Expanding Idling Regulation

The State of California currently has an idling regulation for commercial heavy-duty diesel vehicles and school buses. While light-duty vehicles -- cars, SUVs, vans, pickup trucks -- comprise more than 85% of the vehicles on California's roads, there is no restriction for idling of these vehicles when parked. This has a significant negative impact on air quality, carbon emissions that contribute to climate change, and the wasting of energy. As seven U.S. states already have all motor vehicle idling regulations/laws, it is time to consider expanding California's regulation to include light-duty vehicles.


When considering expanding the regulation to include all vehicles, however, there is a strong likelihood of pushback and that implementation could take years. Therefore, in what can be looked at as an incremental step, let's target the most egregious aspect of light-duty vehicle idling: exposure to children at schools, as currently addressed by California's non-binding ACR 160. To help raise awareness of this regulation, the installation of NO IDLING signs would be mandated at all schools.









1. Light-duty vehicles (LDVs), despite emission controls, emit harmful exhaust chemicals that negatively impact air quality and health; because idling engines are not operating at peak temperature, they emit more pollution than when traveling


2. Commercial heavy-duty diesel powered vehicles emit four timesLos Angeles ozone pollution in 2015 more pollutants than LDVs. But LDVs comprise more than 85% of the vehicles in California


3. The onset of mobile devices has led to greatly increased idling while parked


4. LDV IDLING AT SCHOOLS negatively impacts the health of students. To help address this issue, California ACR 160 -- Relative to vehicular air pollution -- encourages motorists to not idle their motor vehicles near places where children congregate; an LDV idling regulation on school property would make this non-binding resolution more effective.


Further, the EPA states, "Idling vehicles contribute to air pollution and emit air toxins, which are pollutants known or suspected to cause cancer or other serious health effects. Monitoring at schools has shown elevated levels of benzene, formaldehyde, acetaldehyde and other air toxics during the afternoon hour coinciding with parents picking up their children. Children’s lungs are still developing, and when they are exposed to elevated levels of these pollutants, children have an increased risk of developing asthma, respiratory problems and other adverse health effects. Limiting a vehicle’s idling time can dramatically reduce these pollutants and children’s exposure to them."


5. An all motor vehicle regulation would provide recourse for those affected by prolonged idling of LDVs in neighborhoods, schools, etc.


6. An all motor vehicle regulation will make all motorists responsible - more equitable than targeting commercial vehicles alone


7. Financial impacts of idling:

A. Idling gets negative MPG. The average LDV consumes .375 gallons of fuel an hour. With gasoline at $2.75 a gallon, needlessly idling while parked for 15 minutes a day will consume around $100 a year

B. Idling puts "ghost miles" on an engine causing needless wear including carbon soot buildup on engine components, shortening the life of motor oil, spark plugs, and exhaust system


8. Many vehicle owners' manuals advise limiting idling


9. Idling LDVs are here to stay: despite California being a leader in sales of non-idling hybrid and electric vehicles, more than 90% of California vehicles sold in 2015 and 2016 are powered by conventional internal combustion engines


10. Reducing idling of LDVs will help California meet requirements in AB 32 to reduce its GHG emissions to 1990 levels by 2020


11. Seven U.S. states have all motor vehicle regulations/laws (CT, HI, MA, MD, NH, NJ, VT)


12. In California it can be roughly estimated that idling of all vehicles when parked emit 3.75 million tons of carbon dioxide annually, in the process consuming 375 million gallons of fuel; conservatively, about one half of this is attributable to LDVs.*


*The U.S. Dept. of Energy states, "Each year, U.S. passenger cars, light-duty trucks, medium-duty trucks, and heavy-duty vehicles consume more than 6 billion gallons of diesel fuel and gasoline—without even moving." For California then, while there are no far ranging studies on vehicle idling in the state, a rough estimate is the idling of all vehicles wastes 750,000,000 gallons of fuel. This is 7.5 million tons of CO2 emitted by all idling vehicles in California. Studies show that about one-half of all idling occurs when parked (not in traffic).1, 2. Therefore, it is estimated all vehicles idling when parked in California waste about 375,000,000 gallons of fuel and emit 3.75 million tons of CO2.

1Vanderbilt University study: Costly myths: An analysis of idling beliefs and behavior in personal motor vehicles (p.4). "...the average American idles for roughly 16 min a day. Over 51%...can be accounted for by individuals idling while in traffic...the remaining 49%...results from idling to warm and while waiting, both of which are avoidable and, in many cases, unnecessary."

2University of Vermont study: Passenger vehicle idling in Vermont (p.25): "Discretionary idling is a large enough percent of all idling in Vermont (approximately half) to suggest policies to pursue behavior change over purely vehicle technologies which eliminate all idling emissions by turning off during travel and at stops."



The State of California's idling regulation for commercial heavy-duty diesel vehicles and school buses usually limits idling to five minutes. For an LDV statewide idling regulation, Idle-Free California recommends a three-minute idling limit; for a school property only LDV idling regulation, a 30-second idling limit (with exceptions). For a school property only LDV idling regulation, Idle-Free California proposes a mandate for the installation of NO IDLING signage at all schools.


To make a difference, an all vehicle regulation will require more than just enforcement. It will require a far reaching educational campaign by a State of California agency. It will also require education from various sectors, including health and environmental organizations, and schools.