Median AQI
33
Good
Minnesota · County air quality · 2025
Carlton County, Minnesota
Median AQI 33 (Good). 82.8% of monitored days rated Good, direct from EPA Air Quality System stations.
- 33
- Median AQI
- 82.8%
- Good-air days
- 7
- Unhealthy days
- 63%
- Cleaner than US counties
Carlton County's 2025 annual median AQI is 33 (Good), with 82.8% Good days
According to the U.S. EPA Air Quality System, Carlton County, Minnesota posted a 2025 median AQI of 33 (Good) across 355 monitored days, with 82.8% rated Good and 7 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Carlton County's 82.8% Good-day share places it cleaner than 63% of US counties in 2025.
- Closest median-AQI peer
- Apache County (86.2% Good, median AQI 33) is the closest nationwide median-AQI peer to Carlton County.
- 2020–2025 trend
- Carlton County's floor-qualifying Good-day share is worsening from 2020 to 2025 (98.0% → 82.8%).
- Median AQI
- Median AQI: 33
The verdict
According to EPA Air Quality System monitoring data, Carlton County's air is good on balance, cleaner than the median US county, a median AQI of 33 with 82.8% of 355 monitored days in the Good band, driven mainly by PM2.5.
- 33
- median AQI · Good
- 82.8%
- days rated Good
- PM2.5
- main pollutant
- 63%
- cleaner than US counties
7 days reached Unhealthy or worse; the worst single reading hit AQI 184.
Annual release change
What changed in the 2025 EPA annual release
- Carlton County's Unhealthy-category days rose from 0 to 7 between the 2024 and 2025 EPA annual releases, a change of +7 days.
- Carlton County's peak single-day AQI rose from 114 to 184 between the 2024 and 2025 EPA annual releases, a change of +70 points.
- Carlton County's Good-day share fell from 89.1% to 82.8% between the 2024 and 2025 EPA annual releases, a change of -6.3 percentage points.
Data updated August 2026
- Good · 294 d · 82.8%
- Moderate · 49 d · 13.8%
- USG · 5 d · 1.4%
- Unhealthy · 7 d · 2.0%
How did Carlton County's air break down in 2025?
Across 355 monitored days, 294 fell in the Good band (AQI 0–50) and 7 reached Unhealthy or worse. The worst single day peaked at AQI 184 (Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 355 days monitored. Median AQI: 33 (Good).
Insights: Carlton County, Minnesota. EPA monitors recorded a median Air Quality Index of 33 across 355 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 294 (83%) fell in the Good band (AQI 0–50), 49 (14%) registered Moderate readings, and 5 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 62, while the worst single-day peak hit 184 (Unhealthy). Residents averaged about 24.8 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (202 days), Ozone (153 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -15.2 points and the median AQI moved +8 points, placing the multi-year trajectory at worsening. The annual record contains 7 days at Unhealthy or worse. On those days, the EPA recommends that sensitive groups limit prolonged outdoor exertion. Nearby counties show comparable readings: Anoka (74.1% good, AQI 38); Becker (74.0% good, AQI 38); Beltrami (79.1% good, AQI 36); Blue Earth (65.3% good, AQI 42); Cass (82.7% good, AQI 28); Cook (88.0% good, AQI 16).
Air Quality Summary
Good Days
82.8%
294 of 355 monitored days
7.8pp vs 75% target
Max AQI Recorded
184
Unhealthy
Health Grade
Good
90th-pct AQI 62
Carlton County, Good days share 82.8%
National avg
Share of monitored days at AQI 0-50 (Good band).
Carlton County, Unhealthy-or-worse share 19.7%
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 355 monitored days across EPA AQI categories.
Good
294
83%
Moderate
49
14%
USG
5
1%
Unhealthy
7
2%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Carlton County.
- PM2.5 · 202 days · 56.9%
- Ozone · 153 days · 43.1%
Health Impact Assessment
Good
Carlton County's air quality is rated Good based on 82.8% good air days. There were 7 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 5 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 184. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is PM2.5, driving AQI on 202 of 355 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Carlton County. Highest Good-day share: 2022 (98.9%, 351 of 355 monitored 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 | 294 | 49 | 5 | 7 | 33 | 184 |
How does Carlton County compare?
How Carlton County compares
Good-day share better than typical
Carlton County 82.8%
Apache County, Arizona 86.2%
Typical US county 76.0%
Median AQI better than typical
Carlton County 33
Apache County, Arizona 33
Typical US county 39
Unhealthy days / yr worse than typical
Carlton County 7
Apache County, Arizona 0
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Carlton County (33), not geographic neighbors.
Apache County, Arizona
Median AQI 33 · 86.2% Good-day share
Ascension County, Louisiana
Median AQI 33 · 95.6% Good-day share
Clark County, Illinois
Median AQI 33 · 93.8% Good-day share
Clark County, Washington
Median AQI 33 · 82.7% Good-day share
Clay County, Alabama
Median AQI 33 · 81.1% Good-day share
Denali County, Alaska
Median AQI 33 · 99.7% Good-day share
Same primary pollutant: PM2.5
PM2.5 led the AQI on the most monitored days here. These peers share that driver and the closest Good-day share (a second relationship type beyond median-AQI neighbors).
Washington County, Rhode Island
82.7% Good-day share · median AQI 37
Cass County, Minnesota
82.7% Good-day share · median AQI 28
Hampton City County, Virginia
83.0% Good-day share · median AQI 38
Hall County, Nebraska
82.5% Good-day share · median AQI 34
Marquette County, Michigan
82.4% Good-day share · median AQI 19
Grant County, Oklahoma
82.3% Good-day share · median AQI 31
Minnesota counties on the map
Geographic containment only, other monitored counties in Minnesota, independent of AQI or pollutant match.
What Carlton County's air means for you
On most days the air here is fine, but PM2.5 drives 7 unhealthy-or-worse days 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 33 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 355 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
Keep exploring the annual AQI record
Air-quality reading list
Frequently Asked Questions
What is the air quality in Carlton County, Minnesota? ▼
Carlton County has a median Air Quality Index (AQI) of 33, rated "Good." 82.8% of monitored days (294 out of 355) had good air quality in 2025.
What is the main pollutant in Carlton County? ▼
The primary pollutant in Carlton County is Fine Particles (PM2.5), which was the main AQI driver on 202 days (57% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Carlton County have? ▼
In 2025, Carlton County recorded 7 unhealthy air days (7 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 184.
Is the air quality in Carlton County getting better or worse? ▼
Air quality in Carlton County is worsening across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2022 at 98.9% (351 of 355 days). Lowest qualifying Good-day share: 2023 at 73.5% (266 of 362 days).
What does AQI 33 mean for health? ▼
Carlton County's median AQI of 33 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Carlton County compare to other counties in Minnesota? ▼
Carlton County has 82.8% good air days. Nearby counties in Minnesota: Anoka (74.1% good), Becker (74.0% good), Beltrami (79.1% good), Blue Earth (65.3% good), Cass (82.7% good), Cook (88.0% good).
What is the 90th percentile AQI in Carlton County? ▼
The 90th percentile AQI for Carlton County is 62, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 184 (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. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Carlton County, Minnesota · 2020–2025
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Every figure on PlainAirData 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.