On board for a clean ride

BUSES BRING ENORMOUS PUBLIC BENEFITS -- except for those breathing the air behind them. Those black clouds of exhaust have prompted state and local air-quality officials to crack down on bus emissions for years. Today, the state Air Resources Board will revisit one of those crackdowns, which seems to have been too tough for engine makers to keep up with.

Five years ago, the board declared that by 2007 any new buses bought by public transit agencies would have to meet a very strict emissions standard that is far lower than today’s buses (except those powered by overhead electrical lines) can achieve.

But the board didn’t specify what technologies the agencies had to use. As a result, 28 of the state’s 76 transit agencies opted to power their buses with alternative fuels such as natural gas, realizing such engines are cleaner than diesel and would be more likely to meet the standard. The rest kept their diesel-powered fleets, gambling that diesel engines with super-low emissions would eventually be developed.

So far, that’s not looking like a good bet. Today there are no diesel engine makers that say they can meet the California standard for buses by 2007. Meanwhile, there are at least two makers of alternative-fuel engines that say they can.

This has created a serious quandary for the Air Resources Board. It has three options to consider: leave the standard unchanged, change the California standard to match the more lenient federal standard or force all of the state’s transit agencies to switch to alternative fuels.

They all have drawbacks. But the third option clearly goes too far, while the second doesn’t go far enough. If the state standard remains the same, the agencies operating diesel buses wouldn’t be able to buy new vehicles until 2010, when diesel engines capable of meeting it are expected to be available. But that would be easy to remedy later -- the air board could simply amend its rules to allow agencies to buy the cleanest buses available and offset the difference by either retrofitting highly polluting buses or taking them off the road.

What’s more, there is little justification for rewarding shortsighted transit agencies that stuck with diesel because it was cheaper and punishing those that invested in technology designed to meet the coming emissions standard. Changing the rules so late in the game would effectively do that.

At the same time, forcing all transit agencies to switch to alternative fuels would be prohibitively expensive. The six Southern California agencies that hadn’t already made the switch were forced to do so last month by the Air Resources Board because of the region’s severe pollution problems, but forcing the rest of the state’s agencies to follow suit would cost hundreds of millions of dollars and result in serious cutbacks in bus service. The costs stem not just from buying new buses but from buying new fueling systems and retrofitting maintenance facilities.

Diesel engines are expected to get cleaner, so there’s no reason to call for a wholesale switch. Changing to the federal standard punishes those that invested in clean technologies, undermines the credibility of state regulators and does nothing to spur progress. The air board should leave its bus emissions rule alone.