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Making School Buses Cleaner


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Replacing Old School Buses

Older, more polluting school buses can lead to significant health risks for students who typically ride these buses for one-half to two hours a day. Children are more susceptible to air pollution than healthy adults because their respiratory systems are still developing and they have faster breathing rates. Asthma, which affects 6.3 million American school children, is the most common long-term childhood disease in America, making newer, cleaner buses an urgent priority.

In addition to affecting the health of students, emissions from older buses can have a negative impact on the whole community. Particulate matter (PM) damages hearts and lungs. Other diesel emissions contribute to

Older buses are excellent candidates for replacement with newer, cleaner vehicles which will greatly reduce children’s exposure to diesel exhaust and provide considerable safety improvements.  To see if there is a school bus replacement or retrofit rebate currently available, please visit DERA School Bus Rebates.

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Reviewing Age and Condition of Bus Fleet

Districts should assess the buses in their fleet for age and condition to determine which buses need to be replaced first. Compiling this information in advance allows districts to plan for future expenditures and to be prepared when funds become available. Fleet information can be collected on a Fleet Information Table (XLS)(1 pg, 26 K, June 2012) .

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Prioritizing School Bus Replacements

Targeting pre-1998 school buses for replacement is not only key to retiring buses that pollute the most, but is also a cost-effective strategy. Older buses often have increased maintenance concerns, decreased fuel economy benefits, and less stringent safety equipment.  Below are groupings of engine model years in order of replacement priority.

  1. Pre-1998
  2. 1998-2003
  3. 2004-2006
  4. Post 2007

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Buses Built Before 1998

Buses built before 1998 that are used for student transport should be ranked as a high priority for replacement. Consider using them on shorter routes, for special events or as emergency back-ups to limit student exposure until they can be replaced. Implement an idle reduction program and keep the engines in good working order.

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Buses Built Between 1998 and 2010

If school buses built between 1998 and 2010 are still in use, there are ways to reduce the emissions they produce.

  • Idle Reduction - Implementing an idle reduction program is a simple, cost-effective way to reduce emissions while saving money on fuel and preventing engine wear and tear.
  • Retrofit Technologies - For older buses that will be used for several more years, retrofitting them with emission controls or idle reduction technologies can be a cost effective way to reduce emissions. More information on DERA funding for retrofits can be found on the Make Your School Bus a Clean, Green Transportation Machine - Flyer (PDF) (1 pp, 342 K, July 2020, EPA-420-F-20-038, About PDF).
  • Engine Replacements - Older diesel engines can be replaced with newer engines using diesel, biodiesel or compressed natural gas (CNG). The new engine should be certified to meet the most recent emission standards and come with a diesel particulate filter (DPF) or diesel oxidation catalyst (DOC).
  • Fuel Selection - Cleaner fuels such as biodiesel or compressed natural gas (CNG) can further reduce emissions from school buses.

When replacing buses built between 1998 and 2010, the school district should check with nearby districts. If the neighboring districts are operating older buses and can’t afford brand new buses, they may be able to use the relatively newer buses as a replacement alternative. Overall, this is a win-win situation for the whole community.

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Bid Specifications

Bid specifications for new bus purchases should require information about the emission levels of the new, certified bus engines and specify any additional technologies available to further reduce those levels.  Additional bus safety considerations should be also be included as a part of the specification process.

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Finding Financing for Cleaner Buses

Although some communities have schedules for replacing school buses, they may not have the resources to do so as quickly as they would like. By assessing the fleet age and condition, the school district will be more prepared to apply for available funding. Fleet information can be collected on Fleet Information Table (XLS)(1 pg, 26 K, June 2012) .

Outside funding sources may require or recommend the school district to provide matching funds using financial or other resources. Try to determine the school district’s available resources, whether in-kind (such as staff time) or financial, that could be used as a match for the funds.

If funding is limited, try to identify districts that are replacing their buses. The buses being replaced may be relatively newer and purchasing them could result in overall emission reductions for the school district.

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