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 stops.

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 kids."

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.