Publication Date


Document Type


Organizational Units

Chemistry and Biochemistry


Atmospheric chemistry, Emissions, Pollutants


The United States Environmental Protection Agency (EPA) computer model of mobile source emissions is used to estimate the benefits of future emissions control programs. Four input assumptions are discussed, each of which tends to overestimate the benefits of biennial testing programs. The assumptions are: each model year drives the same number of miles; high/superemitters, absent initially, increase linearly with mileage; inspection and maintenance (I/M) readings are invariant, and I/M repairs last forever. States opting for these programs should be aware that the predicted benefits may not materialize.

Copyright Statement / License for Reuse

Creative Commons Attribution-NonCommercial 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

Publication Statement

This article was originally published as Stedman, D. H. (1996) EPA Overestimates the Benefit of Biennial Inspection and Maintenance, Environ. Manager, Dec. 27- 29. Copyright held by the author. User is responsible for all copyright compliance.