbons. Their exhaust pipes belch them along downtown sidewalks, residential curbs, construction sites, rail yards, port docks, fleet garages, mines and croplands. In a study released in February, the Boston-based Clean Air Task Force calculated that diesel exhaust causes 21,000 Americans to die prematurely every year and afflicts tens of thousands more with heart attacks, strokes and asthma attacks.

The U.S. Environmental Protection Agency and California Air Resources Board have ordered manufacturers, starting with the 2004 models, to cut hydrocarbon, nitrogen oxide and particulate emissions from new diesel trucks and buses to levels 50 times lower than before. Next year, new regulations will force petroleum refiners to sell only low- sulfur fuel for highway diesel engines. EPA is following up by ordering 90 percent reductions for new marine vessels, locomotives, tractors, bulldozers, and other machinery that's operated off the nation's roadways. The California Highway Patrol now tickets drivers who leave diesel engines idling more than five minutes in a truck or 10 minutes in a bus.

In time, as more regulations are enforced, air quality will measurably improve. But full progress could take decades since diesels now in use have been built to last for decades. Locomotives can run for 50 years, for instance, and bulldozers, tractors and other durable equipment can keep going for three or four decades. "Because of this longevity," the Clean Air Task Force reports, "we will be left with a legacy of pollution from dirty diesel vehicles for decades to come."

The group's solution: mandate that operators equip all their old diesels with state-of-the-art emissions controls over the next 15 years. A number of communities around the country already have begun fitting old diesel school buses with add-on emission controls. This February, EPA distributed $1.6 million in grants to finance diesel retrofits for Sacramento commuter trains, Baltimore fire trucks, Houston dock cranes, St. Louis refuse trucks and machinery in 14 other cities. California and Texas already offer to pick up a portion of the retrofit bill as part of their clean-air programs, and the Massachusetts Turnpike Authority helped contractors install oxygen catalysts on backhoes, bulldozers, front-end loaders and other machinery during Big Dig tunnel construction in Boston.

These Big Fix retrofits cost an average of $2,500 for each machine, using a technology that cuts particulate emissions roughly 30 percent. More advanced tailpipe filters eliminate up to 95 percent, but the cost averages $5,000 and can reach $20,000 for powerful engines. The filters work well on buses, garbage and delivery trucks and some construction equipment that run at high temperatures for sustained periods of time. Improvements haven't been as promising with machinery that throttles up to full power in short bursts but runs at idle in between. "We know a lot about retrofitting a school bus because of how standardized they all are, but the devices don't work the same with all these different types of vehicles," says Allen Schaeffer, director of the Diesel Technology Forum, an industry organization.

Nobody has calculated the tab yet (although the Clean Air Task Force is working on it). But it would take a huge financial commitment to convert or scrap diesels. Governments at all levels run a good deal of this diesel-powered equipment to provide day-to-day public services. More should get started on mitigating diesel pollution by equipping buses and trucks with proven emissions-control technology. The Clean Air Task Force contends that an all-out retrofitting campaign could save 100,000 lives over the next 25 years. That may be hard to achieve, but giving it a try would help make the air easier to breathe everywhere.


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