EnviroNearby

Cook County, Minnesota air quality history

Daily Air Quality Index summaries from EPA monitors in Cook, Minnesota, 2006–2025.

88%
Good days in 2025
16
Median daily AQI, 2025
12
Days above 100 in 2025
358
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Cook, Minnesota on 358 days. 315 of those days (88%) were in the Good range, and the median daily AQI was 16. That median is lower than the typical monitored county in Minnesota (median 37 across 21 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 358 days. Across the years with fuller monitoring, the share of Good days fell: an average of 93% in 2006–2008 versus 89% in 2023–2025.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Share of monitored days in each AQI category, by year0%25%50%75%100%2006: Good 208 of 233 days2006: Moderate 25 of 233 days20062007: Good 310 of 329 days2007: Moderate 19 of 329 days2008: Good 325 of 345 days2008: Moderate 20 of 345 days20082009: Good 302 of 320 days2009: Moderate 18 of 320 days2010: Good 212 of 263 days2010: Moderate 51 of 263 days20102011: Good 235 of 307 days2011: Moderate 71 of 307 days2011: Unhealthy for Sensitive Groups 1 of 307 days2012: Good 293 of 334 days2012: Moderate 41 of 334 days20122013: Good 231 of 270 days2013: Moderate 39 of 270 days2014: Good 310 of 336 days2014: Moderate 26 of 336 days20142015: Good 248 of 258 days2015: Moderate 10 of 258 days2016: Good 346 of 356 days2016: Moderate 10 of 356 days20162017: Good 332 of 351 days2017: Moderate 19 of 351 days2018: Good 330 of 353 days2018: Moderate 23 of 353 days20182019: Good 317 of 334 days2019: Moderate 17 of 334 days2020: Good 340 of 345 days2020: Moderate 5 of 345 days20202021: Good 306 of 328 days2021: Moderate 18 of 328 days2021: Unhealthy for Sensitive Groups 3 of 328 days2021: Unhealthy 1 of 328 days2022: Good 327 of 330 days2022: Moderate 3 of 330 days20222023: Good 298 of 346 days2023: Moderate 47 of 346 days2023: Unhealthy for Sensitive Groups 1 of 346 days2024: Good 330 of 358 days2024: Moderate 25 of 358 days2024: Unhealthy for Sensitive Groups 3 of 358 days20242025: Good 315 of 358 days2025: Moderate 31 of 358 days2025: Unhealthy for Sensitive Groups 4 of 358 days2025: Unhealthy 7 of 358 days2025: Very Unhealthy 1 of 358 days2025
  • Good
  • Moderate
  • Unhealthy for Sensitive Groups
  • Unhealthy
  • Very Unhealthy
  • Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median and 90th-percentile daily AQI, by year0501002006: 90th percentile AQI 512007: 90th percentile AQI 372008: 90th percentile AQI 362009: 90th percentile AQI 362010: 90th percentile AQI 552011: 90th percentile AQI 562012: 90th percentile AQI 522013: 90th percentile AQI 532014: 90th percentile AQI 472015: 90th percentile AQI 442016: 90th percentile AQI 392017: 90th percentile AQI 402018: 90th percentile AQI 422019: 90th percentile AQI 392020: 90th percentile AQI 282021: 90th percentile AQI 362022: 90th percentile AQI 212023: 90th percentile AQI 542024: 90th percentile AQI 462025: 90th percentile AQI 542006: Median AQI 142007: Median AQI 122008: Median AQI 112009: Median AQI 92010: Median AQI 272011: Median AQI 312012: Median AQI 252013: Median AQI 292014: Median AQI 232015: Median AQI 262016: Median AQI 182017: Median AQI 242018: Median AQI 232019: Median AQI 222020: Median AQI 132021: Median AQI 92022: Median AQI 42023: Median AQI 132024: Median AQI 162025: Median AQI 1620062008201020122014201620182020202220242025
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2025

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

PollutantDays as main pollutantShare of monitored days
Fine particles (PM2.5)358100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253583153147101654201PM2.5
20243583302530001646138PM2.5
20233462984710001354120PM2.5
20223303273000042154PM2.5
2021328306183100936153PM2.5
202034534050000132859PM2.5
2019334317170000223981PM2.5
2018353330230000234269PM2.5
2017351332190000244062PM2.5
2016356346100000183958PM2.5
2015258248100000264491PM2.5
2014336310260000234767PM2.5
2013270231390000295374PM2.5
2012334293410000255265PM2.5
20113072357110003156126PM2.5
2010263212510000275576PM2.5
200932030218000093666PM2.5
2008345325200000113673PM2.5
2007329310190000123787PM2.5
2006233208250000145168PM2.5

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

Counties in Minnesota with a similar median AQI in 2025

All monitored counties in Minnesota

Source: U.S. EPA AirData, “Annual AQI by County” files for 2006–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem