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Updated: Jul 4, 2026

Implementation of Portable Emissions Measurement Systems (PEMS) for the Real-driving Emissions (RDE) Regulation in Europe
Published on: December 4, 2016
A decade of on-road emissions measurements
Gary A Bishop1, Donald H Stedman
1Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, USA. gbishop@du.edu
Abstract:
A multiyear, on-road emission measurement program carried out in the cities of Chicago, Illinois; Denver, Colorado; Los Angeles (LA), California; and Phoenix, Arizona shows large, fuel-specific tailpipe emissions reductions at all of the sites for carbon monoxide (CO), hydrocarbons (HC), and nitric oxide (NO). CO emissions decreased between 56% (Denver) and 71% (Chicago), HC emissions decrease between 27% (Phoenix) and 63% (Denver), and NO emissions have dropped between 48% (West LA) and 68% (Chicago). Three observed factors common to all of the sites are that the emission reductions are occurring in vehicles of all ages, that the influence of engine load on fuel-specific emissions, especially for CO and NO, is reduced and that fleet-averaged emission deterioration is near zero for model years newer than 2001 and older than 1990. These nationwide data sets imply that the majority of these on-road emissions reductions are the result of continued improvements in function and durability of vehicle emission control systems and that inspection and maintenance and fuel reformulation programs have only played a minor role.
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