Which county in Missouri has the best air quality?

Based on 2024 EPA AQS data, Taney County had the best air quality in Missouri with a median AQI of 26 and 104 good-air days.

2024 monitoring year Public dataset EPA AQS

Missouri Air Quality Rankings

Compiled by PlainEnviro Editorial, Environmental Data Editorial Team · July 13, 2026

County-level AQI rollup using EPA Air Quality System monitor records. Refreshed as new EPA AQS data lands.

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County-by-county air quality data for Missouri based on EPA AQS annual AQI readings. Data covers 21 monitored counties for 2024.

Missouri (2024): 21 counties monitored. State average median AQI: 41 (national average: 38.8). 79% of monitored days rated "Good." Most unhealthy air: St Louis (city) County (1 days above AQI 100).

Missouri air quality on this page is drawn from the EPA Air Quality System (AQS), which aggregates daily readings from federal, state, tribal, and local monitors into annual summaries per county. The current dataset covers 21 Missouri counties with at least ten days of valid AQI readings in 2024, out of the state's total monitored counties.

The state-average median AQI across those counties is 41, compared with a national average of 38.8 in the same reporting period. On average, 79% of monitored days fell into the "Good" AQI bucket (0–50). The heaviest burden of unhealthy days lands on St Louis (city) County (1 day above AQI 100), while Taney County records the cleanest air with a median AQI of 26.

AQI values translate ambient concentrations of pollutants (ozone, PM2.5, PM10, NO₂, SO₂, CO) onto a single 0–500 scale with six health-based bands. A low median AQI reflects typical daily conditions; peak values matter separately because short-term exposure drives most acute health effects. Counties without monitors are not "clean" - they are simply unmeasured by EPA AQS. For site-specific exposure guidance, check AirNow.gov alongside the county detail links below.

Counties with Data

State Avg Median AQI

National Avg Median AQI

38.8

Avg Good Days %

79%

Which Missouri counties have the worst air quality?

Ranked by median AQI (higher = worse). Click a county for full environmental data.

#	County	Median AQI	Good Days	Good %	Unhealthy Days	Peak AQI
1	St Louis (city)	54	139	38%	1	156
2	Jackson	46	213	59%	0	109
3	Greene	45	227	63%	0	90
4	St Charles	44	191	73%	0	129
5	Buchanan	44	216	60%	0	77
6	St Louis	43	266	73%	0	122
7	Ste. Genevieve	43	225	91%	0	100
8	Andrew	43	223	86%	0	100
9	Lincoln	42	222	85%	0	143
10	Perry	42	214	87%	0	93
11	Cass	42	278	77%	0	107
12	Clay	41	280	78%	0	122
13	Jasper	41	289	81%	0	99
14	Clinton	41	219	85%	0	101
15	Jefferson	40	292	81%	0	105
16	Cedar	40	305	85%	0	80
17	Callaway	40	249	95%	0	77
18	Boone	39	244	94%	0	77
19	Monroe	36	350	97%	0	84
20	Stoddard	29	99	88%	0	71
21	Taney	26	104	89%	0	73

Frequently Asked Questions

What is the air quality like in Missouri?

In 2024, Missouri had an average median AQI of 41 across 21 monitored counties, with 79% of monitored days rated "Good" (AQI 0–50). The national average median AQI is 38.8.

Which county in Missouri has the worst air quality?

Based on 2024 EPA AQS data, St Louis (city) County had the most unhealthy air days in Missouri - 1 days above AQI 100, with a median AQI of 54.

Explore More

National AQI Rankings → Missouri Full Profile → Missouri Water Quality →

About This Data

Air quality data is from the EPA Air Quality System (AQS), Annual AQI by County dataset. Counties with fewer than 10 monitored days are excluded. "Unhealthy days" counts days with AQI above 100 (Unhealthy for Sensitive Groups or worse). All data is for 2024.

Source: U.S. Environmental Protection Agency, Air Quality System (AQS) U.S. Environmental Protection Agency, Air Quality System (AQS)

Read our methodology - how this data is sourced, computed, and verified.

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Data sourced from the U.S. Environmental Protection Agency (EPA). See our methodology for details. Retrieved and formatted by PlainEnviro Editorial