Minnesota · County air quality · 2025
Cook County, Minnesota
Median AQI 16 (Good). 88.0% of monitored days rated Good, direct from EPA Air Quality System stations.
- 16
- Median AQI
- 88.0%
- Good-air days
- 8
- Unhealthy days
- 76%
- Cleaner than US counties
Cook County's 2025 annual median AQI is 16 (Good), with 88.0% Good days
According to the U.S. EPA Air Quality System, Cook County, Minnesota posted a 2025 median AQI of 16 (Good) across 358 monitored days, with 88.0% rated Good and 8 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Cook County's 88.0% Good-day share places it cleaner than 76% of US counties in 2025.
- Closest median-AQI peer
- Pacific County (99.7% Good, median AQI 16) is the closest nationwide median-AQI peer to Cook County.
- 2020–2025 trend
- Cook County's floor-qualifying Good-day share is worsening from 2020 to 2025 (98.6% → 88.2%).
- Median AQI
- Median AQI: 16
According to the 2025 EPA AQS county release on PlainAirData, Cook County, Minnesota ranks #21 of 951 by median AQI (16) and #225 by good-day share (88.0%). Ponce County, Puerto Rico is #1 of 951 by median AQI (3, 91.4% Good days) at good-day-share #159 ≠ largest of 7 at 100.0% Good days #1 by good-day share (100.0%, median AQI 9) at median-AQI #7.
Annual release change
What changed in the 2025 EPA annual release
- Cook County's Unhealthy-category days rose from 0 to 7 between the 2024 and 2025 EPA annual releases, a change of +7 days.
- Cook County's peak single-day AQI rose from 138 to 201 between the 2024 and 2025 EPA annual releases, a change of +63 points.
- Cook County's Good-day share fell from 92.2% to 88.0% between the 2024 and 2025 EPA annual releases, a change of -4.3 percentage points.
Data updated August 2026
- Good · 315 d · 88.0%
- Moderate · 31 d · 8.7%
- USG · 4 d · 1.1%
- Unhealthy · 7 d · 2.0%
- Very Unhealthy · 1 d · 0.3%
How did Cook County's air break down in 2025?
Across 358 monitored days, 315 fell in the Good band (AQI 0–50) and 8 reached Unhealthy or worse. The worst single day peaked at AQI 201 (Very Unhealthy).
EPA AQS →Share of monitored days at AQI 0-50 (Good band).
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
Where Cook County sits nationally
COUNT-derived placement among 951 US counties with at least 100 monitored days in 2025. Cook County's Good-day share is 88.0% - cleaner than 76% of that comparison set.
Cook County Good-day share vs. every US county
Share of monitored days in the Good band (AQI 0–50) - EPA AQS annual release
88.0% Cleaner than 76% higher than 76% of 951 US counties
Each bar is a band; taller bars hold more US counties. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source U.S. Environmental Protection Agency, Air Quality System (AQS) · 2025
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Cook County.
- PM2.5 · 358 days · 100.0%
2024 daily-monitor rhythm in Cook County
Month-by-month median AQI from EPA day-level county monitors (361 reported days in 2024). Jul posted the highest typical readings (median AQI 40, peak 66); Apr was cleanest at median 9. Summer months (Jun–Aug) averaged median AQI 32 vs 14 in Dec–Feb.
Five-year seasonal record
EPA day-level county files · 2020–20241,710 daily readings show a recurring local pattern: Jul has the highest matched-month median AQI (25), while Apr is lowest (7). Each cell is that month’s median daily AQI, not a current-air forecast.
Lower AQI is better. The colors summarize EPA AQI bands; gaps mean the county had no day-level record for that month.
Health Impact Assessment
Cook County's air quality is rated Good based on 88.0% good air days. There were 8 unhealthy days in 2025 when outdoor activity should be limited.
Air quality reached unhealthy levels on 8 days in 2025 (7 Unhealthy, 1 Very Unhealthy). Sensitive groups, including people with asthma, COPD, cardiovascular conditions, children, and adults over 65, should review the daily breakdown below and follow local air-quality advisories on high-AQI days.
Sensitive group advisory
People with asthma, COPD, heart disease, children, pregnant women, and adults 65+ should follow EPA AQI alerts daily and limit outdoor exertion when AQI exceeds 100. Real-time conditions: airnow.gov.
The dominant pollutant is PM2.5, driving AQI on 358 of 358 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Cook County. Highest Good-day share: 2022 (99.1%, 327 of 330 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 340 | 5 | 0 | 0 | 13 | 59 |
| 2021 | 306 | 18 | 3 | 1 | 9 | 153 |
| 2022 | 327 | 3 | 0 | 0 | 4 | 54 |
| 2023 | 298 | 47 | 1 | 0 | 13 | 120 |
| 2024 | 333 | 25 | 3 | 0 | 16 | 138 |
| 2025 | 315 | 31 | 4 | 7 | 16 | 201 |
How does Cook County compare?
How Cook County compares
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 Cook County, Minnesota · 2020–2025
Download this county's annual AQI row as CSV , with the same EPA fields and denominator shown on this page.
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.