A single bus can produce between twice and 10 times as much diesel soot as a big rig.
Detroit Auto Insider - May 25, 2006
Aging school buses spew harmful diesel fumes across the United States, according to a report based on federal and state data, and major funding is needed to address the problem.
The report released Wednesday by the Union of Concerned Scientists found the nation's 505,000 school buses are some of the oldest and dirtiest vehicles on the road. More than a third have been in use for more than a decade, and a single bus can produce between twice and 10 times as much diesel soot as a big rig.
While school buses have become safer to ride because of safety belts or other improvements, the authors and other experts said related studies were showing large amounts of soot can accumulate inside the buses from open crankshafts.
About 95 percent of the nation's school bus fleet is powered by diesel, and high levels of diesel exhaust and soot expose children to higher risk of asthma, cancer and other significant health problems, the report concluded.
"Even if you have a very good (cleanup) program, kids are still riding on very high polluting buses," said lead author Patricia Monahan, a former air pollution and toxics scientist with the U.S. Environmental Protection Agency.
After examining data supplied by all 50 states and the District of Columbia, the organization found that the district and Delaware, which received B grades, had the lowest rates of soot pollution: just over 9 pounds of pollution per bus last year. Fourteen other states also received Bs.
The worst polluter was South Carolina, closely followed by South Dakota. Both earned D grades, as did 11 other states.
Several states are using alternative-fuel buses, replacing older buses with cleaner-burning models or retrofitting buses with devices that trap emissions. A considerably more low-tech method also can reduce children's exposure to bus pollution, especially as they wait in the parking lot for a ride home.
"We're recommending you just turn the engines off whenever you can," said Dwight Sinila, transportation director of Michigan's education department.
Experts estimated $16 billion would be needed to retrofit or replace more than half a million buses across the United States.