AIR POLLUTANT EMISSIONS FROM TRANSPORTATION

AIR POLLUTANT EMISSIONS FROM TRANSPORTATION

Index of Key Air Pollutant Emissions from Transportation (annual data)

Index of Key Air Pollutant Emissions from Transportation (annual data)

Modal Shares of Key Air Pollutants from Transportation, 1998

Modal Shares of Key Air Pollutants from Transportation, 1998

Despite rapid growth in vehicle use over the past two decades, emissions of carbon monoxide (CO) and volatile organic compounds (VOC) have declined, and lead emissions have been almost eliminated, leading to improved air quality. There have been reductions in particulate emissions (PM) at the 10 micron classification. Only emissions of nitrogen oxides (NOX) remain above 1970 levels. (Ammonia and PM-2.5 were added to the list of regulated pollutants recently.)

With the exception of lead, onroad vehicles contribute the largest share of air pollutants among all modes.

Thousands of Short Tons of Transportation Air Emissions 1998 1999
Carbon monoxide (CO) 58,108 55,773
Oxides of nitrogen (NOx) 11,522 11,306
Volatile organic compounds (VOC)  6,829  6,681
Particulate matter < 10 microns (PM-10)    475    458
Particulate matter < 2.5 microns (PM-2.5)    387    368
Ammonia    262    270
Lead    0.5    0.5

SOURCE: U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards (OAQPS), National Emissions Inventory, available at: http://www.epa.gov/ttn/chief/index.html