Pennsylvania now is enforcing the Diesel-Powered Motor Vehicle Idling Act, which restricts most diesel-powered motor vehicles more than 10,000 pounds from idling more than five minutes in any continuous 60-minute period, with a number of exemptions, including allowing buses and school buses to idle for 15 minutes in a 60-minute period. The law also prevents localities from enacting any new ordinances.
Gov. Ed Rendell signed the act into law on Oct. 9, 2008, after a Senate bill (SB 295) was significantly amended and passed the Pennsylvania General Assembly on the last active day of the session. The law was to take effect 120 days from enactment.