The Diesel Emissions Quantifier (DEQ)

• Provides an interactive, web-based tool for users with little or no modeling experience.
• Evaluates clean diesel projects and upgrade options for medium-heavy and heavy-heavy duty diesel engines.
• Estimates baseline emissions, reduced emissions, cost effectiveness for NOx, PM_2.5, HC, CO and CO₂, and PM-related health benefits.
• Cannot provide estimates for Category 3 marine engines.
• May not be used for State Implementation Plans (SIPs) and Conformity. Consult your EPA Regional Office or SIP and Conformity guidance documents.

Helpline and Resources

DEQ Helpline: DEQhelp@epa.gov

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.

• User Guide for the Diesel Emissions Quantifier (DEQ) (PDF)(21 pp, 825 K, July 15, 2021)
• DEQ Release Notes v. 6.0-9.1 (PDF)(8 pp, 238 K, May 2, 2022)
• Electrified Parking Spaces Facility: Emission Reduction Calculation (PDF)(1 pg, 456 K, May 2020)
• Diesel Emissions Quantifier Default Values (PDF)(2 pp, 200 K, April 2017)
• Locomotive Idling Guidance
• Shore Power Technology Assessment at U.S. Ports
• Diesel Emissions Quantifier Health Benefits Methodology (PDF)(46 pp, 1 MB, August 11, 2010, EPA-420-B-10-034)

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