USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

7-6 Highway Vehicle Air Pollutant Emissions: 1990-2012 (Table)

Tuesday, January 14, 2014

Graphic Version | Excel

Index: 1990 = 1.0

Year Carbon monoxide Nitrogen oxide Volatile organic compounds PM-10 PM-2.5 Sulfur dioxide Ammonia
1990 1.00 1.00 1.00 1.00 1.00 1.00 1.00
1991 0.95 0.99 0.94 0.96 0.95 0.93 1.09
1992 0.90 0.97 0.89 0.91 0.90 0.87 1.17
1993 0.86 0.96 0.83 0.87 0.85 0.80 1.26
1994 0.81 0.94 0.78 0.83 0.81 0.73 1.35
1995 0.76 0.93 0.72 0.79 0.76 0.67 1.43
1996 0.71 0.91 0.66 0.74 0.71 0.60 1.52
1997 0.69 0.92 0.64 0.71 0.67 0.60 1.71
1998 0.66 0.90 0.62 0.66 0.62 0.60 1.65
1999 0.62 0.87 0.61 0.62 0.57 0.60 1.72
2000 0.62 0.88 0.57 0.59 0.54 0.52 1.77
2001 0.58 0.81 0.53 0.55 0.49 0.49 1.79
2002 0.55 0.82 0.52 0.52 0.46 0.49 1.90
2003 0.51 0.77 0.50 0.51 0.45 0.42 1.91
2004 0.48 0.72 0.47 0.49 0.43 0.36 1.92
2005 0.44 0.67 0.43 0.48 0.42 0.29 1.91
2006 0.40 0.70 0.40 0.64 0.58 0.27 1.57
2007 0.36 0.72 0.36 0.80 0.75 0.25 1.23
2008 0.32 0.74 0.32 0.96 0.91 0.23 0.88
2009 0.31 0.70 0.31 0.93 0.86 0.19 0.83
2010 0.29 0.62 0.28 0.87 0.76 0.13 0.74
2011 0.26 0.52 0.25 0.80 0.64 0.07 0.63
2012 0.22 0.41 0.21 0.74 0.53 0.03 0.50

Key: PM-10 = airborne particulates of less than 10 microns; PM-2.5 = airborne particulates of less than 2.5 microns.

Notes: Data for 2008 and later years may not be comparable to previous years due to changes in methodology. Indices are calculated using data on highway vehicle emissions only. Particulate matters include PM without condensibles.

Source: U.S. Department of Transportation, Research and Innovative Technology Administration, Bureau of Transportation Statistics, National Transportation Statistics, tables 4-45 through 4-50, available at www.bts.gov as of October 2013.