SmogRank / World / North America / United States / Missouri

Most polluted cities in Missouri, United States

10 measured cities, this year; 10 above the WHO annual guideline. Worst: St. Louis at 8.6 µg/m³, #1,527 in the world.

Ranked by unhealthy days: the share of each city's measured days with a daily mean over 35.4 µg/m³ (US AQI 101+), Unhealthy for Sensitive Groups or worse on the US EPA's scale. Ties go to the higher average.

← Kansas City 0% 0.75%0

Low-cost sensors: consumer units, counted only in cities with no government-grade monitor; they read close to reference monitors on the whole, but 15 to 25% high in humid air. How we use them.

The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales

Estimated: cities without a monitor

Missouri cities we can't measure, with model estimates for the last 7 days. Listed by population, not ranked: estimates aren't precise enough to rank. Model estimates from the Copernicus Atmosphere Monitoring Service (CAMS), adjusted to measured cities nearby where there are any. Adjusted, a single day lands within ×1.5 of what a monitor would read about two times in three; unadjusted, it can be off by half or double. Treat them as a guide, not a measurement.

City	7-day estimate	Band
Independence	≈ 7 µg/m³	Good
Lee's Summit	≈ 6 µg/m³	Good
O'Fallon	≈ 9 µg/m³	Moderate
Saint Charles	≈ 11 µg/m³	Moderate
Blue Springs	≈ 7 µg/m³	Good
Saint Peters	≈ 9 µg/m³	Moderate
Florissant	≈ 11 µg/m³	Moderate
Joplin	≈ 5 µg/m³	Good
Chesterfield	≈ 11 µg/m³	Moderate
Jefferson City	≈ 6 µg/m³	Good
Cape Girardeau	≈ 7 µg/m³	Good
Oakville	≈ 11 µg/m³	Moderate
Wildwood	≈ 9 µg/m³	Good
Wentzville	≈ 9 µg/m³	Moderate
Ballwin	≈ 11 µg/m³	Moderate
Liberty	≈ 7 µg/m³	Good
Raytown	≈ 7 µg/m³	Good
Mehlville	≈ 11 µg/m³	Moderate
Kirkwood	≈ 11 µg/m³	Moderate
Maryland Heights	≈ 11 µg/m³	Moderate
Gladstone	≈ 7 µg/m³	Good
Hazelwood	≈ 11 µg/m³	Moderate
Grandview	≈ 6 µg/m³	Good
Webster Groves	≈ 11 µg/m³	Moderate
Sedalia	≈ 4 µg/m³	Good
Ferguson	≈ 11 µg/m³	Moderate
Nixa	≈ 4 µg/m³	Good
Affton	≈ 11 µg/m³	Moderate
Rolla	≈ 6 µg/m³	Good
Warrensburg	≈ 4 µg/m³	Good
Spanish Lake	≈ 11 µg/m³	Moderate
Old Jamestown	≈ 11 µg/m³	Moderate
Ozark	≈ 4 µg/m³	Good
Creve Coeur	≈ 11 µg/m³	Moderate
Manchester	≈ 11 µg/m³	Moderate
Farmington	≈ 6 µg/m³	Good
Hannibal	≈ 6 µg/m³	Good
Kirksville	≈ 4 µg/m³	Good
Poplar Bluff	≈ 6 µg/m³	Good
Sikeston	≈ 6 µg/m³	Good

Bad-air episodes in Missouri

• Northern United States and Canada, July 202614 to 21 July 2026, 8 days327 cities548 µg/m³peak, Superior
• Northern United States, July 20264 to 5 July 2026, 2 days10 cities85 µg/m³peak, Omaha
• North-eastern United States and Canada, 29 July to 9 August 202512 days292 cities112 µg/m³peak, Marquette
• North-eastern United States, July 20254 to 5 July 2025, 2 days68 cities74 µg/m³peak, Lincolnwood
• Northern United States and Canada, June 202510 to 14 June 2025, 5 days134 cities71 µg/m³peak, Wilmington
• Northern United States and Canada, May and June 202531 May to 9 June 2025, 10 days247 cities116 µg/m³peak, Nepean

Times when many cities around here had PM2.5 at twice their usual or more on the same days.

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SmogRank, most polluted cities in Missouri, United States, PM2.5, this year to 6 Oct 2026, 22:00 UTC, smogrank.com/us/region/missouri?w=year.

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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.

Updated 2026-10-06 22:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index.