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Diesel Retrofit Information

Federal and state regulation are significantly reducing pollution from new diesel engines. However, these rules will not begin to take effect right away. Retrofitting existing trucks, buses and other diesel equipment and using cleaner fuel can reduce emissions today.

Diesel Retrofit Demonstration Project Grants


  • Clean School Bus Funds to be available from EPA
    When it's available, the US EPA posts it's funding information at the National Clean Diesel Campaign, Grants & Funding page.
  • $20 Million Was Distributed for School Bus Retrofits
    In December 2004, several Pennsylvania school districts were selected in a lottery process to receive funds from Toyota Motor Corporation's Clean Buses for Kids program for purchase of ultra-low sulfur diesel and installation of particulate filters.


  • First Pennsylvania Retrofit Project Completed!
    Wissahickon School District, Montgomery County, has completed their school bus retrofit project, which was funded by DEP. The district is receiving praise from motorists in the area for the cleaner exhaust. See the final report on the project (PDF).
  • Greener Truck and Bus Fleets in Pa
    Heavy-duty vehicle fleets of many kinds and in many areas across Pennsylvania are taking actions to reduce emissions through fuel changes, retrofit and early replacement. Are you aware of a fleet that should be recognized? Let us know!
  • Technology for Diesel Retrofit
    Many options are available for modernizing and upgrading existing diesel fuel and equipment. Consider:
    • refuel - using cleaner diesel or alternative fuels such as biodiesel.
    • retrofit - installing exhaust aftertreatment technologies.
    • repower - replacing an older engine with a new clean diesel engine.
    • repair/rebuild - conducting regular engine maintenance.
    • replace - retiring old equipment and replacing it with new engines or vehicles.

The Diesel Technology Forum has a "toolkit" that can help fleets get started. The Forum's members include leading vehicle and engine manufacturers, key component suppliers, petroleum refineries, and makers of emissions control devices.

The EPA verifies the emission reduction potential of diesel emission reduction technology developed by vendors to provide confidence in the emission-reducing performance of these products. After evaluating testing done according to EPA protocols for the products on appropriate engine families, the agency then posts this information on their website. The protocol includes ensuring the technology performs well in the field. In June 2004, EPA agreed to accept verification done by the California Air Resources Board. Visit EPA's Diesel Retrofit site which also includes links to California's verification pages.

Information on alternative fuels is available from the US Department of Energy's Alternative Fuels Data Center.

Philadelphia Diesel Difference
A coalition of diverse partners with a mutual interest in reducing air pollution from diesel engines in the greater Philadelphia area.

Just For School Buses

EPA's Clean School Bus USA
The goal of Clean School Bus USA is to reduce both children's exposure to diesel exhaust and the amount of air pollution created by diesel school buses.