Future hazy for cleaner school buses
By Janet Wilson
Environmental Health News
November 18, 2008
The big yellow school buses look identical at first glance. But DeeGarcia, transportation supervisor for schools in Azusa, Calif., can easily tell the difference from the back end.
Next door sits Bus #22, a shiny new rig powered by compressed natural gas. Experts say it spews 90% less soot than many of the old, high-polluting diesel models still carrying school children today. But natural gas buses, as well as new, cleaner diesel ones, cost $150,000 to $185,000 each.
While pollution-fighting technologies are widely available, fledgling efforts to clean up the nation's aging fleet of half a million school buses may stall as budget revenues plummet.
"Some states are making progress, but we are not investing enough to solve the problem by a long shot," said Patricia Monahan of the Union of Concerned Scientists. "I know it's tough economic times...but kids are traveling on dirty buses, and they will continue to unless we make a major investment."
Garcia grew up in the Los Angeles area’s smoggy Moreno Valley, and drove a school bus there for seven years. She remembers the pursed lips of children suffering asthma attacks, and radioing for a school nurse or medic to meet the bus.
"Transportation is the first thing to go, it's easy to cut when school districts are worrying about how to pay for teachers and text books," she said.
In California, however, schools won’t have much choice if a controversial new regulation that would require bus clean-up is adopted next month. No other state has such a rule.
About 24 million American children spend an average of an hour and a half every weekday riding school buses, nearly all of them powered by diesel fuel. Scientists say diesel exhaust contains carcinogens, and that its fine particles can sink deep into lungs, triggering respiratory infections, asthma attacks and heart attacks, and reducing lung capacity.
Every day, school buses in California alone spew a half-ton of soot and 28 tons of nitrogen oxides and carbon monoxide into the air, according to the state Air Resources Board’s 2006 inventory.
More controversial is the pollution that children are breathing inside the school buses.
UCLA and University of California, Riverside scientists reported that an old bus, with the windows closed, had five times more soot inside than the natural gas and newer diesel vehicles, and up to 2.5 times more than the road outside. They concluded most of the pollution was being created by the bus itself.
For their 2003 study, the scientists rode seven school buses on actual routes, including a 1975 diesel model, a newer one equipped with a particulate trap and a natural gas one.
The scientists reported that commuting by school bus for 13 years would increase a child's lifetime cancer risk by approximately 4%, or an additional 30 cancers per million, compared with car drivers’ already higher risks on Los Angeles roads.
"There was enough self-pollution in all the diesel buses...that we thought there would also be a significantly increased risk of a kid having an asthma attack or a respiratory infection," said ScottFruin, one of the researchers, who is now a USC School of Medicine assistant professor in preventive medicine. "The symptoms could be wheezing or a chest cold all the way to pneumonia."
But diesel engine manufacturers dispute the findings.
“We’ve analyzed the data in that study and we don’t agree with it,” said Tom Hesterberg, a toxicologist who oversees emission tests for Navistar’s school bus manufacturing division, based in Illinois.
Hesterberg said industry-funded tests showed “tiny” amounts of diesel soot inside buses driven in locations other than polluted Los Angeles roads, and that it was not coming from the bus engine. He disputed whether emissions inside buses are hurting children.
“As far as I know they haven’t done any studies where they measure pollution on the bus, and then asthma attacks for kids on that bus, or any other health effects,” he said.
One prime difference between the two sides’ work is that the industry-funded teams only tested 1995 and newer buses. Robert Ireson, an engineering consultant for the engine manufacturers, said that was because they comprise the majority of school buses in use. He agreed it was likely higher emissions might come from older diesel vehicles.
School buses were built to last. About 37% are more than a decade old, according to Monahan. They are not equipped with modern pollution control features, and have been estimated to emit as much as 60 times more soot than buses that meet 2007 standards, according to the U.S. Environmental Protection Agency.
Many states, cities and school districts have begun to tackle the issue. Manufacturers have worked to perfect filters, traps, and alternative fuels to meet new federal emission standards. Many models now can be retrofitted and partly cleaned up for $10,000 to $20,000 each.
In California last year, voters approved $200 million in bond funds for replacement of the oldest schoolbuses, and Congress allocated $50 million in 2005 for cleaner diesel equipment of all kinds. Greater Atlanta, Massachusetts and Houston have recently replaced or retrofitted hundreds of its vehicles. New York City’s Department of Education is retrofitting part of its fleet, the largest in the nation, but environmentalists are urging cleanup of all 6,700 of them, at a cost of $30 million.
So far, the efforts are a tiny percent of the billions needed, clean air advocates say.
Monahan of the Union of Concerned Scientists estimated it would take $16 billion to retrofit or replace polluting buses. Strapped government officials at every level will be hard-pressed to find that kind of cash.
In California, however, school districts could be forced to clean up their bus fleets no matter what their budget woes, under a proposed regulation the state air board will vote on next month.
The state regulation would require replacement or retrofit of any diesel schoolbus built before 2007. All pre-1977 buses would have to be off the road in four years. The rest will have to be fitted with diesel filters or traps that cut emissions by 85%, or retired by 2018.
It would be the toughest law of its kind. Once state bond monies ran out, districts could be required to cough up an estimated $260 million total from local taxpayers. Industry groups haven’t taken a formal position, but say they prefer voluntary measures.
“We sell the filters, we sell the buses, so if California wants that equipment…we have it,” said Hesterberg. “I’m just not convinced there’s a need.”
Some school officials have balked at the retrofit mandate in particular, saying it would be better to spend more money gradually to replace them, reducing maintenance costs and pollution.
"You're putting band aids on older buses. I would much prefer monies available be used for vehicle replacement," said Enrique Boull't, transportation director for Los Angeles Unified School District. He persuaded air board staff to push the proposed implementation deadline back to 2018.
"Funding obviously is a major concern,” he said.
LAUSD is a study in contrasts--it has the largest number of old school buses in the country, with 675 vehicles built before 1987, and the most new natural gas buses in the state, at 172.
The buses Boull't drove for the district 30 years ago to pay for college are still on the road, although they are due to be replaced next year. Southern California and other warm regions can keep buses in use far longer than cold weather areas, which salt roads during snowy winters for instance.
Except for the exhaust, many school drivers like the old diesel models.
"They're durable beasts, I love 'em," said Garcia. The rumbly old diesel buses hold up to 90 small passengers, can go 400 miles on a tank of gas, and are dependable. The new ones hold fewer passengers because they have seat belts. Natural gas bus brakes are different, there are more fuel checks, and the engines seem finicky, drivers say.
As for the diesel particulate traps, the first ones at least were poorly designed, quickly jamming with fine soot. Jim Sucheki of the Engine Manufacturers Association said any early kinks have been ironed out.
Albert Payson, a 35-year veteran school bus driver, has the pick of the lot in Azusa because of his seniority. After a year driving the district's first natural gas bus, he switched back to a diesel one with 112,000 miles on it. It rides better, he says, gets more miles and stalls less.
"It's got real long legs," he says. He does open the windows before every shift "to keep the exchange of air going."
As he made his circuit on a recent November afternoon, gently separating two seven year olds, and maneuvering between lumbering trash trucks and speeding cars, the bus cabin gradually filled with the faint but unmistakable scent of diesel smoke.
Payson says that despite technological glitches and high costs, eliminating polluting buses is a must. "I was wondering if we could see one run on an alternate fuel, a biofuel."
Tucked above the driver's side window is a picture of his son, Albert Payson III, who died five years ago at the age of 21. He had a severe asthma attack in a gas station restroom after driving his old car for two hours in rush hour traffic.
"He was a good kid, a really good kid," says Payson. "The lung association told me no one should die in the 21st century of asthma. But he did."
Janet Wilson is a freelance writer based in Southern California. You can reach her at email@example.com