The most ozone-polluted city in the United States between 2020 and 2022 was Los Angeles-Long Beach in California, with an average of 175 days with high ozone. Seven of the 10 most ozone-polluted cities in the U.S. were in California during this period. Ground-level ozone is formed in the atmosphere when nitrogen oxides (NOx) and volatile organic compounds (VOC) react with each other in sunlight and hot temperatures.
Cities and areas with the highest average days with unhealthy ozone pollution levels in the United States between 2020 and 2022
(in weighted average days)
The majority of U.S. counties don’t have monitors — which means that many communities, especially rural ones, don’t have official monitored information on their air quality. Please note that the population figures in this statistic are only for those places that collect air pollution data, and do not reflect the entire population of these groups in the U.S.
The 2020, 2021, and 2022 AQS hourly ozone data were used to calculate the daily 8-hour maximum concentration for each ozone-monitoring site. The highest 8-hour daily maximum concentration in each county for 2020, 2021, and 2022, based on EPA-defined ozone season, was identified. The current National Ambient Air Quality Standard for ozone is 70 parts per billion (ppb) measured over eight hours.
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American Lung Association. (April 16, 2024). Cities and areas with the highest average days with unhealthy ozone pollution levels in the United States between 2020 and 2022 (in weighted average days) [Graph]. In Statista. Retrieved November 23, 2024, from https://www.statista.com/statistics/1358136/most-polluted-cities-in-the-us-by-ozone/
American Lung Association. "Cities and areas with the highest average days with unhealthy ozone pollution levels in the United States between 2020 and 2022 (in weighted average days)." Chart. April 16, 2024. Statista. Accessed November 23, 2024. https://www.statista.com/statistics/1358136/most-polluted-cities-in-the-us-by-ozone/
American Lung Association. (2024). Cities and areas with the highest average days with unhealthy ozone pollution levels in the United States between 2020 and 2022 (in weighted average days). Statista. Statista Inc.. Accessed: November 23, 2024. https://www.statista.com/statistics/1358136/most-polluted-cities-in-the-us-by-ozone/
American Lung Association. "Cities and Areas with The Highest Average Days with Unhealthy Ozone Pollution Levels in The United States between 2020 and 2022 (in Weighted Average Days)." Statista, Statista Inc., 16 Apr 2024, https://www.statista.com/statistics/1358136/most-polluted-cities-in-the-us-by-ozone/
American Lung Association, Cities and areas with the highest average days with unhealthy ozone pollution levels in the United States between 2020 and 2022 (in weighted average days) Statista, https://www.statista.com/statistics/1358136/most-polluted-cities-in-the-us-by-ozone/ (last visited November 23, 2024)
Cities and areas with the highest average days with unhealthy ozone pollution levels in the United States between 2020 and 2022 (in weighted average days) [Graph], American Lung Association, April 16, 2024. [Online]. Available: https://www.statista.com/statistics/1358136/most-polluted-cities-in-the-us-by-ozone/
