Vehicle anti-idling initiatives

Evidence Rating  
Some Evidence
Evidence rating: Some Evidence

Strategies with this rating are likely to work, but further research is needed to confirm effects. These strategies have been tested more than once and results trend positive overall.

Health Factors  

Anti-idling initiatives include organizational policies and awareness campaigns to minimize the time that drivers idle the engines of their personal or fleet vehicles. These efforts are often implemented in support of federal, state, or local anti-idling laws but can also be standalone efforts by neighborhoods or near schools. Anti-idling campaigns typically include education efforts, anti-idling signs in loading/unloading zones, and pledges to change behavior. Initiatives can promote use of idle reduction technologies for buses or trucks such as auxiliary power units (APUs), automatic shutdown/start-up devices, or battery-powered air conditioning1. When idling, gasoline- and diesel-powered engines consume fuel and produce greenhouse gas emissions and hydrocarbons that can react to form smog and emit pollutants such as nitrogen oxides, particulate matter, and toxic air pollutants that negatively affect cardiovascular and respiratory health, especially for children, and contribute to climate change2, 3.

What could this strategy improve?

Expected Benefits

Our evidence rating is based on the likelihood of achieving these outcomes:

  • Reduced vehicle idling

Potential Benefits

Our evidence rating is not based on these outcomes, but these benefits may also be possible:

  • Reduced emissions

  • Improved air quality

  • Improved health outcomes

What does the research say about effectiveness? This strategy is rated some evidence.

There is some evidence that anti-idling initiatives reduce vehicle idling time and emissions, and improve air quality, especially near schools with high levels of traffic4, 5, 6, 7, 8, 9. Research shows that idling school buses increase children’s exposure to air pollutants in the school vicinity10, 11, 12, 13. Vehicles that are turned off do not use fuel or emit the air pollutants and greenhouse gases emitted when idling. Several idle reduction technologies have been shown to significantly reduce fuel use and emissions of pollutants such as nitrogen oxides, particulate matter, and carbon dioxide1, 14, 15. However, additional evidence is needed to confirm the effects of anti-idling initiatives on idling levels.

An evaluation of a Georgia school district’s anti-idling program that used an on-board idle detection and warning system suggests such programs can reduce idle times, save fuel, and reduce emissions8. A Cincinnati-based effort indicates that anti-idling campaigns near schools with many buses and high levels of traffic can also improve indoor air quality by reducing traffic aerosols7. A short anti-idling campaign focused on school drop-off zones in Salt Lake City, Utah, appeared to modestly improve air quality and to reduce the time and number of vehicles observed idling4. An Australian study also finds a 4-week, low-intensity intervention with parents improves air quality and reduces idling near schools5. Surveys suggest that community and driver knowledge of the health benefits of reducing idling increases with anti-idling education efforts16.

Research suggests that successful anti-idling policies establish a baseline, educate drivers, gather and analyze data, set goals, have a written policy, and measure and report success9. Planners should also consider local weather and regional climate variability in designing initiatives and measuring effects4. Experts also recommend prioritizing anti-idling policies and incentives to reduce using gas- and diesel-powered vehicles, over strategies which reduce emissions’ effects, such as vegetation barriers17.

Pairing idle reduction technologies for buses and trucks with anti-idling policies can increase reductions in emissions1. Idle reduction initiatives are a low cost way to reduce idling and emissions and to save fuel9. Several idle reduction technologies have been shown to be cost-effective with payback times of half a year or less1. Experts suggest that educational campaigns may change idling behavior among some drivers of personal vehicles, but that technology-based solutions with education may be most effective at reducing idling, especially when vehicle power is needed for occupational purposes (e.g. long-haul trucking, police and ambulance fleets, school buses)18.

Idling is estimated to waste six billion gallons of fuel annually, with personal vehicles accounting for three billion gallons and generating 30 million tons of CO2. Stopping unnecessary idling of personal vehicles equates to taking five million vehicles off the road19.

How could this strategy advance health equity? This strategy is rated potential to decrease disparities: suggested by expert opinion.

Efforts to reduce exhaust emissions – including through reduced vehicle idling – have the potential to decrease existing disparities in air pollution exposure rates by race, ethnicity, and income26, 27, 28. Anti-idling campaigns can reduce idling time and emissions, and improve air quality4, 5, 6, 7, 8, 9, and idle reduction technologies significantly reduce fuel use and pollutant emissions1, 14, 15. Available evidence suggests that racial disparities in air pollution exposure have declined, although racial disparities persist27. Experts suggest programs should identify neighborhoods where emissions reductions can reduce average exposure, exposure inequality, and exposure injustice as well as account for meteorology and the movement of air pollution to reduce disparities in exposure28.

Higher exposure to air pollution and toxic emissions has been associated with disparities in health outcomes between people of color and people with low incomes and white people and people with higher incomes26. Air pollution exposure and living in neighborhoods with heavy traffic is associated with many adverse health effects, including asthma, respiratory disease, cardiovascular disease, cancers, adverse birth outcomes, cognitive decline, dementia, and more27, 29. Children living near heavy traffic are more likely to have asthma than children living in neighborhoods without traffic; children of color are also more likely to have or develop asthma than white children29. Other studies suggest more Black individuals are diagnosed with and hospitalized for asthma, compared with white individuals30.

Individuals living nearer to bus depots are exposed to toxic emissions from large numbers of idling buses. Existing research suggests that cleaner transportation options, like commuter rail, tend to be more accessible to wealthier communities, while buses are more accessible to communities with lower incomes and more individuals of color. A study of New York City finds that census tracts with higher percentages of Hispanic or Black individuals tend to be closer to bus depots in most boroughs and suggests that belonging to a marginalized racial group may contribute to pollution exposure, in some cases regardless of socio-economic status. An analysis estimates that transitioning New York City’s bus fleet to electric buses would save $150,000 per bus through reductions in hospitalizations, emergency room costs, and missed work, and experts suggest that initiatives addressing air pollution from buses could reduce disparities in lung-related illness and financial burden among Black individuals. Experts recommend that planners consider race and class disparities when deciding where to focus efforts to reduce idling and where to test and implement cleaner technologies30.

What is the relevant historical background?

Throughout U.S. history, discriminatory housing, lending, and exclusionary zoning policies entrenched racial residential segregation and concentrated poverty31, 32. Many urban areas in the U.S. experienced unrestrained industrialization without environmental regulations or land use controls creating environmental problems, including water and air pollution, waste production, overconsumption of natural resources, and loss of green space33. Early U.S. environmental movements focused on conservation and nature preservation and did not consider urban environmental inequities or public health34. The built environment in under-resourced communities is a significant contributor to health inequities for people of color with low incomes35, 36, 37. Formerly redlined neighborhoods remain more likely to include vacant lots and blighted properties, older homes in poor condition, coal-fired power plants, hazardous waste disposal sites, and other health risks38. Communities with low incomes and communities of color still have fewer places to engage in outdoor activities, have less access to cooling shade, experience more extreme heat, and experience poorer air quality39, 40, 41.

The Air Pollution Control Act of 1955 was the first federal legislation to identify and provide funds for air pollution research. The Clean Air Act of 1963 began the process of air pollution control, and many iterations of the legislation followed. Notably, the Clean Air Act of 1970 authorized the U.S. Environmental Protection Agency (EPA) to establish, regulate, monitor, and enforce National Ambient Air Quality Standards to protect public health from widespread hazardous air pollutants, especially particulate matter, ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead. This legislation regulates and enforces reductions of many types of air pollution from multiple pollution sources, including motor vehicles. The 1990 Clean Air Act Amendments established updated goals and technology standards to reduce hazardous air pollution42, 43, 44. The federal Clean Air Act has reduced disparities in hazardous pollutant exposure, although racial disparities continue to persist45. EPA standards for cleaner vehicles and fuel aim to reduce pollutants which harm human health and the environment, as emissions from personal and commercial vehicles, and their fuel, continue to be a large source of pollution exposure46.

Environmental justice groups, such as West Harlem Environment Action (WE ACT) in New York City, have campaigned for equitable siting of bus depots and for cities to invest in cleaner buses, since the 1980s. These groups have also partnered with academic researchers to study health risks associated with New York City’s transit systems. Some cities have had anti-idling laws since the 1970s but enforcing the laws remains difficult. In 2015, New York City began offering financial incentives for citizens to report idling through its Air Complaint Program30.

Equity Considerations
  • What neighborhoods in your community suffer from poor air quality and high levels of pollutant exposures?
  • What anti-idling laws or ordinances are in place in your community and state? How are they enforced? How are the laws’ effects measured?
  • Who is leading local efforts to reduce emissions from idling? Are there efforts in multiple sectors (e.g., transportation, tourism) to reduce idling and disproportionate exposure to air pollution (e.g., by occupation, neighborhood)?
  • Is there investment locally in strategies which stop idling altogether, including alternatives to vehicle use (e.g., improving bike and pedestrian routes)?
Implementation Examples

As of 2023, 28 states and Washington, D.C. have laws or regulations that address idling; 38 states have state-wide incentives20. New Jersey’s state anti-idling law applies to heavy duty trucks and passenger vehicles and is supported by a Stop the Soot campaign21.

Many municipalities support anti-idling efforts; for example, San Antonio passed an anti-idling ordinance for heavy duty trucks with a five minute idling limit, effective in January 201722, and Park City, Utah prohibits vehicle idling for more than one minute23. Municipalities and business owners can install electrified parking spaces at truck stops, rest areas, and distribution centers to provide power, heating, and cooling to the cab without idling; however, these efforts are not yet widespread24.

Several federal programs support reductions in emissions through idle reduction efforts, such as the Congestion Mitigation and Air Quality (CMAQ) Improvement Program, Clean Cities Coalition Network, Clean School Bus USA, and the SmartWay Transport Partnership. The federal government also offers an idle reduction equipment excise tax exemption and an idle reduction technology weight exemption. The federal weight exemption allows states to permit heavy duty vehicles equipped with idle reduction technology to exceed the maximum gross vehicle weight limit and axle weight limit to compensate for the additional weight of idle reduction technology without affecting state highway funding eligibility25.

Implementation Resources

Resources with a focus on equity.

US DOE-AFDC idle reduction - U.S. Department of Energy (U.S. DOE), Energy Efficiency & Renewable Energy (EERE). Alternative Fuels Data Center (AFDC): Idle reduction.

US DOE-VTO idle reduction - U.S. Department of Energy (U.S. DOE), Energy Efficiency & Renewable Energy (EERE). Vehicle Technologies Office (VTO): Idle reduction research and resources.

US DOE-IdleBox toolkit - U.S. Department of Energy (U.S. DOE), Energy Efficiency & Renewable Energy (EERE). Clean cities: IdleBox toolkit for idling reduction projects.

NRC-Idle free - Natural Resources Canada (NRC). Idle free zone resources for communities and government.

US EPA-Idle free schools - U.S. Environmental Protection Agency (U.S. EPA). Region 8: Idle free schools toolkit and resources.

US EPA-SmartWay - U.S. Environmental Protection Agency (U.S. EPA). SmartWay.

US DOT-Idle reduction - U.S. Department of Transportation (U.S. DOT). Congestion mitigation and air quality improvement (CMAQ) program: Idle reduction techniques.

World Emissions Clock - World Data Lab. World Emissions Clock.


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20 US DOE-AFDC laws and incentives - U.S. Department of Energy (U.S. DOE), Energy Efficiency & Renewable Energy (EERE). Alternative Fuels Data Center (AFDC): Search federal and state laws and incentives.

21 NJ DEP-Idling restrictions - State of New Jersey Department of Environmental Protection (NJ DEP), Bureau of Mobile Sources. Idling restrictions.

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23 Park City-Anti-idling - Park City, Utah. Anti-idling ordinance.

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