|
By Patricia Monahan
More than half a million school buses are on the road today, carrying more than 25 million children to and from school. About 95 percent of these buses run on diesel fuel, which produces multiple forms of air pollution that have been linked to asthma, cancer, and other serious health problems in children (see the sidebar “In Harm’s Way” below).
Since state agencies are not required to monitor school bus pollution, UCS conducted its own evaluation of state school bus fleets. Our research, outlined in the report School Bus Pollution Report Card 2006, found that the average U.S. school bus releases about twice as much pollution per mile (in the form of soot particles) as a tractor-trailer truck (or “big rig”). While all of today’s school buses pollute, the oldest models release anywhere from 10 to more than 100 times as much soot as cleaner alternatives available today.
Cleaner fuels and pollution controls could have a dramatic and immediate effect on school bus pollution, and some states have made progress in this direction. Much more needs to be done, however, to ensure that all of our kids, in every state, ride in “clean” school buses.
Grading the States
UCS contacted all 50 states to obtain the age and fuel type of each bus in their fleet and to learn about existing or proposed school bus cleanup programs. Using these data, we assigned each state a letter grade for the soot emitted by its average school
|
 To read the report, or to find out your state's school bus fleet score, click here. You can also call (617) 547-5552 to order a printed copy for $10, or order online from our publications page.
| bus. (We focused on soot because of its potential to cause toxic “hot spots”—areas of higher exposure for kids riding in or playing near buses.)
The emission performance of a diesel bus equipped with a diesel particulate filter, or “soot trap,” established the baseline for our highest grade (A). No states came close to achieving an A, and we distributed the remaining grades on a curve.
We also ranked state performance in two secondary categories: smog-forming pollution and school bus cleanup programs. States were assigned a curve-based ranking of Above Average, Average, or Poor for smog-forming pollution and a ranking of Good, Above Average, Average, or Poor for programs that reduce pollution through advanced technologies and cleaner fuels such as natural gas and biodiesel. The table below lists each state’s ranking in all three categories.
Here are some of the key findings that emerged from our research:
Age. School buses are some of the oldest vehicles on the road. The average school bus is nine years old, but some are 20, 30, or even 40 or more years old. Thirty-seven percent of U.S. school buses are more than a decade old, and 1 in 12 were built before soot pollution standards existed (and therefore are not required to meet any soot standards today).
|
In Harm’s Way
Diesel exhaust contains many pollutants that pose risks to human health, and the risks for children are especially high.
Fine diesel soot particles can evade the body’s normal defense mechanisms and lodge deep within the lungs, causing or exacerbating serious respiratory and cardiovascular illnesses that can lead to premature death in adults. Diesel exhaust can also contain more than 40 toxic air contaminants, many of which are linked with cancer, immune system disorders, and reproductive problems.
A growing body of evidence suggests children are particularly vulnerable to the harmful effects of air pollution. Children breathe more rapidly than adults, taking in more air (and pollution) per unit of body weight, and their developing bodies do not yet have the full range of defense mechanisms that can protect them against harmful exposures. As a result, air pollution has been linked with decreased lung growth, asthma exacerbations and hospitalizations, and even the possible development of asthma in healthy children.
What’s worse, because particulate matter and toxic air contaminants can remain in the general vicinity of the emission source, children in or near diesel school buses are exposed to more of these pollutants. Based on a limited study of air pollution inside Los Angeles school buses, the California Air Resources Board estimates that children traveling on these buses two hours per school day from kindergarten through high school experience a five percent increase in lifetime cancer risk. | Pollution. The pollution performance of school buses varies widely from state to state, with the average school bus in South Carolina or South Dakota (the states with the dirtiest fleets) emitting nearly three times more soot than the average bus in Delaware (the state with the cleanest fleet). Only five states—Alaska, Connecticut, Maine, Nevada, and New York—scored above the national average in all three categories we evaluated.
Cleanup programs. Over the last several years, soot pollution from U.S. school buses has been reduced more than two percent through local, state, and federal programs. California and Washington lead the country in state cleanup programs, reducing school bus soot more than seven percent through retrofits and cleaner fuels. Twelve other states scored above the national average, reducing school bus soot between 2.5 and 7 percent. However, many states are still ignoring the problem; nine states and the District of Columbia received an “Incomplete” grade for not taking any apparent action to clean up school buses as of 2005.
A Lesson Plan for Improvement
Kids deserve cleaner air, and replacing the oldest school buses and retrofitting more recent models should be a priority for both the states and the federal government. This will cost money, of course. Equipping all school buses built after 1993 with particulate traps and closed crankcase filters would cost approximately $2.6 billion; replacing all buses built before 1994 with new low-emission buses would cost approximately $13.4 billion.
Some states, such as California and Washington, have committed funding for these purposes, but many others would have difficulty in making such an investment on their own. Since cash-strapped school districts should not have to face a trade-off between books and buses, the federal government must help pay for cleaner fuels and advanced emission controls.
|
The Five Rs
It’s not a new way of teaching—it’s the options we have available today (or expect in the near future) for reducing pollution from school buses.
Retrofitting: Older diesel school buses can be equipped with pollution controls such as particulate traps and closed crankcase filters that have the potential to cut tailpipe soot emissions 85 percent or more while also reducing onboard pollution (i.e., soot that enters the bus).
Refueling: Switching to cleaner-burning fuels can also reduce tailpipe pollution. Natural gas is the cleanest option commercially available today, emitting 90 percent less soot than conventional diesel. Biodiesel (a blend of conventional diesel fuel and vegetable oils or animal fats) is particularly useful in reducing emissions from older buses that cannot easily be retrofitted with pollution controls. A common formulation containing 20 percent vegetable oils (known as B20) reduces soot emissions up to 10 percent.
Replacement: Newer buses are held to increasingly stringent safety and tailpipe standards. Starting in 2007, for example, all new school buses must be equipped with particulate traps. These newer buses emit 95 percent less soot than standard diesel buses built in 1988.
Repair: Emissions gradually increase as an engine ages, so routine maintenance and periodic engine rebuilds can keep an engine cleaner over its lifetime.
Reduced idling: Setting limits on unnecessary idling (whether voluntary or mandatory) can save school districts both fuel and money, and keeps the air cleaner.
Click on the graphic to view a
larger image.
| Thanks in part to the efforts of UCS and a coalition of engine manufacturers, retrofit companies, school bus providers, and environmental groups, the U.S. Environmental Protection Agency initiated the Clean School Bus USA grant program in 2003, and we have been working closely with the agency to ensure the program is implemented properly. To date, the program has been funded at only about seven million dollars annually—not nearly enough to meet the nationwide demand for cleaner school buses. UCS built an alliance of more than 500 groups across the country to call for a substantial increase in funding, and we used our campaign website, www.CleanSchoolBus.org, to educate and rally the public.
This hard work paid off in the form of two new grant programs passed by Congress in 2005: the National Clean School Bus Grant Program and the Diesel Emission Reduction Act. As Catalyst went to press, these programs had received $28 million in appropriations from the House of Representatives and $20 million from the Senate. We’re now working with our coalition to guarantee that Congress dedicates adequate funding to school bus cleanup.
Starting in 2007, all school buses will come equipped with advanced pollution controls for soot. But buses already on the road can continue to pollute unnecessarily for decades to come. The welfare of our children ought to be driving investments in school buses that meet the strictest pollution and safety standards, but this is happening only on a localized basis. UCS is not suggesting that parents keep their children from riding school buses, which are still the safest way for kids to get to school. Rather, we encourage parents to work with their school district on an appropriate cleanup plan. That kind of involvement, backed by increased state and federal investment, will truly protect our children’s health.
Patricia Monahan is a senior analyst in the Clean Vehicles Program.
|
