After months of harangues from riders fed up with wheezing, jam-packed buses, the Metropolitan Transportation Authority last month proudly announced delivery of 20 brand-new transit coaches, all of them wheelchair accessible – and all of them diesel-powered.

In a remarkable coincidence, the California Air Resources Board, which regulates mobile-source emissions throughout the state, on the very same day added diesel to its list of toxic air contaminants.

The board action came after nine years of study, and with the strong recommendation of many of the state's top environmental scientists. The evils of diesel are no secret in the mass-transit world: Diesel exhaust contains some 22 chemicals listed under California law as known cancer-causers, and diesel truck, car, boat and bus exhausts contribute two-thirds of the state's particulate matter – grimy specks that find their way into lung tissue. Even the newest diesel buses emit more than twice as many of the lethal particles as buses that run on alternative fuels, such as ethanol, methanol and compressed natural gas.

But in the nation's most polluted city, the MTA powered on, violating its own 5-year-old pledge to buy only clean-fuel buses in what appears to be a general shift within the organization back to diesel. “The real question is why have a clean-fuel policy at all if you're going to turn around and make a deal with the devil and buy diesel,” says Gail Ruderman Feuer, senior attorney at the Natural Resources Defense Council. “That's what the MTA has done.”

MTA spokesman Marc Littman insists that the August diesel bus purchase was the quickest way to appease riders, and that it was a one-time event. The wait for buses that run on compressed natural gas would have been up to 18 months, he says, while the diesel buses were available in a matter of weeks. About a quarter of the MTA buses on the streets operate on compressed natural gas and constitute the nation's largest clean-fuel fleet. “The agency has a real commitment to cleaner buses,” Littman says. “All the buses the MTA has purchased in the past few years have been compressed natural gas, except these 20.”

At the same time, however, the MTA is replacing the ethanol/methanol engines that power more than 15 percent of its 2,100-bus active fleet with diesel-powered ones. John Drayton, acting director for vehicle acquisitions at the agency, says that those buses, purchased seven years ago, have caused the agency nothing but headaches. When they tried to convert one of the buses to compressed natural gas, he says, the results were dismal. The bus, which developed frame cracks and other structural problems, was operable for just 15,000 miles over a yearlong period, less than half the average mileage of other buses in the fleet. “They have not been able to make that bus run reliably,” Drayton says. “You can't make a bus one way, then completely change its configuration and expect the same level of performance.”

Tim Carmichael, policy director at the Coalition for Clean Air, acknowledges that converting ethanol-methanol buses to compressed natural gas may be a losing proposition. But he says the MTA had no business abandoning the ethanol/ methanol buses in the first place. He says serious questions are being raised about whether MTA mechanics were properly trained to repair and maintain the buses. And this summer, state Assemblyman Scott Wildman (D-Glendale) asked the Bureau of State Audits to investigate allegations that the MTA did not make full use of the warranties provided by the ethanol-methanol bus manufacturers. “Instead of trying to fix the buses,” Carmichael says, “they'd just park them and walk away.”

As for MTA claims that it needed to buy diesel to bolster its fleet, Rita Burgos, an organizer with the Labor Community Strategy Center and the Bus Riders Union, is not impressed. “The need for more buses is not something that just popped up overnight,” she says. “The MTA knew about the bus shortage for a long time. Instead of meeting their responsibility, they waited until the last possible moment and went running back to diesel.”

The MTA's Drayton says until the technology for natural-gas buses improves, he prefers operating a largely diesel fleet. Diesel buses are $20,000 to $40,000 cheaper to buy than natural-gas buses, and, he claims, they're cheaper to maintain and repair. “I'm very concerned about the environment,” he says, “but my fundamental concern has to be service. You can't compromise your service for air-quality issues.”

Yet other California cities that operate both diesel and natural-gas buses are finding natural gas to be the cheaper option. In Sacramento, natural-gas buses cost 9 cents per mile less to operate than diesel buses, according to that city's most recent bus-service report. “I don't think the MTA is giving us the full story [on alternative-fuel buses] by any stretch of the imagination,” Carmichael says. “I see the MTA doing this as 'Let's open the door so we can open it wider and make the case to buy more diesel buses in the future.'”

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