Median AQI
41
Good
Wisconsin · County air quality · 2025
Forest County, Wisconsin
Median AQI 41 (Good). 79.7% of monitored days rated Good, direct from EPA Air Quality System stations.
- 41
- Median AQI
- 79.7%
- Good-air days
- 1
- Unhealthy days
- 51%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Forest County's air is good on balance, cleaner than the median US county, a median AQI of 41 with 79.7% of 177 monitored days in the Good band, driven mainly by Ozone.
- 41
- median AQI · Good
- 79.7%
- days rated Good
- Ozone
- main pollutant
- 51%
- cleaner than US counties
1 day reached Unhealthy or worse; the worst single reading hit AQI 155.
Data updated July 2026
- Good · 141 d · 79.7%
- Moderate · 33 d · 18.6%
- USG · 2 d · 1.1%
- Unhealthy · 1 d · 0.6%
How did Forest County's air break down in 2025?
Across 177 monitored days, 141 fell in the Good band (AQI 0–50) and 1 reached Unhealthy or worse. The worst single day peaked at AQI 155 (Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 177 days monitored. Median AQI: 41 (Good).
Insights: Forest County, Wisconsin. EPA monitors recorded a median Air Quality Index of 41 across 177 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 141 (80%) fell in the Good band (AQI 0–50), 33 (19%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 61, while the worst single-day peak hit 155 (Unhealthy). Residents averaged about 23.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (129 days), PM2.5 (48 days). Across the 2020–2025 trend window, good days shifted by -170 and the median AQI moved +5 points, placing the multi-year trajectory at worsening. Residents and visitors experienced 1 unhealthy-or-worse days combined, periods when the EPA recommends sensitive groups limit prolonged outdoor exertion. Nearby counties show comparable readings: Ashland (85.6% good, AQI 39); Brown (79.0% good, AQI 37); Columbia (84.6% good, AQI 42); Dane (71.8% good, AQI 40); Dodge (76.4% good, AQI 39); Door (85.7% good, AQI 40).
Air Quality Summary
Good Days
79.7%
141 of 177 monitored days
4.7pp vs 75% target
Max AQI Recorded
155
Unhealthy
Health Grade
Good
90th-pct AQI 61
Forest County, Good days share 79.7%
National avg
Share of monitored days at AQI 0-50 (Good band).
Forest County, Unhealthy-or-worse share 0.6%
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 177 monitored days across EPA AQI categories.
Good
141
80%
Moderate
33
19%
USG
2
1%
Unhealthy
1
1%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Forest County.
- Ozone · 129 days · 72.9%
- PM2.5 · 48 days · 27.1%
Health Impact Assessment
Good
Forest County's air quality is rated Good based on 79.7% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 2 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 155. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is Ozone, driving AQI on 129 of 177 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Forest County. Best year: 2022 (321 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 311 | 55 | 0 | 0 | 36 | 93 |
| 2021 | 282 | 75 | 3 | 1 | 38 | 165 |
| 2022 | 321 | 42 | 0 | 0 | 37 | 77 |
| 2023 | 252 | 99 | 9 | 3 | 42 | 178 |
| 2024 | 313 | 50 | 0 | 1 | 37 | 153 |
| 2025 | 141 | 33 | 2 | 1 | 41 | 155 |
How does Forest County compare?
How Forest County compares
Good-day share better than US avg
Forest County 79.7%
Ashland County, Wisconsin 85.6%
US average 76.5%
Median AQI worse than US avg
Forest County 41
Ashland County, Wisconsin 39
US average 38
Unhealthy days / yr worse than US avg
Forest County 1
Ashland County, Wisconsin 1
US average 0
Other Counties in Wisconsin
Air quality comparison for nearby counties in Wisconsin.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Forest County.
Albemarle County, Virginia
AQI 41 · 77.9% good
Anderson County, South Carolina
AQI 41 · 90.0% good
Berkshire County, Massachusetts
AQI 41 · 71.6% good
Berrien County, Michigan
AQI 41 · 80.9% good
Blair County, Pennsylvania
AQI 41 · 71.9% good
Bonner County, Idaho
AQI 41 · 71.3% good
What Forest County's air means for you
On most days the air here is fine, but Ozone drives 1 unhealthy-or-worse day a year that sensitive groups should plan around.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 41 means for exposure. Health guidance
- See how Forest County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Forest County with its Wisconsin neighbours before drawing a conclusion about the region. All of Wisconsin
Based on 177 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 Forest County, Wisconsin? ▼
Forest County has a median Air Quality Index (AQI) of 41, rated "Good." 79.7% of monitored days (141 out of 177) had good air quality in 2025.
What is the main pollutant in Forest County? ▼
The primary pollutant in Forest County is Ozone (O3), which was the main AQI driver on 129 days (73% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Forest County have? ▼
In 2025, Forest County recorded 1 unhealthy air days (1 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 155.
Is the air quality in Forest County getting better or worse? ▼
Air quality in Forest County is worsening based on 5-year trends (2020-2025). Best year: 2022 with 321 good days. Worst year: 2025 with 141 good days.
What does AQI 41 mean for health? ▼
Forest County's median AQI of 41 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 Forest County compare to other counties in Wisconsin? ▼
Forest County has 79.7% good air days. Nearby counties in Wisconsin: Ashland (85.6% good), Brown (79.0% good), Columbia (84.6% good), Dane (71.8% good), Dodge (76.4% good), Door (85.7% good).
What is the 90th percentile AQI in Forest County? ▼
The 90th percentile AQI for Forest County is 61, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 155 (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.
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.