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Chemistry and Biochemistry


Atmospheric chemistry, Emissions, Pollutants


As part of the 2010 Van Nuys tunnel study, researchers from the University of Denver measured on-road fuel-specific light-duty vehicle emissions from nearly 13,000 vehicles on Sherman Way (0.4 miles west of the tunnel) in Van Nuys, CA with its multi-species FEAT remote sensor a week ahead of the tunnel measurements. The remote sensing mean gram per kilogram carbon monoxide (CO), hydrocarbons (HC), and oxides of nitrogen (NOx) measurements are 8.9% lower, 41%, and 24% higher than the tunnel measurements respectively. The remote sensing CO/NOx and HC/NOx mass ratios are 28% lower and 20% higher than the comparable tunnel ratios. Comparisons with the historical tunnel measurements show large reductions in CO, HC and NOx over the past 23 years, but little change in the HC/NOx mass ratio since 1995. The fleet CO and HC emissions are increasingly dominated by a few gross emitters with more than a third of the total emissions being contributed by less than 1% of the fleet. An example of this is a 1995 vehicle measured 3 times with an average HC emission of 419g/kg fuel (2-stroke snowmobiles average 475g/kg fuel) responsible for 4% of the total HC emissions. The 2008 economic downturn dramatically reduced the number of new vehicles entering the fleet, leading to an age increase (>1 model year) of the Sherman Way fleet which has increased the fleet’s ammonia (NH3) emissions. The mean NH3 levels appear little changed from previous measurements collected in the Van Nuys tunnel in 1993. Comparisons between weekdays and weekend data show few fleet differences although the fraction of light-duty diesel vehicles decreased from the weekday (1.7%) to Saturday (1.2%) and Sunday (0.6%).

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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 is an Accepted Manuscript for the article

Bishop, G. A.; Schuchmann, B. G.; Stedman, D. H.; Lawson, D. R. (2012) Multi-species Remote Sensing of Vehicle Emissions on Sherman Way in Van Nuys California, J. Air & Waste Manage. Assoc., 62:10, 1115-1121. DOI: 10.1080/10962247.2012.699015.

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Gary A. Bishop, Brent G. Schuchmann, Donald H. Stedman, Douglas R. Lawson


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English (eng)


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