Riders on diesel school buses exposed to toxins, study says
LOS ANGELES, California (CNN) -- A ride on a school bus may prove hazardous to one's health, a study of air quality inside diesel school buses said.
But a trade group representing the school bus industry accused the environmental groups who sponsored the study of exaggerating the risks to further their political agenda.
Children who ride a diesel school bus may be exposed to four times the diesel exhaust as someone riding in a car behind the bus, the Natural Resources Defense Council and Coalition for Clean Air report found.
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Called "No Breathing in the Aisles: Diesel Exhaust Inside School Buses," the report found excess exhaust levels inside buses were more than eight times the average levels found in ambient air in California and a significant cancer risk.
"Children are especially sensitive to environmental hazards, yet they're the ones getting dosed with diesel riding to school," said Dr. Gina Solomon, NRDC senior scientist. "The levels we measured on some of these buses both surprised and worried us. Worse still, we have reason to believe that these high levels are fairly typical."
Tests inside and outside buses
Researchers from NRDC, the University of California, Berkeley, School of Public Health and the Coalition for Clean Air rented four school buses and drove them for a total of nearly 20 hours along school bus routes in the Los Angeles area.
They compared air quality inside the front and back of the bus and with the windows open and closed. They also tested air quality outside the bus and in a passenger car traveling ahead of it. Buses were tested while idling, climbing or descending hills, and traveling slowly with frequent stops.
Assuming children ride in buses for one or two hours per day, 180 days per year for a decade, the groups estimated the diesel exhaust exposures result in an additional 23 to 46 cancer cases per million children exposed.
This level of cancer risk is 23 to 46 times the level the Environmental Protection Agency says poses a significant cancer risk under the federal Clean Air Act and the Food Quality Protection Act.
"These monitoring results teach schools a tough lesson -- they need to clean up their bus fleets in order to protect the health of their kids," said Gail Ruderman Feuer, NRDC senior attorney.
Report: Diesel exhaust particles worsen asthma
Diesel exhaust is a major source of fine particles that can lodge in the lungs and worsen asthma, the report said.
Diesels also emit smog-forming oxides of nitrogen that have been linked to decreased lung function growth in children, whose faster breathing rate, less developed lungs and immature immune systems leave them more susceptible to air pollution, the report added.
Most of the nation's school bus fleets run on diesel fuel.
Switching to school buses that use alternative fuels could reduce a child's exposure to smog-forming chemicals by as much as 43 percent and toxic particles by another 78 percent, said Todd Campbell, policy director for the Coalition for Clean Air. "Diesel school buses remain the dirtiest option available on the market today."
Particulate traps and low-sulfur fuel can reduce the pollution, the NRDC said, though the specialized fuel is not available nationally.
The groups recommend bus drivers keep windows open on buses where practical, seat children closer to the front of the bus and switch to buses that use alternative fuels.
Bus makers say report outdated, unfair
The group representing school bus makers dismissed the study as outdated and unfair. "These sensational allegations are based on anecdotal evidence from just four older buses in Los Angeles, California, a city with the dubious distinction historically of being one of the smoggiest in the nation," said a statement from the School Bus Information Council.
The buses in the study appear to have been manufactured before the implementation of diesel engine emissions requirements in 1988, said the statement.
"In fact, school buses are a great American success story, with a safety record that is unequaled in motor vehicle transportation. It would be unfortunate if any parent in California or elsewhere removes a child from a school bus in reaction to this story."
The group said environmental organizations have campaigned to reduce the use of diesel engines in California. "Frightening parents and children about the safety of school bus transportation is an unfair way for the environmental advocates to promote their agenda and stoke the fires of debate about air quality in California," their statement said.
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School Bus Information Council
Natural Resources Defense Council
Coalition for Clean Air
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