A study published in the April 15th, 2005 issue of the Environmental Science and Technology Journal reveals that children riding in diesel powered school buses are exposed to larger amounts of pollution inside the bus than outside. The study which was carried out by researchers at the University of California, Berkeley measured pollution levels in six empty school buses traveling established routes in Los Angeles.
Researchers found that in a single day, on average, a child riding a school bus is likely to breathe in 7 to 70 times more exhaust from the bus when compared to the school bus emissions a resident is likely to inhale in an urban area. It was observed that emissions from the engine crankcase were directly entering the bus before they were treated by scrubbers. Estimates indicate that for every metric ton of pollution emitted by a school bus, the cumulative mass of pollution inhaled by 40 or more kids on the bus was comparable to or larger than the cumulative mass inhaled by all other people in an urban area. Scientists concluded that the clean-up of school buses would be more cost effective in terms of health care savings when compared to clean-up of other heavy-duty vehicles. There are approximately 500,000 school buses in the country of which 90% are diesel powered.
Abstract of the study available at: