New ‘State of the Air’ Report Finds St. Louis Metro Area Residents Are Breathing Some of the Most Polluted Air in the Country

The air quality in Greater St. Louis has worsened according to the American Lung Association’s 2025 “State of the Air” report, released today. Residents are being exposed to more unhealthy ozone smog and particle pollution the report finds. The St. Louis Metro Area ranks as 21st worst in the nation for ozone pollution with 10.5 unhealthy days per year and received an F grade. The metro area also received a D grade for particle pollution and is ranked 88th worst in the nation with 2.2 unhealthy days per year.

The report also found that nearly half of the U.S. population, 156 million people, live in areas with unhealthy levels of air pollution. Researchers add extreme heat and wildfires contributed to the worsening air quality across much of the country.

The Lung Association’s 26th annual “State of the Air” report grades exposure to unhealthy levels of ozone air pollution and particle pollution over a three-year period (2021-2023). The report looks at the latest quality-assured air quality data from 2021-2023. Findings for the St. Louis metro area include:

• Ground-level Ozone Pollution in the St. Louis-St. Charles-Farmington, MO-IL metro area: 
  • National Ranking: 21st worst out of 228 (30th worst in 2024 report)
  • Number of Unhealthy Days Per Year: 10.5 days per year (6 days per year in 2024 report)
  • Grade: F, Madison County, IL worst in metro area (F in 2024 report)
• Particle Pollution in the St. Louis-St. Charles-Farmington, MO-IL metro area:
  • National Ranking: 88th worst out of 223 (51st worst in 2024 report)
  • Number of Unhealthy Days Per Year: 2.2 days per year (2.2 days per year in 2024 report)
  • Grade: D, St. Louis County, MO worst in metro area (D in 2024 report)
• Year-Round Average Level of Particle Pollution in the St. Louis-St. Charles-Farmington, MO-IL metro area:
  • National Ranking:17th worst in the nation (33rd worst in 2024 report)
  • Grade: Failing grade, pollution levels above the federal standard

Ozone smog and particle pollution are widespread and can impact anyone’s health. Both pollutants can cause premature death and other serious health effects such as asthma attacks, heart attacks and strokes, preterm births and impaired cognitive functioning later in life. Particle pollution can also cause lung cancer.

“Unfortunately, too many people in the Greater St. Louis area are living with unhealthy levels of ozone and particle pollution. This air pollution is a threat to human health at every stage of life – from increasing the risk of premature birth and low birth weight babies to causing or worsening lung disease,” said Laura Turner, Advocacy Director for the American Lung Association. “We urge Missouri policymakers to take action to improve our air quality, including prioritizing placement of air quality monitors in the 95 counties without them, and we are calling on everyone to support the incredibly important work of the U.S. Environmental Protection Agency (EPA).”

On a national level, the “State of the Air” report found that 156 million people in the U.S. (46%) live in an area that received a failing grade for at least one measure of air pollution. 42.5 million people live in areas with failing grades for all three measures. The report also found that a person of color in the U.S. is more than twice as likely as a white individual to live in a community with a failing grade on all three pollution measures. Notably, Hispanic individuals are nearly three times as likely as white individuals to live in a community with three failing grades.

In Missouri, there are far fewer monitoring stations than are needed to provide a complete picture of real-time air quality for all localities. Only nineteen of the 114 counties in Missouri have monitors, which means that most Missouri communities, especially rural ones, do not have official monitored information on their air quality. Some rural communities must rely on air quality data from monitors that are hundreds of miles away. However, the lack of monitoring does not necessarily mean the absence of pollution. Rural communities often face pollution from agriculture, mining and industry, yet lack adequate monitoring systems. It is essential to address gaps in official monitoring to ensure communities can access comprehensive air quality data, which will support efforts to clean up pollution and protect public health.

To address these gaps, Missouri can:

• Support research programs to gather data and justify future monitoring stations.
• Use satellite technology to enhance cleanup plans with a focus on public health in vulnerable communities.
• Integrate supplemental data into alert systems for better public health protection.

The Lung Association is calling on everyone to support the U.S. Environmental Protection Agency. The EPA is essential to protecting people’s health from ozone and particle pollution. Join the American Lung Association in advocating to protect EPA’s expert staff and lifesaving programs. See the full report results and take action at Lung.org/sota.

The “State of the Air” report relies on data from air quality monitors managed by state, local and Tribal air pollution control authorities in counties across the U.S. The rankings are based on the worst county in the area’s average number of unhealthy days.

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