Document Type
Article
Publication Date
2015
Organizational Units
Chemistry and Biochemistry
Abstract
Repeated, fuel specific, emission measurements in Denver (2005/2013), Los Angeles (2008/2013) and Tulsa (2005/2013) provide long-term trends in on-road reactive nitrogen emissions from three light/medium duty U.S. fleets. Reductions in oxides of nitrogen (NOx) emissions ranged from 21% in Denver (5.6 ± 1.3 to 4.4 ± 0.2 gNOx/kg of fuel) to 43% in Tulsa (4.4 ± 0.3 to 2.5 ± 0.1 gNOx/kg of fuel) since 2005 while decreases in fleet ammonia (NH3) emissions ranged from no change in Denver (0.45 ± 0.09 to 0.44 ± 0.02 gNH3/kg of fuel) since 2005 to a 28% decrease in LA (0.80 ± 0.02 to 0.58 ± 0.02 gNH3/kg of fuel) since 2008. The majority of the reduction in gasoline vehicle NOx emissions occurred prior to the full implementation of the Tier II emission standards in 2009. High in-use NOx emissions from small engine diesel passenger vehicles produced a significant contribution to the fleet means despite their small numbers. NH3 emissions decreased at a slower rate than NOx emissions due to modest NH3 emissions reduction among the newest vehicles and increased emissions from a growing number of older vehicles with active catalytic converters. In addition, the reactive nitrogen emissions from many new model year vehicles are now dominated by NH3.
Recommended Citation
Bishop, G. A.; Stedman, D. H. (2015) Reactive Nitrogen Species Emission Trends in Three Light-/Medium-Duty United States Fleets. Environ. Sci. Technol., 49(18), 11234-11240. DOI: 10.1021/acs.est.5b02392.
Copyright Statement/License for Reuse
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Publication Statement
This is an Accepted Manuscript for
Bishop, G. A.; Stedman, D. H. (2015) Reactive Nitrogen Species Emission Trends in Three Light-/Medium-Duty United States Fleets. Environ. Sci. Technol., 49(18), 11234-11240. DOI: 10.1021/acs.est.5b02392.
Copyright held by the American Chemical Society. User is responsible for all copyright compliance.