Median AQI
39
Good
Iowa · County air quality · 2025
Woodbury County, Iowa
Median AQI 39 (Good). 80.8% of monitored days rated Good, direct from EPA Air Quality System stations.
- 39
- Median AQI
- 80.8%
- Good-air days
- 0
- Unhealthy days
- 54%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Woodbury County's air is good on balance, cleaner than the median US county, a median AQI of 39 with 80.8% of 265 monitored days in the Good band, driven mainly by Ozone.
- 39
- median AQI · Good
- 80.8%
- days rated Good
- Ozone
- main pollutant
- 54%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 122.
Data updated July 2026
- Good · 214 d · 80.8%
- Moderate · 48 d · 18.1%
- USG · 3 d · 1.1%
How did Woodbury County's air break down in 2025?
Across 265 monitored days, 214 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 122 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 265 days monitored. Median AQI: 39 (Good).
Insights: Woodbury County, Iowa. EPA monitors recorded a median Air Quality Index of 39 across 265 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 214 (81%) fell in the Good band (AQI 0–50), 48 (18%) registered Moderate readings, and 3 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 61, while the worst single-day peak hit 122 (USG). Residents averaged about 24.2 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (213 days), PM2.5 (52 days). Across the 2020–2025 trend window, good days shifted by +122 and the median AQI moved +0 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 122, usg but never Unhealthy. Nearby counties show comparable readings: Black Hawk (56.6% good, AQI 48); Bremer (87.1% good, AQI 38); Clinton (59.9% good, AQI 45); Harrison (83.0% good, AQI 39); Johnson (71.0% good, AQI 36); Linn (61.2% good, AQI 44).
Air Quality Summary
Good Days
80.8%
214 of 265 monitored days
5.8pp vs 75% target
Max AQI Recorded
122
USG
Health Grade
Good
90th-pct AQI 61
Woodbury County, Good days share 80.8%
National avg
Share of monitored days at AQI 0-50 (Good band).
Woodbury 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 265 monitored days across EPA AQI categories.
Good
214
81%
Moderate
48
18%
USG
3
1%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Woodbury County.
- Ozone · 213 days · 80.4%
- PM2.5 · 52 days · 19.6%
Health Impact Assessment
Good
Woodbury County's air quality is rated Good based on 80.8% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 80.8% of monitored days in 2025, with a median AQI of 39. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 213 of 265 monitored days.
5-Year Air Quality Trend
Air quality is improving in Woodbury County. Best year: 2024 (224 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 92 | 30 | 0 | 0 | 39 | 81 |
| 2021 | 79 | 35 | 0 | 1 | 42 | 168 |
| 2022 | 91 | 22 | 0 | 0 | 36 | 76 |
| 2023 | 71 | 45 | 0 | 2 | 43 | 169 |
| 2024 | 224 | 60 | 0 | 0 | 43 | 93 |
| 2025 | 214 | 48 | 3 | 0 | 39 | 122 |
How does Woodbury County compare?
How Woodbury County compares
Good-day share better than US avg
Woodbury County 80.8%
Black Hawk County, Iowa 56.6%
US average 76.5%
Median AQI worse than US avg
Woodbury County 39
Black Hawk County, Iowa 48
US average 38
Unhealthy days / yr about average
Woodbury County 0
Black Hawk County, Iowa 1
US average 0
Other Counties in Iowa
Air quality comparison for nearby counties in Iowa.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Woodbury 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 Woodbury 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 39 means for exposure. Health guidance
- See how Woodbury County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Woodbury County with its Iowa neighbours before drawing a conclusion about the region. All of Iowa
Based on 265 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 Woodbury County, Iowa? ▼
Woodbury County has a median Air Quality Index (AQI) of 39, rated "Good." 80.8% of monitored days (214 out of 265) had good air quality in 2025.
What is the main pollutant in Woodbury County? ▼
The primary pollutant in Woodbury County is Ozone (O3), which was the main AQI driver on 213 days (80% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Woodbury County have? ▼
In 2025, Woodbury County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 122.
Is the air quality in Woodbury County getting better or worse? ▼
Air quality in Woodbury County is improving based on 5-year trends (2020-2025). Best year: 2024 with 224 good days. Worst year: 2023 with 71 good days.
What does AQI 39 mean for health? ▼
Woodbury 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 Woodbury County compare to other counties in Iowa? ▼
Woodbury County has 80.8% good air days. Nearby counties in Iowa: Black Hawk (56.6% good), Bremer (87.1% good), Clinton (59.9% good), Harrison (83.0% good), Johnson (71.0% good), Linn (61.2% good).
What is the 90th percentile AQI in Woodbury County? ▼
The 90th percentile AQI for Woodbury County is 61, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 122 (USG).
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.