CLEAN SCHOOL BUS
CO
What You Should Know About Reducing
Diesel Exhaust from School Buses
buses provide our nation's children with
safe, convenient transportation. Diesel exhaust
from school buses, however, poses a health
risk, particularly to children. Diesel exhaust contains
small particles as well as smog-forming and toxic air
pollutants. Exposure to diesel exhaust can cause
lung damage and respiratory problems and can
exacerbate asthma and existing allergies. Buses that
idle outside schools can pollute the air inside the
school building as well as outdoors. Fortunately,
there are several steps that schools can take to
reduce diesel exhaust from school buses.
Recommended Actions
to Reduce Diesel Pollution
Clean School Bus USA encourages school districts
to reduce the health risks associated with exposure
to diesel exhaust by:
Deducing school bus idling time and reinforcing
smart driving practices, such as following at least
three car lengths behind any vehicle with visible
exhaust or a noticeable odor.
retrofitting current school bus fleets with new
technologies and introducing cleaner fuels.
replacing the oldest buses with new ones that
meet stringent pollution control standards.
How Are Children Affected?
Air pollution from diesel vehicles has health
implications for everyone, but children are
more susceptible to this pollution because
they breathe at a faster rate than adults.
Children's lungs are still developing, and
children are more likely to play actively
outdoors. More than 24 million children in
the United States ride a bus to and from
school every day.
Help Clear the Air with
Clean School Bus USA
Clean School Bus USA is an initiative sponsored
by the U.S. Environmental Protection Agency
(EPA) to help communities reduce pollution from
school buses. It's a partnership of educators,
industry, businesses, school officials, school bus
fleet and transportation managers, state and local
governments, public health officials, and other
community leaders who are committed to
protecting children's health and modernizing
America's school bus fleet.
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Clean School Bus USA
Case Studies
Communities across the country are
developing effective local
partnerships to reduce air pollution from
diesel school buses. School children in
these areas reap immediate air quality
benefits from effective anti-idling policies,
buses that run on cleaner fuels, and
buses retrofitted with state-of-the-art
emission reduction technologies.
Portland, Maine
In the last five years, the Portland school
district has replaced 90 percent of its
school bus fleet with newer, cleaner
buses. This pioneering effort is part of a
multi-faceted statewide campaign to
reduce emissions from diesel school
buses. The campaign—a partnership
between the Portland School
Transportation Department, the Maine
Departments of Education and
Environmental Protection, the Asthma
Regional Council, and the U.S.
Environmental Protection Agency-
focuses on: anti-idling and fuel
conservation; aggressive investments in
newer, cleaner buses; and route
management to assign the cleanest buses
to the longest routes.
State of Washington
With support from Washington's
legislature, schools throughout the state
will retrofit bus fleets, reducing toxic
H
ere are some specific actions school districts can take
to achieve these goals:
Implement Anti-idling and
Smart Driving Practices
• Train school bus drivers to turn off their buses as
soon as they arrive at loading or unloading areas and
to refrain from restarting their buses until they are
ready to depart.
• Establish a program to recognize drivers who
successfully reduce idling.
• Consider changing circuit configurations if necessary
to power flashing lights with the battery.
• Limit idling time during early morning warm-up to
what is recommended by the manufacturer (generally
3 to 5 minutes). In colder climates, block heaters can
help warm the engine of older vehicles to avoid
starting difficulties and shorten warm-up time. Newer
buses are designed to start easily at all temperatures
without idling.
• In the winter, provide a space inside the school where
bus drivers who arrive early can wait.
• Follow the anti-idling laws and guidelines that many
states have in place. Post signs as reminders.
• Revise bus schedules and operational logistics to
minimize school bus caravanning.
• Assign cleanest buses to the longest trips. Inform
drivers that following other diesel vehicles too closely
can contribute to higher concentrations of diesel
exhaust inside and outside the bus.
Jdling wastes fuel and money.
I ypical school buses burn
approximately one-half gallon of
diesel fuel for each hour of idling.
I he less school buses idle, the more
money school districts can save.
continued on next page
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Work Closely with Fleet Managers
and Bus Drivers to Reinforce
'radices
• Make sure both fleet managers and bus drivers
understand the potential health risks from
breathing diesel exhaust and the benefits of not
idling or caravanning.
• Highlight the economic benefit of reduced fuel
consumption as a result of less idling. For exam-
ple, if a fleet operates 50 buses and each bus
reduces its idling time by 30 minutes per day, at
$1 per gallon of diesel fuel, the fleet would save
$2,250 per school year in fuel costs.
• Maintain engines properly.
Work Closely with Fleet Managers
to Retrofit Buses with
Pollution Controls
Oxidation catalysts and particulate matter filters are
two retrofit technologies that can help reduce diesel
particulate matter. Both devices are housed in the
exhaust system where they break down the pollutants
in the exhaust.
Oxidation Catalysts
Diesel oxidation catalysts are widely available and
commonly used retrofit technologies. They are relative-
ly simple, low cost devices that can be installed in
almost all buses and require very little maintenance.
Diesel oxidation catalysts can be used with regular
diesel fuel. Diesel oxidation catalysts typically cost
between $1,000 and $2,000 and reduce particulate
matter emissions by 20 to 30 percent. Reductions
may be even higher if used together with ultra-low
sulfur diesel fuel.
Particulate Matter Filters
Diesel particulate matter filters provide even greater
particulate matter reductions. Filters are a more com-
plex technology than catalysts and generally are most
appropriate for 1995 and newer buses. Filters typically
cost between $5,000 and $10,000 and require the
use of ultra-low sulfur diesel fuel. The combination of
ultra-low sulfur diesel and particulate matter filter tech-
nology reduces particulate matter emissions by 60 to
90 percent.
Case Studies
(continued)
diesel emissions by 50 to 90 percent. This
program, named the Washington State
Clean School Bus Program, will affect
approximately 5,000 of more than 9,000
school buses throughout the state by
2008, making it the largest state-funded
voluntary school bus retrofit program in
the country. The Puget Sound Clean Air
Agency, in partnership with several state
and local agencies, conducted pilot
programs with U.S. EPA grants during the
past two years to pave the way for rapid
deployment of retrofitted buses. Retrofits
for buses will involve either installation of
particulate matter filters or oxidation
catalysts on school bus exhaust systems,
depending on the age of the bus and the
regional availability of ultra-low sulfur
diesel fuel. To maximize program benefits,
older school buses that pollute the most
will be the first to receive retrofits.
Ardmore, Pennsylvania
Nearly 70 percent of the Lower Merion
School District's fleet of 107 buses
operate on compressed natural gas
(CNG), providing noise relief and clean
air benefits to the residential
neighborhoods where these buses
operate. To build local fast-fill CNG
refueling stations and offset the upfront
costs of the new buses, the district
received several grants from community,
state, and federal partners. Lower
Merion's CNG fleet has now logged
nearly 5 million miles.
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Work Closely with
Fleet Managers to
Purchase Cleaner Fuels
There are a number of alternatives to conventional
diesel fuel that can help reduce particulate matter
emissions from today's school bus fleet. Most of these
fuels can be used with little or no modification to the
bus or its engine:
• Alternative fuels such as compressed natural
gas offer outstanding environmental benefits for
buses designed to run on such fuels.
• Biodiesel is a fuel that contains some
domestically produced, renewable components.
Blends of biodiesel (B20) can be used in
unmodified diesel engines, but pure biodiesel
(B100) may require certain engine modifications.
Pure biodiesel may not be suitable for cold
climates.
• Emulsified diesel fuel is a blended mixture of
diesel fuel, water, and other additives.
Emulsified diesel can be used in any diesel
engine to reduce emissions of particulate matter
as well as nitrogen oxides.
• Ultra-low sulfur diesel fuel is diesel fuel with an
extremely low sulfur content (15 or less parts
per million). The low sulfur levels enable
particulate matter filters to perform most
efficiently. Ultra-low sulfur diesel will be required
nationwide for use in all highway diesel vehicles
beginning in 2006 and is currently available in
some parts of the country.
Work Closely with
Fleet Managers to
Replace the Oldest Buses
with New Ones
• About one third of U.S. school buses were
manufactured before 1990 and are not
equipped with modern pollution controls and
the latest safety features. These buses are
excellent candidates for accelerated
replacement.
• By 2007, EPA will require that new buses rolling
off the assembly lines be 95 percent cleaner
than today's models. Because some buses
might meet EPA standards ahead of schedule,
ask the manufacturer before purchasing a new
bus to see if you can acquire one that meets
these standards.
• Both diesel and compressed natural gas tech-
nologies offer very clean replacement options.
For more information about Clean School Bus USA:
Visit www.epa.gov/cleanschoolbus
Leave a voice message at (734) 214-4780
E-mail cleanschoolbususa@epa.gov
For more information on diesel retrofit options, visit www.epa.gov/otaq/schoolbus/retrofit.htm
EPA420-F-03-038
November 2003
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