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MOVES and Related Models

Mobile Source Observation Database (MSOD)

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Mobile Source Observation Database (MSOD) Overview

The Mobile Source Observation Database (MSOD) is a relational database developed by the Assessment and Standards Division (ASD) of the U.S. EPA Office of Transportation and Air Quality (formerly the Office of Mobile Sources). The database has been designed and documented using entity-relationship data modeling methods. This database requires the user to have considerable knowledge of vehicle emission testing and of relational database design and query methods to effectively use it. This database is not intended for the casual or novice user.

About the Data

The MSOD contains emission test data from in-use mobile air-pollution sources such as cars, trucks, and engines from trucks and nonroad vehicles. Data in the database was collected from 1982 to the present. While the data is not a purely "random" sample, it is intended to be representative of in-use vehicle emissions in the United States. Most of the data in the database is from EPA-sponsored test programs.

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About the Database

The database is a set of approximately 60 tables, supplemented by a larger number of small "translation" or "category" tables which define and explain the legal values for some of its individual data items. All tables are in standard database format (*.DBF) which is usable by a variety of software.

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User Guide and Reference Manual

The MSOD User Guide and Reference Manual (PDF) (192 pp, 4.3 MB, EPA-420B-08-017, November 2008, About PDF) is also in the database. The guide provides detailed information on the MSOD design and input data design. The guide also provides MSOD's input file structures which allow users to use EPA's data checking quality control software to review emission data.

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While EPA has made considerable effort to assure the validity of the data in this database, the Agency is not responsible for the validity of conclusions reached by others using this data. New records are added continuously to the data sample, though EPA cannot guarantee that all currently available, relevant data is included in the database. Because additions and changes are being made to the database, those using it regularly may wish to request an updated copy every year or so.

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Ordering Information

To order a copy of the MSOD database, or if you have questions or comments about the design, linking data fields, input structures, or quality control or quality assurance procedures, please contact Carl Fulper, phone (734) 214-4400 or email him at

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