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Human Exposure and Atmospheric Sciences

EPA Unmix 6.0 Model

EPA’s Unmix Model is one of several receptor models developed by EPA scientists that provide scientific support for current ambient air quality standards and implementation of those standards by identifying and quantifying the relative contributions that various air pollution sources contribute to ambient air quality in a community or region.

Ambient air quality datasets have improved greatly due to the ability to measure more air pollution species, stratify species by particle size, and conduct shorter sampling sessions. Receptor model algorithms have improved greatly to take advantage of these higher quality datasets.

Users of EPA’s Unmix model provide files of sample species concentrations, which the model uses to calculate the number of source types, profiles, relative contributions, and a time-series of contributions. Algorithms used in the Unmix model to compute profiles and contributions have been peer reviewed by leading air quality management scientists.

The Unmix model software uses graphical user interfaces that ease data input, generation, evaluation and exporting of results. The model is free of charge, and does not require a license or other software to use.

System Requirements
Version 6.0 of EPA’s Unmix Model works on Windows 2000, Windows XP, and Windows Vista. The computer should have at least a 2.0 GHz processor and 512 MB of memory. Microsoft Excel is required for saving and exporting output. Unmix may not be entirely compatible with newer versions of Windows (e.g. Windows 7, Windows 8).

Support Materials
The EPA Unmix 6.0 Fundamentals & User Guide provides references and details on how to use Unmix.

Contact: NERL_RM_Support@epamail.epa.gov

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