Median AQI
45
Good
Iowa · County air quality · 2025
Scott County, Iowa
Median AQI 45 (Good). 59.7% of monitored days rated Good, direct from EPA Air Quality System stations.
- 45
- Median AQI
- 59.7%
- Good-air days
- 1
- Unhealthy days
- 14%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Scott County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 45 with 59.7% of 305 monitored days in the Good band, driven mainly by Ozone.
- 45
- median AQI · Good
- 59.7%
- days rated Good
- Ozone
- main pollutant
- 14%
- cleaner than US counties
1 day reached Unhealthy or worse; the worst single reading hit AQI 159.
Data updated July 2026
- Good · 182 d · 59.7%
- Moderate · 121 d · 39.7%
- USG · 1 d · 0.3%
- Unhealthy · 1 d · 0.3%
How did Scott County's air break down in 2025?
Across 305 monitored days, 182 fell in the Good band (AQI 0–50) and 1 reached Unhealthy or worse. The worst single day peaked at AQI 159 (Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 305 days monitored. Median AQI: 45 (Good).
Insights: Scott County, Iowa. EPA monitors recorded a median Air Quality Index of 45 across 305 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 182 (60%) fell in the Good band (AQI 0–50), 121 (40%) registered Moderate readings, and 1 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 74, while the worst single-day peak hit 159 (Unhealthy). Residents averaged about 17.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (140 days), PM2.5 (113 days), PM10 (51 days), CO (1 days). Across the 2020–2025 trend window, good days shifted by +9 and the median AQI moved -7 points, placing the multi-year trajectory at improving. 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: 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
59.7%
182 of 305 monitored days
-15.3pp vs 75% target
Max AQI Recorded
159
Unhealthy
Health Grade
Moderate
90th-pct AQI 74
Scott County, Good days share 59.7%
National avg
Share of monitored days at AQI 0-50 (Good band).
Scott County, Unhealthy-or-worse share 0.3%
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 305 monitored days across EPA AQI categories.
Good
182
60%
Moderate
121
40%
USG
1
0%
Unhealthy
1
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Scott County.
- Ozone · 140 days · 45.9%
- PM2.5 · 113 days · 37.0%
- PM10 · 51 days · 16.7%
- CO · 1 days · 0.3%
Health Impact Assessment
Moderate
Scott County's air quality is rated Moderate based on 59.7% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 1 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 159. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is Ozone, driving AQI on 140 of 305 monitored days.
5-Year Air Quality Trend
Air quality is improving in Scott County. Best year: 2024 (224 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 173 | 190 | 2 | 1 | 52 | 156 |
| 2021 | 145 | 219 | 1 | 0 | 53 | 102 |
| 2022 | 202 | 163 | 0 | 0 | 49 | 96 |
| 2023 | 142 | 200 | 19 | 3 | 53 | 219 |
| 2024 | 224 | 142 | 0 | 0 | 46 | 90 |
| 2025 | 182 | 121 | 1 | 1 | 45 | 159 |
How does Scott County compare?
How Scott County compares
Good-day share worse than US avg
Scott County 59.7%
Black Hawk County, Iowa 56.6%
US average 76.5%
Median AQI worse than US avg
Scott County 45
Black Hawk County, Iowa 48
US average 38
Unhealthy days / yr worse than US avg
Scott County 1
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 Scott County.
Adair County, Oklahoma
AQI 45 · 59.2% good
Allen County, Indiana
AQI 45 · 58.2% good
Atascosa County, Texas
AQI 45 · 58.0% good
Baker County, Florida
AQI 45 · 69.1% good
Carson City County, Nevada
AQI 45 · 79.3% good
Clinton County, Iowa
AQI 45 · 59.9% good
What Scott County's air means for you
On most days the air here is fine, but Ozone 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-Ozone days, the guide explains what a median of 45 means for exposure. Health guidance
- See how Scott County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Scott County with its Iowa neighbours before drawing a conclusion about the region. All of Iowa
Based on 305 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 Scott County, Iowa? ▼
Scott County has a median Air Quality Index (AQI) of 45, rated "Good." 59.7% of monitored days (182 out of 305) had good air quality in 2025.
What is the main pollutant in Scott County? ▼
The primary pollutant in Scott County is Ozone (O3), which was the main AQI driver on 140 days (46% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Scott County have? ▼
In 2025, Scott County recorded 1 unhealthy air days (1 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 159.
Is the air quality in Scott County getting better or worse? ▼
Air quality in Scott County is improving based on 5-year trends (2020-2025). Best year: 2024 with 224 good days. Worst year: 2023 with 142 good days.
What does AQI 45 mean for health? ▼
Scott County's median AQI of 45 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 Scott County compare to other counties in Iowa? ▼
Scott County has 59.7% 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 Scott County? ▼
The 90th percentile AQI for Scott County is 74, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 159 (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.