The Diesel Emission Quantifier should not be used for the calculation of any emission reductions to be incorporated in a State Implementation Plan (SIP) or conformity determination, and certain other technical applications. Please do not continue using the Quantifier until you have read the important usage information.

Complete Quantifier User's Guide (PDF, 42 pages, 152K, About PDF)

Basic Information

Under the Clean Air Act, EPA protects public health and the environment by regulating air pollution from motor vehicles, engines, and the fuels used to operate them. Because there are millions of large, diesel vehicles like trucks, buses, construction equipment, and others, reducing air pollution from diesel vehicles is extremely important.

There are many ways to cut emissions from diesel vehicles, such as using better fuel types that burn cleaner, or building new vehicles that pollute less. Another way is to improve the performance of existing vehicles by "retrofitting" or adding new and improved technology that reduces pollution, improves mileage, or other ways for diesel engines (read more about the Clean Diesel Campaign).

Through grants and technical assistance, EPA sponsors numerous diesel retrofit projects around the nation that are already saving fuel and reducing pollution.

As the number and scope of retrofit projects grow around the country, the need to easily assess emission reductions from such projects and to quantify the cost-effectiveness of various technical options within those projects has also grown.

Both the Energy Policy Act of 2005, and the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) promote cost-effective clean diesel activities and are good reasons for the U.S. Environmental Protection Agency (EPA) to provide assistance with quantifying the benefits of retrofit projects.

EPA has released guidance and models to quantify the benefits of retrofit projects. However, these tools, MOBILE 6.2 and NONROAD2005 models, are aimed at a technical audience with air quality modeling experience.

There is a need for a tool that can be used by those who implement retrofit projects. EPA has built the Quantifier upon existing EPA tools and guidance and can be used by potential grantees, state and local governments, metropolitan planning organizations, and fleet owners and operators, among others. The Quantifier uses emission factors and other information from EPA’s National Mobile Inventory Model (NMIM) that include MOBILE 6.2 and NONROAD2005 models.

The Diesel Emission Quantifier should not be used for the calculation of any emission reductions to be incorporated in a State Implementation Plan (SIP) or conformity determination. If you wish to calculate emission reductions for a SIP or conformity determination, you should review the appropriate SIP and conformity guidance document and consult with your EPA Regional Office.

For long-duration idle reduction, the SIP and conformity guidance can be found in the document Guidance for Quantifying and Using Long Duration Truck Idling Emission Reductions in State Implementation Plans and Transportation Conformity (January, 2004, EPA420-B-04-001, PDF, 33 pages, 379K, About PDF). For retrofit projects, the SIP and conformity guidance can be found in the document Diesel Retrofits: Quantifying and Using Their Benefits in SIPs and Conformity (June, 2006, EPA420-B-06-005, PDF, 69 pages, 530K, About PDF).

For emission reduction strategies not covered by those guidance documents, please consult with your EPA Regional Office.

For directions on how to use the Quantifier, download the Complete Diesel Emission Quantifier User's Guide (PDF, 40 pages, 166K, About PDF) or view the Complete online (HTML) version of the Diesel Emission Quantifier User's Guide. (Note: The back button should not be used when operating the Quantifier.)

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