EPA School Bus Study Shows Idling Worse Than Re-starting Engines

Shut off those diesel school bus engines! The Environmental Protection Agency recently conducted a study that concluded that idling for more than three minutes generates more pollution than stopping and re-starting the engine —debunking a widely held belief of some drivers. Turning the engine off cuts carbon monoxide, fine particles, nitrogen oxide, and carbon dioxide—a greenhouse gas.

Diesel exhaust particles can penetrate deep into the lungs and pose serious health risks, including aggravating the symptoms of asthma and other respiratory problems in healthy individuals. The Northeast has some of the highest asthma rates in the nation, including childhood asthma rates near 12 percent in areas of New York City.

In the U.S., 24 million children ride the school bus every day. On average, students spend an hour and a half each weekday in a school bus. Nationally, school buses drive more than 4 billion miles each year.

Due to the longevity of diesel engines, it is estimated that about one-third of all diesel school buses now in service were built before 1990. Older buses are not equipped with today's pollution controls or safety features and are estimated to emit as much as six times more pollution as the new buses that were built starting in 2004, and as much as sixty times more pollution as buses that meet the 2007 diesel standards. There are steps that school bus operators can take now to reduce pollution levels including idling reduction programs, anti-caravanning practices, ensuring proper maintenance of engines, and replacing and retrofitting older buses.

Visit EPA's Clean School Bus website for more info.