The Environmental Protection Agency studied the exhaust levels from school buses while they were parked and idling compared to when the buses actually were turned off and then restarted. The study concludes that idling for more than three minutes causes more pollution than restarting the engine. By shutting off the bus, levels of carbon monoxide, fine particles, nitrogen oxide, and carbon dioxide were lowered. Alan J. Steinberg, the EPA Regional Administrator who made the announcement, said Pollution from school buses has health implications for everyone, especially asthmatic children. This study shows in no uncertain terms that allowing a bus to idle exposes children to more pollution and shows that a very simple step – shutting off that engine – can really make a difference.”

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