On-Road Evaluation of an Automobile Emission Test Program

Publication Date

1997

Document Type

Article

Organizational Units

College of Natural Science and Mathematics, Chemistry and Biochemistry

Keywords

Atmospheric chemistry, Emissions, Pollutants, Inspection and Maintenance

Abstract

In January 1995, the State of Colorado superseded an annual decentralized idle test program with an EPA recom mended biennial centralized IM240 test program in the six-county metro Denver area. Odd model year 1982−1994 vehicles and any vehicles that entered the counties or changed ownership required testing in 1995. Even model year vehicles were to be tested in 1996. Five days of on-road remote sensing exhaust measurements in winter 1995−1996 provided 26 255 identified, unique, gasoline-fueled vehicle emission measurements to independently evaluate the marginal benefit of the 1-year-old inspection and maintenance program. Eligible, untested even model years form the control group to compare to tested odd model years. Benefits were significant for CO (between 4% ± 2% and 7% ± 2%). Benefits for HC and NO were not detectable. Error bars are obtained using each day as an independent analysis. An effect not observable by other methods shows odd model year cars outside the program jurisdiction with significantly higher average CO emissions than their even model year peers, possibly indicating out migration of registration for failing odd model year vehicles, thus avoiding the new emission test.

Copyright Statement / License for Reuse

All Rights Reserved
All Rights Reserved.

Rights Holder

American Chemical Society

Provenance

Received from author

Language

English (eng)

Extent

5 pgs

Publication Statement

Copyright is held by the American Chemical Society. User is responsible for all copyright compliance.

Publication Title

Environmental Science & Technology

Volume

31

First Page

927

Last Page

931

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