A clean air coup for CLF: a nearly 15-year effort has led to a dramatic reduction in toxic emissions from city of Boston buses.

• Author: Paul, Katherine J.

Help, I'm suffocating, stuck behind an MBTA bus in Boston gridlock and I can't get out of the car because of traffic and parked cars on both sides and the bus is pumping out toxic diesel fumes that are seeping up around my feet and I've read medical studies about diesel and now I wish I could unread them, help!

Encounters with diesel fumes and high anxiety go hand-in-hand, but their days are numbered in Boston, at least where MBTA buses are concerned. After years of filing lawsuits, knocking on doors, demanding results, and negotiating compromises, the Conservation Law Foundation--with help from a few friends--has succeeded in forcing the "T" to replace its conventional diesel fuel with far more benign ultra-low-sulfur diesel (ULSD) fuel. What's more, the T has agreed to install devices that filter out carcinogenic diesel particulate matter, a step that is possible only because the buses are using this cleaner form of diesel fuel. The change to ULSD reduces emissions by up to 30%. The addition of the filters increases that percentage to 95. That translates to a radical reduction in the amount of carcinogenic and otherwise toxic matter spewed to the air by T buses--from an estimated 250 tons per year to only 11.

It's been a hard-fought victory for the health of Boston citizens. More important, says CLF Senior Attorney Seth Kaplan--director of CLF's Clean Air and Climate Change Project--the T's actions have set the stage for long-term structural changes that could ultimately speed the process of cleaning up other Boston area diesel fleets, including those of school buses and commercial trucks. "A lot of the work we do at CLF is aimed at achieving long-term changes," Kaplan says. "As a result of the process we've gone through with the T, we've taken a significant step towards the day when all diesel fleets will be required to switch to low-sulfur fuel. When that happens, Boston will be able to lead the way by having shown that this cleaner form of diesel is a readily available commodity. Fleet operators won't be able to dodge deadlines on the basis of a lack of available technology, fuel, or facilities capable of maintaining the new technology."

Although Kaplan couldn't have predicted it back in 1990, when CLF first took up the quest to improve Boston's bus system, his vision may turn to reality sooner than he imagined. The U.S. Environmental Protection Agency (EPA) has mandated that by 2006 all heavy-duty trucks and buses adopt the same technology that the T is now starting to use--nationally.

The payoff for these efforts is both long- and short-term. "This work has been deeply satisfying," Kaplan says, "because benefits for the urban environment are so immediate and clear. The day after the MBTA switched 40% of its buses (nearly 400) to ULSD it was spewing measurably less toxic and carcinogenic soot [diesel particulate matter, or DPM] into the air. With the complete switch to ULSD, the lungs of every Boston citizen are getting a break. With complete conversion to buses utilizing filters that remove 95% of this pollution from the exhaust stream, we're looking at a dramatic step towards having cleaner air in the heart of the city."

The Long and Winding Road to Cleaner Air

The push to clean up T buses dates back nearly 15...