* A change in methodology for onroad mobile emission sources in 2021 led to increased emission rates for ammonia from 2021 onwards. Wildfire emissions excluded for all pollutants except for NH₃ pre-2002; PM emissions also exclude miscellaneous emissions (i.e. agricultural dust and prescribed fire emissions).
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Air pollution emission trends in the U.S. 1990-2023, by pollutant
Emissions of key air pollutants in the United States have fallen considerably over the past three decades. Emissions of sulfur dioxide (SOâ‚‚) have experienced the greatest reductions, dropping ** percent between 1990 and 2023. Annual carbon monoxide (CO) and nitrogen oxides (NOx) emissions also fell dramatically during this period.
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Environmental Protection Agency. (January 8, 2025). Percent change in air pollutant emissions in the United States from 1990 to 2023, by key pollutant [Graph]. In ÌÇÐÄÆƽâ°æ. Retrieved July 14, 2026, from /statistics/1225626/air-pollutant-emissions-reductions-us-by-type/
Environmental Protection Agency. "Percent change in air pollutant emissions in the United States from 1990 to 2023, by key pollutant." Chart. January 8, 2025. ÌÇÐÄÆƽâ°æ. Accessed July 14, 2026. /statistics/1225626/air-pollutant-emissions-reductions-us-by-type/
Environmental Protection Agency. (2025). Percent change in air pollutant emissions in the United States from 1990 to 2023, by key pollutant. ÌÇÐÄÆƽâ°æ. ÌÇÐÄÆƽâ°æ Inc.. Accessed: July 14, 2026. /statistics/1225626/air-pollutant-emissions-reductions-us-by-type/
Environmental Protection Agency. "Percent Change in Air Pollutant Emissions in The United States from 1990 to 2023, by Key Pollutant." ÌÇÐÄÆƽâ°æ, ÌÇÐÄÆƽâ°æ Inc., 8 Jan 2025, /statistics/1225626/air-pollutant-emissions-reductions-us-by-type/
Environmental Protection Agency, Percent change in air pollutant emissions in the United States from 1990 to 2023, by key pollutant ÌÇÐÄÆƽâ°æ, /statistics/1225626/air-pollutant-emissions-reductions-us-by-type/ (last visited July 14, 2026)
Percent change in air pollutant emissions in the United States from 1990 to 2023, by key pollutant [Graph], Environmental Protection Agency, January 8, 2025. [Online]. Available: /statistics/1225626/air-pollutant-emissions-reductions-us-by-type/
