SmogRank / World / North America / United States / Missouri

Most polluted cities in Missouri, United States

10 measured cities, last 30 days; 0 above the WHO 24-hour guideline. Worst: St. Louis at 7.9 µg/m³, #1,001 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.

← St. Louis 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.

Use this board

SmogRank, most polluted cities in Missouri, United States, PM2.5, last 30 days to 6 Oct 2026, 22:00 UTC, smogrank.com/us/region/missouri?w=30d.

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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.