Median AQI
39
Good
Minnesota · County air quality · 2025
Hennepin County, Minnesota
Median AQI 39 (Good). 78.0% of monitored days rated Good, direct from EPA Air Quality System stations.
- 39
- Median AQI
- 78.0%
- Good-air days
- 1
- Unhealthy days
- 46%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Hennepin County's air is good on balance, more polluted than the median US county, a median AQI of 39 with 78.0% of 182 monitored days in the Good band, driven mainly by PM2.5.
- 39
- median AQI · Good
- 78.0%
- days rated Good
- PM2.5
- main pollutant
- 46%
- cleaner than US counties
1 day reached Unhealthy or worse; the worst single reading hit AQI 155.
Data updated July 2026
- Good · 142 d · 78.0%
- Moderate · 39 d · 21.4%
- Unhealthy · 1 d · 0.5%
How did Hennepin County's air break down in 2025?
Across 182 monitored days, 142 fell in the Good band (AQI 0–50) and 1 reached Unhealthy or worse. The worst single day peaked at AQI 155 (Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 182 days monitored. Median AQI: 39 (Good).
Insights: Hennepin County, Minnesota. EPA monitors recorded a median Air Quality Index of 39 across 182 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 142 (78%) fell in the Good band (AQI 0–50), 39 (21%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 64, while the worst single-day peak hit 155 (Unhealthy). Residents averaged about 23.4 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (88 days), Ozone (85 days), NO2 (8 days), CO (1 days). Across the 2020–2025 trend window, good days shifted by -64 and the median AQI moved -9 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: Anoka (82.1% good, AQI 38); Becker (84.7% good, AQI 38); Beltrami (88.8% good, AQI 37); Blue Earth (82.7% good, AQI 38); Carlton (92.9% good, AQI 35); Cass (94.4% good, AQI 22).
Air Quality Summary
Good Days
78.0%
142 of 182 monitored days
3.0pp vs 75% target
Max AQI Recorded
155
Unhealthy
Health Grade
Good
90th-pct AQI 64
Hennepin County, Good days share 78.0%
National avg
Share of monitored days at AQI 0-50 (Good band).
Hennepin County, Unhealthy-or-worse share 0.5%
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 182 monitored days across EPA AQI categories.
Good
142
78%
Moderate
39
21%
USG
0
0%
Unhealthy
1
1%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Hennepin County.
- PM2.5 · 88 days · 48.4%
- Ozone · 85 days · 46.7%
- NO₂ · 8 days · 4.4%
- CO · 1 days · 0.5%
Health Impact Assessment
Good
Hennepin County's air quality is rated Good based on 78.0% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 0 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 155. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is PM2.5, driving AQI on 88 of 182 monitored days.
5-Year Air Quality Trend
Air quality is improving in Hennepin County. Best year: 2022 (244 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 206 | 158 | 1 | 1 | 48 | 158 |
| 2021 | 213 | 149 | 0 | 3 | 45 | 157 |
| 2022 | 244 | 121 | 0 | 0 | 42 | 96 |
| 2023 | 173 | 175 | 14 | 3 | 52 | 187 |
| 2024 | 243 | 119 | 3 | 1 | 42 | 166 |
| 2025 | 142 | 39 | 0 | 1 | 39 | 155 |
How does Hennepin County compare?
How Hennepin County compares
Good-day share better than US avg
Hennepin County 78.0%
Anoka County, Minnesota 82.1%
US average 76.5%
Median AQI worse than US avg
Hennepin County 39
Anoka County, Minnesota 38
US average 38
Unhealthy days / yr worse than US avg
Hennepin County 1
Anoka County, Minnesota 1
US average 0
Other Counties in Minnesota
Air quality comparison for nearby counties in Minnesota.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Hennepin 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 Hennepin 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 Hennepin County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Hennepin County with its Minnesota neighbours before drawing a conclusion about the region. All of Minnesota
Based on 182 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 Hennepin County, Minnesota? ▼
Hennepin County has a median Air Quality Index (AQI) of 39, rated "Good." 78.0% of monitored days (142 out of 182) had good air quality in 2025.
What is the main pollutant in Hennepin County? ▼
The primary pollutant in Hennepin County is Fine Particles (PM2.5), which was the main AQI driver on 88 days (48% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Hennepin County have? ▼
In 2025, Hennepin County recorded 1 unhealthy air days (1 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 155.
Is the air quality in Hennepin County getting better or worse? ▼
Air quality in Hennepin County is improving based on 5-year trends (2020-2025). Best year: 2022 with 244 good days. Worst year: 2025 with 142 good days.
What does AQI 39 mean for health? ▼
Hennepin 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 Hennepin County compare to other counties in Minnesota? ▼
Hennepin County has 78.0% good air days. Nearby counties in Minnesota: Anoka (82.1% good), Becker (84.7% good), Beltrami (88.8% good), Blue Earth (82.7% good), Carlton (92.9% good), Cass (94.4% good).
What is the 90th percentile AQI in Hennepin County? ▼
The 90th percentile AQI for Hennepin County is 64, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 155 (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.