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School Buses Belch Bad Air

Children exposed to high levels of probable carcinogens, two studies claim

TUESDAY, Feb. 19, 2002 (HealthDayNews) -- You might want to worry about the air your children breathe during their trips to and from school.

Two new reports show that many of the 24 million American children who travel on the nation's 600,000 school buses are inhaling too much diesel exhaust, a toxic health threat that increases the risk of asthma, heart disease, cancer and premature death.

Diesel fuel powers more than 90 percent of American school buses, and researchers say American children spend a total of 3 billion hours on school buses each year.

"We felt this was an important area to explore because children are on school buses every day, so they have daily exposure to the pollutants that could be coming out of the tailpipes of school buses," says Patricia Monahan, a senior analyst with the Clean Vehicles Program of the Union of Concerned Scientists.

Monahan was lead author of the Massachusetts-based group's recent report, which graded school bus fleets in each state based on emissions of particulates, smog-forming pollution and greenhouse gases.

Only six states and the District of Columbia were ranked "ahead of the curve," while 23 states received a "middle-of-the-road" ranking. The remaining 21 states did poorly or failed. No state came close to the highest grade for pollution performance, which is achieved using school buses powered by natural gas, Monahan says.

Environment and Human Health Inc., a Connecticut group of doctors, public health professionals and policy experts, released the second report recently.

That study included information from portable monitors worn by 15 children as they went through their school day, including riding buses.

The data collected from those monitors showed particulate concentrations from exhaust on the diesel school buses were five to 10 times higher than average levels measured at 13 monitoring stations in Connecticut.

Those levels of fine particles and black carbon were especially high when the buses idled with their doors or windows open, when the buses were in slow-moving traffic, when the buses followed other diesel vehicles, and when the buses were lined up to load or unload students.

"Diesel exhaust is a nasty (mix) of toxic materials. Because they are on small particulates, these nasty materials are able to be delivered into the lungs," explains Nancy Alderman, president of the Connecticut group.

The study notes diesel exhaust contains 40 hazardous air pollutants, including benzene, formaldehyde and acetaldehyde. The U.S. Environmental Protection Agency (EPA) has designated the components of diesel exhaust as probable human carcinogens.

"If I was a parent with children on a school bus, I would be lobbying my local school board to please, immediately, move over to low-sulfur fuel. You can get immediate exposure reductions by going to low-sulfur fuel, and you don't have to refit the bus," Alderman says.

She suggests parents should push for state laws that ban school buses from idling too long while loading and unloading children.

"You could reduce the exposure enormously by doing that," Alderman says.

Monahan says the best solution is to switch school buses to natural gas.

"School buses that run on natural gas can reduce toxic soot by 90 percent, relative to a standard diesel bus," Monahan says.

She says switching to natural gas school buses is an expensive solution that shouldn't be financed by school districts. The federal and state governments need to provide the money.

"We really want to make sure school districts aren't going to be tasked with having to pay for these technologies," Monahan says. "The idea of a trade-off between books and buses is really not what we want to accomplish here. We want to make sure that the funding for cleaner technologies comes from outside sources."

What To Do

Check out the report card on school bus fleets, and read the second study on bus diesel fumes.

For more about air pollution, go to the National Library of Medicine.

To find out how air pollution affects children, go to the EPA.

SOURCES: Interviews with Patricia Monahan, senior analyst, Clean Vehicles Program, Union of Concerned Scientists, Cambridge, Mass.; Nancy Alderman, M.E.S., president, Environment and Human Health Inc., North Haven, Conn.
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