Median AQI
42
Good
Missouri · County air quality · 2025
Callaway County, Missouri
Median AQI 42 (Good). 85.6% of monitored days rated Good, direct from EPA Air Quality System stations.
- 42
- Median AQI
- 85.6%
- Good-air days
- 0
- Unhealthy days
- 67%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Callaway County's air is good on balance, cleaner than the median US county, a median AQI of 42 with 85.6% of 104 monitored days in the Good band, driven mainly by Ozone.
- 42
- median AQI · Good
- 85.6%
- days rated Good
- Ozone
- main pollutant
- 67%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 74.
Data updated July 2026
- Good · 89 d · 85.6%
- Moderate · 15 d · 14.4%
How did Callaway County's air break down in 2025?
Across 104 monitored days, 89 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 74 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 104 days monitored. Median AQI: 42 (Good).
Insights: Callaway County, Missouri. EPA monitors recorded a median Air Quality Index of 42 across 104 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 89 (86%) fell in the Good band (AQI 0–50), 15 (14%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 54, while the worst single-day peak hit 74 (Moderate). Residents averaged about 25.7 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (104 days). Across the 2020–2025 trend window, good days shifted by -145 and the median AQI moved +7 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 74, moderate but never Unhealthy. Nearby counties show comparable readings: Andrew (84.3% good, AQI 42); Boone (89.1% good, AQI 41); Buchanan (64.2% good, AQI 39); Cass (82.2% good, AQI 41); Cedar (81.8% good, AQI 40); Clay (80.1% good, AQI 42).
Air Quality Summary
Good Days
85.6%
89 of 104 monitored days
10.6pp vs 75% target
Max AQI Recorded
74
Moderate
Health Grade
Good
90th-pct AQI 54
Callaway County, Good days share 85.6%
National avg
Share of monitored days at AQI 0-50 (Good band).
Callaway County, Unhealthy-or-worse share 0.0%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 104 monitored days across EPA AQI categories.
Good
89
86%
Moderate
15
14%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Callaway County.
- Ozone · 104 days · 100.0%
Health Impact Assessment
Good
Callaway County's air quality is rated Good based on 85.6% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 85.6% of monitored days in 2025, with a median AQI of 42. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 104 of 104 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Callaway County. Best year: 2024 (249 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 234 | 11 | 0 | 0 | 35 | 87 |
| 2021 | 229 | 16 | 0 | 0 | 39 | 80 |
| 2022 | 222 | 22 | 0 | 0 | 40 | 74 |
| 2023 | 197 | 43 | 5 | 0 | 43 | 133 |
| 2024 | 249 | 13 | 0 | 0 | 40 | 77 |
| 2025 | 89 | 15 | 0 | 0 | 42 | 74 |
How does Callaway County compare?
How Callaway County compares
Good-day share better than US avg
Callaway County 85.6%
Andrew County, Missouri 84.3%
US average 76.5%
Median AQI worse than US avg
Callaway County 42
Andrew County, Missouri 42
US average 38
Unhealthy days / yr about average
Callaway County 0
Andrew County, Missouri 0
US average 0
Other Counties in Missouri
Air quality comparison for nearby counties in Missouri.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Callaway County.
Adams County, Pennsylvania
AQI 42 · 73.8% good
Anderson County, Tennessee
AQI 42 · 91.0% good
Andrew County, Missouri
AQI 42 · 84.3% good
Armstrong County, Pennsylvania
AQI 42 · 68.1% good
Baldwin County, Alabama
AQI 42 · 72.2% good
Belmont County, Ohio
AQI 42 · 63.0% good
What Callaway County's air means for you
The air here stays in the breathable range year-round, with Ozone the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 42 means for exposure. Health guidance
- See how Callaway County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Callaway County with its Missouri neighbours before drawing a conclusion about the region. All of Missouri
Based on 104 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
More Air Quality Data
Air Quality Guides
Frequently Asked Questions
What is the air quality in Callaway County, Missouri? ▼
Callaway County has a median Air Quality Index (AQI) of 42, rated "Good." 85.6% of monitored days (89 out of 104) had good air quality in 2025.
What is the main pollutant in Callaway County? ▼
The primary pollutant in Callaway County is Ozone (O3), which was the main AQI driver on 104 days (100% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Callaway County have? ▼
In 2025, Callaway County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 74.
Is the air quality in Callaway County getting better or worse? ▼
Air quality in Callaway County is worsening based on 5-year trends (2020-2025). Best year: 2024 with 249 good days. Worst year: 2025 with 89 good days.
What does AQI 42 mean for health? ▼
Callaway County's median AQI of 42 falls in the "Good" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does Callaway County compare to other counties in Missouri? ▼
Callaway County has 85.6% good air days. Nearby counties in Missouri: Andrew (84.3% good), Boone (89.1% good), Buchanan (64.2% good), Cass (82.2% good), Cedar (81.8% good), Clay (80.1% good).
What is the 90th percentile AQI in Callaway County? ▼
The 90th percentile AQI for Callaway County is 54, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 74 (Moderate).
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer.
Every figure on PlainAir is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.