Are hybrid buses in my city really helping to reduce air pollution?

Are hybrid buses in my city really helping to reduce air pollution?

—Jennifer Cross, New York, NY

According to the Natural Resources Defense Council, 20 percent of U.S. air pollution comes from diesel buses—and many of them are concentrated in cities. The Environmental Protection Agency (EPA) currently runs a program called Clean School Bus USA, an effort to reduce both children”s exposure to diesel exhaust and the amount of air pollution created by diesel school buses. The EPA has also recently passed tougher standards for all diesel-powered vehicles, but they won’t go into effect until 2006. In the meantime, many cities are still trying to meet federal Clean Air Act rules, especially given rising rates of asthma, particularly in children. One of the ways cities can clean up their air is by employing alternatives to traditional diesel engines for both public and school buses.

“Retrofitting” (modifying) older buses, which includes adapting them to use cleaner-burning fuels and incorporating pollution controls, can reduce emissions, but hybrid buses offer increased benefits. A Department of Energy study reports that hybrid buses, which combine a diesel engine with an electric motor, outperform regular diesel buses in a variety of categories, offering 10 percent higher fuel economy, 19 percent lower carbon dioxide emissions and a whopping 97 percent reduction in carbon monoxide emissions. John Powell, executive director of the Advanced Transportation Technology Institute, sees the dual-fueled hybrids as the optimal choice with the most benefits. Hybrids have already been successfully introduced in New York City, New Jersey, Connecticut, Minnesota, Washington state and Toronto, Canada.

However, many environmentalists would like to do away with using diesel fuel altogether: “Replacing diesel buses with those fueled with natural gas or electricity will help to provide important health protections for people with lung disease,” says Bonnie Holmes-Gen, assistant vice president for government relations with the American Lung Association of California. Some cities, like Boston, already run compressed natural gas buses. Still others are looking into blending hydrogen with natural gas to create a low-emission fuel for buses called “hythane.” Whatever the alternatives, putting pressure on your local transit authority to buy hybrid vehicles or burn cleaner fuels will result in cleaner air for everyone.

CONTACTS: Natural Resources Defense Council, (212) 727-2700,; EPA”s Clean School Bus USA,; Advanced Transportation Technology Institute, (423) 622-3884,; American Lung Association of California, (510) 638-LUNG,