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National Clean Diesel Campaign (NCDC)

Working Together for Cleaner Air

Clean School Bus

no engine idling sign

Idle Reduction Campaign

There are 25 million reasons why it's important to reduce school bus idling. The key to reducing idling is you!

Clean School Bus's National Idle Reduction Campaign helps your community take action toward a cleaner, healthier environment. It recognizes the important role of the school bus driver as a professional who is responsible for the safety and security of children.

The National Idle Reduction Campaign:

  • Encourages idle reduction to protect the health of children, bus drivers and the community, as well as to improve air quality.
  • Promotes idle reduction as a simple way to save money by saving fuel and reducing wear and tear on engines.
  • Recognizes the positive contributions being made by school bus drivers.
  • Provides materials to help school districts, transportation managers, bus drivers, teachers, parents, and students learn about air quality and diesel emissions.

Why Idle Reduction Matters

Unnecessary school bus idling affects human health, pollutes the air, wastes fuel, and causes excess engine wear. Fortunately, it's easy to implement practices that reduce school bus idling.

Human Health Impacts

Diesel exhaust from excessive idling can affect human health. Diesel exhaust contains significant levels of particles, known as fine particulate matter, which are so small that several thousand of them could fit on the period at the end of this sentence. These fine particles pose a significant health risk because they can pass through the nose and throat and lodge in the lungs, causing lung damage and premature death. Particulate matter is responsible for thousands of premature deaths across the nation every year.

EPA has determined that diesel exhaust is a likely human carcinogen and can contribute to other acute and chronic health concerns (see EPA's Health Assessment Document for Diesel Exhaust). People with existing heart or lung disease, asthma, bronchitis or other respiratory problems are most sensitive to the health effects of fine particles. The elderly and children are also at risk. Children are more susceptible to air pollution than healthy adults because their respiratory systems are still developing and they have a faster breathing rate.

Air Pollution

Idling school buses can pollute air in and around the bus. Exhaust from buses can also enter school buildings through air intakes, doors, and open windows. Diesel exhaust contains pollutants that contribute to ozone formation, haze, acid rain, and global climate change. Fine particles from diesel engines contribute to haze which restricts our ability to see long distances.

Wasted Fuel and Money

Idling buses waste fuel and money. When idling, a typical school bus engine burns about half a gallon of fuel per hour. School districts that eliminate unnecessary idling can have significant savings in fuel costs each year. Use the Fuel Savings Calculator to estimate the fuel and money saved by reducing idling in your school bus fleet.

Engine Wear-and-Tear

School bus engines do not need to idle more than a few minutes to warm up. In fact, extended idling causes engine damage. Engine manufacturers generally recommend no more than three to five minutes of idling.

Idling Reduction Technologies

To learn more about idling reduction technologies verified by EPA, visit SmartWay Technologies

To learn more about idle reduction accessories such as auxiliary heaters and other equipment, visit NCDC Technologies

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Idling Myths (Click here to expand/hide)

  • Myth:
    It's important to warm up the engine with a long idle period, especially in cold weather.
    • Fact:
      With today's school bus engines, bus and engine manufacturers routinely suggest a warm up time of less than five minutes. In fact, running an engine at low speed (idling) causes significantly more wear on internal parts than driving at regular speed.
  • Myth:
    It's better for an engine to run at low speed (idling) than to run at regular speed.
    • Fact:
      Running an engine at low speed causes twice the wear on internal parts as driving at regular speeds.
  • Myth:
    Idling is necessary to keep the cabin comfortable.
    • Fact:
      Depending on the weather, many buses will maintain a comfortable interior temperature for a while without idling. Idling is not an efficient way to keep the cabin warm. Bus routes should be timed so children and drivers do not need to spend a lot of extra time on the bus when it is not en route, particularly in hot or cold weather. In addition, auxiliary heaters can be purchased and installed to keep the cabin comfortable.
  • Myth:
    It’s better to just leave the engine idling because a "cold start" produces more pollution.
    • Fact:
      A recent EPA study found that the emissions measured after a school bus is restarted contains less carbon monoxide, nitrogen oxides, and other pollutants than if the school bus idled continuously over a 10-minute period. The analysis indicated that continuous idling for more than three minutes emits more fine particles (soot) than a restart.

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Participate in the National Idle Reduction Campaign

The National Idle Reduction Campaign offers simple ways for your school or school district to get involved in idle reduction.

Establish an Idle Reduction Policy

At a minimum, the policy should include the following:

  • Buses should typically be moving whenever the engine is on.
  • Engines should be turned off as soon as possible after arriving at loading or unloading areas.
  • School buses should not be restarted until ready to depart.
  • Limit idling time during early morning warm up to what the manufacturer recommends (generally no more than five minutes).

Tips to help your idle reduction policy succeed include:

  • Train bus drivers to understand and follow the idle reduction policy.
  • Provide a comfortable space inside where bus drivers can wait.
  • Spot-check loading and unloading areas, delivery areas and bus depots for compliance with the idling guidelines.
  • Consider idle reduction technologies to help with cabin comfort, extreme weather, and equipment operation.
  • Follow idling laws and guidelines in your state or community, where applicable. See the Compendium of Idling Regulations (2012) (PDF) (10 pp, 350K, January 2012) Exit EPA Disclaimer

Here is a sample School Bus Idling Policy you can use as a model.

Estimate Fuel and Dollar Savings from Idle Reduction

Use our easy, interactive Fuel Savings Calculator to estimate fuel and dollars savings from reducing school bus idling.

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Promote your Idle Reduction Campaign

Clean School Bus's National Idle Reduction Campaign offers a selection of materials that can be tailored to your program. Items can be downloaded from the Publications page or ordered using the Idle Reduction Order Form

A Teacher's Guide is also available that includes four modules (Health, Science, Social Studies, and Math) about idle reduction. Each module contains Overview, Teacher’s Prep, Classroom Questions & Answers, Classroom Activities, and Research Activities. Order by e-mailing cleanschoolbususa@epa.gov

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Sustain and expand your Idle Reduction Program

Recognize drivers who successfully reduce idling.

  • Award drivers with a certificate of recognition.
  • Ask local businesses, non-profits working on clean air, or parent/teacher organizations to donate gift certificates or other items to reward bus drivers who successfully reduce idling.

Urge your community leaders to issue a local Idle Reduction Proclamation

Share your success with other school districts, the media and the general public by issuing a press release about your program.

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