EnviroNearby

Lyon County, Minnesota air quality history

Daily Air Quality Index summaries from EPA monitors in Lyon, Minnesota, 2005–2025.

77%
Good days in 2025
37
Median daily AQI, 2025
7
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Lyon, Minnesota on 365 days. 281 of those days (77%) were in the Good range, and the median daily AQI was 37. That median is about the same as 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 183 days. Across the years with fuller monitoring, the share of Good days rose: an average of 62% in 2005–2007 versus 70% 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%2005: Good 129 of 222 days2005: Moderate 90 of 222 days2005: Unhealthy for Sensitive Groups 3 of 222 days20052006: Good 236 of 358 days2006: Moderate 120 of 358 days2006: Unhealthy for Sensitive Groups 2 of 358 days2007: Good 220 of 353 days2007: Moderate 132 of 353 days2007: Unhealthy for Sensitive Groups 1 of 353 days20072008: Good 186 of 358 days2008: Moderate 172 of 358 days2009: Good 193 of 355 days2009: Moderate 161 of 355 days2009: Unhealthy for Sensitive Groups 1 of 355 days20092010: Good 155 of 355 days2010: Moderate 197 of 355 days2010: Unhealthy for Sensitive Groups 3 of 355 days2011: Good 267 of 356 days2011: Moderate 88 of 356 days2011: Unhealthy for Sensitive Groups 1 of 356 days20112012: Good 245 of 364 days2012: Moderate 117 of 364 days2012: Unhealthy for Sensitive Groups 2 of 364 days2013: Good 263 of 365 days2013: Moderate 100 of 365 days2013: Unhealthy for Sensitive Groups 2 of 365 days20132014: Good 290 of 364 days2014: Moderate 73 of 364 days2014: Unhealthy for Sensitive Groups 1 of 364 days2015: Good 310 of 365 days2015: Moderate 54 of 365 days2015: Unhealthy for Sensitive Groups 1 of 365 days20152016: Good 327 of 356 days2016: Moderate 28 of 356 days2016: Unhealthy for Sensitive Groups 1 of 356 days2017: Good 307 of 360 days2017: Moderate 53 of 360 days20172018: Good 308 of 365 days2018: Moderate 57 of 365 days2019: Good 306 of 362 days2019: Moderate 56 of 362 days20192020: Good 309 of 360 days2020: Moderate 51 of 360 days2021: Good 263 of 359 days2021: Moderate 91 of 359 days2021: Unhealthy for Sensitive Groups 3 of 359 days2021: Unhealthy 2 of 359 days20212022: Good 303 of 356 days2022: Moderate 51 of 356 days2022: Unhealthy 2 of 356 days2023: Good 206 of 361 days2023: Moderate 142 of 361 days2023: Unhealthy for Sensitive Groups 10 of 361 days2023: Unhealthy 3 of 361 days20232024: Good 276 of 366 days2024: Moderate 88 of 366 days2024: Unhealthy for Sensitive Groups 2 of 366 days2025: Good 281 of 365 days2025: Moderate 77 of 365 days2025: Unhealthy for Sensitive Groups 5 of 365 days2025: Unhealthy 2 of 365 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 year0501002005: 90th percentile AQI 712006: 90th percentile AQI 642007: 90th percentile AQI 652008: 90th percentile AQI 702009: 90th percentile AQI 672010: 90th percentile AQI 712011: 90th percentile AQI 612012: 90th percentile AQI 642013: 90th percentile AQI 642014: 90th percentile AQI 572015: 90th percentile AQI 542016: 90th percentile AQI 482017: 90th percentile AQI 532018: 90th percentile AQI 552019: 90th percentile AQI 542020: 90th percentile AQI 542021: 90th percentile AQI 642022: 90th percentile AQI 542023: 90th percentile AQI 782024: 90th percentile AQI 602025: 90th percentile AQI 652005: Median AQI 472006: Median AQI 432007: Median AQI 452008: Median AQI 502009: Median AQI 482010: Median AQI 522011: Median AQI 412012: Median AQI 432013: Median AQI 412014: Median AQI 372015: Median AQI 332016: Median AQI 322017: Median AQI 352018: Median AQI 362019: Median AQI 342020: Median AQI 352021: Median AQI 392022: Median AQI 382023: Median AQI 462024: Median AQI 402025: Median AQI 3720052007200920112013201520172019202120232025
  • 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)18350%
Ozone15542%
Coarse particles (PM10)277%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253652817752003765161PM2.5
20243662768820004060142PM2.5
2023361206142103004678173PM2.5
20223563035102003854172Ozone
20213592639132003964187PM2.5
2020360309510000355480PM2.5
2019362306560000345487PM2.5
2018365308570000365586PM2.5
2017360307530000355396Ozone
20163563272810003248110Ozone
20153653105410003354119PM2.5
20143642907310003757109PM2.5
201336526310020004164101PM2.5
201236424511720004364101PM2.5
20113562678810004161101PM2.5
201035515519730005271109PM2.5
200935519316110004867122PM2.5
20083581861720000507099PM2.5
200735322013210004565115PM2.5
200635823612020004364105PM2.5
20052221299030004771115PM2.5

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 2005–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem