On-Road Vehicle Emissions Measurements with Remote Sensing Devices

This page last reviewed April 27, 2015


Remote sensing devices (RSDs) have been shown to be capable of measuring real-world vehicular emissions from a large number of vehicles. Usually in those measurements, RSDs send infrared or ultra violet beams horizontally through vehicle exhaust plumes, and measure the exhaust emissions of criteria pollutants in ratio to CO2. These ratios and the carbon content of fuels can be used to determine the emissions of pollutants per mass (kilogram) of fuel, which can be further converted to the emissions of pollutants per volume (gallon) of fuel, with the knowledge of the average fuel density. The emissions per volume of fuel results can be combined with fuel sales data to yield estimates of fuel-based emission inventories.

Since 1989, ARB has sponsored several research studies that employed RSDs to measure on-road vehicle emissions at several California locations. Those studies, carried out by Dr. Donald Stedman, Dr. Gary Bishop, and their team with the University of Denver (DU), started with CO measurement, with VOC and NO measurements added over the years. In 2008, new capabilities were added to the RSD equipment to also measure NH3, SO2, and NO2. Historical data at the same locations form emission trends for various pollutants, which can demonstrate the efficacy of ARB and U.S. national programs in reducing vehicular emissions. Data collected at different locations around the same periods of time can inform ARB of regional variation of vehicular emissions. Those studies also can benefit ARB in developing and improving emission inventories for mobile sources.



Publications for Peer-reviewed Journals

  • Gary A. Bishop et al., (2014). The Recession of 2008 and Its Impact on Light-Duty Vehicle Emissions in Three Western United States Cities. Environmental Science and Technology. Link
  • Gary A. Bishop et al., (2010). On-Road Emission Measurements of Reactive Nitrogen Compounds from Three California Cities. Environmental Science and Technology. Link
  • Stuart P. Beaton et al., (1995). On-Road Vehicle Emissions: Regulations, Costs, and Benefits. Science. Link
  • Douglas R. Lawson et al., (1990). Emissions from In-Use Motor Vehicles in Los Angeles: A Pilot Study of Remote Sensing and the Inspection and Maintenance Program. Journal of Air and Waste Management Association. Link

Conference Presentations

  • Donald H. Stedman et al., (2009). On-Road Motor Vehicle Emissions Including Ammonia, Sulfur Dioxide, and Nitrogen Dioxide. 19th CRC On-Road Vehicle Emissions Workshop, March 23-25, 2009, San Diego, CA. Poster (PDF - 952KB)

Other Related Publications

A "Fuel Efficiency Automobile Test" (FEAT) website, maintained by Dr. Donald Stedman's team with the University of Denver, includes some remote sensing studies at California locations that were funded by organizations other than ARB. It is also worth noting that remote sensing studies at California locations are only a portion of a larger literature on RSD. The FEAT website includes some remote sensing studies conducted at other U.S. locations and worldwide.