Skip Navigation to main content U.S. Department of Energy U.S. Department of Energy Energy Efficiency and Renewable Energy
Bringing you a prosperous future where energy is clean, abundant, reliable, and affordable EERE Home
Vehicle Technologies Program
 
About the ProgramProgram AreasInformation ResourcesFinancial OpportunitiesTechnologiesDeploymentHome

Fact #319: May 10, 2004
Highway Vehicle Emissions: 1970–2001 Comparison

Although the number of highway vehicles in the United States has more than doubled from 1970 to 2001, the emissions from those vehicles actually declined during that period of time. The graph shows the percent change from 1970 to 2001 for all highway vehicle emissions of carbon monoxide (CO), nitrogen oxides (NOx), volatile organic compounds (VOCs), and particulate matter smaller than 10 microns (PM10). It also shows the percent change in the number of highway vehicles. Vehicular emission controls along with changes in fuel properties have made it possible for twice the vehicles to emit less in 2001 than the vehicles did in 1970.

Total Highway Vehicle Emissions Change from 1970 to 2001
Graph showing the percent change of highway vehicle emissions from 1970 to 2001.

Supporting Information

Highway Vehicle Emissions, 1970 and 2001
  1970
(Thousand Short Tons)		 2001
(Thousand Short Tons)		 Percent
Change
Carbon monoxide 163,231 74,825 -54.2%
Nitrogen oxides 12,624 8,249 -34.7%
Volatile organic Compounds 16,910 4,874 -71.2%
Particulate matter 480 218 -54.6%
       
Number of highway vehicles 111,242,295 235,331,382 111.5%

Source: U.S. Environmental Protection Agency, National Emission Inventory (NEI) Air Pollutant Emission Trends.
Federal Highway Administration, Highway Statistics, Table VM-1.
Federal Highway Administration, Highway Statistics Summary to 1995, Table VM201a.

Return to 2004 Facts of the Week