Median AQI
35
Good
Minnesota · County air quality · 2025
Carlton County, Minnesota
Median AQI 35 (Good). 92.9% of monitored days rated Good, direct from EPA Air Quality System stations.
- 35
- Median AQI
- 92.9%
- Good-air days
- 0
- Unhealthy days
- 83%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Carlton County's air is good on balance, cleaner than most US counties, a median AQI of 35 with 92.9% of 169 monitored days in the Good band, driven mainly by Ozone.
- 35
- median AQI · Good
- 92.9%
- days rated Good
- Ozone
- main pollutant
- 83%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 93.
Data updated July 2026
- Good · 157 d · 92.9%
- Moderate · 12 d · 7.1%
How did Carlton County's air break down in 2025?
Across 169 monitored days, 157 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 93 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 169 days monitored. Median AQI: 35 (Good).
Insights: Carlton County, Minnesota. EPA monitors recorded a median Air Quality Index of 35 across 169 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 157 (93%) fell in the Good band (AQI 0–50), 12 (7%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 47, while the worst single-day peak hit 93 (Moderate). Residents averaged about 27.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (116 days), PM2.5 (53 days). Across the 2020–2025 trend window, good days shifted by -190 and the median AQI moved +10 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 93, moderate but never Unhealthy. 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); Cass (94.4% good, AQI 22); Cook (100.0% good, AQI 12).
Air Quality Summary
Good Days
92.9%
157 of 169 monitored days
17.9pp vs 75% target
Max AQI Recorded
93
Moderate
Health Grade
Excellent
90th-pct AQI 47
Carlton County, Good days share 92.9%
National avg
Share of monitored days at AQI 0-50 (Good band).
Carlton 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 169 monitored days across EPA AQI categories.
Good
157
93%
Moderate
12
7%
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 Carlton County.
- Ozone · 116 days · 68.6%
- PM2.5 · 53 days · 31.4%
Health Impact Assessment
Excellent
Carlton County's air quality is rated Excellent based on 92.9% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 92.9% of monitored days in 2025, with a median AQI of 35. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 116 of 169 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Carlton County. Best year: 2022 (351 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 347 | 7 | 0 | 0 | 25 | 84 |
| 2021 | 318 | 43 | 4 | 0 | 31 | 143 |
| 2022 | 351 | 4 | 0 | 0 | 25 | 57 |
| 2023 | 266 | 91 | 4 | 1 | 38 | 156 |
| 2024 | 326 | 39 | 1 | 0 | 34 | 114 |
| 2025 | 157 | 12 | 0 | 0 | 35 | 93 |
How does Carlton County compare?
How Carlton County compares
Good-day share better than US avg
Carlton County 92.9%
Anoka County, Minnesota 82.1%
US average 76.5%
Median AQI better than US avg
Carlton County 35
Anoka County, Minnesota 38
US average 38
Unhealthy days / yr about average
Carlton County 0
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 Carlton County.
Androscoggin County, Maine
AQI 35 · 85.5% good
Asotin County, Washington
AQI 35 · 73.8% good
Benton County, Washington
AQI 35 · 88.9% good
Benzie County, Michigan
AQI 35 · 91.1% good
Brooke County, West Virginia
AQI 35 · 79.3% good
Bucks County, Pennsylvania
AQI 35 · 87.5% good
What Carlton 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 35 means for exposure. Health guidance
- See how Carlton County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Carlton County with its Minnesota neighbours before drawing a conclusion about the region. All of Minnesota
Based on 169 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 Carlton County, Minnesota? ▼
Carlton County has a median Air Quality Index (AQI) of 35, rated "Good." 92.9% of monitored days (157 out of 169) had good air quality in 2025.
What is the main pollutant in Carlton County? ▼
The primary pollutant in Carlton County is Ozone (O3), which was the main AQI driver on 116 days (69% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Carlton County have? ▼
In 2025, Carlton County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 93.
Is the air quality in Carlton County getting better or worse? ▼
Air quality in Carlton County is worsening based on 5-year trends (2020-2025). Best year: 2022 with 351 good days. Worst year: 2025 with 157 good days.
What does AQI 35 mean for health? ▼
Carlton County's median AQI of 35 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 Carlton County compare to other counties in Minnesota? ▼
Carlton County has 92.9% good air days. Nearby counties in Minnesota: Anoka (82.1% good), Becker (84.7% good), Beltrami (88.8% good), Blue Earth (82.7% good), Cass (94.4% good), Cook (100.0% good).
What is the 90th percentile AQI in Carlton County? ▼
The 90th percentile AQI for Carlton County is 47, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 93 (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.