EMFAC2025 Technical Documentation#
Dedication
This EMFAC2025 Technical Documentation is dedicated to Jeff Long, whose decades of expertise and steady guidance shaped California's mobile-source emissions inventory. Jeff shared his knowledge generously and supported the EMFAC team for many years with integrity and care. Those who worked with him remember how he could recall the history of EMFAC with near-pinpoint accuracy. That institutional memory was invaluable, but what people carry with them just as much is his patience, his laughter, the way he brought a quiet warmth to the work and made even the most technical discussions feel human. His contributions strengthened the State's efforts to reduce air pollution and protect public health. His attitude, passion, and perseverance remain in the people he mentored and in the rigor reflected in this model.
EMission FACtor (EMFAC) is a model that estimates the official emissions inventories of on-road mobile sources in California. It is developed by the Mobile Source Analysis Branch in Air Quality, Science, and Planning Division at California Air Resources Board.
This web document provides EMFAC2025 Technical Documentation, a comprehensive resource that provides detailed information about the updates and changes made in EMFAC2025, including the model’s structure, methodologies, and data sources. It is intended for users seeking a comprehensive understanding of the model’s functionalities and the scientific basis behind its calculations.
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EMFAC2025 Technical Documentation is available in PDF format at the following links:
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The EMFAC Web Platform provides all the functionalities of the EMFAC2025 PC Application, utilizing pre-generated EMFAC2025 outputs for convenient access and use. Additionally, it offers access to outputs from previous versions of EMFAC, including EMFAC2021 and EMFAC2017.