%0 Journal Article %K Emissions %K Carbon monoxide %K Vehicle %K Ammonia %K CO %K Heavy-duty %K Light-duty %K NH3 %K Nitrogen oxides %K NOx %K On-road %K Trends %A Andrew J Kean %A David Littlejohn %A George A Ban-Weiss %A Robert A Harley %A Thomas W Kirchstetter %A Melissa M Lunden %B Atmospheric Environment %D 2008 %N 8 %P 1565-1570 %R 10.1016/j.atmosenv.2008.09.085 %T Trends in On-Road Vehicle Emissions of Ammonia %V 43 %8 03/2009