In 2023, there were 822 unhealthy days for ozone and fine particle pollution in the United States. Although this was an increase of more than 220 days from the previous year, the number of unhealthy air days in the U.S. has shown long-term improvement over the past two decades. In the first years of the 2000s, the number of days reaching unhealthy for sensitive groups or above the AQI was typically more than 2,000.
Number of unhealthy air quality days in the United States from 2000 to 2023
Number of days reaching unhealthy for sensitive groups level or above on the Air Quality Index (AQI) based on 35 major U.S. cities for ozone and PM2.5 combined.
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Environmental Protection Agency. (July 12, 2024). Number of unhealthy air quality days in the United States from 2000 to 2023 [Graph]. In Statista. Retrieved April 21, 2025, from https://www.statista.com/statistics/889466/unhealthy-air-pollution-days-us/
Environmental Protection Agency. "Number of unhealthy air quality days in the United States from 2000 to 2023." Chart. July 12, 2024. Statista. Accessed April 21, 2025. https://www.statista.com/statistics/889466/unhealthy-air-pollution-days-us/
Environmental Protection Agency. (2024). Number of unhealthy air quality days in the United States from 2000 to 2023. Statista. Statista Inc.. Accessed: April 21, 2025. https://www.statista.com/statistics/889466/unhealthy-air-pollution-days-us/
Environmental Protection Agency. "Number of Unhealthy Air Quality Days in The United States from 2000 to 2023." Statista, Statista Inc., 12 Jul 2024, https://www.statista.com/statistics/889466/unhealthy-air-pollution-days-us/
Environmental Protection Agency, Number of unhealthy air quality days in the United States from 2000 to 2023 Statista, https://www.statista.com/statistics/889466/unhealthy-air-pollution-days-us/ (last visited April 21, 2025)
Number of unhealthy air quality days in the United States from 2000 to 2023 [Graph], Environmental Protection Agency, July 12, 2024. [Online]. Available: https://www.statista.com/statistics/889466/unhealthy-air-pollution-days-us/
