REMOTE-SENSING MEASUREMENT OF REAL WORLD VEHICLE HIGH-EXHAUST EMITTERS

CRC Project No. E-23

Leaders:    M. Natarajan
                  S. H. Cadle

Scope and Objective

The objectives of this project were to follow vehicle conditions and emissions using remote-sensing measurements of on-road vehicles at selected sites to identify trends over a multi-year period and to use the information to estimate high-exhaust emitter populations.

Current Status and Future Program

Investigators have used remote sensing of on-road emissions to find the fraction of vehicles that are high hydrocarbon (HC) and carbon monoxide (CO) emitters, and have shown that a small fraction of on-road cars contribute most of the mobile emissions. Until the start of this project, there was little information from one site over a period of years to examine trends.  CRC was interested in long-term monitoring at several sites to examine the influence of new technology, use of enhanced Inspection/Maintenance (I/M) programs, and the use of on-board diagnostic systems.
CRC contracted with the University of Denver (DU) to observe sites over a period of several years where CO, HC, and oxides of nitrogen (NOx) emissions were measured.  CRC also arranged for cooperative efforts with states and other agencies.   The plan called for collecting information on about 20,000 vehicles each year at each site.  Later, the frequency of measurements was changed to every two years.  Investigators made measurements during the same time of year at the selected sites. EPA supplied data collected in Raleigh/Durham, NC.  Georgia Institute of Technology supplied data from Atlanta and other locations in Georgia.  CRC established a five-year phased contract to collect data in Los Angeles, Phoenix, Denver, and Chicago. Final Reports for E-23-4 (“On-Road Remote Sensing of Automobile Emissions”) have been completed in the Chicago Area: Years 1-7, Los Angeles-Riverside: Years 1-4, Los Angeles-La Brea Years 1-4, Phoenix Area: Years 1-6, and Denver Area: Years 1-5.  The data collection effort in an EPA addition to E-23 was completed for Omaha in September 2002 and 2004 and for Tulsa in September 2003.

Consultant Dr. Robert Slott (retired from Shell) integrated and analyzed the data collected from the E-23 project.  Dr. Slott developed a data collection guidance document for consistent reporting in the program.  This document was adopted by EPA and will be used as a key component in EPA's effort to evaluate the effectiveness of I/M programs.  Dr. Slott completed a data analysis report on data collected by EPA in North Carolina.  Dr. Slott has also completed several interim reports for use by the Real World Vehicle Emissions and Emissions Modeling Group summarizing data from the Georgia remote sensing program and approaches for making city-to-city comparisons.

Dr. Slott prepared an interim program report, which provided a comprehensive overview of progress in the E-23 program in 2003.  This report is posted on the CRC website, as are the several site reports.  EPA added the non-I/M city study (Omaha, NE & Tulsa, OK) to the E-23 project in 2002 through direct funding to CRC via a competitive solicitation. A journal article summarizing some results from the E-23 program was published in Environmental Science & Technology (2003)37, 5097-5101.  Dr. Slott’s report, “Analysis of Remote Sensing Data to Determine Deterioration Rates for OBDII Equipped Vehicles,” was issued September 2006 and is posted on the CRC website.

Data collection has been completed. Dr. Robert Slott’s program summary Final Report was released in early 2008.

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