UW Study Nets Surprising Discovery In School Bus Pollution

UW Study Nets Surprising Discovery In School Bus Pollution

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Story Published: Aug 22, 2006 at 2:24 PM PDT

Story Updated: Aug 31, 2006 at 8:35 AM PDT

By Akiko Fujita

SEATTLE - A new study conducted by the University of Washington and the University of Basel in Switzerland reveals a majority of school bus pollution comes from the crankcase, instead of the tailpipe.

It also reveals emission levels are much higher when the windows are closed than when they're open.

"Children riding school buses may be exposed 5- to 10-times higher pollution than what has been measured in the ambient air," said Dr. L.J. Sally Liu, lead researcher and Associate Professor in the Department of Environmental and Occupational Health Sciences at the UW.

Liu tracked two different buses over the last year to measure emissions in the fuel tank and crankcase.

Iridium was added to diesel fuel as tracer for emissions in the fuel tank, while an organic tracer was added to the engine oil as a tracer for lubricating oil. The study found 80% of emissions came from the crankcase. That's contrary to previous studies.

"In the past years, we thought most of the emissions were from the tailpipe," Liu said. "That's what the retrofit programs have been focusing on in the past."

Three years ago, the state Legislature set aside $5 million to install retrofit emission controls on diesel school buses. The focus of that projects has been on tailpipes and the Environmental Protection Agency has set aside grants for schools to do the same.

The Seattle School District has already retrofitted tailpipes on 75 of its 415 buses. This study means the focus will have to change.

District Transportation Manager David Anderson says plans are in place to begin retrofitting crankcases next year and says that will be a lot cheaper. Fixing each one costs a few hundred dollars while a tailpipe costs up to $5,000.

"We're still in the preliminary stages with this study, but it's encouraging that this could be a less costly fix for this problem," he said.

In addition to those changes, Anderson says each school bus will be filled up with biodiesel.

Madison Flint takes the school bus to James Madison Middle School in Seattle and says this new study would not make his bus ride any smoother.

"Sometimes the engine leaks on our bus and it smells really bad," he said.

Diesel fumes have been linked to decreased lung growth and can potentially cause cancer. Flint's grandmother doesn't like what she hears and says she plans to drive him to school herself this school year.

"We don't care for the buses," said Renee Brown. "They're not safe enough."

This is the first year of a three year study.

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