Airborne Toxic Control Measure to Limit Diesel-Fueled Commercial Motor Vehicle Idling

This page last reviewed July 7, 2016


On July 22, 2004, the Air Resources Board (ARB) initially adopted an Airborne Toxic Control Measure (ATCM) to limit idling of diesel-fueled commercial motor vehicles (idling ATCM) and subsequently amended it on October 20, 2005, October 19, 2009, and December 12, 2013. This ATCM is set forth in title 13, CCR, section 2485, and requires, among other things, that drivers of diesel-fueled commercial motor vehicles with gross vehicle weight ratings greater than 10,000 pounds, including buses and sleeper berth equipped trucks, not idle the vehicle’s primary diesel engine longer than five minutes at any location. The ATCM also requires owners and motor carriers that own or dispatch these vehicles to ensure compliance with the ATCM requirements.

The regulation consists of new engine and in-use truck requirements and emission performance requirements for technologies used as alternatives to idling the truck’s main engine. Under the new engine requirements, 2008 and newer model year heavy-duty diesel engines need to be equipped with a non-programmable engine shutdown system that automatically shuts down the engine after five minutes of idling or optionally meet a stringent oxides of nitrogen idling emission standard. Emissions producing alternative technologies such as diesel-fueled auxiliary power systems (APS) and fuel-fired heaters are also required to meet emission performance requirements that ensure emissions are not exceeding the emissions of a truck engine operating at idle. Specifically, the regulation requires diesel APSs installed on trucks with 2007 and newer engines to control particulate matter (PM) emissions by either routing the APS exhaust through the PM trap of the truck engine or by retrofitting the diesel APS with a verified level 3 PM control device that reduces PM emissions by at least 85 percent. Fuel fired heaters installed on trucks with 2007 and newer engines are also required to meet the Ultra-Low Emission Vehicle requirements specified in the Low Emission Vehicle regulations. These requirements are effective beginning in 2008.

For trucks equipped with 2006 and older engines, any APS with a California or federally certified diesel-fueled off-road engine or fuel-fired heater may be used.

The regulation also contains a number of exemptions that allow engine operation for power take-off, maintenance, extreme weather or emergency conditions, emergency vehicles, military and tactical vehicles, armored vehicles, workover rigs, etc.

What's New

  • Page has been updated to reflect the most current regulation.
  • Regulatory Documents for Proposed Amendments to the ATCM to Limit Diesel-Fueled Commercial Motor Vehicles Idling (Posted October 24, 2013)
    The Air Resources Board will conduct a public hearing on December 12, 2013, in Sacramento, to discuss proposed amendments to the ATCM to Limit Diesel-Fueled Commercial Motor Vehicle Idling (title 13, CCR, section 2485). The public hearing notice and staff report have been posted on the proposed regulations webpage. The amended regulatory language can be found in Appendix 1-D.

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