The Wargo Report: What the
News Stories Won't Tell You

By Robin Leeds

Scientists, pseudo-scientists, and the media have focused a lot of attention lately on the yellow school bus -- not because of its safety record, but because of its health record. And that record isn't looking good.

Sure, some of the "studies" can be dismissed: we know the NRDC's report has been discredited by the scientific community, and the most recent entry, the Report Card from the Union of Concerned Scientists, is little more than a survey of the average age of school bus fleets in each state. But that doesn't mean we don't have a problem, both of perception and of substance.

Research conducted by professor John Wargo of Yale University released last month is credible. This is the first research to monitor children during their school day, rather than simply monitoring buses. After all, the important factor is not how much exhaust is emitted, but how much exposure children have to the pollutants in that exhaust, and for that matter, to other pollutants as well.

For the study, 15 Connecticut students carried three different personal monitors from the time they left home in the morning until they returned home after school, an average of seven hours a day. A research assistant accompanied each student to monitor the equipment and record the child's behavior and movement as well as environmental conditions. Readings from the monitors were charted to show elevations during the school day, and to determine how they compared to background pollution measured by state monitoring facilities.

The news reports of this study were quick to point out that the levels of particulates inside school buses were sometimes 10-15 times higher than background levels. These measurements occurred when buses were lined up at school and idling, producing the worst concentrations of particulates and black carbon both inside and outside the vehicles. But the media didn't report the finding that the children were also exposed to particulate levels many times higher than the mean state background during gym class, while moving between classes and during other activities in school.

One of the charts in the report shows the daily exposure of five children to particulates. The two children with the highest levels did not ride the bus; they walked to school on a route adjacent to an interstate highway, with construction activity nearby. Another finding in the report is that concentrations of pollutants inside school buses rise when the buses are in traffic, particularly when they follow other diesel vehicles. Well, that probably happens in personal cars, too.

Contrary to what news reports would have us believe, the Wargo study does not suggest that school buses are the cause of all pollution, or that they single-handedly make kids sick. In fact, the report notes that seven million heavy trucks drive nearly 200 billion miles annually in the U.S., emitting 1.5 grams of total carbon per mile traveled, compared to 600,000 [sic] school buses that drive 4.3 billion miles annually. It also notes that children are exposed to residential use of tobacco products, wood stoves, candles, kerosene heaters and other indoor sources of carbon-based particulates that threaten their health. One of the main themes of the report is that EPA-required stationary testing does not adequately assess exposure to harmful pollutants, because it does not take into account indoor or in-vehicle pollution, or peaks of exposure, regardless of the source. The study is an indictment of the current measuring procedures as much as it is an indictment of diesel exhaust.

Why, then, focus on school buses? Because children, who are at greater risk of harmful effects from particulates because they have smaller airways and they inhale twice as much air as adults, spend a lot of time in and around school buses. And because with relatively simple and inexpensive changes in the way we operate school buses, we can make a big difference in the amount of diesel exhaust children inhale. It's not that school buses cause pollution; but school buses add to pollution that's already too high, and they add to it in relatively small, concentrated areas where children congregate.

Unlike the other "studies," the Wargo report does not recommend replacing all diesel school buses with natural gas buses. It does recommend moving to cleaner diesel buses and ultra-low sulfur fuel sooner than the EPA requirement. But the recommendation that gives us the most bang for our buck -- for no bucks, in fact -- is to eliminate unnecessary idling, especially at schools. This is a no-expense no-brainer; in fact, reducing idling may actually reduce expenses. And it will not only help clear the air for the kids, for our drivers, and for all of us, but it will also show our critics that we are as concerned about children's health as we are about their safety.

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Robin L. Leeds is a regulatory liaison for the National School Transportation Association. For a sample anti-idling policy or more suggestions on how you can reduce diesel emissions, contact Leeds at 860/751-7138 or email rleeds@yellowbuses.org.