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Nitrogen Oxides

1999 National Emissions by Source: Nitrogen Oxides

Nitrogen oxides form when fuel burns at high temperatures, such as in motor vehicle engines. Mobile sources are responsible for more than half of all nitrogen oxide emissions in the United States. Both on-road and nonroad mobile sources are major nitrogen oxide polluters

Click on a mobile source category for detailed information.

General information about other (not mobile) sources can be found at www.epa.gov/air/data/netdb.html and at www.epa.gov/air/urbanair/6poll.html

View the entire 1999 Trends Report for detailed information on hydrocarbon emissions by various sources.

Nitrogen oxides can travel long distances, causing a variety of health and environmental problems in locations far from their emissions source. These problems include ozone and smog, which are created in the atmosphere from nitrogen oxides, hydrocarbons, and sunlight. On smoggy days, you might notice difficulty breathing or trouble seeing objects in the distance. Nitrogen oxide emissions also contribute to the formation of particulate matter through chemical reactions in the atmosphere.

Learn more about nitrogen oxides and ground-level ozone, the major component of smog. Also, find out about nitrogen oxide levels where you live.

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1999 National Emissions by Source: Nitrogen Oxides
On-Road Mobile Sources

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1999 National Emissions by Source: Nitrogen Oxides
Nonroad Mobile Sources

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This page is maintained by EPA's Office of Transportation and Air Quality (OTAQ).
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