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RMSS-AWMA presents It’s the Emission Distribution that Matters, or Why Zero Emissions Vehicles may not be a Panacea for Reducing Criteria Pollutants

Please join RMSS-AWMA for their next virtual lunch meeting, where Dr. Gary Bishop of the University of Denver’s Department of Chemistry and Biochemistry, will present on “It’s the Emission Distribution that Matters, or Why Zero Emissions Vehicles may not be a Panacea for Reducing Criteria Pollutants.”

The meeting will be held online via Microsoft Teams, from 12PM-1PM, on Thursday, April 22nd.

If you plan to attend this meeting, please RSVP to Miriam Hacker (miriamhacker@aspenoutlook.com ) by 5PM on Wednesday, April 21st to receive instructions on how to attend online.


In August of 2019, the State of Colorado’s Air Quality Control Commission voted to adopt California rules requiring manufacturers to sell an increasing percentage of zero emission vehicles (ZEVs) starting in 2023. These new rules have been trumpeted by state officials and local newspapers as an important strategy in reducing ozone-forming pollutants along the Front Range.

Automobile emissions are not normally distributed but follow a gamma distribution. This results in a small fraction of the fleet being responsible for a disproportionate amount of the total. For example, in 2017 the top 1% of the Denver fleet was responsible for more than a third of the carbon monoxide and hydrocarbon emissions and a quarter of the oxides of nitrogen emissions. This means that an overwhelming majority of the fleet contributes very little to the overall inventories for the criteria pollutants. In-use data will be presented to illustrate the difficulty in significantly reducing criteria pollutants through the introduction of ZEVs.

Presenter’s Bio:

For the past 34 years in collaboration with the late Dr. Donald H. Stedman at the University of Denver, Dr. Bishop has spent his career inventing, developing, and using novel remote sensing instrumentation and techniques to collect fuel specific in-use vehicle emission measurements. This has resulted in an emissions data repository (www.feat.biochem.du.edu) that contains millions of measurements on light-duty cars and trucks collected in more than 21 countries and from more than 30 U.S. locations to date. In addition, Dr. Bishop and co-workers have used these instruments and techniques to measure heavy-duty diesel trucks, commercial aircraft in London, snowmobiles and snow coaches in Yellowstone National Park, and line-haul locomotives in Nebraska. This work has resulted in coauthoring 10 patents, more than 60 peer reviewed journal publications, and a growing list of publications by others using the emissions data collected in their research.