Median AQI
37
Good
Minnesota · County air quality · 2025
Lyon County, Minnesota
Median AQI 37 (Good). 84.5% of monitored days rated Good, direct from EPA Air Quality System stations.
- 37
- Median AQI
- 84.5%
- Good-air days
- 0
- Unhealthy days
- 64%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Lyon County's air is good on balance, cleaner than the median US county, a median AQI of 37 with 84.5% of 181 monitored days in the Good band, driven mainly by Ozone.
- 37
- median AQI · Good
- 84.5%
- days rated Good
- Ozone
- main pollutant
- 64%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 140.
Data updated July 2026
- Good · 153 d · 84.5%
- Moderate · 27 d · 14.9%
- USG · 1 d · 0.6%
How did Lyon County's air break down in 2025?
Across 181 monitored days, 153 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 140 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 181 days monitored. Median AQI: 37 (Good).
Insights: Lyon County, Minnesota. EPA monitors recorded a median Air Quality Index of 37 across 181 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 153 (85%) fell in the Good band (AQI 0–50), 27 (15%) registered Moderate readings, and 1 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 61, while the worst single-day peak hit 140 (USG). Residents averaged about 25.4 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (117 days), PM2.5 (61 days), PM10 (3 days). Across the 2020–2025 trend window, good days shifted by -156 and the median AQI moved +2 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 140, usg but never Unhealthy. Nearby counties show comparable readings: Anoka (82.1% good, AQI 38); Becker (84.7% good, AQI 38); Beltrami (88.8% good, AQI 37); Blue Earth (82.7% good, AQI 38); Carlton (92.9% good, AQI 35); Cass (94.4% good, AQI 22).
Air Quality Summary
Good Days
84.5%
153 of 181 monitored days
9.5pp vs 75% target
Max AQI Recorded
140
USG
Health Grade
Good
90th-pct AQI 61
Lyon County, Good days share 84.5%
National avg
Share of monitored days at AQI 0-50 (Good band).
Lyon County, Unhealthy-or-worse share 0.0%
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 181 monitored days across EPA AQI categories.
Good
153
85%
Moderate
27
15%
USG
1
1%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Lyon County.
- Ozone · 117 days · 64.6%
- PM2.5 · 61 days · 33.7%
- PM10 · 3 days · 1.7%
Health Impact Assessment
Good
Lyon County's air quality is rated Good based on 84.5% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 84.5% of monitored days in 2025, with a median AQI of 37. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 117 of 181 monitored days.
5-Year Air Quality Trend
Air quality is stable in Lyon County. Best year: 2020 (309 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 309 | 51 | 0 | 0 | 35 | 80 |
| 2021 | 263 | 91 | 3 | 2 | 39 | 187 |
| 2022 | 303 | 51 | 0 | 2 | 38 | 172 |
| 2023 | 206 | 142 | 10 | 3 | 46 | 173 |
| 2024 | 276 | 88 | 2 | 0 | 40 | 142 |
| 2025 | 153 | 27 | 1 | 0 | 37 | 140 |
How does Lyon County compare?
How Lyon County compares
Good-day share better than US avg
Lyon County 84.5%
Anoka County, Minnesota 82.1%
US average 76.5%
Median AQI better than US avg
Lyon County 37
Anoka County, Minnesota 38
US average 38
Unhealthy days / yr about average
Lyon County 0
Anoka County, Minnesota 1
US average 0
Other Counties in Minnesota
Air quality comparison for nearby counties in Minnesota.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Lyon County.
Alachua County, Florida
AQI 37 · 90.1% good
Beltrami County, Minnesota
AQI 37 · 88.8% good
Benewah County, Idaho
AQI 37 · 74.6% good
Brevard County, Florida
AQI 37 · 89.7% good
Brown County, Indiana
AQI 37 · 94.5% good
Brown County, Wisconsin
AQI 37 · 79.0% good
What Lyon County's air means for you
The air here stays in the breathable range year-round, with Ozone the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 37 means for exposure. Health guidance
- See how Lyon County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Lyon County with its Minnesota neighbours before drawing a conclusion about the region. All of Minnesota
Based on 181 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
More Air Quality Data
Air Quality Guides
Frequently Asked Questions
What is the air quality in Lyon County, Minnesota? ▼
Lyon County has a median Air Quality Index (AQI) of 37, rated "Good." 84.5% of monitored days (153 out of 181) had good air quality in 2025.
What is the main pollutant in Lyon County? ▼
The primary pollutant in Lyon County is Ozone (O3), which was the main AQI driver on 117 days (65% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Lyon County have? ▼
In 2025, Lyon County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 140.
Is the air quality in Lyon County getting better or worse? ▼
Air quality in Lyon County is stable based on 5-year trends (2020-2025). Best year: 2020 with 309 good days. Worst year: 2025 with 153 good days.
What does AQI 37 mean for health? ▼
Lyon County's median AQI of 37 falls in the "Good" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does Lyon County compare to other counties in Minnesota? ▼
Lyon County has 84.5% good air days. Nearby counties in Minnesota: Anoka (82.1% good), Becker (84.7% good), Beltrami (88.8% good), Blue Earth (82.7% good), Carlton (92.9% good), Cass (94.4% good).
What is the 90th percentile AQI in Lyon County? ▼
The 90th percentile AQI for Lyon County is 61, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 140 (USG).
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.
Every figure on PlainAir 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.