For years, the familiar cloud of black exhaust pumped from U.S. school buses has fueled growing concerns over harmful effects of diesel emissions on students’ health. Now, environmentalists say, new technologies to reduce the potency of these pollutants are helping clear the air.

So far this year, the U.S. Environmental Protection Agency (EPA) has awarded $5 million to retrofit 5,000 school buses with environmentally friendly diesel oxidation catalysts and lower emission fuels as part of its two-year-old Clean School Bus USA demonstration program.

The funds were disbursed among 21 federal grants to school systems across the country to showcase cleaner technologies for school buses. President Bush hopes the success of the program will prompt Congress to approve his 2005 budget request, which includes a $65 million proposal to retrofit and upgrade the nation’s entire school bus fleet.

Launched in April 2003, the EPA program was intended to reduce children’s exposure to harmful diesel exhaust and the amount of air pollution created by diesel school buses. Last year, the agency awarded $5 million to 17 school districts in an effort to upgrade engines and reduce diesel emissions on an estimated 4,000 school buses nationwide. EPA officials predict more fuel-efficient technologies will remove as much as 200,000 pounds of diesel-produced smog from the air over the next 10 years.

“By retrofitting these buses, we bring tomorrow’s technology to today’s children,” said EPA Administrator Mike Leavitt at a June 14 event in Ann Arbor, Mich., during which the agency awarded $165,357 to two Michigan school districts. “We’ll cut harmful emissions from these buses by 20 to 50 percent, and that means that kids and parents alike can breathe a little easier.”

The EPA granted $95,357 to Ann Arbor Public Schools to retrofit 110 buses and to provide a two-year supply of biodiesel fuel for 18 buses belonging to the neighboring Manchester Community Schools. A $70,000 grant went to the Okemos Public Schools and six neighboring districts for retrofitting 40 to 50 buses, according to an agency statement.

The buses will be equipped with diesel oxidation catalysts that use a chemical process to break down pollutants in the exhaust stream into less harmful components. Sold for from $600 to $2,000 apiece, the catalysts can be installed on any new or used bus and run on regular diesel fuel, EPA officials said. The devices take between one and three hours to install and can be selected from a pre-approved list provided by the EPA. The catalysts then are purchased through school systems’ normal competitive-bidding processes.

Biodiesel is a domestically produced renewable fuel that can be made from vegetable oil or animal fat. Unlike regular diesel fuel, it is biodegradable and reduces air pollutants such as particulate matter, carbon monoxide, hydrocarbons, and air toxics, the agency said.

The Clean School Bus program already is providing a healthier commute for students in one Arizona school district.

Last year, officials at the 30,000-student Paradise Valley Unified School District received $300,000 to retrofit 20 buses with particulate-matter filters and fuel 114 buses with ultra-low sulfur diesel, another low-emission fuel meant to reduce the amount of harmful chemicals pumped into the air.

According to district transportation manger Jeff Cook, school officials have reported “a noticeable decline” in harmful emissions since launching the retrofitting and clean-fuel initiatives.

Although the district was able to outfit only a small portion of its 175-vehicle fleet with the catalysts, he said, the low-sulfur fuel has proven effective at powering the district’s school buses and cutting down on unnecessary pollutants.

That’s good news for Arizonans, he added, where wind-swept deserts and a dry, dusty climate are a natural recipe for poor air quality.

“We’re very happy with the way the program has gone so far,” Cook said. With a year left on its grant, the district already has used up all the money allotted to retrofit its school buses. The leftover funds, he said, will be used to purchase more low-sulfur fuel, which has to be trucked in from California.

According to statistics on the EPA web site, 24 million U.S. schoolchildren spend an hour and half each weekday on a school bus. All told, the nation’s school buses travel more than 4 billion miles each year–roughly equivalent to 20 trips to the sun and back.

Over the course of the last three years, several nonprofit and independent research groups have conducted studies linking student health problems to smog and other diesel-generated emissions. According to the American Lung Association, scientists have tied school bus pollutants to everything from increased asthma attacks and missed school days to hospitalizations, chronic bronchitis, heart disease, cancer, and even premature death.

In February 2002, the Union of Concerned Scientists, which runs an online campaign called, released a report card on diesel emissions from the nation’s school buses, stating that buses in all 50 states released toxins that could be detrimental to students’ health.

At that time, the report stated, there were very few programs in place to monitor the amount of pollution released from school buses or that required schools to explore low-emission alternatives to traditional diesel fuels.

Robin Leeds, an industry specialist for the National School Transportation Association (NSTA), said the overall lack of public awareness was one of the reasons her organization chose to get involved.

In 2003, the association received a $500,000 grant from the Clean School Bus program to provide member school districts with clean-air and retrofitting technologies.

The goal, she said, is to provide the “safest ride possible.”

Industry representatives also are pitching in to make school bus travel safer–and cleaner–for the nation’s students.

On June 3, Caterpillar Inc., a worldwide manufacturer of diesel engines, awarded $250,000 to retrofit more that 240 buses in Arizona, Illinois, and Texas with its own brand of emissions reduction catalyst.

Caterpillar Group President Stu Levenick made the announcement as part of the National Retrofit Conference in Washington, D.C. Grant recipients included District 150 in Peoria, Ill.; four school districts in Ellis County, Texas, south of Dallas; and the Tucson, Ariz., Unified School District.

Despite the risks of pollution, NSTA’s Leeds said parents and teachers shouldn’t lose sight of the fact that school bus travel is still the safest way for students to get to and from school.

“Taking kids off the bus is not the answer,” she said, adding that whether children travel in buses, in cars with their parents, or walk to school, they still breathe the same air.

In fact, Leeds said, school buses account for a very small portion of the overall problem. The trouble, she said, is that school buses “operate in an environment highly populated by children,” which makes them an easy and likely target for reform.


American Lung Association

Caterpiller Inc.

Clean School Bus USA

Environmental Protection Agency

National School Transportation Association

Union of Concerned Scientists