Heavy-Duty Diesel Vehicle Idling Information

The issue of exposure to diesel particulate matter (DPM) from vehicle idling has been raised frequently in communities. Concerns include bus idling near schools, truck idling in or around distribution centers or warehouses, and traffic congestion that can contribute to increased PM burden at sensitive receptors.

Presented below are some of CARB’s on-going activities and strategies to address heavy-duty idling.  


Links to CARB’s two idling-related Airborne Toxic Control Measures (ATCMs), adopted in 2003-2004, are provided above.  CARB is currently reviewing the health protectiveness of these regulations that limit operators of heavy-duty diesel vehicles from idling their engines.  This review is expected to be completed in early 2020 and consists of two phases designed to inform whether the regulations are still health-protective or need to be strengthened:

  • Phase I - Update the technical analyses initially conducted to support CARB’s ATCMs using the latest available input data, like new emission rates for heavy-duty trucks from the latest version of CARB’s EMFAC emission model, and consideration of new guidelines for conducting toxic risk assessments published by the Office of Environmental Health Hazard Assessment (OEHHA); and
  • Phase II - Considering updates to the truck idling scenarios used in the original ATCM analyses to ensure that this updated analysis is representative of the activities of today's fleets (e.g., changes due to e-commerce, warehousing, etc.)  The development of new scenarios will involve talking with residents of AB 617 communities about truck idling activities of concern in their neighborhoods. Community specific fleet and idling activity data will be collected at various locations in AB 617 communities to assess site-specific protectiveness of the ATCMs.