Median AQI
39
Good
Missouri · County air quality · 2025
Buchanan County, Missouri
Median AQI 39 (Good). 64.2% of monitored days rated Good, direct from EPA Air Quality System stations.
- 39
- Median AQI
- 64.2%
- Good-air days
- 1
- Unhealthy days
- 21%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Buchanan County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 39 with 64.2% of 148 monitored days in the Good band, driven mainly by PM2.5.
- 39
- median AQI · Good
- 64.2%
- days rated Good
- PM2.5
- main pollutant
- 21%
- cleaner than US counties
1 day reached Unhealthy or worse; the worst single reading hit AQI 256.
Data updated July 2026
- Good · 95 d · 64.2%
- Moderate · 52 d · 35.1%
- Very Unhealthy · 1 d · 0.7%
How did Buchanan County's air break down in 2025?
Across 148 monitored days, 95 fell in the Good band (AQI 0–50) and 1 reached Unhealthy or worse. The worst single day peaked at AQI 256 (Very Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 148 days monitored. Median AQI: 39 (Good).
Insights: Buchanan County, Missouri. EPA monitors recorded a median Air Quality Index of 39 across 148 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 95 (64%) fell in the Good band (AQI 0–50), 52 (35%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 61, while the worst single-day peak hit 256 (Very Unhealthy). Residents averaged about 19.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (127 days), PM10 (21 days). Across the 2020–2025 trend window, good days shifted by -153 and the median AQI moved -3 points, placing the multi-year trajectory at worsening. Residents and visitors experienced 1 unhealthy-or-worse days combined, periods when the EPA recommends sensitive groups limit prolonged outdoor exertion. Nearby counties show comparable readings: Andrew (84.3% good, AQI 42); Boone (89.1% good, AQI 41); Callaway (85.6% good, AQI 42); Cass (82.2% good, AQI 41); Cedar (81.8% good, AQI 40); Clay (80.1% good, AQI 42).
Air Quality Summary
Good Days
64.2%
95 of 148 monitored days
-10.8pp vs 75% target
Max AQI Recorded
256
Very Unhealthy
Health Grade
Moderate
90th-pct AQI 61
Buchanan County, Good days share 64.2%
National avg
Share of monitored days at AQI 0-50 (Good band).
Buchanan County, Unhealthy-or-worse share 0.7%
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 148 monitored days across EPA AQI categories.
Good
95
64%
Moderate
52
35%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
1
1%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Buchanan County.
- PM2.5 · 127 days · 85.8%
- PM10 · 21 days · 14.2%
Health Impact Assessment
Moderate
Buchanan County's air quality is rated Moderate based on 64.2% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.
Air quality reached unhealthy levels on 1 days in 2025 (0 Unhealthy, 1 Very Unhealthy). Sensitive groups, including people with asthma, COPD, cardiovascular conditions, children, and adults over 65, should review the daily breakdown below and follow local air-quality advisories on high-AQI days.
Sensitive group advisory
People with asthma, COPD, heart disease, children, pregnant women, and adults 65+ should follow EPA AQI alerts daily and limit outdoor exertion when AQI exceeds 100. Real-time conditions: airnow.gov.
The dominant pollutant is PM2.5, driving AQI on 127 of 148 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Buchanan County. Best year: 2020 (248 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 248 | 116 | 1 | 0 | 42 | 126 |
| 2021 | 235 | 127 | 3 | 0 | 44 | 109 |
| 2022 | 237 | 126 | 2 | 0 | 42 | 106 |
| 2023 | 196 | 165 | 2 | 0 | 48 | 129 |
| 2024 | 216 | 143 | 0 | 0 | 44 | 77 |
| 2025 | 95 | 52 | 0 | 0 | 39 | 256 |
How does Buchanan County compare?
How Buchanan County compares
Good-day share worse than US avg
Buchanan County 64.2%
Andrew County, Missouri 84.3%
US average 76.5%
Median AQI worse than US avg
Buchanan County 39
Andrew County, Missouri 42
US average 38
Unhealthy days / yr worse than US avg
Buchanan County 1
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 Buchanan County.
Ada County, Idaho
AQI 39 · 80.6% good
Aiken County, South Carolina
AQI 39 · 89.1% good
Albany County, New York
AQI 39 · 67.4% good
Alexander County, North Carolina
AQI 39 · 92.4% good
Ashland County, Wisconsin
AQI 39 · 85.6% good
Bennington County, Vermont
AQI 39 · 82.9% good
What Buchanan County's air means for you
On most days the air here is fine, but PM2.5 drives 1 unhealthy-or-worse day a year that sensitive groups should plan around.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM2.5 days, the guide explains what a median of 39 means for exposure. Health guidance
- See how Buchanan County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Buchanan County with its Missouri neighbours before drawing a conclusion about the region. All of Missouri
Based on 148 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 Buchanan County, Missouri? ▼
Buchanan County has a median Air Quality Index (AQI) of 39, rated "Good." 64.2% of monitored days (95 out of 148) had good air quality in 2025.
What is the main pollutant in Buchanan County? ▼
The primary pollutant in Buchanan County is Fine Particles (PM2.5), which was the main AQI driver on 127 days (86% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Buchanan County have? ▼
In 2025, Buchanan County recorded 1 unhealthy air days (0 Unhealthy, 1 Very Unhealthy, 0 Hazardous). The maximum AQI reached 256.
Is the air quality in Buchanan County getting better or worse? ▼
Air quality in Buchanan County is worsening based on 5-year trends (2020-2025). Best year: 2020 with 248 good days. Worst year: 2025 with 95 good days.
What does AQI 39 mean for health? ▼
Buchanan County's median AQI of 39 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 Buchanan County compare to other counties in Missouri? ▼
Buchanan County has 64.2% good air days. Nearby counties in Missouri: Andrew (84.3% good), Boone (89.1% good), Callaway (85.6% good), Cass (82.2% good), Cedar (81.8% good), Clay (80.1% good).
What is the 90th percentile AQI in Buchanan County? ▼
The 90th percentile AQI for Buchanan County is 61, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 256 (Very Unhealthy).
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.