EPA Confirms St. Louis, Missouri Air Meets Federal Ozone Standards
Official: Air Plan Approval; Missouri; Clean Data Determination for the 2015 8-Hour Ozone Standard for the Missouri Portion of the St. Louis Nonattainment Area
Reading: The EPA approves Missouri's attainment of existing 2015 ozone standards and suspends further planning obligations, maintaining the current air quality framework without tightening or weakening it.
The determination was based partly on exceptional weather events that the EPA agreed to exclude from the calculation.
In clear language
The EPA has determined that the Missouri side of the St. Louis area has met federal air quality standards for ozone pollution based on 2023–2025 monitoring data. This means Missouri can suspend certain air quality planning requirements as long as the area continues to meet these standards. The determination was based partly on exceptional weather events that the EPA agreed to exclude from the calculation.
How does this affect you?
Pick the type of resident or organization you most identify with — we'll generate a plain-language breakdown of what changes for you and what you can do about it.
Who does this affect?
- Residents in the Missouri portion of the St. Louis metropolitan area (who benefit from confirmed cleaner air)
- The Missouri Department of Natural Resources (which no longer must submit certain air quality improvement plans)
- Businesses and industries in Missouri's St. Louis area (which face fewer new regulatory requirements for now)
What can you do?
- Monitor local air quality reports to verify the area continues to meet standards
- Support or engage with regional air quality initiatives to help maintain this achievement
Timeline
- Effective: 2026-09-14
- Effective: 2026-09-14
- Effective: 2026-09-14
- Effective: 2026-09-14
- Effective: 2026-09-14
- Effective: 2026-09-14
- Effective: 2026-09-14
- Effective: 2026-09-14
- Effective: 2026-09-14
- Effective: 2026-09-14
- Effective: 2026-09-14
- Effective: 2026-09-14
- Effective: 2026-09-14
- Effective: 2026-09-14
- Effective: 2026-09-14
- November 3, 2025 — Missouri submitted clean data determination request
- January 27, 2026 — EPA concurred on exceptional events
- September 14, 2026 — This rule becomes effective
No New Jersey official has a verified action on this policy yet.
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