The United States emitted approximately 6.8 million tons of nitrogen oxide (NOx) in 2023 – without considering wildfire emissions. This was a decrease of roughly 5.8 percent from the previous year, and 73 percent compared to 1990 levels.
What are nitrogen oxides?
Nitrogen oxides are a group of highly reactive gases consisting of nitrogen dioxide, nitric oxides, and other oxides containing nitrogen. These gases are produced naturally or from fuel combustion processes. NOx is responsible for smog, as well as particle pollution when they react with ammonia and other compounds. Ozone is also formed when NOx gases react with volatile organic compounds (VOC).
Sources of NOx
NOx pollution is produced by several sources, including power plants, domestic combustion, and manufacturing processes. However, transportation is the main source of NOx pollution. In 2023, road vehicles accounted for nearly one-quarter of NOx emissions in the United States.
Annual nitrogen oxides (NOx) emissions in the United States from 1970 to 2023
(in 1,000 tons)
The source used 2002 and 2005 MOVES data to update 2002-2007 figures. The change in model resulted in noticeable changes in highway emissions from 2001 to 2002 for various pollutants.
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Environmental Protection Agency. (February 9, 2024). Annual nitrogen oxides (NOx) emissions in the United States from 1970 to 2023 (in 1,000 tons) [Graph]. In Statista. Retrieved December 30, 2024, from https://www.statista.com/statistics/501284/volume-of-nitrogen-oxides-emissions-us/
Environmental Protection Agency. "Annual nitrogen oxides (NOx) emissions in the United States from 1970 to 2023 (in 1,000 tons)." Chart. February 9, 2024. Statista. Accessed December 30, 2024. https://www.statista.com/statistics/501284/volume-of-nitrogen-oxides-emissions-us/
Environmental Protection Agency. (2024). Annual nitrogen oxides (NOx) emissions in the United States from 1970 to 2023 (in 1,000 tons). Statista. Statista Inc.. Accessed: December 30, 2024. https://www.statista.com/statistics/501284/volume-of-nitrogen-oxides-emissions-us/
Environmental Protection Agency. "Annual Nitrogen Oxides (Nox) Emissions in The United States from 1970 to 2023 (in 1,000 Tons)." Statista, Statista Inc., 9 Feb 2024, https://www.statista.com/statistics/501284/volume-of-nitrogen-oxides-emissions-us/
Environmental Protection Agency, Annual nitrogen oxides (NOx) emissions in the United States from 1970 to 2023 (in 1,000 tons) Statista, https://www.statista.com/statistics/501284/volume-of-nitrogen-oxides-emissions-us/ (last visited December 30, 2024)
Annual nitrogen oxides (NOx) emissions in the United States from 1970 to 2023 (in 1,000 tons) [Graph], Environmental Protection Agency, February 9, 2024. [Online]. Available: https://www.statista.com/statistics/501284/volume-of-nitrogen-oxides-emissions-us/
