Median AQI
31
Good
Minnesota · County air quality · 2025
Lake County, Minnesota
Median AQI 31 (Good). 85.9% of monitored days rated Good, direct from EPA Air Quality System stations.
- 31
- Median AQI
- 85.9%
- Good-air days
- 7
- Unhealthy days
- 72%
- Cleaner than US counties
Lake County's 2025 annual median AQI is 31 (Good), with 85.9% Good days
According to the U.S. EPA Air Quality System, Lake County, Minnesota posted a 2025 median AQI of 31 (Good) across 361 monitored days, with 85.9% 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
- Lake County's 85.9% Good-day share places it cleaner than 72% of US counties in 2025.
- Closest median-AQI peer
- Athens County (83.4% Good, median AQI 31) is the closest nationwide median-AQI peer to Lake County.
- 2020–2025 trend
- Lake County's floor-qualifying Good-day share is worsening from 2020 to 2025 (94.2% → 85.9%).
- Median AQI
- Median AQI: 31
The verdict
According to EPA Air Quality System monitoring data, Lake County's air is good on balance, cleaner than the median US county, a median AQI of 31 with 85.9% of 361 monitored days in the Good band, driven mainly by PM2.5.
- 31
- median AQI · Good
- 85.9%
- days rated Good
- PM2.5
- main pollutant
- 72%
- cleaner than US counties
7 days reached Unhealthy or worse; the worst single reading hit AQI 191.
Annual release change
What changed in the 2025 EPA annual release
- Lake County's peak single-day AQI rose from 110 to 191 between the 2024 and 2025 EPA annual releases, a change of +81 points.
- Lake County's Unhealthy-category days rose from 0 to 7 between the 2024 and 2025 EPA annual releases, a change of +7 days.
- Lake County's Good-day share fell from 90.2% to 85.9% between the 2024 and 2025 EPA annual releases, a change of -4.3 percentage points.
Data updated August 2026
- Good · 310 d · 85.9%
- Moderate · 36 d · 10.0%
- USG · 8 d · 2.2%
- Unhealthy · 7 d · 1.9%
How did Lake County's air break down in 2025?
Across 361 monitored days, 310 fell in the Good band (AQI 0–50) and 7 reached Unhealthy or worse. The worst single day peaked at AQI 191 (Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 361 days monitored. Median AQI: 31 (Good).
Insights: Lake County, Minnesota. EPA monitors recorded a median Air Quality Index of 31 across 361 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 310 (86%) fell in the Good band (AQI 0–50), 36 (10%) registered Moderate readings, and 8 (2%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 60, while the worst single-day peak hit 191 (Unhealthy). Residents averaged about 25.8 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (206 days), Ozone (155 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -8.4 points and the median AQI moved -3 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); Carlton (82.8% good, AQI 33); Cass (82.7% good, AQI 28).
Air Quality Summary
Good Days
85.9%
310 of 361 monitored days
10.9pp vs 75% target
Max AQI Recorded
191
Unhealthy
Health Grade
Good
90th-pct AQI 60
Lake County, Good days share 85.9%
National avg
Share of monitored days at AQI 0-50 (Good band).
Lake County, Unhealthy-or-worse share 19.4%
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 361 monitored days across EPA AQI categories.
Good
310
86%
Moderate
36
10%
USG
8
2%
Unhealthy
7
2%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Lake County.
- PM2.5 · 206 days · 57.1%
- Ozone · 155 days · 42.9%
Health Impact Assessment
Good
Lake County's air quality is rated Good based on 85.9% good air days. There were 7 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 8 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 191. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is PM2.5, driving AQI on 206 of 361 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Lake County. Highest Good-day share: 2022 (95.8%, 342 of 357 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 344 | 21 | 0 | 0 | 34 | 71 |
| 2021 | 315 | 43 | 3 | 1 | 31 | 160 |
| 2022 | 342 | 15 | 0 | 0 | 31 | 78 |
| 2023 | 282 | 81 | 2 | 0 | 36 | 114 |
| 2024 | 330 | 35 | 1 | 0 | 32 | 110 |
| 2025 | 310 | 36 | 8 | 7 | 31 | 191 |
How does Lake County compare?
How Lake County compares
Good-day share better than typical
Lake County 85.9%
Athens County, Ohio 83.4%
Typical US county 76.0%
Median AQI better than typical
Lake County 31
Athens County, Ohio 31
Typical US county 39
Unhealthy days / yr worse than typical
Lake County 7
Athens County, Ohio 0
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Lake County (31), not geographic neighbors.
Athens County, Ohio
Median AQI 31 · 83.4% Good-day share
Clackamas County, Oregon
Median AQI 31 · 87.6% Good-day share
Grant County, Oklahoma
Median AQI 31 · 82.3% Good-day share
Kent County, Rhode Island
Median AQI 31 · 92.8% Good-day share
Kootenai County, Idaho
Median AQI 31 · 77.8% Good-day share
Lake County, California
Median AQI 31 · 99.2% 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).
Norfolk City County, Virginia
86.0% Good-day share · median AQI 33
Bayamon County, Puerto Rico
86.0% Good-day share · median AQI 29
Hawaii County, Hawaii
86.0% Good-day share · median AQI 32
Delta County, Colorado
85.7% Good-day share · median AQI 29
Clallam County, Washington
85.5% Good-day share · median AQI 29
Loudon County, Tennessee
85.5% Good-day share · median AQI 39
Minnesota counties on the map
Geographic containment only, other monitored counties in Minnesota, independent of AQI or pollutant match.
What Lake 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 31 means for exposure. Health guidance
- See how Lake County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Lake County with its Minnesota neighbours before drawing a conclusion about the region. All of Minnesota
Based on 361 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 Lake County, Minnesota? ▼
Lake County has a median Air Quality Index (AQI) of 31, rated "Good." 85.9% of monitored days (310 out of 361) had good air quality in 2025.
What is the main pollutant in Lake County? ▼
The primary pollutant in Lake County is Fine Particles (PM2.5), which was the main AQI driver on 206 days (57% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Lake County have? ▼
In 2025, Lake County recorded 7 unhealthy air days (7 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 191.
Is the air quality in Lake County getting better or worse? ▼
Air quality in Lake 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 95.8% (342 of 357 days). Lowest qualifying Good-day share: 2023 at 77.3% (282 of 365 days).
What does AQI 31 mean for health? ▼
Lake County's median AQI of 31 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Lake County compare to other counties in Minnesota? ▼
Lake County has 85.9% good air days. Nearby counties in Minnesota: Anoka (74.1% good), Becker (74.0% good), Beltrami (79.1% good), Blue Earth (65.3% good), Carlton (82.8% good), Cass (82.7% good).
What is the 90th percentile AQI in Lake County? ▼
The 90th percentile AQI for Lake County is 60, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 191 (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 Lake 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.