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Are children breathing in dangerous exhaust fumes by
riding the school bus?
More than 24 million children ride the bus to school
every day and as a result are regularly exposed to harmful diesel-exhaust
emissions. Major components of diesel exhaust include carbon monoxide,
sulfur dioxide, formaldehyde, and tiny soot particles that carry substances
called polynuclear aromatic hydrocarbons. The U.S. Environmental Protection Agency classifies
diesel emissions as a “likely carcinogen.” Diesel emissions are
estimated to be responsible for 70 percent of the cancer risk arising from
air pollution, according to the California Air Resources Board. Dangers
from diesel exhaust can range from respiratory illnesses including asthma
and bronchitis to lung cancer and heart disease. Children are more vulnerable to the effects of diesel
exhaust than are adults because they breathe more quickly and take more air
into their developing lungs. On average, schoolchildren who ride the bus
spend an average of 90 minutes each weekday in transit. The EPA estimates that approximately 390,000 diesel
school buses are on the road in the United States today. A third of these
were made before 1990, when stricter emissions guidelines were first
enforced. According to the National Resources Defense Council, a child
riding inside a school bus may be exposed to as much as four times the
toxic diesel fumes that someone riding in a car directly ahead of it would
be exposed to. Recently the EPA pledged more than $1 million to a
partnership called the Northeast Diesel Collaborative, which comprises
eight different public and private entities working together to improve
emissions on thousands of school buses throughout the northeastern United
States. Recipient groups are using the money primarily to reduce emissions
on older buses by installing advanced pollution controls.
Retrofitting old buses with such controls involves
installing emissions-reducing filters. Diesel particulate filters, which
cost around $700 each, can cut tailpipe emissions by a whopping 85 percent.
“Closed-crankcase filtration systems,” which are installed
under the hood and filter the discharges that come directly from the
engine’s crankcase vent, can cut engine soot by nearly 90 percent at
a cost of around $7,500 each. Buses can be retrofitted with one or both
filters. Nationwide, several school-bus emission-reduction
programs are under way with the help of the EPA’s Clean School Bus
USA program. In addition to retrofit projects, the program seeks to replace
older buses with new, less polluting buses and encourage unnecessary
school-bus idling. Concerned parents can help reduce their children’s exposure to diesel emissions from
school buses by advocating at town and school-board meetings for the use of
new or retrofitted school buses. Also, bus windows should remain open when
weather allows, and children are safer sitting nearer the front of the bus,
because exhaust tends to accumulate in the back.
For more information:
EPA Clean School Bus USA, www.epa.gov/cleanschoolbus; Northeast Diesel
Collaborative, www.northeastdiesel.org; NRDC,
www.nrdc.org/air/transportation/qbus.asp.
Send questions to Earth Talk, care of E/The Environmental Magazine,
P.O. Box 5098, Westport, CT 06881 or e-mail earthtalk@emagazine.com.
This article appears in May 24-30, 2007.
