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Public Radio's Environmental News Magazine (follow us on Google News)

School Buses

Air Date: Week of

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CURWOOD: It's Living on Earth. I'm Steve Curwood. Millions of children ride diesel-powered buses to and from school. Now a new study has found that the trips may expose kids to high levels of diesel fumes and increase their vulnerability to cancer and asthma. The Natural Resources Defense Council tested the air inside moving school buses in Los Angeles, in part because other studies have shown that children are more susceptible to toxic fumes than adults. Gina Solomon is a physician with the NRDC, who authored the study.

SOLOMON: The levels of diesel exhaust were consistently about four times higher inside the school buses than they were in the streets of L.A. or in the cars driving in the streets ahead of the buses.

CURWOOD: How is the diesel exhaust getting into the bus?

SOLOMON: Our theory is that the exhaust systems of these buses would over time develop some cracks. The particles that we were measuring are very, very small, and would tend to just sort of ooze their way through the exhaust system up into the bus, and then they would get trapped in there. And we found that when the windows were closed, the levels would continue to rise, whereas when the windows were open it would sort of flush out the air and the levels would drop again.

CURWOOD: What kind of recommendation would you make to deal with these buses?

SOLOMON: I would ask school districts in the short term to consider trying to keep windows slightly cracked on the buses when the weather permits. Older diesel buses can be equipped with particle traps or filters. And those decrease the emissions out the end of the tailpipe, though we're not sure what affect they would have on the levels inside the bus. The third and most definite fix would be switching to cleaner fuel buses, like natural gas buses, propane buses, or electric. In addition, I would ask school districts to seat children toward the front of the bus before they seat children in the back of the bus.


SOLOMON: We found higher levels of diesel exhaust in the back than in the front of the buses. The differences were not huge but they were certainly worth making the effort to sit toward the front if there was a choice.

CURWOOD: Well, that's kind of hard, because in school bus culture, the cool kids sit at the back.

SOLOMON: Hmm. Isn't that interesting. (Curwood laughs) I actually was one of those cool kids for a while. And I remember that smell of diesel exhaust in the back of the bus. Part of why we did this study was that we were hearing from parents and even from kids that they noticed a strong smell of diesel, particularly in the backs of the buses. And there were folks who knew that we had done some work measuring diesel exhaust. And indeed, the levels are higher in the back than in the front.

CURWOOD: One thing that strikes me, it's a very small study. You folks looked at four buses, just four buses. How can you draw such strong results from looking at just four buses?

SOLOMON: This study is certainly not comprehensive or complete. It's basically a first look. No one had really tried to look at the insides of school buses before. If we had had the resources, the money, and the ability to do many more buses, we would have done so. For example, we were only able to look at a relatively narrow age range of buses, buses from the late 1980s. Now, about one-third of the buses that are on the roads are older than the buses we sampled. You know, nearly two-thirds of the buses on the road are newer. We don't know how those would compare with the buses we tested.

CURWOOD: In my town, in front of the school, they'll line up, oh, seven, eight, nine, ten of these buses all at once, idling. The kids line up and then the air is really pretty foul. Have you looked at this as a risk to kids?

SOLOMON: That's probably our next step. We have done some observations at school bus stops. We've observed also what you've observed, that the buses line up, the kids stand there on the sidewalk, and you can notice the smell of diesel in the air. We've counted the buses, counted the idling time, but we haven't yet actually done the monitoring. And we're planning as a next step to add in the time that children spend at bus stops to the time that they already are spending on the buses.

CURWOOD: Dr. Gina Solomon is a physician and senior scientist with the Natural Resources Defense Council. Thanks for joining us today.

SOLOMON: Thank you.

(Music up and under: The Who, "The Magic Bus")



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