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NRDC: Toxic Release from Diesel School Buses

Gary Greenberg Gary.Greenberg at Duke.edu
Tue Feb 13 07:19:07 EST 2001


Press contact: Tammy Boyer, NRDC, at (323) 934-6900; Todd Campbell, CCA,
at (310) 441-1544 

Tests Reveal High Levels Of Toxics Inside Diesel School Buses

New Report Finds Children's Exposure Dozens Of Times Higher Than EPA
Acceptable Cancer Risk Level 

LOS ANGELES (February 12, 2001) - A ride on a school bus may prove
hazardous to your child's health, according to a new study of air
quality inside diesel school buses, the kind of school bus most commonly
used across the country. More than 23 million children in the United
States ride a bus to school. 

An NRDC (Natural Resources Defense Council) and Coalition for Clean Air
report released today, No Breathing in the Aisles: Diesel Exhaust Inside
School Buses, shows that children who ride a diesel school bus may be
exposed to up to four times more toxic diesel exhaust than someone
traveling in a car directly in front of it. The excess exhaust levels on
the buses were more than eight times the average levels found in the
ambient air in California and 23 to 46 times higher than levels
considered to be a significant cancer risk according to the U.S
Environmental Protection Agency (EPA) and federal guidelines. 

"Children are especially sensitive to environmental hazards, yet they're
the ones getting dosed with diesel riding to school," said Gina Solomon,
M.D., M.P.H., 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." 

Researchers from NRDC, the U.C. Berkeley School of Public Health and the
Coalition for Clean Air rode rented school buses along actual elementary
school bus routes in the Los Angeles area. Using sophisticated equipment
to continuously sample the air inside the buses for diesel exhaust, 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

The nearly 20 hours of sampling results on four school buses produced
dramatic results. Assuming bus rides totaling one or two hours per day,
180 days per year for 10 years, the groups estimated the diesel exhaust
exposures are likely to 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 considered to pose a significant cancer risk by the EPA
under the federal Clean Air Act and the Food Quality Protection Act.
Under California's Safe Drinking Water and Toxic Enforcement Act
(Proposition 65), it also could trigger an obligation to provide
warnings to children that they are being exposed to a cancer-causing
chemical. "Parents have a right to expect their kids will have a healthy
and safe ride to school every day, but our monitoring results tell a
different story," said Gail Ruderman Feuer, NRDC senior attorney. "We
were troubled to learn that kids are getting more toxic diesel exhaust
inside the school bus than outside, even if it's not a 'smoking' diesel
bus. These monitoring results teach schools a tough lesson - they need
to clean-up their bus fleets in order to protect the health of their

Increasing numbers of health authorities, including EPA and the state of
California, have recognized the cancer-causing effects of diesel
exhaust. Diesel exhaust is also known to be a major source of fine
particles that can lodge deep in the lungs and exacerbate asthma, a
condition most prevalent among children. In addition, smog-forming
oxides of nitrogen, or "NOx," which are also emitted from diesel engines
in large quantities, have recently been linked to decreased lung
function growth in children. Children are generally more susceptible
than adults to the negative health effects of air pollution because they
breathe faster and have less developed lungs and immune systems. 

The vast majority of the nation's school bus fleets still run on diesel
fuel. Many include large numbers of buses that are over 10 years old,
which are much more polluting than the diesel buses manufactured today.
In fact, some fleets - including those in California, Washington and
Texas -- include buses manufactured prior to 1977, before federal
highway safety standards were even adopted. 

Cleaner alternatives to diesel buses, such as those that run on natural
gas and propane, are widely available and are being used by an
increasing number of school districts across the country. There are over
2,600 school buses that run on natural gas or propane in the nation
today, and this number increases every day. Additionally, federal, state
and local governments have begun to set aside funds earmarked
exclusively to help public and private school fleet operators cover the
incremental costs of purchasing these cleaner alternatives. 

"School districts can reduce a child's exposure to smog-forming
chemicals by as much as 43 percent and toxic particles by another 78
percent just by making a switch to alternative fuel school buses," said
Todd Campbell, policy director for the Coalition for Clean Air. "Diesel
school buses remain the dirtiest option available on the market today." 

Interim solutions also exist to help clean up existing diesel school
buses prior to their replacement. Most notably, particulate traps can be
installed and used in conjunction with low-sulfur diesel fuel to reduce
particle emissions. However, the needed low-sulfur diesel fuel is only
currently available in California, New York City and Houston, Texas, and
it will not be required nationally until 2006. 

In the meantime, NRDC and the Coalition for Clean Air recommend that bus
operators improve air quality by keeping the windows open on the bus
where possible and seating children closer to the front of the bus
before seating children in the rear. They also urge schools to switch to
alternative fuel school buses when making future purchase decisions and
urge policy-makers to make public funds available to help defray the
cost of this investment. 

Southern California may be well on the way to cleaner school buses. The
South Coast Air Quality Management District (SCAQMD) will decide whether
to mandate that local school districts purchase only alternative fuel
school buses at a hearing in March. Environmentalists strongly support
adoption of an alternative fuel fleet rule and urge air districts around
the country to adopt similar rules. 

The Natural Resources Defense Council is a national, nonprofit
organization of scientists, lawyers and environmental specialists
dedicated to protecting public health and the environment. Founded in
1970, NRDC has more than 400,000 members nationwide, served from offices
in New York, Washington, Los Angeles and San Francisco. 

The Coalition for Clean Air is a non-profit environmental organization
dedicated to restoring clean healthful air to California by advocating
responsible public health policy; providing technical and educational
expertise; and promoting broad-based community involvement. More
information is available through the coalition's website. 

= - = - = - = - = - = - = - = - = - = - = - = 

This report is available in Adobe Acrobat format (491k).



Introduction (html)

Introduccion en Español (html)

Chap 1: Diesel Exhaust Exposures on California School Buses -- Study

Chap 2: The Serious Health Impacts of Diesel Exhaust

Chap 3: Cleaner Alternative Fuel School Buses Are Available Today

Chap 4: Clean Fuel School Bus Success Stories Across America

Chap 5: So-Called "Clean" and "Green Diesel" School Buses Remain Dirtier
Than Alternative Fuel School Buses

Chap 6: Aftertreatment, Repowers, and Rebuilds: How We Can Make Our
Existing Diesel School Bus Fleet Cleaner

Chap 7: Funding Is Available to Help School Districts Switch to
Alternative Fuel School Buses, But More Is Needed

Chap 8: Local Air Quality Agencies Can Adopt Fleet Rules Requiring
School Districts to Purchase Only Clean Alternative Fuel School Buses

Chap 9: Conclusions and Recommendations Report Credits and


App: A: School Bus Monitoring Study Protocol

App: B: Potential Cancer Risk to Children in School Buses

App: C: The Aethalometer

App: D: Portable Monitor/Data Logger

App: E: Emissions Comparisons of ARB Certified Diesel, CNG, Propane
(LPG) School Bus Engines and Non-Certified "Green" Diesel School Bus
Engine Technology

App: F: Examples of Available Funding Sources for Conversion to
Alternative Fuels

App: G: Sample Letters to the Air Board, the School District and Elected

App: H: Sample School Board Resolution in Support of an Alternative Fuel
School Bus Policy

Gary N. Greenberg, MD MPH    Sysop / Moderator Occ-Env-Med-L MailList
gary.greenberg at duke.edu     Duke Occupat, Environ, Int & Fam Medicine
OEM-L Maillist Website:                      http://occhealthnews.com


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