State’s Anti-Idling Rule

The California Air Resources Board (ARB) regulation affects diesel-fueled commercial vehicles weighing more than 10,000 pounds that are operating in California, regardless of where they are registered.

The rule applies to vehicles that are not engaged in work activities, and states that the vehicles may not idle for more than five minutes (buses may idle for up to ten minutes when passengers are boarding or onboard). Vehicles may not idle auxiliary power systems for more than five minutes to power heaters, air conditioners or any other equipment if the vehicle has a sleeper berth and is within 100 feet of a restricted area (homes and schools).

Idling of auxiliary power systems is allowed if the vehicle has a sleeper berth and is farther than 100 feet away from a restricted area. Idling of vehicles is also allowed in some other restricted circumstances, including for testing, servicing or repairing purposes, or to operate defrosters or other equipment to prevent a safety emergency.

According to ARB data, the average diesel heavy-duty engine burns about one gallon of fuel per hour as it idles, and outreach to drivers will highlight the fuel-saving and cost-saving advantages of shutting off engines when they are not in use. The new rule will be enforced primarily by ARB diesel truck inspectors; however, local law enforcement agencies and the California Highway Patrol can also issue citations. ARB encourages people who wish to report an idling truck or bus to use an online complaint form on ARB’s website, or to call a complaint number (see info below).

ARB issued a similar measure to control idling near schools in 2003. That rule requires school buses and other heavy-duty vehicle operators to turn off their engines immediately whenever they are within 100 feet of a school.

The idling rules are among a series of rules adopted by the ARB as part of its Diesel Risk Reduction Plan that is designed to cut diesel emissions by 75 percent from 2000 levels by 2010. To date twenty other states and cities have enacted anti-idling rules similar to the ones adopted by the ARB.

To report idling vehicles:

For more information on anti-idling rules, and to see the full text of the regulations, see the ARB factsheet here: this page on ARB’s website: